speciation pack 9 Flashcards
species
a group of closely related individuals with similar morphology, physiology and behaviour that interbreed to produce fertile offspring and are not reproductively isolated by time, place of behaviour
what is the formation of new species called
speciation
what must there be for speciation to occur
an isolating mechanism
what does an isolating mechanism prevent?
successful interbreeding between populations of a species
what is reproductive isolation
successful interbreeding between populations of species
what does reproductive isolation prevent
gene flow between the populations
allopatric
- when populations are geographically isolated
- prevents a group of individuals from breeding with eachother
- over time they will be subject to different selection pressures and accumulate different random mutations
- allele frequencies in each population will become different
- two populations become reproductively isolated and there is no gene flow between them
- if the populations meet again they will not be able to interbreed to produce fertile offspring
- they are now considering 2 separate species
sympatric
when populations become reproductively isolated without a geographical barrier, they became isolated in the habitat due to another isolating mechanism which results in reproductive isolation and there is no gene flow
ecological isolation
individuals occupy different parts of the same habitat
temporal isolation
individuals reproduce at different times
behavioural isolation
individuals don’t recognise another’s courtship behaviour
physical incompatibility
there are physical reasons to prevent mating
hybrid inviability
offspring are produced but don’t survive to reproductive age
hybrid sterility
offspring survive to reproductive age but are infertile
