Evidence supporting evolution Fossil record u transition species

Evidence supporting evolution § Fossil record u transition species § Anatomical record homologous & vestigial structures u embryology & development u § Molecular record u protein & DNA sequence § Artificial selection u AP Biology human-caused evolution

Fossil record § Layers of sedimentary rock contain fossils new layers cover older ones, creating a record over time u fossils within layers show that a succession of organisms have populated Earth throughout a long period of time u AP Biology

Evolutionary change in horses 550 500 Body size (kg) 450 Equus 400 350 300 250 Merychippus 200 150 100 Mesohippus Hyracotherium 50 AP Biology Nannippus 60 55 50 45 40 35 30 25 20 15 10 5 0 Millions of years ago

Anatomical record § Homologous structures u AP Biology similarities in characteristics resulting from common ancestry

Homologous structures § Similar structure § Similar development § Different functions § Evidence of close evolutionary relationship u AP Biology recent common ancestor

Homologous structures spines leaves succulent leaves needles AP Biology colored leaves tendrils

Analogous structures § Separate evolution of structures similar functions u similar external form u different internal structure & development u different origin u no evolutionary relationship u Don’t be fooled by their looks! Solving a similar problem with a similar solution AP Biology

Convergent evolution § Flight evolved in 3 separate animal groups evolved similar “solution” to similar “problems” u analogous structures u AP Biology Does this mean they have a recent common ancestor?

Convergent evolution § Fish: aquatic vertebrates § Dolphins: aquatic mammals similar adaptations to life in the sea u not closely related u AP Biology Those fins & tails & sleek bodies are analogous structures!

Parallel Evolution § Convergent evolution in common niches u u filling similar ecological roles in similar environments, so similar adaptations were selected but are not closely related marsupial mammals placental mammals AP Biology

Vestigial organs § Modern animals may have structures that serve little or no function u u remnants of structures that were functional in ancestral species deleterious mutations accumulate in genes for non-critical structures without reducing fitness § snakes & whales — remains of pelvis & leg bones of walking ancestors § eyes on blind cave fish § human tail bone AP Biology This is not La. Marck’s loss from “disuse”!

Vestigial organs § Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures? AP Biology

Comparative embryology § Similar embryological development in closely related species u all vertebrate embryos have similar structures at different stages of development § gill pouch in fish, frog, snake, birds, human, etc. AP Biology

Molecular record § Comparing DNA & protein structure u universal genetic code! Why compare these genes? § DNA & RNA u compare common genes § cytochrome C (respiration) § hemoglobin (gas exchange) Human/kangaroo Closely related species have sequences that are more similar than distantly related species § DNA & proteins are a molecular record of evolutionary relationships Nucleotide substitutions 100 75 Rabbit/ rodent 50 Horse/ donkey Llama/ cow Sheep/ goat 25 Human/rodent Horse/cow Pig/ cow Goat/cow 0 AP Biology Dog/ cow Human/ cow 0 25 50 75 100 Millions of years ago 125

Artificial selection § Artificial breeding can use variations in populations to create vastly different “breeds” & “varieties” “descendants” of wild mustard AP Biology “descendants” of the wolf