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Conservation Ecology: Assessing Extinction Risk
This site discusses how genetic variability is correlated with the risk of organism extinction. It also discusses how bottlenecks can reduce genetic variability in populations leading to extinctions.
Sophia Learning
Sophia: Evolution: Lesson 3
This lesson will introduce the concept of evolution and describe how and why organisms evolve.
University of California
Ucmp: Introduction to Trilobita
One of the most famous fossil organisms, trilobites were once a complex group. Learn to tell them apart in this illustrated article that tells how they lived, their body structure, there place in evolution, and the like.