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Historical evolution from continental drift to plate tectonics

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Historical evolution from continental drift to plate tectonics

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HISTORICAL EVOLUTION

INDEX

1. CONTINENTAL DRIFT TO PLATE TECTONICS

2. PANGAEA

3. INVESTIGATION PROCESS

4. NOW

5. VIDEO

6. THANKS

CONTINENTAL DRIFT TO PLATE TECTONICS

Continental drift describes one of the earliest ways geologists thought continents moved.Today, the theory of continental drift has been replaced by the science of plate tectonics.

PANGAEA

Wegener was convinced that all of Earth's continents were once part of a single landmass called Pangaea.

Wegener

1

In the early 20th century, Wegener published his theory that the continental landmasses were "drifting" across the Earth. He called this movement continental drift.

2

He suggested that the rotation of the Earth caused the continents to shift towards. (It doesn't.).

Investigation process

NOW

It is now known that Pangea separated due to convective currents in the Earth's mantle and this is known as plate tectonics.

VIDEO

www.nationalgeographic.com.es/ciencia/todo-empezo-en-pangea_8812

es.wikipedia.org/wiki/Pangea

www.nationalgeographic.org/encyclopedia/plate-tectonics

Fonts

Thanks for listening

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HISTORICAL EVOLUTION by trabajobioo on Genially

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HISTORICAL EVOLUTION INDEX 1. CONTINENTAL DRIFT TO PLATE TECTONICS 2. PANGAEA 3. INVESTIGATION PROCESS 4. NOW 5. VIDEO 6. THANKS CONTINENTAL DRIFT TO PLATE TECTONICS Continental drift describes one of the earliest ways geologists thought continents moved.Today, the theory of continental drift has been replaced by the science of plate tectonics.

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EVALUACIÓN DE MI TRABAJO EN LA 2ª PARTE (CARTAS)

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Origin and evolution of living beings: evidences for evolution, phylogenetic trees.

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Origin and evolution of living beings: evidences for evolution, phylogenetic trees.

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Origin and evolution of living beings

Paula Mora e Irene Jiménez

Evidences of evolution and information of evolution

What is it?

Differents explain of evidences of evolution

index

phylogenetic trees, variability, adaptation, speciation

What is it?

1

It is a theory in biology postulating that the various types of plants, animals, and other living things on Earth have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations. The theory of evolution is one of the fundamental keystones of modern biological theory.

What is it?

EVOLUTION

Differents explanations of evidences of evolution

2

￼

Species may share similar physical features because the feature was present in a common ancestor.

Anatomy:

The global distribution of organisms and the unique features of island species reflect evolution and geological change.

Biogeography:

DNA and the genetic code reflect the shared ancestry of life. DNA comparisons can show how related species are.

Molecular biology:

Differents explanations of evidences of evolution

Evidences of evolution comes from many differents areas of biology:

The global distribution of organisms and the unique features of island species reflect evolution and geological change.

Fossils:

We can directly observe small-scale evolution in organisms with short lifecycles.

Direct observation:

Differents explanations of evidences of evolution

Evidences of evolution comes from many differents areas of biology:

phylogenetic trees, variability, adaptation, speciation

3

Inheritance traits are determinate by gene. Each living organism has two versions of alleles for each gene. Produce organisms with new combination of traits

Sexual reproduction

Are alterations that happen by random chance on the DNA of an organism. Produce organisms with new traits in population. The most mutations are harmful

Mutations

The origin of Variety

When Darwin and Wallace purposed their evolutionary theory Knowledge on genetics and inheritance traits could not yet to explain the variability But today we know two processes to determinate the variety

adaptation and natural selection

Adaptations are the traits that allow an organism of a species to survive and reproduce under abiotic and biotic conditions natural selection helps us understand adaptations as they explain their existence when the adaptations compete with the traits finally for the improvement of the conditions, the adaptations will govern the population. Sexual selection selects the traits that increase survival and reproduce better

Between the species of the past and the current ones we can see a kinship that is called as phylogenetic or evolutionary relationships we can represent them schematically in a phylogenetic tree

Phylogenetic tree

Are elements of the landscape that prevent populations from occupying the same space

Geographical barriers

Occur when two individuals in a population have different numbers of chromosomes or structure because their gametes become unsupported

Chromosomal barriers

Two species can be isolated because they do not coincide in their reproduction or flowering time

Temporary barriers

Speciation

speciation is the process through a species gives rise to one or more different species reproductive isolation between populations of a species is necessary for speciation due to reproductive barriers

Occur when differences with mating appear

Ethological barriers

Video

"

"

file:///home/alumno/Downloads/evolution%20.png

science bits

Sources

Paula Mora

Irene Jiménez

group

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Origin and evolution of living beings Paula Mora e Irene Jiménez Evidences of evolution and information of evolution What is it? Differents explain of evidences of evolution index phylogenetic trees, variability, adaptation, speciation What is it?

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Geology: relative age, stratigraphy, geological time scale...

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Geology: relative age, stratigraphy, geological time scale...

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In simple terms, a geological map shows the surface distribution of rocks in a particular area. However, in order to fully understand a geological map, it is necessary to be familiar with several basic geological principles, including the laws of stratigraphy, geological age, and geological structures. To the experienced eye, a geological map reflects the three-dimensional distribution of rocks, and also serves as a visual guide to the geological history of the area.

Principles of Stratigraphy

Relative Age

Geological Time Scale

Geological Map

What is shown on a Geological Map?

Geological Mapping Tools

Principles of Stratigraphy

Sediments (mineral grains and fragments of rock) are produced by weathering at the Earth's surface. They are removed by erosion and deposited elsewhere as layers, which thicken over time and, as the weight and pressure increases, they are eventually compressed and lithified to form sedimentary rock.

The father of modern geology was James Hutton, an eighteenth century scientist. After observing modern rates of sediment accumulation, Hutton concluded that long periods of time were required to build up the thick layers of sedimentary rock strata seen today. Hutton also concluded that geological processes similar to those today must have operated in the past. This led to the theory of Uniformitarianism, which states that all ancient rocks and geological features can be explained by observing the operation of modern-day processes. Uniformitarianism is usually referred to by the more explanatory phrase "the present is the key to the past".

The study of rock layers preserved in the geological record is called stratigraphy (Figure 1).

Figure 1: Late Palaeozoic layered sedimentary rocks
(strata) exposed in Grand Canyon National Park, the U.S.A.
(photo by courtesy of US Geological Survey).

Stratigraphy is based on two underlying principles:

The Law of Superposition was introduced by Nicolas Steno in 1699, after recognizing that successive beds of sediments laid down in horizontal layers have the oldest beds at the base, and the youngest beds at the top, forming a stratigraphical sequence.

The Law of Fossil Assemblages was introduced by William Smith, a mining geologist in England. Smith observed that, in any one area, the individual rock layers, or strata, were arranged in a predictable pattern. Importantly, groups of strata containing similar types of fossils (fossil assemblages) always occurred in the same relative stratigraphical (age) position. This fact enables groups of strata in different areas to be correlated, and allowed Smith to produce the first national geological map in 1815.

The two principles of stratigraphy allow the relative age of rocks in a stratigraphical sequence to be determined. Relative age refers to whether a rock layer in a sequence is older (or younger) than other layers in the sequence. There is, however, no implication of the true age (i.e. absolute age) of the rock.

Relative Age

Consider Figure 2. According to the Law of Superposition, the sediments of sandstone, siltstone, mudstone, limestone, volcanic ash and conglomerate were deposited in a sequence. Sandstone is the oldest rock, and conglomerate is the youngest.

Two other principles enable the relative age of rocks and geological events to be inferred, namely:

The Principle of Cross-cutting Relationships, which states that any geological feature (such as a dyke) that cuts across an existing rock unit must be younger than that unit.

The Principle of Included Fragments, which states that any rock containing fragments of another rock body must be younger than the rock body from which the included fragments are derived.

Figure 2: Relative age relationship of sedimentary and igneous rocks.

Table 1: The sequence of geological events shown in Figure 2.

