The Theory of Evolution Chapter 15 The Theory of Evolution

Theory of Evolution Idea supported by scientific evidence (but no concrete experiments) over a long period of time Change in a species due to mutation of the DNA code that occurs over a long time

Evolution Evidence: 1. Adaptations 2. Fossils 3. Comparative anatomy 4. Comparative embryology 5. Comparative Biochemistry 6. Plate Tectonics

Evolution of Brains:

Charles Darwin Developed theory of evolution Based it on natural selection Visited the Galapagos Islands

Trip of Darwin and HMS Beagle

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

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

Adaptations: features suited to a particular environment that allow organisms to survive Inuit people, who live in the extreme cold of the Arctic, have short, stout bodies that conserve heat.

Masai people, who live in the arid lands of eastern Africa, have tall, lean bodies that disperse heat well.

Stabilizing Natural Selection genetic diversity decreases and the population mean stabilizes on a particular trait value

Directional Natural Selection an extreme phenotype is favored over other phenotypes

Disruptive Natural Selection Extreme values for a trait are favored over intermediate values. Often results in the population divided into two distinct groups.

Charles Darwin Developed theory of evolution Based it on natural selection Visited the Galapagos Islands

Trip of Darwin and HMS Beagle

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

Speciation The evolution of species Occurs when members of similar populations no longer interbreed to produce fertile offspring Geographic isolation Behavioral isolation

Finches of the Galapagos

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…slide 1 When distantly related species evolve similar traits because of similar environments

Convergent evolution---slide 2

Convergent evolution…slide 3

Adaptations- Evidence of Evolution…pg 397 Structural- next slide Mimicry-below, pg 398 Camouflage- leaf frog--> Physiological-Plant/animal cells

Other Evidence for Evolution Fossils: Ch 14 Homologous structures Common evolutionary ancestor Similar in arrangement/function or both Analogous structures Similar in function, but not a similar ancestor.

More Evolutionary Evidence Vestigial structures Whale pelvic bone…pg 402 Embryology---> Lizard, Tortoise, Pig, Human Biochemistry DNA ATP