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Both tasks can be found here https://drive.google.com/open?id=1LHlqRzflmnQjBlYvAORF9wLRDV2LR4gQ

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https://drive.google.com/file/d/172Wp7I0QM5NMTDEWpp6I8woC9Oqrvtri/view

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https://drive.google.com/file/d/1Y_wEkJk-tSKW0_4wssfM4Y21ywNA3S-5/view?usp=sharing

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Dont have a padlet group, this one was empty? 

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Dont have a padlet group, this one was empty? 

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eLearning- Dinatra.

video: https://drive.google.com/open?id=1-TYwRISnItHz-nKbqT5_2htazZVDZfp2

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https://eric.ed.gov/?id=EJ829264

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Activity helped module and assessment strategies

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Activity helped module and assessment strategies

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Yes today's field study was helpful in knowing how to approach it for my own classes. Assessment strategies include a summative assessment in the form of a report, but also a formative assessment of marking participation and effort in recording data

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Attempt as a group to connect the ideas of the inquiry questions of this module. Use the whiteboard.Has this activity helped to clarify the module?Would this be a good method of formative or summative assessment?

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Attempt as a group to connect the ideas of the inquiry questions of this module. Use the whiteboard.Has this activity helped to clarify the module?Would this be a good method of formative or summative assessment?

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Has this activity helped to clarify the module?

Would this be a good method of formative or summative assessment?

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1) Has this activity helped to clarify the module?
2) Would this be a good method of formative or summative assessment?

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Two samples taken, one near the fountain (relatively clear) and one further upstream (quite green with pond slime)

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Maximum diversity occurs with maximum dispersal - Cretaceous period
Minimum Diversity with minimum dispersal - Pangaea

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Squiggly Gum

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Unidentified. Can anyone help?

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Sydney Red Gum

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Cabbage Gum

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Walking North, taking a photo every 5m for a transect.

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Walking North, taking a photo every 5m for a transect.

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Distance not measured, however, using the guie, the transect was around 65 Metres

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Flodded Gum

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Along transect, 5m apart: -6.8% --> -3.6% --> -7.6% --> -6.8% --> -7.1%
Alex has the pictures

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Canopy 10m in, 7000LUX

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transect part 3 (DO NOT LISTEN WITH SOUND! SAVE YOUR INNOCENCE!)

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Measurements of light on a light meter app on the phone.

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Measurements of light on a light meter app on the phone.

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133 lux water, 215 lux water side, 165 lux where the slope start to increase, 506 lux where we started the route (location on google map), the rest were taken at a point 5 metres away to the east, 178 lux facing the water, 1186 lux facing the sky, 109 lux facing the east (bush) and 2214 lux facing the sun.

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Macquarie University (coordinates -33.77, 151.11)

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example of leaf litter "quadrant"

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walked towards the north

Light intensity facing the sky

5m - 4000 lux
10m - 7000 lux

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We need to be prepared.

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In the late 1980s, as the world's governments were waking up to the problem of climate change, the mud at the bottom of the ocean near Antarctica revealed a surprise. Earth had lived through rapid global warming before.

About 55 million years ago global temperatures spiked. Then, as now, sea levels rose, the oceans became more acidic, and species disappeared forever.

Little wonder, then, that researchers view this ancient event - known as the "Palaeocene-Eocene Thermal Maximum" or PETM - as a potential goldmine of useful information for understanding modern climate change.

We now know that the PETM was one of the most rapid and dramatic instances of climate change in Earth's history. Its causes are still up for debate, but there seem to be eerie parallels with the causes of modern climate change. What is absolutely clear is that the PETM's effects were far-reaching. It may have altered the course of life on Earth.

The geologists who studied those Antarctic sediments in the 1980s published their findings in 1991. They reported that the shells of tiny planktonic fossils in the muds had betrayed the rapid temperature swings.

The PETM seems to have been caused by greenhouse gases just like modern-day climate change

More precisely, it was the oxygen isotopes locked away in those shells. At around the 55-million-year mark, the amount of "heavy" oxygen-18 in the shells rose relative to "lighter" oxygen-16.

That greater abundance of oxygen-18 is a sure sign that conditions were getting warmer. Water evaporates more readily at higher temperatures, and it's the "light" oxygen-16 that is most easily vapourised. This means that warmer water contains more oxygen-18, and the plankton living in warmer water incorporate more of the stuff into their shells.

Those planktonic shells turned out to be useful for another reason. They hinted at exactly why ocean temperatures rose.

This is because of the carbon they contain.

Today's global warming is not simply a rerun of the PETM

Like oxygen, carbon exists in different isotopic forms. At exactly the same time that the plankton shells became rich in oxygen-18, they also began carrying much more carbon-12 relative to carbon-13. The oceans must suddenly have gained a big supply of carbon-12.

This is something that generally happens after a massive injection of carbon-rich greenhouse gases - carbon dioxide (CO2) or methane - into the atmosphere.

In other words, the PETM seems to have been caused by greenhouse gases just like modern-day climate change.

But today's global warming is not simply a rerun of the PETM. Earth was a very different place 55 million years ago.

One of the biggest concerns today is that the Antarctic ice sheet is shrinking because of climate change. This wasn't a problem during the PETM, because there probably was no Antarctic ice sheet. Even before the onset of the PETM, global temperatures were several degrees warmer than they are now.

All researchers agree that the unusually warm conditions lasted about 170,000 years

Some researchers think the pace of climate change during the PETM distinguishes the event from today too. A controversial study published in 2013 made the case.

