origin of species Flashcards
what is a species? (extinct)
- did they hybridize
- based on changes in morphological features
what is a species (extant)
- more then morphology (behavior, geography)
- luxury and curse
- lines less distinct
phylogenetic species concept
smallest group descended from common ancestor (unique derived traits)
- phylogenetic history, semantics
biological species concept
groups of potentially inbreeding pops that are reproductively isolated from other groups
- sexually reproducing animals, common
general lineage species concept
species are metapopulations of organisms that evolve independently from other metapopulations
- metapop - spatially separated same species that interact at some point
allopatry
geographic barrier
sympatry
reproductive barrier
postmating and prezygotic barriers
physical damage - hybridization results in damage to female reproductive tract
gametic incompatibility - sperm or pollen fails to penetrate and fertilize other species
postzygotic barriers
hybrids are produced but have low fitness
hybrid inviability, insterile
ecological inviability
behavioral sterility
bateson dobzhansky muller incompatibility
genetic incompatibility of hybrids
- arises from epistatic interactions at two or more loci
allopatric speciation
- vicariance - physical splitting of habitat
- dispersal - pop moves to new pop
reinforcement
selection favors prezygotic isolation mechanisms preventing formation of hybrids with reduced fitness
- Mechanisms that “reinforce” the divergence that has already begun
- Premating barriers
- Means of preventing hybridization
- Often occurs through reproductive character displacement
parapatric speciation
neighboring pops diverge but still exchange alleles
- cline - eg. ph or temp
