The Theory of Evolution Chapter 15 The Theory of Evolution
So, what is evolution? Change in a species over time Why do we get a flu shot every year? Why are some bacteria resistant to antibiotics? Why are humans taller than they used to be? Why are bedbugs suddenly so common?
Natural Selection Something in nature chooses who is most suited for the environment Certain individuals have better traits for an environment than others – inherited or random mutation They will survive to reproduce, passing on that desired adaptation Those who do not have the desired trait, most likely, do not reproduce and will die
Artificial Selection Humans interfere with nature picking the best suited. Humans select the most desired traits and allow only those individuals to reproduce Farmers, animal breeders
So, who evolves? Populations, not individuals!!!!! Evolution works on phenotypes, not genotypes!!!!! Individuals with the desired trait help change the overall appearance of the population Gene pools will change due to mutations, gene recombinations, and reproduction rates The most evolution will occur in large populations that undergo sexual reproduction
Stabilizing Natural Selection
Directional Natural Selection
Disruptive Natural Selection
Charles Darwin Developed theory of evolution Based it on natural selection Visited the Galapagos Islands
Speciation The evolution of species Occurs when members of similar populations no longer interbreed to produce fertile offspring Geographic isolation Behavioral isolation
Speciation Rates Gradualism vs. Punctuated Equilibrium
Patterns of Evolution Adaptive radiation (divergent evolution) When an ancestral species gives rise to many new species Each new species is adapted to a specific niche Darwin’s finches Hawaiian honeycreepers
Hawaiian Honeycreepers
Convergent evolution When distantly related species evolve similar traits because of similar environments
Adaptations Structural Mimicry Camouflage Physiological
Other evidence for evolution Fossils Homologous structures Analogous structures
Vestigial structures Embryology Biochemistry DNA ATP