Ecocline
a gradual, continuous change in the genotype/phenotype composition between two ecosystems or communities of organisms across an environmental gradient.
Issues with speciation
- ecocline - where did the changes in genotype/phenotype take place
- genetically identifiable ecotype - local conditions
how to know if it is distinct enough to be a new species
- asexual reproduction/hybridization
Reproductive isolation
isolating mechanisms to maintain reproductive isolation among populations
prezygotic = no formation e.g. matinf cues
postzygotic = formation (no reproduction after)
Causes of speciation
- allopatric
- parapatric
- sympatric
allopatric speciation
single population is subdivided into multiple subpopulations with physical boundaries (mountain river ect)
parapatric speciation
population expands into new habitat within range of parent species
e.g have mutations to live in another habitat
sympatric speciation
single population forms genetically distinct subpopulation w/ no spatial isolation
- not genetic drift. but natural selection
- assortative mating
