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External:

broad head

heavy paws

powerful non-retractile claws

fur coats

short tail

small rounded ears

males are larger than females (sometimes double their size)

different species vary in height

Internal:

extended jaws

small eyes

massive frames, heavily built

large, sharp and powerful teeth

large, elongated skulls

strong sense of smell

Behavioral:

intelligent, curious, playful, social with siblings and mother when young

solitary as adults

protective of their young

have a slow reproductive rate (take about 4-6 years to reach sexual maturity)

Males and females tend to mate in the female's territory

they can (some tend to) mate with different partners each breeding season

most are omnivores and eat a wide range of foods (vegetation, fruits, honey, human food, fish, meat, etc.

will travel long distance for food

some climb trees with their strong claws to find food

some hibernate during winter

Habitat:

found on all continents except Antarctica and Australia

mostly in the northern hemisphere

hey can live in a variety of habitats from species to species - from a tropical rainforest to the arctic region

the majority live in areas that are wooded (forests) and/or mountainous

land-dwelling (terrestrial) mammals

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-All of the fossils have similar skull structures and teeth, so they are related
-the more similar the bone structures of the fossils are, shows how closely related the species (former and present) are
-In this photo, it shows 3 different panda species
-A and D are Ailuropoda microta (shown in fossil evidence #1)
-B and E are Ailuropoda Baconi (descendant of Ailuropoda microta, and ancestor of the modern giant panda)
-C and F are Ailuropoda melanoleuca, the current panda species
-this shows how the pandas have evolved (slightly larger skulls and broader teeth), but they are still very closely related and resemble each other

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Giant Panda Bears (Ailuropoda melanoleuca)

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Giant Panda Bears (Ailuropoda melanoleuca)

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Physical Characteristics:
-distinctive black and white coat (markings)
-black fur around their eyes and on their ears, muzzle, legs and shoulders
-their thick, wooly coat helps keep them warm in their mountainous home (cool  climate)
-rounder heads than other bears
-stocky build
-larger shoulders and neck, smaller back
-powerful jaws
-wide, flat molar teeth for crushing bamboo
-a larger wrist bone that functions like an opposable thumb (called

"the panda's thumb")
-4 to 6 feet tall
-females weigh 150 – 220 lbs
-males weigh 200-250 lbs

Behavioral Characteristics:
-relaxed, laid-back, mostly just rest and eat
-a very low threat to humans
-physiologically, giant pandas are meant to be carnivores
-therefore they are vegetarians (not herbivores)
-Bamboo makes up 99% of their diet
-do not hibernate
-migrate down the mountains to stay warm during winter
-communicate with one another by leaving scent marks
-Female pandas ovulate for a very short time (once a year in the spring for only 2-3 days)
-part of why they're endangered
-may appear sedentary or lethargic, but they are skilled tree-climbers and efficient swimmers
Habitat Requirements:
-live only in remote, mountainous regions in central China
-mostly within the provinces of Sichuan, Gansu, and Shanxi
-live in high bamboo forests that are cool and wet

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Physical Characteristics:
-smallest member of the bear family
-4 to 5 ft long
-60 to 150 lbs
-bib-shaped golden or white patch on their chest (legend says it represents the rising sun)
-stocky, muscular build
-wide, flat head
-small ears and a short muzzle, which has earned them the nickname “dog bear"
-sleek & dark black or brown-
black fur
-coat is short to avoid overheating in the tropical weather
-although, it is thick & coarse to protect them from twigs, branches, and rain, etc.
-grow to only about half the size of an American black bear
-very long claws and strong legs for climbing  trees
-strong, long claws also for tearing termite nests and ripping open trees
-very long tongue for getting honey from bee nests
-loose skin that allows them to twist when being bitten, to protect from predators

Behavioral Characteristics:
-shy & reclusive
-live in trees, great (agile) climbers
-sleep and relax in trees at heights from 2 to 7 meters
-nocturnal, active at night
-omnivores (bees, termites, earthworms, fruit, etc.)
-may be monogamous
-dont’ hibernate
-can get food all year long & can mate at any time of year
-this is because they live in warm/tropical temps
-male and female sun bears may stay together while raising the cubs (unlike north american bears)
-usually have two cubs at a time and care for them for two years