In Figure 2, because fragments of mudstone are found within the granite body (The Principle of Included Fragments), the granite intrusion must be younger than (post-date) the formation of limestone and mudstone. Furthermore, the dyke cuts across the layers of sandstone, siltstone, mudstone, limestone and volcanic ash, and also the granite body, but not the conglomerate. This relationship confirms that the intrusion of the dyke post-dated the formation of sandstone, siltstone, mudstone, limestone, volcanic ash and granite, but pre-dated the deposition of conglomerate. Finally, a normal fault has displaced the rock sequence so that the right hand side has been downthrown.

Therefore, a brief history of the geological events shown in Figure 2 can be summarised as Table 1.

It is very important to be aware that the rock layers observed in a particular stratigraphical sequence may not be a complete record of the history of deposition. Some sediments or rock layers within the sequence may have been weathered and partly removed by erosion. There may have been long periods with no deposition. There may even be other rock layers that have been completely removed by erosion, with the result that an entire period of the geological history of the area is missing. In fact, more geological events are probably missing from the geological record than are recorded by the surviving rock sequences.

Having established the geological history of a particular locality from the stratigraphical relationships, the relative ages of the different sedimentary rock layers can be determined by examining the fossil content. Rock sequences that are separated by long distances can then be correlated by applying the Law of Fossil Assemblages, even though the fossils may not occur in the same rock type due to changes in sedimentary environment across an ancient ocean or landmass.

Geological Time Scale

A geological map shows the surface distribution of different rock types, their structural features, and their age relationships.

The first geological maps simply showed the relative stratigraphical positions of groups of rocks that contained similar fossil assemblages. Over time, as more areas were mapped and knowledge increased, the geological time-scale was developed, based on a wide range of rock and fossil occurrences. Geological Time Units were subsequently devised, which placed particular groups of rocks and fossils into relative age categories. Many of these time units are named after groups of strata that were first described from type localities in the British countryside (e.g. the Devonian).

The last 542 million years to the present is known as the Phanerozoic (meaning "life presence") era. It contains the most subdivisions in the geological time scale because this period in Earth history was teeming with recognisable and evolving plant and animal life. The boundaries between geological time units of the Phanerozoic era are marked by widespread extinctions in the fossil record and by major unconformities in the rock sequence that signify global events, such as major magmatic episodes and meteorite impacts events. Examples include the voluminous global outpourings of magma at the end of the Permian and Cretaceous periods, and a meteorite impact at the end of the Cretaceous.

Until the beginning of the twentieth century, there were no scientific methods available for determining the true (absolute) age of rocks. Thus, the Geological Time Units represented only relative ages. Over the years, various theories had been proposed for the age of the Earth. Theological estimates suggested that the Earth was very young, but even the early geologists recognised that long periods of time were required to accumulate the vast thicknesses of sedimentary rocks. Based on estimates of the time needed for the exterior of the Earth to cool from a molten state, the British physicist Lord Kelvin calculated, in 1846, that the Earth was about 20 to 30 million years old.

In the early twentieth century, it was recognized that the natural radioactivity inherent in rocks could be used to date rocks in the geological record. This development enabled ages to be assigned to the Geological Time Units, and led to the establishment of the Geological Time Scale (Figure 3), a framework that is still being refined as age-dating techniques are developed and improved.

The first geological time scale was proposed in 1913 by Arthur Holmes (1890 - 1965), a British geologist. Periodically, as new data becomes available, the ages of the boundaries between geological time units are revised by the International Commission on Stratigraphy, and ratified by the International Union of Geological Sciences. The latest revision was completed and promulgated in 2008.

Absolute Age

Radioactive isotopes ("the clocks in rocks") are used to determine the absolute (or numerical) age of a rock. The absolute age of a rock is calculated as a specific number of years.

In simple terms, isotopes of an element exist when the same element has a different number of neutrons in the nucleus, but the same number of electrons and protons. Some of these isotopes (the parent isotope) are unstable (i.e. radioactive), and decay to a more stable isotope (the daughter isotope) by releasing energy. The rate of decay from parent to daughter isotope is constant, and is unique for each particular isotope.

Many minerals contain radioactive isotopes. Once a mineral is formed, the parent isotope in the mineral begins to decay to produce a daughter isotope. In theory, the age (time since formation) of these minerals, and thus the age of the rock bearing them, can be determined by counting the ratio of parent to daughter isotopes in the mineral. The age of the mineral is the length of time that is required to produce the quantity of daughter isotope that has accumulated in the mineral. This length of time required can be calculated using the known decay rate for the isotope.

Age of the Earth

It is now known that the oldest dated rocks on the Earth are about 4.28 billion years old. However, since these original rocks have been recycled and destroyed during the process of plate tectonic movements, they do not provide a reliable age for the Earth. Instead, the most reliable estimate of the age of the Earth is based on the radiometric dating of meteorites. Meteorites are believed to be material left over from the formation of the Solar System. The age of the oldest minerals contained in iron meteorites that have entered the earth's atmosphere is about 4.57 billion years, which is currently regarded as being the best estimate for the age of the Earth.

Figure 3: A simplified Geological Time Scale.

Geological Map

Geological maps are a visual representation of a wide variety of geological data, including the distribution of rocks and sediments in a particular area, the types of rocks, their age relationships, and the structural features in that area.

A geological map normally comprises a topographical base map, overlain by areas of colour, to show the distribution of stratigraphical units (rocks and sediments), and special symbols, to show structural and other geological information. Geological maps include a legend that explains the meaning of the symbols, the ages of the stratigraphical units, and provides a key to the units. In some cases, the geological legend may also show stratigraphical relationships. To assist the user with an interpretation of the geology, geological maps usually include one or more representative cross-sections (Figure 4).

Figure 4. Hong Kong Geological Survey
1:100,000-scale Hong Kong Geological Map
(Click to enlarge).

Geological maps are used for a wide variety of purposes including land use planning, natural hazard assessments, mineral resource investigations, water resources evaluations, and engineering construction projects.

A geological map is a summary document from which the geological history of an area can be deciphered. However, it should be realised that a geological map is an interpretation, by a geologist, of the geological facts that were available at the time that the map was prepared. The accuracy of a geological map is largely a function of the time spent walking over the area, and time available for data collection. Geological maps can be revised and improved as more field work is carried out, and as more data from boreholes and excavations becomes available.

Groups, Formations and Suites

A stratigraphical unit is a discrete stratum or body of rock that occurs as a definable and mappable feature. Stratigraphical units with distinctive lithological, physical and chemical characteristics are shown as formations on geological maps. Two or more geographically associated formations with similar characteristics may be assigned to a group, which is the next order above a formation.

Large, single intrusive units are shown on geological maps as plutons or granite bodies, named after the particular geographical locality in which they occur. The stratigraphical status of these features is equivalent to a formation. Closely associated plutons or granite bodies with a characteristic chemistry and mineralogy are grouped as suites.

In Hong Kong, the volcanic formations are commonly assigned to a group that represents a particular magmatic episode, a phase or period of volcanic activity. Suites are the plutonic (intrusive) equivalent of volcanic (extrusive) groups, and represent a particular magmatic episode. The unconsolidated superficial sediments are the youngest stratigraphical units, which form a cover over most of the solid (consolidated) bedrock. In Hong Kong, superficial deposits comprise alluvium (river deposits) and colluvium (hillslope deposits) onshore, and marine mud, sand, and Pleistocene alluvium offshore.

What is shown on a Geological Map?

Coloured Areas

A unique colour is assigned to each stratigraphical unit (but not to each lithological type) on a geological map. The selection of colours usually depends on the age of the stratigraphical units, with several internationally recognised colour schemes adopted for specific stratigraphical units and geological periods. However, to a greater or lesser extent, almost all geological maps depart from the standard colour schemes, depending upon the specific purposes of the map.

