speciation Flashcards
what is allopatric speciation
single popluation with a barrier
no gene flow and genetics change
what is peripatric speciation
colonization of a new habitate
isolated in this new habitat
what is parapatric speciation
local adaptation
gene flow, selection pressures are great
results in idffeernt species
niches are adjacent and flow can still occur between them
what is sympatric speciation
new species arise within same geographical area
what are modes of speciation categorised by?
geography
what does spatial segregation facilitate
reproductive isolation
define allopatric speciation
populations diverging due to selection and or drift untill they are no longer able to interbreed
what are darwins finches
collection of islands with varying habitats and phlogency of species and divergence
how does post zygotic isolation evolve?
conceptual model
genetic changes are broad
what fitnes do hybrids have
low fitness
what is the Dobzhansy muller theory
model of the evolution of genetic incompatibility, important in understanding the evolution of Reproductive isolation during speciation and the role of natural selection in bringing it about.
where posyzygotic isolating mechanisms already exisit what does selection favour
pre-zygotic isolation such as assortibe mating to avoid hydriisation
if there ws a cost to hydrisation what would happen
expect selection to give rise to prozyogitic isolation and stop them breeding altogether
why would reinforcement fail to evolve
he rarer allele goes extinct
Gene flow blurs the distinction between genotypes (in multilocus genotypes)
Recombination disrupts multigene complexes.
where does speiciation by hydrisation occur?
rare in animals
common plants
when 2 plants hydrise they form a new intemediate species
how has diversity evolved?
sexual selectrion
ecological diversification
what does polypooidy cause differences in
morpolohu
breeding systems
ecological tolerances