Habitat Requirements:
-live in the dense lowland forests of Southeast Asia
-can be found from southern China to eastern India and as far south as Indonesia
-also called Malayan sun bears
-remote habitat

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Physical Characteristics:
- 7.25 to 8 ft, and about 900 to 1,600 lbs
-a thick coat of insulated fur & a warm layer of fat underneath
-white fur, which helps them camouflage with the snow and ice
-large front paws, which they use to paddle through water (slightly webbed)
-elongated back paws
-hind limbs are longer than the forelimbs. This makes the (large and muscular) hind end stand higher than the shoulders
-more slender bodies and longer necks and heads than other bears
-oblong head, elongated muzzle, and slightly arched snout
- the sole of a polar bear's foot has thick, black pads covered with small, soft dermal bumps called papillae
-the papillae (and paw fur) create friction between the paw and ice to prevent them from slipping
-black skin under fur to attract heat

-the largest land carnivore

Behavioral Characteristics:
- powerful predators
-the most carnivorous of the bear species
-feed primarily on seals
-great swimmers
-solitary
-can be harmful to humans
Habitat Requirements:
-have a ¨circumpolar distribution¨
-they are distributed throughout the Arctic region (North Pole) in 19 subpopulations
-including Alaska, Canada, Russia, Greenland and Norway
-Ursus maritimus, means sea bear
-frequently seen along or near coasts and on islands, but they spend the majority of their lives on the sea ice

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#1 - Ailuropoda microta

-called the pygmy panda

-from about 2 to 3 million years ago

-Cenozoic era
-It´s the oldest known species of the genus Ailuropoda (which includes the modern giant panda)

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#2 - Arctodus Simus

-from 12,500 to 800,000 years ago, during the ice age
-called the short-faced bea
-Pleistocene Epoch
-believed to have evolved from Plionarctos
- Pilonarctos is the oldest known genus of the subfamily Tremarctinae.

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Bears share homologous structures like:

broad skulls

extended jaws

massive frames

heavy paws

powerful claws

Specifically, some bear species are smaller than others, such as the sun bear.  This means some of these structures will be a little different, like the skull and body size, etc.  Something that all bears have are powerful, sturdy, broad paws.  They provide bears with balance, tools for hunting, eating and fighting, padded soles for protection (like Polar bears on the ice), to paddle when swimming, and so on
-the fact that these structures are so similar across the entire Family of Ursidae, demonstrates that they have evolved from a common ancestor

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#3 - Protarctos abstrusus

-3 to 3.3 million years ago
-mid-Pliocene warm phase
-called the Basal Ursine bear

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#4 - Ursus spelaeus

-Pleistocene epoch
-18,000-25,000 years ago

-The genome is among the oldest ever reconstructed outside of a permafrost environment
-called a cave bear

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#5 - Ursus Minimus

-approximately 5.3 million years ago
-Pliocene epoch
-also known as the Auvergne bear
-evolved from bout 5.3 million years ago

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Example of DNA evidence:

-a Polar Bear jawbone fossil (found in Norwegian coastal cliffs) showed that polar bears evolved from brown bears

¨...they [the scientists] had reconstructed the sequence of the bear's mitochondrial DNA.¨

-they found the polar and brown bears DNA to be very similar, with low nucleotide diversity

This shows that:
-Low levels of nucleotide diversity
-Leads to low levels of diversity in genetics
-which leads to low levels of diversity in the species & family
- Genetic difference due to reproductive isolation

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Even without any other information, the taxonomy of organisms can tell you a lot about the relatedness of species.  Each classification of a species is based directly on specific characteristics. Therefore, with every additional level of taxonomy two organisms share, the closer related they are (because they share those specific characteristics).

