Speciation and Convergent Evolution
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What does speciation mean?
Evolution of two or more species from one ancestral species (examples from notes are bears,
wild canines, and whales).
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What does convergent evolution mean?
Convergent evolution occurs when two very different species end up “looking” and/or behaving
like one another due to the fact that they occupy the same or similar niches in different
ecosystems. For example, convergent evolution has been well documented between marsupial
mammals in Australia and placental mammals (see notes). Another example is the wings of
birds and bats - the same forelimb structures were modified independently, in very different
ways (bats fly with their fingers while birds fly with their arms).
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What does the tree of life illustrate?
The tree of life (more formally known as the phylogenetic tree in biology) is a model that
describes the common descent (evolutionary relationships) of all Earth’s organisms (living and
extinct) from LUCA (last universal common ancestor) to those that currently inhabit Earth.
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How does divergence lead to new species (this is speciation)?
Divergence occurs when a population of one species (usually in isolation) adapts (genetically),
over time, to a new niche resulting in the formation of a new species. For example, the
divergence of the grizzly bear and the polar bear 500,000 years ago.