In addition to a unique colour, a letter symbol is commonly used to identify the stratigraphical unit in a particular area. The first letter, a capital, usually refers to the geological age of the unit. For example, J designates the Jurassic (about 200 to 145 million years ago), P the Permian (about 299 to 251 million years ago), and D the Devonian (about 416 to 359 million years ago). Subsequent (lower case) letters identify the formation name or the principle lithological type.

Geological Lines

The type of contact between different rock units is a critical factor to observe on a geological map. There are three main types of geological contact: an intrusive contact, a depositional contact, and a fault contact. On geological maps, intrusive and depositional contacts are generally shown by fine lines, whereas a fault contact is represented by a heavy line.

Not all the faults shown on a geological map are active (i.e. earthquake-related) at present. Rocks can preserve a record of faults that have been inactive for a very long period. Thus, the fault lines shown on a geological map simply represent the traces (locations) of faults that are preserved in the rocks.

Geological boundaries are shown as either solid or dashed lines on a geological map. This reflects the degree of certainty, and hence accuracy, of the geological contact represented on the map. Usually, in the field, geological contacts are obscured by vegetation, soil, or urban construction. Wherever a geological boundary is observable, it is shown as a solid line on the map, but where a boundary is uncertain, or is inferred, the line is dashed. Generally, the shorter the dash, the more uncertain is the location of the boundary.

The lines on a geological map may be modified using symbols (for example, filled triangles, small tick marks, arrows, etc.). These symbols provide additional information about the nature of the geological line. For example, faults (heavy lines) with triangle symbols show that the fault is a thrust fault, and that the side of the line with the triangles has been pushed over the side without the triangles. Other line symbols are explained on the map legend.

Geological Symbols

Strike and dip symbols provide information about the three-dimensional orientation of geological surfaces such as bedding, joints, faults or foliations (Figure 5). Using a compass and clinometer, geologists measure the orientation of these structures wherever they can find suitable solid rock exposures (as opposed to loose boulders). The orientation and angle are recorded as a strike and a dip respectively. Each dip and strike symbol on a geological map usually represents the average of several measurements.

Strike: The strike of an inclined geological plane is the direction of an imaginary horizontal line projected across the surface (Figure 6). Strike may be visualised by immersing a sheet of glass into a bowl of water. Because the water surface is horizontal, the waterline on the glass is a horizontal line, or a strike line. The direction (azimuth) of the waterline is the strike.

Dip: Dip generally refers to the dip angle, which is the angle between a geological plane and the horizontal, i.e. the angle at which the plane slopes downwards, as measured in the dip direction. The dip direction is always perpendicular to the strike, and is the direction of maximum slope of an inclined plane. Thus, an horizontal plane has dip of 0°, and a vertical plane has a dip of 90°.

Map Legends

An important component of geological maps is the legend (or key), on which examples of all the colours, lines and symbols are reproduced and explained. A legend is necessary for a full understanding of a geological map. The legend itemises the colour and the letter symbol of each stratigraphical unit as a column, with the youngest, or most recently formed, units (e.g. the man-made deposits) at the top, and the oldest units in the area at the bottom. The name of the stratigraphical unit, a short description of the types of rocks or sediments present, and their age, are also included. Legends also explain the types of geological lines used, the strike and dip symbols, and the other kinds of geological symbols shown. These may include mineral occurrences, fossil locations, and other geological features that might be important in the area.

Figure 5: Examples of some geological symbols.

Figure 6: Strike and dip of inclined sedimentary layers.

Geological Mapping Tools

Traditionally, geological maps are made by geologists who walk over as much of the map area as possible, noting where rocks can be seen (outcrops), the rock types (lithology), their structure, degree of weathering, and any other features that might be useful. All observations are marked upon a topographical base map, and measurements are taken using a magnetic compass and clinometer. Aerial photographs may help the geologist to identify target features in the field.

Topographical base maps show the landscape of an area in the form of contours (lines of equal height), rivers, lakes, reservoirs, roads, buildings, footpaths, etc. Topographical maps are drawn at various scales, the most common scales in Hong Kong being 1:20,000 and 1:5,000, with 1:1,000 scale maps also available. This means, for example, that on a 1:10,000 scale map, 1 centimetre on the map represents 10,000 centimetres (100 metres) on the ground. The scale of the topographical base map selected depends upon the survey objectives, i.e. the amount of geological detail required on the finished map.

Aerial photographs (Figure 7) are taken from aircraft flying at fixed heights above the ground. Adjacent pairs of aerial photographs with about 60% overlap can be used under a stereoscope to provide a three-dimensional image of the landscape, which is useful for reconnaissance surveys. The scale of the aerial photograph can be determined if the flying height and the focal length of the camera lens are known. Aerial photographs of limited areas of Hong Kong are available for some years between 1924 and 1963. Systematic, annual, territory-wide black and white aerial photographic coverage began in 1963, twice-annual black and white photography began in 1985, and routine, twice-annual colour photography began in 1993.

Magnetic compasses (Figure 8) are instruments used to determine the direction of the magnetic north pole. They work on the principle that the molten core of the earth causes the earth to act like a giant magnet, with the ends (positive and negative poles) of the magnet located in the vicinity of the north and south geographical poles. A magnetic compass, which has a magnetised needle that pivots freely over a 360 degree graduated dial, is used to determine the direction of the north pole from the position of the observer. However, the magnetic north pole migrates up to about 1,167 kilometres from the geographical north pole, a value that varies annually. In Hong Kong, the magnetic north pole and the geographical north pole are in the same relative direction. In other parts of the world, this difference must be compensated for by adding, or subtracting, an angle of up to about 30 degree (the magnetic declination) from the compass reading.

Clinometers (Figure 9) are used to measure the angle of inclination of a surface, such as the angle of dip of rock strata. They employ a spirit level (a bubble of air in a liquid enclosed in a glass tube) or a pendulum to determine the horizontal and vertical inclination respectively. Clinometers are equipped with graduated half circles from which the angle of dip of a surface from the horizontal can be read.

Figure 7: Aerial photographs.

Figure 8: Magnetic compasses.

Figure 9: Clinometer.

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Surveying the Landscape - Introduction to Geological Mapping - Hong Kong Geology

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In simple terms, a geological map shows the surface distribution of rocks in a particular area. However, in order to fully understand a geological map, it is necessary to be familiar with several basic geological principles, including the laws of stratigraphy, geological age, and geological stru…

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This is where all specific concepts can be found. Compilation made by the students.

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We would like to thank Mr. David Rosa (IES Rosa Chacel, Madrid) whose excellent project "¡Me estáis calentando!" inspired this one. You can find it here and here.
In addition to him, we'd also like to thank Mrs. Cristina Flores (@bioESOsfera), whose similar project helped us visualize the final product we could ask for.
And, of course, we'd like to thank Asmodee for its great game "TIMELINE"!!

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Project schedule (4ºESO A; Bold = IT Room instead of our classroom)

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Project schedule (4ºESO A; Bold = IT Room instead of our classroom)

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WEDNESDAY 17 MAR: Timeline: playing from square 1/ Presentation of the Project

THURSDAY 18 MAR: Group work at home with the teacher (Padlet & TEAMS)

TUESDAY 23 MAR: Group work at home without the teacher (Padlet)

WEDNESDAY 24 MAR: JORNADAS CULTURALES.

THURSDAY 29 APR: Padlet presentations
FRIDAY 7 MAY: Padlet presentations

MONDAY 10 MAY: Preparing the game (cards)
TUESDAY 11 MAY: Preparing the game (cards)

MONDAY 10 MAY: Autoevaluation/Coevaluation/Quick Socrative Test. End of part 1. Beginning of part 2: Periods distribution.

MONDAY 24 MAY: Autoevaluation/Coevaluation/Quick Socrative Test. End of the project

THE BIG GAME will take place as soon as the cards are printed and prepared.
JUNE: Let's challenge any other class!!

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Plate tectonics: Earth’s internal layers, dynamics and plate motion

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Plate tectonics: Earth’s internal layers, dynamics and plate motion

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TECTONIC PLATES

Introduction

Pangea

Seafloor Spreading

Volcanoes

Earthquakes

Landform

Video

Equipo

01

02

03

04

05

06

07

08

INDEX

we are going to tolk abought the tectonics plaquets

PAGEA

- Relatively rigid fragment of lithosphere moving over the asthenosphere.- All the continents were united, there wasn´t separation.