Researchers examined another set of muds that formed at the bottom of the ocean 55 million years ago, this time in the north-west Atlantic. They found banding in the muds that they argued was formed by annual cycles.

When they traced the oxygen and carbon isotope blips associated with the PETM, they found that they were contained in just 13 bands. This means, they said, that the PETM temperature surge came in just 13 years.

This does not imply that the PETM came and went in little more than a decade. All researchers agree that the unusually warm conditions, with global temperatures at least 5 °C above average, lasted about 170,000 years.

Modern climate change doesn't have such a dramatic trigger

What it would imply is that global temperatures ramped up to that 5 °C figure in just 13 years. Today, in contrast, global temperatures have risen about 1 °C since the late 19th century.

If PETM climate change really were so rapid, there would be implications for the event that triggered the warming. To create such a rapid rise in global temperature, the atmosphere would have had to be flooded with greenhouse gases almost literally overnight.

Perhaps the release of gases from the melting of a huge carbon-rich comet that flew too close to the Earth would do the trick. Modern climate change doesn't have such a dramatic trigger.

But it's important to stress that many researchers strongly reject that 13-year figure.

There are all sorts of problems with the idea, says Richard Zeebe at the University of Hawaii at Manoa. Most importantly, it is physically impossible for the oceans to heat up that quickly.

Most researchers think the PETM warming really took place over a long period

The Earth's oceans contain a vast amount of water, and heating it up takes time. Even if there was a massive and sudden injection of CO2 into Earth's atmosphere, the oceans simply could not heat up in just 13 years.

"You can heat up the atmosphere relatively quickly, but it takes centuries to millennia to heat up the oceans," says Zeebe.

Other researchers now suggest that the 13 bands in the rock must each represent centuries, not single years. That's if the bands are real at all: some sediment drilling experts say they might simply be an artefact of the drilling process the researchers used to extract the muds.

Most researchers think the PETM warming really took place over a long period, but exactly how long is still up for discussion.

One 2011 estimate suggests that the carbon was released over a period of perhaps 20,000 years.

Such a slow release is very different from today. It might indicate that the greenhouse gases came from the relatively gradual release of gases from volcanic activity.

It looks like the carbon was released into the atmosphere over about 1500 years

Research published in 2014 points to a middle ground. Gabriel Bowen at the University of Utah in Salt Lake City and his colleagues examined the carbon isotopes preserved in soils that formed 55 million years ago in what is now Wyoming.

Whereas the ocean sediments tell us about conditions in the PETM oceans, the soils sample the PETM atmosphere, which responds more rapidly to climate change.

The by-now-familiar surge in carbon-12 popped up again, this time preserved in carbonate nodules that grew in the soil. In this case, it looks like the carbon was released into the atmosphere over about 1500 years: a timescale that looks more similar to today's atmospheric changes.

The ancient soils also indicate the pace of carbon emissions.

The researchers calculated that something approaching 1 billion tonnes of carbon entered the ancient atmosphere each year. That is within an order of magnitude of the current annual release rate of 9.5 billion tonnes.

In light of these findings, the PETM looks like a more reasonable model for today's climate change.

When the oceans warm up a little, vast deposits of methane that are "frozen" in the seabed begin to melt

Bowen and his colleagues made another discovery in Wyoming. They realised that there were actually two distinct pulses of warming 55 million years ago.

A few thousand years before the PETM itself, a vast quantity of carbon-rich greenhouse gases entered the atmosphere from an unidentified source, again at a rate of about 1 billion tonnes per year.

The environment seemed seems to have almost brushed off this "pre-onset event". Atmospheric temperatures rose, but within a couple of thousand years they fell again. Conditions had apparently returned to normal.

The fall in atmospheric temperatures probably came about because the oceans absorbed the heat from the pre-onset event. That might have paved the way for the PETM itself.

When the oceans warm up a little, vast deposits of methane that are "frozen" in the seabed begin to melt. The methane - a potent greenhouse gas - bubbles up, enters the atmosphere and raises global temperatures.

I think that in general the jury is still out

This leads to more ocean warming, triggers more methane release from the seabed, and causes atmospheric temperatures to rise more, and so on. Soon the planet becomes very warm, which is exactly what happened 55 million years ago during the PETM.

Something similar might be happening today. As the modern oceans warm there is good evidence that methane is once again bubbling up from the seabed. The PETM offers us a preview of where that can lead.

However, all of these explanations for the onset of the PETM are still just proposals. There is no scientific consensus on the exact cause of the PETM, beyond the fact that it clearly involved a release of greenhouse gases from somewhere.

"I think that in general the jury is still out," says Bowen.

While the PETM's exact cause is still elusive, its effects are clear

Under the more controversial scenarios, like the idea of a passing comet, the trigger for the event and the pace of climate change have very few parallels with the warming our planet is now experiencing.

Under the more plausible scenarios, like the snowballing release of methane from beneath the sea, the parallels with today are clear.

Regardless, while the PETM's exact cause is still elusive, its effects are clear.

Even back in 1991 when it was first described, it was evident that the PETM was a killer.

Other microbes may have taken advantage of those oxygen-poor conditions

Some of the microfossil species preserved in the Antarctic sediments disappeared as the warming began. The species impacted were those that lived deep in the oceans. They experienced their most severe extinction in tens of millions of years.

Curiously, many microscopic species that lived in the shallower ocean waters actually flourished - an early sign that there were winners and losers as the climate changed.

