Lesson 2- Speciation/History Flashcards
Smallest heritable unit
Genes
3 ways sexual reproduction gives new genes
crossing over, random assortment, random fertilization
If you decrease generation time…
Increase mutation probability
Hardy-Weinberg equation
shows whether population is evolving, if p^2+2pq+q^2=1then not evolving
When not evolving…
no gene flow, large population, no natural selection, random mating, no mutation
Genetic drift (causes departure from H-W)
Random fluctuation of genes from generations (not always more beneficial)
Gene flow (causes departure from H-W)
Random movement of bad/good genes from populations (bad genes = genetic pollution)
3 types of Natural Selection (causes departure from H-W)
Directional: one extreme phenotype favored over another
Disruptive: both phenotypic extremes favored over middle
Stabilizing: middle phenotype favored over extremes
All are always favorable.
Allopatric speciation
Geographically isolated populations prevent gene flow
Sympatric speciation
no geographic barrier, can happen through habitat differentiation (where subgroups specialize resources), or sexual selection (not always random, due to preferences)
History: 3.5 bya
Oldest prokaryotic fossils (bacteria)
History: 1.8 bya
Origin of eukaryotes, endosymbiant theory (big cells engulf small cells)
History: 1.2 bya
Multicellular organisms (evolved communication and nutrient distribution among colonies)
History: 540 mya
Cambrian explosion- increase in biodiversity (evolve predation, eyes, teeth)
History: 488 mya
Move to land, plants/fungi first (to escape predators and get access to more resources)
History: 250 mya
Permian extinction- massive volcanic activities cause climate change
History: Mesozoic
Plants, insects, reptiles had adaptive radiation
History: 65 mya
Cretaceous extinction (meteor impact)
History: Cenozoic
Mammals start to dominate
Founder effect
first to a new area
Bottleneck effect
whatever survives a disaster