SEAFLOOR SPREADING

It is the creation of new seafloor due to de movements of two ocean plate tectonics:-Divergent plates:The oceanic ridges are formed by a movement of the tectonic plates which separate, letting gases escape from the asthenosphere to the lithosphere, in which new ones are created.-Convergent plates:oceanic trinceras are made by a collision between two plates from which one falls and the other destroys the material of the lysosphere

VOLCANOES

Volcanoes are an erosion of gases and the movement of tectonic plates which form an area in which if it erupts, it expels lava and magma with toxic gases and ash. volcanic regions are classified into the following types:-Oceanic shores:-Continental Rifts:-Continental arches:-Arches of islands:

EARTHQUAKES

Are vibrations of earth´s surface

- The vibrations are produced by a sudden fracture of a large volume of rocks

LANDFORM

-Mountains-Valleys-Rivers

types of surface of a planet

Resumen

Paula Camacho

Equipo

Lavínia Fabian

.https://padlet.com/joseantonio_alba/tshrjs7cve4r742n Wikipedia. Wikipedia

¡Gracias!

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Tectonic Pltaes by paulini.camacho on Genially

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TECTONIC PLATES Introduction Pangea Seafloor Spreading Volcanoes Earthquakes Landform Video Equipo 01 02 03 04 05 06 07 08 INDEX we are going to tolk abought the tectonics plaquets PAGEA - Relatively rigid fragment of lithosphere moving over the asthenosphere.- All the continents were united, there wasn´t separation.

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geological timescale

start

Subdivisions

Ainhoa JiménezMaría López

Index

Cenozoic

PALEOZOIC 1

MesozoicPrecambrian

PALEOZOIC 1.2

DEFINITIONS

eons:it's an indefinitely long period of time

era: is a span of time defined for the purposes of chronology or historiography

Period:the completion of a cycle, a series of events, or a single action

Precambrian (supereon)

NeoarcheanMesoarcheanPaleoarcheanEoarchean

NeoproterozoicMesoproterozoicPaleoproterozoic

Archean

Proterozoic

(4600 to 542.0 mya)

Hadean

(542.0 mya to present)

PHANEROZOIC

Paleozoic 1

Pridoli (418.7 to 416.0 mya ) Ludlow(422.9 to 418.7 mya )Wenlock (428.2 to 422.9 mya)Llandovery (443.7 to 428.2 mya)

Upper(460.9 to 443.7 mya)Middle (471.8 to 460.9 mya )Lower (488.3 to 471.8 mya )

Furongian(499 to 488.3 mya) Series 3(55.8 to 33.9 mya)Series 2 (521 to 510 mya)Terreneuvian (542.0 to 521 mya)

Silurian(443.7 to 416.0 mya)

Ordovician(488.3 to 471.8 mya )

Cambrian(542.0 to 488.3 mya )

251.0 to 65.5 mya

P E R I O D S

Paleozoic 1.2

Lopingian (260.4 to 251.0 mya )Guadalupian (270.6 to 260.4 mya )Cisuralian (299.0 to 270.6 mya)

Pennsylvania(318.1 to 299.0 mya)Upper (307.2 to 299.0 mya )Middle (311.7 to 307.2 mya )Lower (318.1 to 311.7 mya )Mississippian(359.2 to 318.1 mya) Upper (328.3 to 318.1 mya ) Middle (345.3 to 328.3 mya ) Lower (359.2 to 345.3 mya )

Upper (33.9 to 23.03 mya)Middle (55.8 to 33.9 mya)Lower (416.0 to 397.5 mya)

Permian(299.0 to 251.0 mya)

Carboniferous(359.2 to 270.6 mya )

Devonian(416.0 to 359.2 mya )

251.0 to 65.5 mya

E R I O D S

P E R I O D S

Mesozoic

Upper (99.6 to 65.5 mya )Lower (145.5 to 99.6 mya )

Upper (161.2 to 145.5 mya )Middle (175.6 to 161.2 mya )Lower (199.6 to 175.6 mya )

Oligonocene (33.9 to 23.03 mya)Eocene (55.8 to 33.9 mya)Pelocene (65.5 to 55.8 mya)

Cretaceous(145.5 to 65.5 mya)

Jurassic(199.6 to 145.5 mya )

Triassic(251.0 to 199.6 mya )

251.0 to 65.5 mya

P E R I O D S

Cenozoic

Holocene (11.700 yrs to present)Pleistocene ( 2.588 mya to 11.700 yrs)

Pliocene (5.332 to 2.588 mya)Miocene (23.03 to 5.332 mya)

Oligonocene (33.9 to 23.03 mya)Eocene (55.8 to 33.9 mya)Pelocene (65.5 to 55.8 mya)

Quartenary(2.588 mya to present)

Neogene(23.03 to 2.588 mya)

Pelogene(65.5 to 23.03 mya )

65.5 mya to present

P E R I O D S

¡THANKS!

María López y Ainhoa Jiménez

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PRESENTACIÓN NATURALEZA by expotrabajocultura on Genially

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geological timescale start Subdivisions Ainhoa JiménezMaría López Index Cenozoic PALEOZOIC 1 MesozoicPrecambrian PALEOZOIC 1.2 DEFINITIONS eons:it's an indefinitely long period of time era: is a span of time defined for the purposes of chronology or historiography Period:the completion of a cycle, a series of events, or a single action Precambrian

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human evolution

WHAT IS IT?

EVOLUTION PROCESS

HUMAN PHASES

HOW DO WE KNOW?

VIDEO

THANKS

INDEX

what is it?

Human evolution is the lengthy process of change by which people originated from apelike ancestors. Scientific evidence shows that the physical and behavioral traits shared by all people originated from apelike ancestors and evolved over a period of approximately six million years.

evolution processes

Lorem Ipsum

MutationGenetic RecombinationChromosomal AbnormalitiesReproductive isolationNatural Selection

HUMAN PHASES

Australopithecus

Homo Habilis

Homo Ergaster

Homo Erectus

Homo Antecessor

Homo Heidelbergensis

Homo Rhodesiensis

Homo Neardenthaliensis

Homo Sapiens

HUMAN PHASES

* The first primates to walk uprigth* Varianted species (because the climate)

AUSTRALOPITHECUS

HOMOHABILIS

HOMOERGASTER

HOMOERECTUS

HOMOANTECESSOR

* The first to leave África and colonize other tetritories

* Ability to develop stone tools* The first to exist in África

* It inhabited Asia* Stone tools and animal skins

* Taller* Small brain* First European human link

Australopithecus

Homo Habilis

Homo Ergaster

Homo Erectus

Homo Antecessor

HUMAN PHASES

HOMOHEIDELBERGENSIS

HOMORHODESIENSIS

HOMONEARDENTHALIENSIS

HOMOSAPIENS

Big skullsProtruding jawsLarge nasal opening

Large, broad and flat facial skeleton

Great cranial capacityShort and robust extremities

The most similar to usHands and feet with five fingersColor vision

Homo Heidelbergensis

Homo Rhodesiensis

Homo Neardenthaliensis

Homo Sapiens

How do we know?

We know about our past thanks to the Human Fossils that provided evidences that modern humans come from them.* Fossils (show changes about the skeleton over the past 6 million years)

VÍDEO

SOURCES

https://concepto.de/evolucion-del-hombre/SCIENCE BITShttps://www.britannica.com/science/human-evolution

Thanks forYOUR ATENTION

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HUMAN EVOLUTION by trabajobioo on Genially

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human evolution WHAT IS IT? EVOLUTION PROCESS HUMAN PHASES HOW DO WE KNOW? VIDEO THANKS INDEX what is it? Human evolution is the lengthy process of change by which people originated from apelike ancestors. Scientific evidence shows that the physical and behavioral traits shared by all people originated from apelike ancestors and evolved over a period of approximately six million years.

