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Evidence of Evolution by Natural Selection

Evidence of Evolution by Natural Selection. Dodo bird. Evidence supporting evolution. Fossil record transition species Anatomical record homologous & vestigial structures embryology & development Molecular record protein & DNA sequence Artificial selection human-caused evolution.

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Evidence of Evolution by Natural Selection

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  1. Evidence of Evolutionby Natural Selection Dodo bird

  2. Evidence supporting evolution • Fossil record • transition species • Anatomical record • homologous & vestigial structures • embryology & development • Molecular record • protein & DNA sequence • Artificial selection • human-caused evolution

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

  4. Anatomical record • Homologous structures • similarities in characteristics resulting from common ancestry

  5. Homologous structures • Similar structure • Similar development • Different functions • Evidence of close evolutionary relationship • recent common ancestor

  6. Analogous structures • Separate evolution of structures • similar functions • similar external form • different internal structure & development • different origin • no evolutionary relationship Don’t be fooledby their looks! Solving a similar problem with a similar solution

  7. Convergent evolution • Flight evolved in 3 separate animal groups • evolved similar “solution” to similar “problems” • analogous structures Does this mean they have a recent common ancestor?

  8. Parallel Evolution • Convergent evolution in common niches • filling similar ecological roles in similar environments, so similar adaptations were selected • but are not closely related marsupial mammals placental mammals

  9. Vestigial organs • Modern animals may have structures that serve little or no function • remnants of structures that were functional in ancestral species • snakes & whales — remains of pelvis & leg bones of walking ancestors • eyes on blind cave fish • human tail bone This is notLaMarck’s loss from “disuse”!

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

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

  12. Building “family” trees Closely related species (branches) share same line of descent until their divergence from a common ancestor

  13. Don’t be a Dodo… Ask Questions!!

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