1 / 15

Evolution: Natural Selection & Adaptation

Evolution: Natural Selection & Adaptation. Chapters 15 and 16. Evolution is the Unifying Principle of all Biology forms foundation for all other concepts answers all “why” questions explains context of boil. phenomena two major aspects:

chico
Download Presentation

Evolution: Natural Selection & Adaptation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Evolution:Natural Selection & Adaptation Chapters 15 and 16

  2. Evolution is the Unifying Principle of all Biology • forms foundation for all other concepts • answers all “why” questions • explains context of boil. phenomena • two major aspects: • descent from a common ancestor  why org. have similar characteristics • adaptation to environment  explains diversity of life • Charles Darwin • developed theory of evolution • 1859: The Origin of Species • descent with modification • “change through time” • evol. occurs through natural selection • env. determines which ind. will survive and reproduce • are fittestind.  possess best adaptations • adaptations • characteristics that increase chance of survival and reproduction

  3. Natural Selection • mechanism of evol. • based on five key points: • ind. vary within pops. • some variation is inherited and affects survival • more offspring are produced than env. can support • offspring with most adaptive traits will survive better and produce more of their own offspring • offspring will also have the adaptive traits • over time, the pop. changes • more adaptive traits become more prevalent • environmental forces affect an individual’s phenotype • to survive, an org’s. phenotype must become adapted to env. • but, genotype determines phenotype • orgs. with most adaptive genotypes survive better and pass their genes onto their offspring • their genotypes produce a more fit and adaptive phenotype • such organisms are “selected for” • variation in pop.  small genetic changes  produce new genotypes  lead to new, better adapted phenotypes • continued phenotypic change  development of new species

  4. variation • occurs in pops. in many different traits • behavioral, biochemical, physical • must be genetically based • two primary sources • mutation • source of new variations • crossing over • source of new combinations of traits • is very beneficial to a pop. evol. cannot occur without it • maintained through a wide variety of mechanisms • dispersal of young • masking recessive alleles • heterozygote advantage • others Fig. 15.7 Variation in a human population

  5. Fig. 16.16 An example of heterozygote advantage

  6. Modern Synthesis – Today’s Theory of Evolution • incorporates genetics into evolution • nat. sel. causes populations to change, not individuals • selection is not a random process • evol. is not based on the needs of organisms • mutations  acted on by nat. sel.  adaptation to local env. conditions • selection has been tested and confirmed many times in many organisms • fittest ind. are those more likely to survive, based on adaptations • evolution is not “survival of the fittest” • survival not as important as reproduction Fig. 16.3 Natural selection in peppered moths

  7. Evidence and Examples of Evolution • fossil record • radioactive dating • hard-bodied vs. soft-bodied organisms • phylogenetic trees Fig. 17.17 Evolutionary history of Equus

  8. Fig. 30.7 Human evolution

  9. biogeography • study of where organisms are found on earth • provides evidence of past evol. history • isolated regions have their own types of plants and animals • similarity of unrelated species in similar environments Page 274 Biogeographical regions Fig. 15.5 An example of evidence through biogeography – the European hare and the Patagonian (S.A.) hare

  10. Fig. 15.14 Biogeography. Some mammals of Australia and their North and South American counterparts.

  11. comparative anatomy • homologous vs. analogous structures • adult and embryological evidence • transitional organisms • vestigial structures Fig. 15.16 Developmental homologies Fig. 15.15 Homologous structures

  12. Fig. 15.13 Ambulocetus – an ancestor of whales and a transitional fossil Fig. 15.12 Transitional fossils - Archaeopteryx

  13. Some vestigial structures Fig. 17.1 Whale evolution, showing transitional organisms

  14. molecular biology • genetic code and cellular structure • DNA and amino acid similarities • number of mutations • phylogenetic trees Fig. 15.17 Biochemical differences – evidence from molecular biology

  15. artificial selection • selective breeding Fig. 15.9 Artificial selection in plants Fig. 15.8 Artificial selection in animals

More Related