Evolution Flashcards
Evolution: changes in _____, _____, and groups of _____; changes in _____ __________ in populations.
populations, species, and groups of species; allele frequency.
Microevolution
evolutionary changes in a species over a short period of time.
Macroevolution
evolutionary changes in a species over a longer period of time.
Phylogeny
evolutionary relationship among species and groups of species.
Genetics incorporated into evolutionary thinking is variously called:
- neo-Darwinism
- synthetic theory of evolution
- modern synthesis
5 evidences of evolution
- Paleontology
- Biogeography
- Embryology
- Comparative anatomy
- Molecular biology
Paleontology
fossils are evidence of evolution and no longer existing species.
Biogeography
similar conditions in different geographic locations give rise to species of similar traits, suggesting evolution due to condition. ex. placental rabbit in USA and marsupial wallaby in Australia.
Embryology
similarities in embryo and developmental stages (ontogeny) suggest evolution and phylogeny. ex. vertebrates have embryos with gill slits and tails.
Comparative anatomy
a) Homologous structures
b) Analogous structures
similarities in body parts.
a) similar body parts between species with common ancestor
b) similar body parts between species without common ancestor but rather similar living environments. ex. fins of sharks, penguins, and porpoises.
Molecular Biology
closely related species have similar genetic code.
Natural selection
survival of the fittest.
Adaptation
superior inherited traits
5 types of selection
- stabilizing selection
- directional selection
- disruptive/diversifying selection
- sexual selection
- artificial selection
Stabilizing selection
trait that is more middle-ground is adaptive while extreme ends of a trait are maladaptive and selected against.
Directional selection
one extreme end of a trait is adaptive. ex) insecticide resistance, industrial melanism of peppered moths.
Disruptive/diversifying selection
extreme ends of a trait are adaptive. ex) tall weeds and short weeds are selectively favored over average-height weeds. tall weeds receive more sunlight and have efficient growth; short weeds escape destruction by mows.
Sexual selection
a) male competition
b) female choice
* sexual dimorphism
males who can reproduce more and better are adaptive.
a) males who are stronger and fitter survive and reproduce
b) males who are attractive to the females reproduce
* disruptive/diversifying selection between males and females as a result of sexual selection.
Artificial selection
directional selection as a result of human tempering of organisms. ex) humans breeding dogs led to different breeds.
5 Sources of Variation
- Mutations
- Sexual reproduction
- Diploidy
- Outbreeding
- Balanced polymorphism
Mutations
changes in genetic code
Sexual reproduction
genetic recombination results in various combinations of alleles; random joining of gametes (fertilization), crossing over (prophase I meiosis), and independent assortment (metaphase I meiosis) are sources of this variation.