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Theories of evolution & evolution mechanisms.

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Theories of evolution & evolution mechanisms.

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The Evolution

PRESENTAtion

empezar

by darek kajetaniak and samuel díaz

INDEX

What are them?

Wich proves we have?

Darwinism

lamarckism

what are them?

mutation

non-random mating

Gene Flow

Natural selection

Theories of evolution

Evolution mechanisms

What are them?

Darwin's theory of evolution by natural selection solved the mystery of how evolution works. Darwin figured out that that certain traits and characteristics are better suited to the environment, which enables organisms with the adapted variant to better survive and multiply.

Theories of Evolution

Wich proves we have?

The Theory of Biological Evolution makes two very bold claims about living creatures:

Theories of Evolution

First: All living things on Earth are related. They evolved from a common ancestorSecond: The evolution of living things is powered by natural processes. Things wich can be studied and understood

Darwinism

Is a theory of biological evolution developed by the English naturalist Charles Darwin (1809-1882) and others, stating that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce.

Theories of Evolution

I publishedOn The Origins of Speciesin 1859, I spent all my life to do this investigation!

Lamarckism

Also known as Lamarckian inheritance or neo-Lamarckism, is the notion that an organism can pass on to its offspring physical characteristics that the parent organism acquired through use or disuse during its lifetime. It is also called the inheritance of acquired characteristics or more recently soft inheritance

Theories of Evolution

What are them?

Correspond to violations of different Hardy-Weinberg assumptions. They are: mutation, non-random mating, gene flow, finite population size (genetic drift), and natural selection

Evolution Mechanism

Mutation

Although mutation is the original source of all genetic variation, mutation rate for most organisms is pretty low. So, the impact of brand-new mutations on allele frequencies from one generation to the next is usually not large

Evolution Mechanism

Non-random Mating

Organisms may prefer to mate with others of the same genotype or of different genotypes. Non-random mating won't make allele frequencies in the population change by itself, though it can alter genotype frequencies. This keeps the population from being in Hardy-Weinberg equilibrium, but it's debatable whether it counts as evolution, since the allele frequencies are staying the same

Evolution Mechanism

Gene Flow

Involves the movement of genes into or out of a population, due to either the movement of individual organisms or their gametes. Organisms and gametes that enter a population may have new alleles, or may bring in existing alleles but in different proportions than those already in the population. Gene flow can be a strong agent of evolution

Evolution Mechanism

Natural Selection

Natural selection occurs when one allele (or combination of alleles of different genes) makes an organism more or less fit, that is, able to survive and reproduce in a given environment. If an allele reduces fitness, its frequency will tend to drop from one generation to the next

Evolution Mechanism

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PRESENTACIÓN NATURALEZA by Darek Kajetaniak on Genially

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The Evolution PRESENTAtion empezar by darek kajetaniak and samuel díaz INDEX What are them? Wich proves we have? Darwinism lamarckism what are them? mutation non-random mating Gene Flow Natural selection Theories of evolution Evolution mechanisms What are them? Darwin's theory of evolution by natural selection solved the mystery of how evolution works.

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DK Findout (developed by the prestigious editorial house Dorling Kindersey) offers great info with diagrams, pictures, etc.

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Earth’s surface appears to be still, but it is actually constantly on the move. Its outer shell is made up of huge slabs of moving rock called tectonic plates. The plates fit together like puzzle pieces to make up Earth’s surface. Their movements change the planet’s features, depending on how the plates meet. Some plates are crunching together, and may form mountains. Others are splitting apart. When this occurs under the ocean, it creates new ocean floor. Some plates grind past each other. These are the most likely to cause earthquakes.

Tectonic plates move on average about 1 in (2.5 cm) per year—this is about as fast as a fingernail grows.

Earth›Tectonic plates

Volcano

Volcanoes often form as a result of movement.
Where are Earth’s volcanoes? ›

The tectonic plates that lie under land are called continental plates. They are thicker than the ones that lie under oceans.

Ocean trenches are narrow, deep depressions on the ocean floor. They form at boundaries where plates move together (converge).

When plates pull apart, they create a spreading, or divergent, boundary. When this happens under oceans, rock from a layer of the earth called the mantle is drawn up into the gap. Some of it melts as it rises. This creates new plate material, including new oceanic floor.

When two plates scrape past each other, they create a transform fault. Also called a strike-slip fault, it is the most common cause of earthquakes.

When a plate with oceanic crust moves toward a plate with thicker, continental crust, it is pushed down, or subducted, creating an ocean trench and often volcanoes. If two continents collide, they push against each other, creating mountain ranges.

When one plate is pushed under a neighboring plate, this is called subduction. In the areas where this happens, earthquakes are common. The process of subduction also causes hot, liquid rock (magma) to form at the bottom of the neighboring plate. This causes volcanoes to form.

As magma (molten rock) rises to fill the gap in a divergent boundary, it eventually hardens to form new oceanic crust (outer shell).

Mountains

When two continents collide at a convergent boundary, they push against each other. Sometimes, this creates mountain ranges.
How are mountains formed? ›

The tectonic plates that lie under the oceans are called oceanic plates. They are thinner than continental plates.

How plates move ›

Tectonic plates are always moving. They can squeeze together, pull apart, or rub against each other.
How plates move ›

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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Easy questions about your Padlets and the TIMELIfE

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Qué es, evidencias de la deriva continental y la expansión del fondo oceánico, tipos de bordes,consecuencias sobre el relieve, procesos tectónicos...

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Answer these questions about believing everything you read...

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(University of Berkeley)

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Online exhibits
Geologic time scale

Take a journey back through the history of the Earth — jump to a specific time period using the time scale below and examine ancient life, climates, and geography. You might wish to start in the Cenozoic Era (65.5 million years ago to the present) and work back through time, or start with Hadean time (4.6 to 4 billion years ago)* and journey forward to the present day — it's your choice. [Note: "mya" means "millions of years ago"]

Ways to begin your exploration:

Use the links in the "time machine" below and explore a specific period that interests you.

Read more about the geologic time scale, its origins and its time divisions.

Find out more about plate tectonics, an important geological concept in any time period!

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Online exhibits Geologic time scale Take a journey back through the history of the Earth - jump to a specific time period using the time scale below and examine ancient life, climates, and geography.

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2 posibles ensayos sobre Geología (Lv 1, 2)

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2 posibles ensayos sobre Geología (Lv 1, 2)

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- A partir de distintos perfiles geológicos de España, analiza las grandes formas de relieve: cordilleras, mesetas, volcanes, islas… y su relación con la Tectónica de Placas. ¿Cómo llegaron a aparecer?

- Con los conocimientos sobre Tectónica de Placas de los que dispones, explica el origen de uno de los últimos grandes seísmos que han conmocionado nuestro planeta. Haití, Fukushima, Indonesia…

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Annotations written by an exSaFa student in 1º Bto.; not so accurate but quite accesible to build a tentative picture on the topic. By the way, there is no need to know the Wilson cycle by heart.

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Create your own creature and explain how it evolved:

http://ies.rosachacel.colmenarviejo.educa.madrid.org/evolucionarte/

Después de leer el apartado “De qué va”, cada alumno se dedicará  a crear su propia criatura siguiendo las instrucciones. Si no funcionara la descarga, se puede probar en: http://eu.spore.com/whatisspore/ccaccept.cfm  o este otro: http://www.spore.com/trial Hay que describirlo, nombrarlo y explicar con base en las teorías evolutivas y sus pruebas cómo ha llegado a aparecer su rasgo más significativo. Después, los alumnos expondrán esta información a sus compañeros en presentaciones de alrededor de 5 minutos. Para terminar, elaboraremos una clave dicotómica con las especies creadas por todos los integrantes de la clase.

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Elemental, queridos humanos: Vida y andanzas del ingenioso planeta Tierra (by Juan Luis Arsuaga & Forges)

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After watching these top level lectures on Human evolution, write an essay explaining what you have learned.