It was probably a combination of factors that killed the deep-sea species. The warmer temperatures would have been unwelcome, but there may also have been less oxygen available in that warmer water.

However, other microbes may have taken advantage of those oxygen-poor conditions.

Some oceanic sediments from the time contain high quantities of an iron-rich magnetic mineral called magnetite. Some species use magnetite in their bodies: either because of its hardness ( it makes good teeth) or its magnetic properties (it can allow some species to orientate themselves with the Earth's magnetic field).

The world's coral reefs faced one of their five greatest crises since they first evolved

Iron can build up in poorly-oxygenated water, so the conditions in the PETM oceans might have led to a radiation of microscopic species using magnetite.

Seawater changed in other ways that were clearly harmful. When the oceans absorb greenhouse gases like carbon dioxide, the process produces a mild acid in the water, lowering the pH: a phenomenon known as ocean acidification. We know it is happening in the world's oceans today, and it happened 55 million years ago too.

Then, as now, ocean acidification was bad news for marine species that build skeletons out of calcium carbonate, because this solid mineral begins to dissolve when the pH drops. Acidification might have been a factor in the deep-sea extinction, and it also affected some shallow living species.

In particular, the world's coral reefs faced one of their five greatest crises since they first evolved 550 million years ago.

There were changes on land too.

In the Arctic, plenty more rain than usual fell during the PETM, probably because stronger ocean evaporation in the tropics delivered more water vapour to higher latitudes.

Seas might have risen by as much as 30m

Geologists have also found evidence, from the styles of rock that formed 55 million years ago, that dry coastal environments were deluged by rising sea levels.

There was little ice to melt, so the sea level rise was probably modest: perhaps in the region of 5m, caused by the expansion of water as it becomes warmer. However, in a worst-case scenario the sea level rise could have been more severe.

For instance, there was magmatic activity in the north Atlantic at roughly this time. That might have warmed up the ocean crust and pushed it upwards, making the oceans shallower than usual and accentuating any sea level rise. Consider factors like this and seas might have risen by as much as 30m.

For life on land, the warm PETM conditions led to dramatic changes.

In Wyoming, plant ranges shifted hundreds of kilometres north as temperatures rose. Conifers apparently disappeared from the area entirely, only returning as temperatures fell after the PETM.

There is strong evidence that about 40% of the mammalian fauna got smaller during the PETM

Some plant species disappeared from the tropics too, but there is evidence that plant diversity actually rose overall here. That may have been a consequence of both the warmer conditions and higher levels of the carbon dioxide plants use to make their food.

The PETM also marks the moment when many of the mammal groups that dominate the world today - including horses, cattle and other hoofed animals - appeared and spread across the northern continents. They probably did so probably in response to the warmer conditions.

But members of these familiar animal groups would have looked odd to our eyes.

"There is strong evidence that about 40% of the mammalian fauna got smaller during the PETM," says Ross Secord at the University of Nebraska in Lincoln. "Nothing appears to have gotten larger."

Some mammals became very small indeed.

In 2012, Secord and his colleagues looked at fossils of Sifrhippus sandrae, a species of early horse that lived in what is now Wyoming.

At the onset of the PETM, when horses first appeared in the fossil record, Sifrhippus was diminutive: it weighed about 5.6kg.

As the temperatures rose, Sifrhippus became even smaller. 130,000 years into the PETM, some adults probably tipped the scales at about 3.9kg: a modest weight for a domestic cat.

At the end of the PETM, as temperatures dropped, Sifrhippus grew again.

Other mammalian herbivores shrank too, and so did some mammalian carnivores.

These size changes might be down to something called Bergmann's rule, says Secord. This says that warm-blooded animals tend to be relatively small in warm regions and larger in cold ones.

When atmospheric CO2 levels rise, the leaves and shoots of plants may become less nutritious

That could be because, in cold regions, it is useful to have a larger body - and a smaller relative surface area - to prevent losing too much body heat.

But Bergmann's rule is usually used to explain why animals in the tropics are smaller than those at higher latitudes, not to explain why animals grew to different sizes as a response to global warming.

Other researchers have suggested other reasons for the PETM changes in mammal size.

In 2013, Philip Gingerich at the University of Michigan in Ann Arbor suggested the mammals might have been responding to changes in vegetation brought on by the PETM.

We have learned a lot about the PETM in the quarter-century since its discovery

When atmospheric CO2 levels rise, the leaves and shoots of plants may become less nutritious and harder for herbivores to digest. If that happened during the PETM, it could have led to slower animal growth, and herbivores might have begun to shrink. Carnivores, forced to target smaller prey, might have followed suit.

Peter Stiling at the University of South Florida in Tampa has investigated this. In 2007 he found that, in a high-CO2 atmosphere, oak leaves did carry less nitrogen. "As a result, herbivores often eat more to compensate," he says.

But there's no direct evidence as yet that herbivores, or the carnivores that eat them, grow more slowly and become smaller adults as a consequence.

We have learned a lot about the PETM in the quarter-century since its discovery, but clearly there are plenty of questions left to answer.

Our particular branch of the primate tree had flourished to such a degree that the world really had become the planet of the apes

One of the most intriguing is whether the warming 55 million years ago was instrumental in the evolution of the first true primates: the group that ultimately gave rise to our species.

Modern primates appeared and spread at the beginning of the PETM, alongside horses and other hoofed animals. Their early fossil record is patchy, but they appear at almost exactly the same time in Asia, Europe, the Americas and Africa.

