3 Anatomical record Animals with different structures on

3. Anatomical record Animals with different structures on the surface But when you look under the skin… It tells an evolutionary story of common ancestors

Compare the bones (anatomical structures) • The same bones under the skin • limbs that perform different functions are built from the same bones How could these very different animals have the same bones?

Homologous structures • Structures that come from the same origin • homo- = same • -logous = information • Forelimbs of human, cats, whales, & bats • same structure • on the inside • same development in embryo • different functions • on the outside • evidence of common ancestor

But don’t be fooled by these… § Analogous structures u look similar § on the outside same function u different structure & development u How is a bird like a bug? § on the inside different origin u no evolutionary relationship u Convergent evolution!! u Solving a similar problem with a similar solution

Analogous structures § Dolphins: aquatic mammal § Fish: aquatic vertebrate both adapted to life in the sea u not closely related u Watch the tail!

Vestigial organs • Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures? Because they used to walk on land!

Vestigial organs • Structures on modern animals that have no function • remains of structures that were functional in ancestors • evidence of change over time • some snakes & whales have pelvis bones & leg bones of walking ancestors • eyes on blind cave fish • human tail bone

Comparative embryology • Development of embryo tells an evolutionary story • similar structures during development all vertebrate embryos have a “gill pouch” at one stage of development

3. Molecular record • Comparing DNA & protein structure • everyone uses the same genetic code! • DNA Human Macaque Dog Bird Frog Lamprey 8 32 45 67 125 § compare common genes § compare common proteins number of amino acids different from human hemoglobin 0 10 20 30 40 50 60 70 80 90 100 110 120

Phylogeny! Building “family” trees Closely related species are branches on the tree — coming from a common ancestor

4. Artificial selection • How do we know natural selection can change a population? • we can recreate a similar process • “evolution by human selection” “descendants” of wild mustard

Selective Breeding Humans create the change over time “descendants” of the wolf

Artificial Selection …and the examples keep coming! I liked breeding pigeons!

Artificial Selection gone bad! • Unexpected consequences of artificial selection Pesticide resistance Antibiotic resistance

Insecticide resistance • Spray the field, but… • insecticide didn’t kill all individuals • variation • resistant survivors reproduce • resistance is inherited • insecticide becomes less & less effective • Genetic Drift!

So…what is a species? • species • population whose members can breed & produce viable, fertile offspring • reproductively compatible Distinct species: songs & behaviors are different enough to prevent interbreeding Eastern Meadowlark Western Meadowlark So, do individuals or populations evolve?

Many factors can affect speciation. (the formation of a new species) But first, populations must be isolated

There are two ways to isolate a population • geographically isolated • reproductively isolated • isolated populations evolve independently based on the conditions they are living in.

Forces of Evolutionary Change So once a population has been isolated…. what mechanisms can cause evolution to occur? Gene Flow Mutation Migration Chemical Changes to DNA Non-random mating Sexual Selection Genetic Drift Small isolated populations Selection Pressure Natural Selection

Patterns of Evolution • Different patterns of evolution occur in different environments • Convergent evolution • Divergent evolution (also called adaptive radiation) • Coevolution

Convergent Evolution • When unrelated species live in similar environments in different parts of the world • similar environmental pressures • similar pressures of natural selection unrelated species

CONVERGENT EVOLUTION EXAMPLE http: //evolution. berkeley. edu/evolibrary/home. php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

• Adaptive radiation is a type of divergent evolution • populations that were once similar change and adapt to different living conditions common ancestor

Adaptive Radiation Example • When one species splits into many species to fill open habitats. • Darwin’s finches 25

Coevolution • Two or more species reciprocally affect each other’s evolution • predator-prey • disease & host • competitive species • mutualism • pollinators & flowers