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Organized by John C. Avise and Francisco J. Ayala

December 10-12, 2009
Irvine, CA

Meeting Overview:
The year of Darwinian celebration will close with a Sackler Colloquium devoted expressly to human evolution. Darwin addressed the topic at length in The Descent of Man and Selection in Relation to Sex (1871). Much has been learned since then, not least from the evidence of paleontology, comparative vertebrate biology, and comparative genomics. This Sackler Colloquium brought together leading biologists with special expertise about human evolution, both biological and cultural.

Video Available
Opening Addresses
John C. Avise, University of California, Irvine
Session I: Human History and the Paleontological Record
Evolution of the Hominids
Bernard Wood, George Washington University

Peopling the Planet: Out of Africa?
Douglas Wallace, University of California, Irvine

Human Population Diversity
Anna DiRienzo, University of Chicago

Session II: Structure and Function of the Human Genome
Chair, Kristen Hawkes, University of Utah

Genomic Footprints of Natural Selection
Carlos Bustamante, Cornell University

Banquet Lecture
Introduction, Francisco J. Ayala, University of California, Irvine

Session III: The Uniqueness of Being Human
Chair, Sarah Tishkoff, University of Pennsylvania

The Skin That Makes Us Human
Nina Jablonski, Pennsylvania State University

How Cultures Evolve
Peter J. Richerson, University of California, Davis

Session IV: Cultural Evolution
Chair, Francisco J. Ayala, University of California, Irvine

Whence Intelligence?
Leda Cosmides, University of California, Santa Barbara

Evolution of the Mind
Steven Pinker, Harvard University

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National Academy of Sciences - http://www.nasonline.org

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In the Light of Evolution: The Human Condition

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Meeting Overview: The year of Darwinian celebration will close with a Sackler Colloquium devoted expressly to human evolution. Darwin addressed the topic at length in The Descent of Man and Selection in Relation to Sex (1871). Much has been learned since then, not least from the evidence of paleontology, comparative vertebrate biology, and comparative genomics.

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Be careful, some info is not really accurate

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Taking an organic chemistry class needs a lot of preparation, and reading textbooks isn't enough. A molecular model kit is an essential tool for any student

Molecular geometry and electron geometry in chemistry are how atoms are arranged around a center in a three-dimensional space. This arrangement provides the familiar molecular

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Taking an organic chemistry class needs a lot of preparation, and reading textbooks isn't enough. A molecular model kit is an essential tool for any student Molecular geometry and electron geometry in chemistry are how atoms are arranged around a center in a three-dimensional space.

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Complete this thrilling activity on life 2nd big bang and the subsequent extinction, one of the worst extinctions ever

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Evolution and the fossil record (Lv 1, 2)

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Evolution and the fossil record (Lv 1, 2)

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Really accesible material on evolution and fossils

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Great site -a bit overwhelming- by the University of Berkeley. Includes lots of info on misconceptions about evolution

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Understanding Evolution - Your one-stop source for information on evolution

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Start here

Evolution 101

Similarities and differences: understanding homology and analogy

The Tree Room

Check out our favorites

Evo in the News: A country weed with city problems

Survival of the Sneakiest

The Arthropod Story

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Learn Evolution - Understanding Evolution

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Copyright © 2022 · UC Museum of Paleontology Understanding Evolution

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Complete evogram about human evolution

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Understanding Evolution - Your one-stop source for information on evolution

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The narratives of human evolution are oft-told and highly contentious. There are major disagreements in the field about whether human evolution is more like a branching tree or a crooked stick, depending partly on how many species one recognizes. Interpretations of almost every new find will be sure to find opposition among other experts. Disputes often center on diet and habitat, and whether a given animal could walk bipedally or was fully upright. What can we really tell about human evolution from our current understanding of the phylogenetic relations of hominids and the sequence of evolution of their traits?

To begin with, let's take a step back. Although the evolution of hominid features is sometimes put in the framework of "apes vs. humans," the fact is that humans are apes, just as they are primates and mammals. A glance at the evogram shows why. The other apes - chimp, bonobo, gorilla, orangutan, gibbon - would not form a natural, monophyletic group (i.e., a group that includes all the descendants of a common ancestor) - if humans were excluded. Humans share many traits with other apes, and those other "apes" (i.e., non-human apes) don't have unique features that set them apart from humans. Humans have some features that are uniquely our own, but so do gorillas, chimps, and the rest. Hominid evolution should not be read as a march to human-ness (even if it often appears that way from narratives of human evolution). Students should be aware that there is not a dichotomy between humans and apes. Humans are a kind of ape.

Virtually all systematists and taxonomists agree that we should only give names to monophyletic groups. However, this evogram shows that this guideline is not always followed. For an example, consider Australopithecus. On the evogram you can see a series of forms, from just after Ardipithecus to just before Homo in the branching order, that are all called Australopithecus. (Even Paranthropus is often considered an australopithecine.) But as these taxa appear on the evogram, "Australopithecus" is not a natural group, because it is not monophyletic: some forms, such as A. africanus, are found to be closer to humans than A. afarensis and others. Beyond afarensis, for example, all other Australopithecus and Homo share "enlarged cheek teeth and jaws," because they have a more recent common ancestor. Eventually, several of these forms will have to have new genus names if we want to name only monophyletic groups. Students should avoid thinking of "australopithecines" as a natural group with uniquely evolved traits that link its members together and set it apart from Homo. Instead they should focus on the pattern of shared traits among these species and the Homo clade, recognizing that each species in this lineage gains more and more features that are shared by Homo.

In popular fiction and movies, the concept of the wild "ape-man" is often that of a tree-living, vine-swinging throwback like Tarzan. However, the pantheon of hominids is much richer than this, as the evogram shows with forms as different as Paranthropus and Ardipithecus shows. For example, imagine going back in time to the common ancestor of humans and chimps (including bonobos). What did that common ancestor look like? In the Origin of Species Darwin noted that the extinct common ancestor of two living forms should not be expected to look like a perfect intermediate between them. Rather, it could look more like one branch or the other branch, or something else entirely.

Did the common ancestor of humans and chimps conform to the ape-man myth and live in the trees, swinging from vines? To answer this, we have to focus not only on anatomy but on behavior, and we have to do it in a phylogenetic context. Apes such as the gibbon and orangutan, which are more distantly related to humans, are largely arboreal (i.e., tree-living). The more closely related apes such as the gorilla and chimps are relatively terrestrial, although they can still climb trees. The feet of the first hominids have a considerable opposition of the big toe to the others but relatively flat feet, as arboreal apes generally do. But other features of their skeleton, such as the position of the foramen magnum underneath the skull, the vertically shortened and laterally flaring hips, and the larger head of the femur, suggest that they were not just mainly terrestrial but habitually bipedal, unlike their knuckle-walking relatives. Most evidence suggests that the hominid lineage retained some of the anatomical features related to arboreal life and quadrupedal gait even after it had evolved a more terrestrial lifestyle and a bipedal gait. There is no fossil record of these behaviors, but the balance of the available evidence supports the hypothesis that the hominid ancestor was terrestrial and bipedal.

Much discussion in human paleontology surrounds the evolution of a bipedal, upright stance. When and why did this occur? One thing to keep in mind is that "bipedal" and "upright" are not equivalent terms. An animal can be bipedal without having a vertical backbone (think T. rex). It seems clear from the fossil record of hominids that habitual bipedality preceded the evolution of a recurved spine and upright stance. Other changes in the gait, such as how the relatively "splayed" gait of chimps evolved into the gait of humans, who put one foot directly in front of the other, involve studying the hip joint, the femur, and the foot. The famous Laetoli footprints attributed to Australopithecus afarensis are bipedal, but they are still relatively splayed compared to the tracks of living humans.