Within a few tens of millions of years, our particular branch of the primate tree had flourished to such a degree that the world really had become the planet of the apes. About 5 million years later, the first upright apes we recognise as our direct ancestors appeared.

Would primates have become so successful if the PETM had never happened? No one can say for sure.

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When global warming made our world super-hot

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In the late 1980s, as the world's governments were waking up to the problem of climate change, the mud at the bottom of the ocean near Antarctica revealed a surprise. Earth had lived through rapid global warming before. About 55 million years ago global temperatures spiked.

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Posted September 07, 2018 13:49:58

Koalas are on track to be extinct by 2050 in New South Wales if current land clearing rates continue, according to conservation biologist Martin Taylor, who today released a new report on the issue.

The report, released by WWF Australia and the Nature Conservation Council (NCC), used select satellite images of northern NSW to assess land clearing and its impact on vulnerable and endangered species.

Mr Taylor said if the rate of clearing wasn't wound back there could be serious consequences for native wildlife.

"We see koala habitat disappearing at an alarming rate," he said.

"The numbers are low, and everybody out there is telling us that koalas are dropping terribly.

"If we project that forward, it could be mid-century by the time we may have no more wild koalas in NSW."

Mr Taylor's report set out to examine changes in the rate and extent of land clearing in north-central NSW following the repeal of the Native Vegetation Act (2003) last year and the impact of the current Biodiversity Conservation Act.

Mr Taylor described the moves as "taking the axe to native vegetation laws".

His report found that from 2016-17 to 2017-18 the rate of land either fully or partly cleared almost tripled, from 2,845 hectares to 8,194 hectares.

The NSW Government has rubbished Mr Taylor's warning of possible koala extinction, with the NSW Environment Minister's office releasing a statement pointing to its ongoing koala strategy.

"The WWF and NCC are playing politics and scaremongering," the statement read.

"The NSW Government's Koala Strategy - the biggest commitment by any state government to secure koalas in the wild - will provide more natural habitat for koalas, tackle diseases, improve research and fix roadkill hotspots.

"The NSW Government has committed $45 million for this strategy."

In July, the NSW Department of Primary Industries also reported it had used ground-breaking recording techniques to find koala numbers were far higher than first thought.

'Satellites don't lie'

Richard Kingsford is a professor of environmental science and the director of the Centre for Ecosystem Science at UNSW.

He said the methodology of the WWF/NCC paper appeared sound, but the prediction of possible koala extinction by 2050 was "blunt".

"[The report] seems to be rigorously done ... the satellite imagery doesn't lie," he said.

"It's clearly identified that clearing has gone on - that seems incontrovertible - I think the more difficult leap is what does that mean in terms of potential extinction of species.

"I think once you get into predictions there are a whole lot of unknowns.

"Like you're assuming the farmers are going to keep clearing at the same rate, you're assuming that governments don't change their policies."

Professor Kingsford said while NSW did have some protected zones and policies to preserve wildlife, his understanding was there was nothing to stop the current level of land clearing.

"That was clearly the intention when the Biodiversity Act came in and the Vegetation Management Act was essentially brought into the Biodiversity Act," he said.

"It was quite clear that the government wanted to allow for farmers to have more opportunity to clear their land."

Topics: conservation, environment, animals, government-and-politics, australia

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Koalas 'on track to be extinct in NSW by 2050'

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Posted September 07, 2018 13:49:58 Koalas are on track to be extinct by 2050 in New South Wales if current land clearing rates continue, according to conservation biologist Martin Taylor, who today released a new report on the issue.

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Moving from single cellular to multi cellular life 

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Moving from single cellular to multi cellular life 

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Billions of years ago, life crossed a threshold. Single cells started to band together, and a world of formless, unicellular life was on course to evolve into the riot of shapes and functions of multicellular life today, from ants to pear trees to people. It's a transition as momentous as any in the history of life, and until recently we had no idea how it happened.

The gulf between unicellular and multicellular life seems almost unbridgeable. A single cell's existence is simple and limited. Like hermits, microbes need only be concerned with feeding themselves; neither coordination nor cooperation with others is necessary, though some microbes occasionally join forces. In contrast, cells in a multicellular organism, from the four cells in some algae to the 37 trillion in a human, give up their independence to stick together tenaciously; they take on specialized functions, and they curtail their own reproduction for the greater good, growing only as much as they need to fulfill their functions. When they rebel, cancer can break out.

Multicellularity brings new capabilities. Animals, for example, gain mobility for seeking better habitat, eluding predators, and chasing down prey. Plants can probe deep into the soil for water and nutrients; they can also grow toward sunny spots to maximize photosynthesis. Fungi build massive reproductive structures to spread their spores. But for all of multicellularity's benefits, says László Nagy, an evolutionary biologist at the Biological Research Centre of the Hungarian Academy of Sciences in Szeged, it has traditionally "been viewed as a major transition with large genetic hurdles to it."

Now, Nagy and other researchers are learning it may not have been so difficult after all. The evidence comes from multiple directions. The evolutionary histories of some groups of organisms record repeated transitions from single-celled to multicellular forms, suggesting the hurdles could not have been so high. Genetic comparisons between simple multicellular organisms and their single-celled relatives have revealed that much of the molecular equipment needed for cells to band together and coordinate their activities may have been in place well before multicellularity evolved. And clever experiments have shown that in the test tube, single-celled life can evolve the beginnings of multicellularity in just a few hundred generations-an evolutionary instant.

