Reproductive Isolation

Hi guys, I really need quick help, my Unit 4 exam is tomorrow (IAL), I'm doing Edexcel and I'm kind of lost. So, exam questions about Speciation, either expect an answer about Reproductive Isolation only, or Geographical Isolation only. Or sometimes both. Most times they reward the mention of natural selection. Sometimes they don't.
And I'm really lost and anxious. When should I write what. Should I look for a specific key word or scenario in the question that would lead me to know exactly what to write about? If yes then what?
Like, what leads to what? Does Geographical Isolation lead to Reproductive Isolation or is it the other way round? How does Speciation take place and in what order?
thanks a lot in advance guys :smile:

Reply 1

anosmianAcrimony

20

Geographical isolation is when members of a species are physically separated by their environment - say a large pond was partially drained and became several smaller ponds, trapping fish from a single species in each. Reproductive isolation is a result of this because the fish in each smaller pond now cannot mate with fish in any of the others. If the subgroups are separated for long enough, they may genetically diverge enough to lose the capacity to interbreed, and become different species, which is what's referred to as speciation.

Reply 2

nadaezraturner

OP

4

Original post by anosmianAcrimony

Geographical isolation is when members of a species are physically separated by their environment - say a large pond was partially drained and became several smaller ponds, trapping fish from a single species in each. Reproductive isolation is a result of this because the fish in each smaller pond now cannot mate with fish in any of the others. If the subgroups are separated for long enough, they may genetically diverge enough to lose the capacity to interbreed, and become different species, which is what's referred to as speciation.