speciation Flashcards
what is speciation
process by which one species splits into 2+ species
(T/F) Speciation links microevolutionary processes with macroevolutionary patterns
T
at what point does speciation occur?
when 2 taxa cannot form fertile hybrids
what is the biological species concept (BSC)
biological species are groups that actually/potentially interbreed and produce fertile offspring in nature
what is reproductive isolation
biological features that reduce/prevent gene exchange with members of other groups
–> result of reproductive barriers
advantages of BSC
biologically relevant: lack of gene exchange is yardstick for species status
disadvantages of BSC
- can’t be applied to asexual taxa/fossils
- hard to assay reproductive battiers
- many ‘good species’ exchange genes with natural selection maintaining divergence
what is morphological species concept
defines species based on morphological similarity
wwhat is ecological species concept?
defines species based on ecological niche (physical/environmental conditions it requires)
what are the 2 kinds of reproductive barriers
prezygotic: prevents attempted mating from being successful
postzygotic: reduces survival/reproductive success of hybrids
what are the prezygotic barriers before mating
- habitat isolation
- temporal isolation
- behavioural isolation
what are prezygotic barriers after mating?
- mechanical isolation
- gametic isolation
what are the kinds of postzygotic barriers
- genetic incompatibilities
- ecologically-dependent postzygotic isolation –> reduction in fitness due to mismatch between phenotype and environment
what is allopatric speciation
when gene flow is interrupted by an extrinsic barrier and populations evolve independently
what is sympatric speciation
speciation in the abscence of any barrier
–> requires gene flow between groups to be reduced by some factor
–> thought to involve evolution of prezygotic barriers that prevent mating
what are the mechanisms of speciation
- ecological
- polyploidization
- reinforcement of prezygotic barrier
wha
what is ecological speciation
reproductive isolation arises as by-produce of adaption to different environments/niches
what is divergent natural selection
natural selection differs in each population due to unique biotic/abiotic environments they inhabit
what is polyploidization
increase in the # of whole sets of chromosomes
what are the 2 kinds of polyploidization
autopolyploid: individual with more than 2 chromosome sets derived from a SINGLE species
allopolyploid: individual with more than 2 chromosome sets derived from DIFFERENT species
what are the ways speciation can be studied
- lab studies
- speciation in nature
what is experimental evolution
technique in which multiple replicate populations are derived from a common ancestor
–> evolution is tracked under controlled conditions
what is ecologically-dependent posyzygotic isolation
occurs when hybrid fitness is reduced bc of mismatch of phenotype with environment