Evolutionary biologists still debate what drove simple aggregates of cells to become more and more complex, leading to the wondrous diversity of life today. But embarking on that road no longer seems so daunting. "We are beginning to get a sense of how it might have occurred," says Ben Kerr, an evolutionary biologist at the University of Washington in Seattle. "You take what seems to be a major step in evolution and make it a series of minor steps."

Hints of multicellularity date back 3 billion years, when impressions of what seem to be mats of microbes appear in the fossil record. Some have argued that 2-billion-year-old, coil-shaped fossils of what may be blue-green or green algae-found in the United States and Asia and dubbed Grypania spiralis -or 2.5-billion-year-old microscopic filaments recorded in South Africa represent the first true evidence of multicellular life. Other kinds of complex organisms don't show up until much later in the fossil record. Sponges, considered by many to be the most primitive living animal, may date back to 750 million years ago, but many researchers consider a group of frondlike creatures called the Ediacarans, common about 570 million years ago, to be the first definitive animal fossils. Likewise, fossil spores suggest multicellular plants evolved from algae at least 470 million years ago.

Plants and animals each made the leap to multicellularity just once. But in other groups, the transition took place again and again. Fungi likely evolved complex multicellularity in the form of fruiting bodies-think mushrooms-on about a dozen separate occasions, Nagy concluded in a preprint posted 8 December 2017 on bioRxiv, based on a review of how different species of fungi-some single-celled, some multicellular-are related to one another. The same goes for algae: Red, brown, and green algae all evolved their own multicellular forms over the past billion years or so.

Nicole King, a biologist at the University of California (UC), Berkeley, found a revealing window on those ancient transitions: choanoflagellates, a group of living protists that seems on the cusp of making the leap to multicellularity. These single-celled cousins of animals, endowed with a whiplike flagellum and a collar of shorter hairs, resemble the food-filtering "collar" cells that line the channels of sponges. Some choanoflagellates themselves can form spherical colonies. More than 2 decades ago, King learned to culture and study these aquatic creatures, and by 2001 her genetic analyses were starting to raise doubts about the then-current view that the transition to multicellularity was a major genetic leap.

Her lab began turning up gene after gene once thought to be exclusive to complex animals-and seemingly unneeded in a solitary cell. Choanoflagellates have genes for tyrosine kinases, enzymes that, in complex animals, help control the functions of specialized cells, such as insulin secretion in the pancreas. They have cell growth regulators such as p53, a gene notorious for its link to cancer in humans. They even have genes for cadherins and C-type lectins, proteins that help cells stick together, keeping a tissue intact.

All told, by surveying the active genes in 21 choanoflagellate species, King's group found that these "simple" organisms have some 350 gene families once thought to be exclusive to multicellular animals, they reported on 31 May in eLife. If, as she and others believe, choanoflagellates offer a glimpse of the one-celled ancestor of animals, that organism was already well-equipped for multicellular life. King and her lab "have put protists at the front of research to address animal origins," says Iñaki Ruiz-Trillo, an evolutionary biologist at the Spanish National Research Council and Pompeu Fabra University in Barcelona, Spain.

You take what seems to be a major step in evolution and make it a series of minor steps.

Ben Kerr, University of Washington in Seattle

The ancestral versions of those genes might not have done the same jobs they later took on. For example, choanoflagellates have genes for proteins crucial to neurons, and yet their cells don't resemble nerve cells, King says. Likewise, their flagellum has a protein that in vertebrates helps create the body's left-right asymmetry, but what it does in the single-celled organism is unknown. And choanoflagellate genomes don't anticipate multicellularity in every respect; they lack some critical genes, including transcription factors such as Pax and Sox, important in animal development. The missing genes give us "a better idea of what the actual animal innovations were," King says.

As cells banded together, they didn't just put existing genes to new uses. Studies of Volvox, an alga that forms beautiful, flagellated green balls, shows that multicellular organisms also found new ways to use existing functions. Volvox and its relatives span the transition to multicellularity. Whereas Volvox individuals have 500 to 60,000 cells arranged in a hollow sphere, some relatives, such as the Gonium species, have as few as four to 16 cells; others are completely unicellular. By comparing biology and genetics along the continuum from one cell to thousands, biologists are gleaning the requirements for becoming ever more complex. "What this group of algae has taught us is some of the steps involved in the evolution of a multicellular organism," says Matthew Herron, an evolutionary biologist at the Georgia Institute of Technology in Atlanta.

These studies show that many functions of specialized cells in a complex organism are not new. Instead, features and functions seen in single-celled organisms are rearranged in time and space in their multicellular relatives, says Corina Tarnita, a theoretical biologist at Princeton University. For example, in a unicellular relative of Volvox, Chlamydomonas, organelles called centrioles do double duty. For much of the cell's lifetime they anchor the two whirling flagella that propel the cell through the water. But when that cell prepares to reproduce, it loses the flagella, and the centrioles move toward the nucleus, where they help pull apart the dividing cell's chromosomes. Later, the daughter cells each regrow the flagella. Chlamydomonas can both swim and reproduce, but not at the same time.

Multicellular Volvox can do both at once, because its cells have specialized. The smaller cells always have flagella, which sweep nutrients over the Volvox's surface and help it swim. Larger cells lack flagella and instead use the centrioles full time for cell division.

Multicellularity made easy

Researchers got single-cell yeast to evolve multicellularity in the lab, demonstrating the relative ease of the transition.

