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An Introduction to Life,Evolution, and Extinctions
Brad Hubeny
Taxonomy as a Tool for Classification
A FamiliarExample
Phylogeny andEvolution
Phylogenyand
Evolution
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Phylogeny and Evolution Evolution• Adaptations
– Specialized features ofanimals and plants thatperform one or moreuseful functions
– Allow that organismto excel in itsenvironment
Charles Darwin
Natural Selection
Galapagos Tortoises
• Additional observations– Anatomical relationships
• Embryos of many vertebrates quite similar• Homology
– Presence in two different groups of animals orplants of organs that have the same ancestralorigin but serve different functions
• Vestigial organs– Organs that serve no apparent purpose but
resemble organs that perform functions in othercreatures
Genes, DNA, and Chromosomes
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Genes, Evolution, and Speciation• Sexual recombination
– Each parent contributes one-half of its chromosomes tooffspring
– Yields new combinations• Mutations increase variability
• Gene pool– Sum total of genetic components of a population or
group of interbreeding individuals• Reproductive barriers limit the pool
• Speciation– Origin of a new species from two or more individuals
of a preexisting species
Evolutionary Radiations
Hexacorals
Extinction Rates of Ammonoids Mass Extinctions
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