Week 3 Flashcards
Biological
Ability to create viable, fertile offspring
Objective criteria, meshes will with gene flow concept
Not appliciple to extinct or asexual species
Morphological
Similarities in bidy structures
Easy to apply, works for asexual and extinct species
difficult defining important structures, microbes have few characters
Phylogenetic
Common evolutionary history
Beased on actual relationships, works for asexual and extinct species
Requires good phylogenetic data
Species
A group od individuals that share a common ancestor and are on a unique evolutionary trajectory
Prezygotic isolation barriers
Habitat isolation: use different habitats, so never enounter each other
Temporal isolation: breed at different times during the year
Behavioral isolation: dont find each other attractive
Mechanical isolation: usable to copulate or deliver gametes
Gametic isolation: sperm incompatible with eggs
Postzygotic isolaton barriers
Hybrid inviability or sterility: non-viable hybrid OR viable sterile hybrid
Hybrid breakdown: hybrids become less viable over generations
Speciation
The process by which new speciesseperste from existing species
Major factors: geography, climate, environment
Microevolution
Emergence of new populations and species (AT species level)
Macroevolution
Emergebce of new grouos above the soecies level through many speciation events (above the specieal level)
Directional selection
Favors individuals at one end of the phenotypic range e.g. lion speed
Disruptive selection
Favors BOTH extremes, intermediate disadvantage
Stabilizing selection
Favors intermediate phyotypes: select against extremes, e.g. human birth weught
Migration
Organisms entering or leaving population (allele flow)
Bottleneck effect
When populations experience a serious reduction and not all alleles got reduced evenly
Founder effect
When a sub population is separated from thr main population but not all alleles got slected evenly
Genetic drift
Unpredictable flunctuations in allele frequency in small populations
Hardy-Weinberg Equilibrium
No mutations, no selective mating, no natural selection, no genetic drift (large, stable population), no gene flow, p^2 + 2pq + 1^2 = 1