2 Multicellularity 1 Selection 3 Differentiation 4 Bottleneck 5 Group-level selection New mutation As single yeast cells grow, the larger ones sink faster. Only those cells are allowed to reproduce; repeated rounds of selection result in ever-bigger yeast. Some cell assemblages do better than others and thrive; others do not. Each freed tip proliferates, and many varieties of multicellular snowflakes form. A few cells specialize to die early, releasing the cells at the tips of the snowflake to start new snowflakes. A single mutation causes a reproducing yeast's daughter cells to stick together. Branching snowflake structures form. Daughter cells

Volvox has repurposed other features of the single cell ancestor as well. In Chlamydomonas, an ancient stress response pathway blocks reproduction at night, when photosynthesis shuts down and resources are scarcer. But in Volvox, the same pathway is active all the time in its swimming cells, to keep their reproduction permanently at bay. What was a response to an environmental signal in the single cell ancestor has been co-opted for promoting division of labor in its more complex descendent, Kerr says.

A third set of organisms hints at how this repurposing of existing genes and functions could have taken place. Over the past decade, Ruiz-Trillo and his colleagues have compared more than a dozen protist genomes with those of animals-a comparison that underscored the greater size and complexity of the animal genomes, they reported on 20 July in eLife. But a more telling finding came when Ruiz-Trillo; Arnau Sebé-Pedrós, now at the Weizmann Institute of Science in Rehovot, Israel; and Luciano di Croce at Barcelona's Centre for Genomic Regulation analyzed the protist Capsaspora's portfolio of gene-regulating signals. They found that the protist uses some of the same molecules as animals to turn genes on and off at particular times and places: proteins called transcription factors and long strands of RNA that don't encode proteins. But its promoters-the regulatory DNA that interacts with transcription factors-were much shorter and simpler than in animals, the groups reported on 19 May 2016 in Cell, suggesting less sophisticated regulation.

To Ruiz-Trillo and his team, the finding points to a key to multicellularity: increased fine-tuning of gene regulation. What seemed a vast leap from single-celled ancestors looks less daunting if it was partly a matter of resetting the genetic switches, enabling existing genes to be active at new times and places. "This is what evolution always does, makes use of things that are around for new purposes," says William Ratcliff of Georgia Tech.

That thrifty repurposing may explain the swift transitions that have unfolded in Ratcliff 's lab. Instead of looking at the fossil record or comparing genomes of existing organisms, he has recreated evolution in lab cultures. "My own research has been not try to find out what happened in the real world, but to look at the process of how cells evolve increased complexity," he explains.

As a postdoc working with Michael Travisano at the University of Minnesota in St. Paul, Ratcliff subjected yeast cultures to a form of artificial selection. He allowed only the biggest cells-measured by how fast they settled to the bottom of the flask-to survive and reproduce. Within 2 months, multicellular clusters began to appear, as newly formed daughter cells stuck to their mothers and formed branching structures.

As each culture continued to evolve-some have now been through more than 3000 generations-the snowflakes got bigger, the yeast cells became more durable and more elongated, and a new mode of reproduction evolved. In large snowflake yeast, a few cells along long branches undergo a form of suicide, releasing the cells at the tip to start a new snowflake. The dying cell sacrifices its life so that the group can reproduce. It's a rudimentary form of cell differentiation, Ratcliff explains. He has just started to explore the genetic basis of these fast appearing traits; it appears to be a mix of existing genes being co-opted for new functions and other genes-such as one that helps dividing yeast cells separate-becoming disabled.

The yeast also developed a safeguard that is key to multicellularity: a way to keep cellular cheaters at bay. Such cheaters arise when mutations make some cells different from others, and possibly less cooperative. In complex organisms such as humans, protection comes in part from having an immune system to destroy aberrant cells. It also depends on a bottleneck between generations, in which a single cell (a fertilized egg, for example) serves as the starting point for the next generation. The result is that all cells in the new generation start out genetically identical. Snowflake yeasts have their own way of purging themselves of deviant cells. Because mutations accumulate over time, the most aberrant cells are found at the tips of the snowflakes. But they break off to form new colonies before they have a chance to become cheaters.

This mechanism also enables group traits to evolve in the yeast. Mutations in the cells released from each snowflake branch are passed on to all cells in the next colony. Consequently, subsequent snowflakes start out with new group traits-in the size and number of cells or the frequency and locations of suicide cells, for example-that become grist for further evolution. From that point on, it's the assemblage, not individual cells, that's adapting.

The yeast results weren't a fluke. In 2014, Ratcliff and his colleagues applied the same kind of selection for larger cells to Chlamydomonas, the single-celled alga, and again saw colonies quickly emerge. To address criticism that his artificial selection technique was too contrived, he and Herron then repeated the Chlamydomonas experiment with a more natural selective pressure: a population of paramecia that eat Chlamydomonas -and tend to pick off the smaller cells. Again a kind of multicellularity was quick to appear: Within 750 generations-about a year-two of five experimental populations had started to form and reproduce as groups, the team wrote on 12 January in a preprint on bioRxiv.

If multicellularity comes so easy, why did it take several billion years after the origin of life for complex organisms to become firmly established? Traditionally, researchers have blamed the early atmosphere's low oxygen levels: To get enough oxygen, organisms needed the highest possible ratio of surface to volume, which forced them to stay small. Only after oxygen levels rose about 1 billion years ago could larger, multicellular organisms arise.

