Reproductive Isolation Flashcards
Keeping populations apart before the stern and egg meet is called
Prezygotic
Define reproductive isolation
Reduction/prevention of gene flow between populations by genetically determined differences between them
Postzygotic is defined as
Populations can meet, mate and reproduce but there will be problems with the resulting offspring
Prezygotic: premating:
Ecological isolation (don't meet) due to temporal, habitat, immigrant inviability Meet but don't mate: sexual behaviour and pollinator in plants
Prezygotic: post mating:
Mechanical, copulatory behaviour, gametic and immigrant inviability
Extrinsic factors of postzygotic:
Hybrid behavioural and ecological inviability - no niche where hybrid is fitter than parents
Intrinsic factors of postzygotic:
Hybrid inviability (fertile but not selected for as lower fitness) and hybrid infertility
Hybrid sterility is limited to the heterogametic sex
Haldanes Rule
Speciation is a gradual process but…
There is variation in divergence of different populations
Hybrid breakdown becomes a postzygotic isolation barrier and to differentiate between species uses a phenotypic trait which develops prezygotic isolation. What is this?
Reinforcement
Which populations never need reinforcement?
Allopatric
Does a barrier oppose selection?
No
This model explains what rule? If each population is pushed up a different peak by selection with a valley in between
Dobzhansky Muller explains Haldanes Rule
What genes could cause reproductive isolation?
“Speciation genes”..duplicated genes possibly
What doesn’t change the amino acid sequence?
Synonymous