Another extremely interesting feature in hominid evolution is the degree of sexual dimorphism (i.e., physical differences between the sexes) in different species. Sexual dimorphism is linked to features of sociality and mate competition in many sorts of animals. To understand the evolution of this feature in humans, which have relatively low sexual dimorphism, we need to consider the other apes, in which sexual dimorphism tends to be moderate to high (with exceptions). We don't have sufficient evidence about Sahelanthropus, Orrorin, and Ardipithecus to understand much about sex differences in these species, but we do know that A. afarensis had relatively high sexual dimorphism: the males were considerably larger than the females. The difference seems to have been less in A. africanus, Paranthropus, and most of the Homo lineage. The evolutionary explanation for A. afarensis' dimorphism is not entirely clear. The larger males may have used their size to attract females and/or repel rivals, which would fit with an explanation based on sexual selection. Or the males and females may have been differently sized because they played different roles in their groups, the males hunting and gathering and the females caring for the young. Darwin thought that this differentiation of the sexes may have played a critical role in human evolution, but we simply do not know much about the role of this feature in A. afarensis. Some, all, or none of these functions may have been in play.

We do know that by the time the animals known as Homo evolved, they could make tools, and their hands were well suited for complex manipulations. These features were eventually accompanied by the reduction of the lower face, particularly the jaws and teeth, the recession of the brow, the enlargement of the brain, the evolution of a more erect posture, and the evolution of a limb more adapted for extended walking and running (along with the loss of arboreally oriented features). The evogram shows the hypothesized order of acquisition of these traits. Yet each of the Homo species was unique in its own way, so human evolution should not be seen as a simple linear progression of improvement toward our own present-day form.

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The emergence of humans - Understanding Evolution

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The narratives of human evolution are oft-told and highly contentious. There are major disagreements in the field about whether human evolution is more like a branching tree or a crooked stick, depending partly on how many species one recognizes. Interpretations of almost every new find will be sure to find opposition among other experts.

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What is the tree of life?

The tree of life shows how all life on earth is related. Each leaf represents a different species. The branches show how these many species evolved from common ancestors over billions of years. In our interactive tree of life you can explore the relationships between 2,235,076 species and wonder at 105,448 images on a single zoomable page.

Popular places to start exploring...

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OneZoom is a registered non-profit in the UK, all our products are available for free. 878 people like you have helped us by making donations. Their names have appeared as sponsors on 1534 leaves of our tree of life leaves of our tree of life.

Only one name per leaf so get your favourite while you can, for yourself or as a gift.

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What we've been up to...

12 September 2023

The Guardian features One Zoom as one of its 50 weirdest, most wonderful corners of the web .

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30 November 2022

OneZoom features as an interactive part of The Whole of Nature - Forces, Orders, Boundaries exhibition at the Museum of Nature Hamburg, Germany. The exhibition combines science and art to show how nature can be ordered.

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29 September 2022

Donors can now renew their support of sponsored leaves. Sponsorships are only for a four year period, however those who do not renew will remain on our tree of life for the time being. Donors will get an e-mail reminder before their sponsored leaves expire.

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23 July 2022

OneZoom features as an interactive component of the Taxonomy: Our Lives Depend On It exhibition at Bishop Musuem , Honolulu, Hawai'i.

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22 May 2022

Thank you to On The Edge for funding our latest project: tree tours. We will bring you a collection of guided tours around our tree of life explorer. These tree tours will take you to particularly interesting parts of the tree and give you more information about evolution, biodiversity and conservation as you go. You will be able to sit back and enjoy the tree tour, or hop off and explore freely around any of the tour stops.

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Amazingly cool... http://tolweb.org/treehouses/?treehouse_id=2974

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Actualizado a fecha de 2013

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SCIENCE BITS BRINGS RESEARCH ON HOW STUDENTS LEARN TO YOUR CLASSES

A Science Curriculum that Enhances Understanding

DISCOVER WHY SCIENCE BITS IS

The Most Awarded Science Instructional Solution in the World!

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SCIENCE BITS BRINGS RESEARCH ON HOW STUDENTS LEARN TO YOUR CLASSES

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Science Bits lessons include all the elements of a complete 5E constructivist learning process, from engaging students to evaluating them, using high quality multimedia interactive content.
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Science Bits lessons are designed around the 5E Instructional Model: a model grounded in the Constructivist Learning Theory and supported by research evidence on how people learn.
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The winds of change are also blowing in education. You can't educate students in the 21st century with tools and methodologies from last century.

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JESÚS MARÍA SCHOOL, HERMANOS GARCÍA NOBLEJAS (MADRID)

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Science Bits has helped me a great deal in instilling passion for science in students

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It is a great resource for teachers and a highly effective tool for students

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It has not only been an all-inclusive curriculum based on my standards ... it has also shown significant trends of growth on district tests.

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What is the evidence for evolution? (Lv 1)

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What is the evidence for evolution? (Lv 1)

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Los elefantes más viejos que habitan el parque nacional de Gorongosa, en Mozambique, portan marcas indelebles de la guerra civil que ha asolado el país durante 15 años: muchos carecen de colmillos. Son los supervivientes solitarios de un conflicto que ha acabado con el 90 por ciento de estos animales asediados, asesinados por su marfil para financiar las armas y por su carne para alimentar a los combatientes.

La caza ha otorgado una ventaja biológica a los elefantes de Gorongosa que no desarrollan colmillos. Las cifras más recientes sugieren que en torno a un tercio de las hembras más jóvenes —la generación nacida tras el final de la guerra en 1992— nunca ha desarrollado colmillos. Normalmente, la falta de colmillos ocurriría solo en entre el dos y el cuatro por ciento de los elefantes africanos hembra.

Según Joyce Poole, experta en el comportamiento de los elefantes y exploradora de National Geographic que estudia los paquidermos del parque, hace décadas vivían en Gorongosa unos 4.000 elefantes. Sin embargo, dichas cifras se han desplomado a los tres dígitos tras la guerra civil. Una nueva investigación no publicada que ella misma ha recopilado indica que, de las 200 hembras adultas conocidas, el 51 por ciento de las que sobrevivieron a la guerra —animales de más de 25 años— carecen de colmillos. Y el 32 por ciento de los elefantes hembra nacidos desde la guerra no tienen colmillos.

Poole, directora científica de una organización sin ánimo de lucro llamada ElephantVoices, explica que los colmillos de un elefante macho son más grandes y pesados que los de una hembra de la misma edad. «Pero cuando la caza furtiva ejerce mucha presión sobre una población, los furtivos empiezan a atacar también a las hembras mayores», explica. «Con el paso del tiempo, y con la población de mayor edad, empiezas a tener una proporción más alta de hembras sin colmillos».

Esta tendencia a la falta de colmillos no solo se limita a Mozambique. Otros países con una historia importante de caza furtiva de marfil también han experimentado cambios similares entre las hembras supervivientes y sus hijas. En Sudáfrica, el efecto ha sido particularmente extremo: el 98 por ciento de las 174 hembras del parque nacional de los Elefantes de Addo carecerían de colmillos a principios de la década del 2000.

Esta matriarca sin colmillos se desplaza con su manada por una llanura aluvial de Gorongosa.

«La prevalencia de la falta de colmillos en Addo es extraordinaria y pone de relevancia el hecho de que los niveles altos de presión de la caza furtiva pueden hacer mucho más que quitar unos cuantos individuos de una población», afirma Ryan Long, ecólogo conductual de la Universidad de Idaho y explorador de National Geographic. «Aún estamos empezando a explorar las consecuencias de cambios tan drásticos en las poblaciones de elefantes».

Josephine Smith, que estudia la conducta de los elefantes como investigadora con el Programa de Elefantes de Tanzania Meridional explica que, entre los elefantes hembra que rastrea en el parque nacional de Ruaha, una zona muy afectada por la caza furtiva en los 70 y los 80, el 21 por ciento de las hembras mayores de cinco años no tienen colmillos. Al igual que en Gorongosa, las cifras más altas se registran entre las hembras mayores. Según ella, aproximadamente el 35 por ciento de las hembras de más de 25 años carecen de colmillos. Y entre los elefantes de entre cinco y 25 años, el 13 por ciento de las hembras no tienen colmillos. (Smith, candidata a doctorado de la Universidad de Stirling, Escocia, explica que los datos todavía no han sido publicados, aunque presentó sus hallazgos en una conferencia científica sobre fauna salvaje el pasado diciembre.)