In 2015, however, Nicholas Butterfield, a paleontologist at the University of Cambridge in the United Kingdom, proposed that low oxygen levels actually favored the evolution of multicellularity in ancient marine organisms. Larger, multicellular organisms-with multiple flagella-were better at sweeping water past their cell membranes to harvest oxygen. Scarce nutrients in the ancient seas would have helped drive the next step, the evolution of specialized cell types, because more complex organisms can harvest food more efficiently. As for why complex organisms took so long to emerge, Butterfield thinks the lag reflects the time it took to evolve the more sophisticated gene regulation needed for multicellularity.

Butterfield's theory "is really quite elegant and simple, building on first principles of physics and chemistry, set into a deep geochemical, biogeochemical, and biophysical context," says Richard Grosberg, an evolutionary biologist at UC Davis.

Once organisms had crossed the threshold to multicellularity, they rarely turned back. In many lineages, the number of types of cells and organs continued to grow, and they developed ever-more-sophisticated ways to coordinate their activities. Ratcliff and Eric Libby, a theoretical biologist at Umeå University in Sweden, proposed 4 years ago that a ratcheting effect took over, driving an inexorable increase in complexity. The more specialized and dependent on one another the cells of complex organisms became, the harder it was to revert to a single-cell lifestyle. Evolutionary biologists Guy Cooper and Stuart West at the University of Oxford in the United Kingdom recently confirmed that picture in mathematical simulations. "Division of labor is not a consequence but a driver" of more complex organisms, Cooper and West wrote on 28 May in Nature Ecology & Evolution.

Touched off by the initial transition from one cell to many, a cycle of increasing complexity took hold, and the richness of multicellular life today is the result.

doi:10.1126/science.aau5806

Liz is a senior correspondent covering many aspects of biology for Science.

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The momentous transition to multicellular life may not have been so hard after all

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Billions of years ago, life crossed a threshold. Single cells started to band together, and a world of formless, unicellular life was on course to evolve into the riot of shapes and functions of multicellular life today, from ants to pear trees to people.

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You can support the continuation of this respected program by contributing to Australian Museum StreamWatch, discover how today.

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According to Darwins approach:
Big book full of evidence
Give Examples
Gather Supporters
Stick to your guns
Ignore the side shows

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Teacher directed questioning to expose the misconception, break down the thinking process and build it up once again in the proper direction

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What do you do about persistent misconception?

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What do you do about persistent misconception?

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Challenge their current understanding by questions to lead them realise the flaws in their understanding. Also, reinforce the appropriate conception in daily teaching and learning, create opportunities to make them "live" with it when they are doing science. Be consistent with the acceptable conception, so remind them and correct them when they express their ideas which could lead to misconceptions.

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PErsistent misconceptions.  How do we sort it out?

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PErsistent misconceptions.  How do we sort it out?

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What do you do about a persistent misconception?

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What do you do about a persistent misconception?

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Core Science 5

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What does a school textbook say about evolution?

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What does a school textbook say about evolution?

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From the Oxford Science Insight: "evolution is a gradual change in the genetic material of a population of organisms over a period of time."
(which could be understood as mutation)

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Year 11-friendly website and the current belief

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Year 11-friendly website and the current belief

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http://discovermagazine.com/2014/march/12-mutation-not-natural-selection-drives-evolution

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school textbook definition of evolution driving

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school textbook definition of evolution driving

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evolution is driven most powerfully by interactions between species, rather than adaptation to the environment.  https://phys.org/news/2010-02-scientists-reveal-evolution.html

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My belief: mutation drives evolution. Natural selection is the secondary driving force/process of evolution.

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Evolution is driven by the various harsh environments that organisms live in, and those organisms ability to flounder or strive in said environments. Organisms that have traits suited to the environment they live in are more likely to survive to reproduce, and pass on their characteristics

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What drives evolution? Environmental pressures (abiotic/biotic)

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My idea -
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Cambridge definition of evolution - Evolution is the process by which the physical characteristics of types of creatures change over time, new types of creatures develop, and others disappear.
kid version -  Natural selection means that some individuals in a species are better at surviving than others and will have more children.

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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2761324/

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Evolution is driven by selective pressures on all organisms, shaping the rate of survival and creating offspring that inherit helpful traits from their parents. (My belief).

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https://news.nationalgeographic.com/2016/07/animals-platypus-evolution-science/

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https://australianmuseum.net.au/obdurodon-dicksoni
Modern Platypus doesn't have teeth, they crush their prey using their bills. However, this ancestor of the platypus does have teeth (molars), suggesting that over time, since there was no need for teeth, that their teeth reduced fully.

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Identify students' misconceptions
Provide opportunities  for students to confront their misconceptions
Then teachers should help students reconstruct their knowledge by using scientific models.

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Identify and alleviate student misconceptions by providing alternative ways of looking at concepts and statements. Teacher can debunk these misconceptions by providing correct explanations to overcome

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400x magnification

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A new study led by scientists from the University of Bristol has used a combination of genomic and fossil data to explain the history of life on Earth, from its origin to the present day.

Palaeontologists have long sought to understand ancient life and the shared evolutionary history of life as a whole.

However, the fossil record of early life is extremely fragmented, and its quality significantly deteriorates further back in time towards the Archaean period, more than 2.5 billion years ago, when the Earth's crust had cooled enough to allow the formation of continents and the only life forms were microbes.

Holly Betts, lead author of the study, from the University of Bristol's School of Earth Sciences, said: "There are few fossils from the Archaean and they generally cannot be unambiguously assigned to the lineages we are familiar with, like the blue-green algae or the salt-loving archaebacteria that colours salt-marshes pink all around the world.

