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Ecology and Evolution: the Creation of Biodiversity

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Divergence along the tree of lifeAn ancestral bear evolved giving rise to many species of bear, which occupy many different niches – in many different habitats.

Grizzly bears and polar bears split from their common ancestor only about 500,000 years ago.

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Wild Canine Adaptations

The canine lineage, in terms of its evolution has been very successful.

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An Artiodactyl Family Tree

Notice the inclusion of whales on the artiodactyl family tree.

Fossil, anatomical, and DNA research has unequivocally shown that whales are a highly modified form of two-toed, hoofed, mammal.

Their closest “terrestrial” relative is the hippo.

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Convergent Evolution: very different species filling the same niches

Sometimes convergent evolution modifies different body parts to look the same and perform the same function.

In this case, insect wings were derived from insect-exoskeleton, while bird and bat wings were derived from forelimbs with an internal skeleton.

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Convergent Evolution: very different species filling the same niches

In the case of bats and birds, the same forelimb structures were modified independently for flight in very different groups (mammals and birds).

As you can see, bats fly with the tips of their fingers while birds fly with their shoulders and arms.

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Convergent Evolution of MammalsMarsupial and placental mammals, case studies in convergent evolution.

The same or similar niches produce great similarities in very different species.

Example of two species cannot occupy the same niche.

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Convergent Evolution of Marine Predators

The Tree of Life contains many remarkable examples of convergent evolution, which attest to the great power of natural selection to adapt different organisms to similar environments.

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What do the mean?

• What does divergent mean?• What does convergent mean?• What does the tree of life illustrate?• How does divergence lead to new species (this

process is called speciation)?• What is convergent evolution?• How do you think they are a product of

habitat and niche?