Tristes imágenes de una cría de elefante sin trompa

Esta cría de elefante no tiene trompa. Podría haberla atacado una hiena o un cocodrilo, aunque la experta en elefantes Joyce Poole cree que quedó atrapado en una trampa. Aunque Poole cree que podría sobrevivir, otro investigador afirma que es poco probable: los animales dependen de sus colas para olfatear, comer, beber y establecer contacto social. Las trampas son un problema grave que amenaza a la fauna salvaje de África.

La caza furtiva también ha hecho que disminuya el tamaño de los colmillos en algunas áreas muy afectadas por la caza, como el sur de Kenia. Un estudio de 2015 llevado a cabo por la Universidad de Duke y el Servicio de Fauna Silvestre de Kenia comparó los colmillos de los elefantes capturados allí entre 2005 y 2013 con los de los elefantes fallecidos entre 1966 y 1968 (esto es, antes de que tuviera lugar una importante caza furtiva a finales de los 70 y principios de los 80) y descubrió diferencias importantes. Los supervivientes de dicho periodo de caza furtiva intensa poseían colmillos mucho más pequeños: eran en torno a un quinto inferiores en machos y más de un tercio inferiores en hembras.

El patrón se repetía en su descendencia. De media, los elefantes macho nacidos tras 1995 poseían colmillos un 21 por ciento más pequeños que los machos de los años 60, y un 27 por ciento más pequeños que las hembras de dicho periodo. Según los autores del estudio, «aunque nuestras pruebas del papel de la genética en el tamaño de los colmillos son indirectas», los estudios en ratones, babuinos y humanos han determinado que el tamaño de los incisivos —homólogos de los colmillos de los elefantes— es hereditario y tiene «una influencia genética importante».

Una hembra adulta sin colmillos en un bosque del parque nacional de Gorongosa a la que le han colocado un collar GPS para que los investigadores puedan rastrear sus movimientos y entender mejor su comportamiento.

Las implicaciones de la falta de colmillos

Pese a la ola de falta de colmillos provocada por los humanos en las últimas décadas, los elefantes sin colmillos sobreviven y parecen gozar de buena salud, según Poole. Los científicos afirman que la proporción significativa de elefantes con esta carencia podría alterar cómo se comportan los individuos y sus comunidades, y quieren determinar, por ejemplo, si estos animales poseen territorios más grandes que otros elefantes, ya que podrían necesitar cubrir más terreno para encontrar alimentos aprovechables.

Los colmillos son básicamente dientes superdesarrollados. Sin embargo, los emplean para la mayoría de las tareas cotidianas: excavan para encontrar agua y minerales fundamentales, quitan la corteza a los árboles para obtener comida fibrosa y ayudan a los machos a competir por las hembras.

La labor que realizan los elefantes con sus colmillos también es fundamental para otros animales. El «papel de los elefantes como especie clave para derribar árboles y excavar agujeros para acceder al agua es importante para una serie de especies inferiores que dependen de ellos», cuenta Long. La acción de los colmillos también contribuye a la creación de hábitats. Algunos lagartos, por ejemplo, prefieren establecer sus hogares en árboles modificados o derribados por elefantes al desplazarse.

Si los elefantes cambian los lugares que habitan, lo rápido que se mueven o adónde van, esto podría tener implicaciones importantes para los ecosistemas que los rodean. «Cualquier cambio de conducta podría dar pie a cambios en la distribución de elefantes por el paisaje, y son esos cambios a gran escala los que tienen más probabilidades de tener consecuencias para el resto del ecosistema», afirma Long.

Ahora, Long y un equipo de investigadores de ecología y genética empiezan a estudiar la vida de los elefantes sin colmillos. En junio, el equipo comenzó a rastrear a seis hembras adultas en Gorongosa —la mitad con colmillos, la mitad sin ellos— de tres manadas reproductoras diferentes. Les colocaron collares GPS, tomaron muestras de sangre y excrementos y pretenden supervisarlas durante un par de años —o hasta que se agote la batería de los collares— tomando más muestras fecales de forma periódica para analizar su dieta.

Su objetivo es descubrir más información sobre cómo se desplazan estos animales, qué comen y cómo son sus genomas. Long espera poder explicar cómo los elefantes que carecen de colmillos como herramienta podrían alterar su comportamiento para acceder a los nutrientes. Rob Pringle, de la Universidad de Princeton, quiere analizar muestras de excrementos para obtener información de la dieta y el ejército de microbios y parásitos que habitan en los intestinos de cada elefante. Otro colaborador, Shan Campbell-Staton, biólogo evolutivo de la Universidad de California en Los Ángeles, estudiará la sangre para desentrañar la influencia de la genética en el fenómeno de la falta de colmillos.

Campbell-Staton explica que la forma en que se hereda este rasgo es «desconcertante». La falta de colmillos no parece tener lugar de forma desproporcionada entre las hembras. Explica que tiene sentido que los machos sin colmillos no pudieran competir por el acceso reproductivo a los elefantes hembra. Pero si este rasgo está ligado al cromosoma X —que ayuda a determinar el sexo y transporta los genes de varios rasgos heredados—, creeríamos que es porque los machos siempre obtienen el cromosoma X de sus madres y tendríamos una población enorme de machos sin colmillos. «Pero no hemos observado eso. La falta de colmillos en elefantes africanos macho es muy inusual», afirma.

Joyce Poole lo corrobora. Según ella, en toda su carrera ha visto solo tres o cuatro machos sin colmillos, y ninguno en Gorongosa.

Soluciones alternativas

Aunque las características conductuales y nutricionales de los elefantes sin colmillos todavía no se han comparado formalmente con las de los elefantes con colmillos de ninguna manada, Smith cuenta de forma anecdótica que en su investigación ha observado que los elefantes sin colmillos parecen haber encontrado soluciones alternativas.

«He observado elefantes sin colmillos que se alimentan de corteza y son capaces de retirarla con las trompas, y a veces con los dientes». Según ella, también podrían contar con la ayuda involuntaria de otros elefantes. Quizá los elefantes seleccionen tipos de árboles diferentes de los que es más fácil retirar la corteza, o árboles cuya corteza ya ha sido retirada por otros elefantes, lo que les daría un punto de apoyo ya preparado para quitarla por sí solos.

Las recientes prohibiciones del comercio de marfil en China y Estados Unidos podrían contribuir a reducir la demanda de colmillos, pero el tiempo que tardará en recuperar sus individuos —y sus colmillos— una población con una alta proporción de falta de colmillos varía. En el caso de los elefantes asiáticos, por ejemplo, es probable que una larga historia de caza por el marfil —así como capturar elefantes salvajes con cuernos para trabajar— contribuyera a una mayor falta de cuernos.

«Si observas los elefantes asiáticos, las hembras no tienen colmillos y, según la población que analices en cada país, la mayor parte de los machos tampoco tiene colmillos», explica Poole. Todavía se desconoce la razón exacta por las que las poblaciones de elefantes asiáticos y africanos tienen porcentajes de falta de colmillos tan diferentes.

Sin embargo, Poole y otros investigadores señalan que en zonas de Asia que históricamente se han visto sometidas a cazas de marfil, los niveles de falta de colmillos son altos —como en África—, insistiendo en que los humanos estamos dejando una huella permanente en el mayor mamífero terrestre del planeta.

Este artículo se publicó originalmente en inglés en nationalgeographic.com.

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Ante la amenaza de la caza furtiva, los elefantes evolucionan para perder los colmillos

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En Mozambique, un equipo de investigadores trata de entender la genética de los elefantes que nacen sin colmillos y las consecuencias de este rasgo.

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Padlet rubric = 30%

Socrative 1 & 2 (average) = 20%

Cards = 10%

TIMELIfE evaluation rubric = 10%

Self evaluation rubric = 10%

Coev. rubrics (average) = 10%

Teacher's rubric = 10%

5 concepts in Vocab Padlet = +0.25