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Polar Bear:
-stabilizing selection
-in stabilizing selection, the population mean stabilizes on a certain ¨non-extreme trait value¨
-the white fur color allele was passed onto future generations, leading to a large decrease in the number of brown bears
-the average/means fur color trait helps them camouflage with the snow and ice of their habitat
Giant Panda Bear:
-Directional Selection
-when the extreme trait is the most desirable
-for the Panda, the trait is adapting to a bamboo diet
-Because of global warming, Pandas had to adapt and learn to eat Bamboo
-Global warming caused water to become hot, killing some fish (large part of the panda´s diet back then)
-forced the Pandas to find new food, and they've adapted well to bamboo
Sun Bear:
-Directional Selection
-an extreme trait provides the most benefits
-The sun bear´s trait is its sharp, long, powerful claws
-These are extremely helpful to this organism when they climb trees to get and eat food, rest, etc.

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-Embryology shows the more similar different species embryos look (similar structures), the more closely related they are
-This can help show the relationship between the two species in early stages of development
-each species of bear, no matter how different they look as adults, start with a very similar figure
-as embryos, different bear species all had very similar paws (round, wide, and soon to be powerful), and similar head (shape) and muzzles

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Giant Panda Bear
Animalia
Chordata
Mammalia
Carnivora
Ursidae
Ailuropoda
melanoleuca

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Polar Bear
Animalia
Chordata
Mammalia
Carnivora
Ursidae
Ursus
maritimus

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-Bears evolve gradually (speciation is called gradualism)
- They evolved from the carnivoran mammals and ancestral bears, which existed millions of years ago.
- Their evolution has been a rather long process, and there doesn't seem to be any big jumps in the process

¨Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans.¨

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Sun Bear
Animalia
Chordata
Mammalia
Carnivora
Ursidae
Helarctos
malayanus

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-Bears follow Divergent Evolution
-Bear species evolved from a common ancestor
-my exemplary organisms (polar Bear, Giant Panda Bear, and Sun Bear) each belong to the Family of Ursidae
-The family diverged from Common ancestral carnivorans into ursidae, then into different species, shown in the photo

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Polar Bear
- Random mating
- Males find their chosen female by following their scent
-Two males may fight over a female
-Polar bears couples only stay together for about a week before they separate
-polygynous
Panda Bear
- Random mating
- The female panda will attract her mate with scent-marking (rubbing against trees and peeing) and bleating calls
Sun Bear
- Random mating
-they choose the first mate they see, because there aren´t many of them
-it is hard to find a mate (sun bears are one of the rarest bears)
-may exhibit delayed implantation
-breed year round (because they live in warm weather and don´t need to hibernate)

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-This Phylogenetic Tree shows
how the Family of Ursidae is split up
-There are 5 genus´ in the family
-There are only 8 extant (still living) species left
-all from a common ancestor (ancestral bear)

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-Descent with modification is one of the two theories of evolution that explains how organisms have evolved over time
-It is simply the passing of traits from parents to offspring, and the evolution (changes) in the offspring that occurs over the course of many generations
- The process of passing genetic traits down in this way is called Heredity

The theory of Descent with Modification is shown throughout the Family of Ursidae in the following ways:
-The parents sex chromosomes pass down their traits (alleles) to their children, like humans
-Although, something particular about Bears is the fact that (a study showed) the male´s ¨...Y-linked genes evolved faster than autosome and X-linked genes, consistent with expectations based on male-driven evolution.¨
-This theory also works in conjunction with natural selection.  The traits (that help the bears survive better) are ¨selected¨, and passed on to the next generation
-Once this spreads to the majority of the population, the species has evolved

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-No differences were found between the two species´ karyotypes.
-Both have the same number and type of chromosomes
-the two Bears are closely related according to their chromosomes and karyotype

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-many Bears deal with Reproductive Isolation
-the Polar Bear lives on ice (like an island)
-the Panda Bear lives in a mountainous region
-Sun bears live on an island or peninsula, in a remote habitat
-These species are isolated and rarely breed with other types of bears
-Although, polar bears have tried to mate with brown bears, but they are too different to be considered the same species