"The problem with the early fossil record of life is that it is so limited and difficult to interpret -- careful reanalysis of the some of the very oldest fossils has shown them to be crystals, not fossils at all."

Fossil evidence for the early history of life is so fragmented and difficult to evaluate that new discoveries and reinterpretations of known fossils have led to a proliferation of conflicting ideas about the timescale of the early history of life.

Co-author Professor Philip Donoghue, also from Bristol's School of Earth Sciences, added: "Fossils do not represent the only line of evidence to understand the past. A second record of life exists, preserved in the genomes of all living creatures."

Co-author Dr Tom Williams, from Bristol's School of Biological Sciences, said: "Combining fossil and genomic information, we can use an approach called the 'molecular clock' which is loosely based on the idea that the number of differences in the genomes of two living species (say a human and a bacterium) are proportional to the time since they shared a common ancestor."

By making use of this method the team at Bristol and Mark Puttick from the University of Bath were able to derive a timescale for the history of life on Earth that did not rely on the ever-changing age of the oldest accepted fossil evidence of life.

Co-author Professor Davide Pisani said: "Using this approach we were able to show that the Last Universal Common Ancestor all cellular life forms, 'LUCA', existed very early in Earth's history, almost 4.5 Billion years ago -- not long after Earth was impacted by the planet Theia, the event which sterilised Earth and led to the formation of the Moon.

"This is significantly earlier than the currently accepted oldest fossil evidence would suggest.

"Our results indicate that two "primary" lineages of life emerged from LUCA (the Eubacteria and the Archaebacteria), approximately one Billion years after LUCA.

"This result is testament to the power of genomic information, as it is impossible, based on the available fossil information, to discriminate between the oldest eubacterial and archaebacterial fossil remains."

The study confirms modern views that the eukaryotes, the lineage to which human life belongs (together with the plants and the fungi, for example), is not a primary lineage of life. Professor Pisani added: "It is rather humbling to think we belong to a lineage that is billions of years younger than life itself."

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nature; evolutionary biology; microbes and more; geology; earth science; near-earth object impacts; fossils; origin of life; evolution

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A timescale for the origin and evolution of all of life on Earth

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A new study led by scientists from the University of Bristol has used a combination of genomic and fossil data to explain the history of life on Earth, from its origin to the present day. Palaeontologists have long sought to understand ancient life and the shared evolutionary history of life as a whole.

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When is an orchid not an orchid? When it's a female orchid praying mantis, a Southeast Asian insect that masquerades as a flower to attract prey.

With petal-like legs and a yellow or whitish pink color, females share little resemblance to males, which are about half the size and sport a dull, greenish brown color.

Now, new research shows that male and female orchid mantises don't just look different-they evolved in a way never before seen in arthropods, the group that includes spiders and insects. (See pictures of amazing insect camouflage.)

The research suggests that the females' strategy of hunting pollinating insects shaped the two known species' evolution, leading to big females that resemble orchids and small males adept at hiding.

Making of a Huntress

To learn more about how female and males evolved, Gavin Svenson of the Cleveland Museum of Natural History and colleagues measured the body sizes of over a hundred orchid mantises with a stereomicroscope in the lab. They also modeled how some of their evolutionary traits, such as color, developed over time.

Lastly, the researchers studied the evolutionary relationships of orchid mantises and their distant relatives, allowing the team to reconstruct the shifts that led to the orchid mantises' unusual appearance. ( See beautiful pictures of orchids from around the world.)

The results suggest that the orchid mantises' ancestors began hanging around flowers at some point, providing them with access to more food options in the form of pollinators.

"Then, a small group within this lineage started evolving larger females to take advantage of all the pollinating insects that visit flowers," says Svenson, whose study appeared recently in the journal Scientific Reports. The bigger the female, the more variety of prey she can take down-both large and small.

"The first lineage that branched off exhibited the same color patterns as most other mantis [species], which is a green-black pattern that breaks up the outline of the body and makes it harder for predators to spot them," says Svenson.

The next evolutionary change took place when females of the two orchid mantis species developed their conspicuous yellow, white, and pink colors.

This meant the big, colorful female orchid mantises could attract insect prey by mimicking flowers. Male orchid mantises, however, remained small and camouflaged, allowing them to avoid predators, seek out mates, and ambush prey. (Also see " A Plant That Looks Like Poop and Other Sneaky Disguises.")

"We think the males remain small because they need to move around the environment to find females and mate," says Svenson. "If you look like a giant conspicuous flower and you're actively moving around, you give yourself away."

Bigger and Brighter

That difference in hunting strategy-previously unknown among arthropods-also likely drove the evolution of bigger and more brightly colored females, he adds.

Although larger females are common in many arthropods-think black widow spiders-it's usually because bigger females produce more eggs and smaller males are more agile at courting them, notes Hojun Song, an entomologist at Texas A&M University who was not involved in this research.

But in this case, larger females evolved from their predatory success-an "entirely novel" discovery, Song says.

"People ask why studying evolutionary relationships or getting accurate species classifications is valuable, and this experiment is an example of a good answer," notes Svenson.

"Once you know the true lineages, you can do interesting research that gives you unique perspective into how evolution works and how things change."
Follow Mary Bates on Twitter and Facebook.

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Praying Mantis Looks Like a Flower-And Now We Know Why

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When is an orchid not an orchid? When it's a female orchid praying mantis, a Southeast Asian insect that masquerades as a flower to attract prey. With petal-like legs and a yellow or whitish pink color, females share little resemblance to males, which are about half the size and sport a dull, greenish brown color.