ohhh yeah that makes sense hhh
i kinda went around that point by saying it is geographically isolated with population C & D? (like i was imagining all the populations are connected by bridges and the bridge between D with C & B collapsed)
I get what u are saying with the parapatric speciation....maybe im wrong hmmm
But i still dont get it when you say two niches are on other sides of a mountain, but still in the same geographic range, there could be complete blockage of gene flow between those two niches--isnt that already a geographical barrier that makes it a allopatric isolation? (im really confused now hahahaha
Anyway, thanks for your reply
That’s where clinal variation comes in. There would be indirect gene flow (idk if that’s the right term to use)
Basically imagine 3 populations connected by bridges
A———-B——-C
Now, there is no gene flow between C and A, but there is gene flow between B and A, that’s kind of what I thought when answering the question. Yes, there is somewhat isolation, but it’s still just one large population that is connected by reduced gene flow.
Or see it this way, a population spreads from east QLD to west QLD. Individuals in the west won’t breed with individuals in the east, but they both bread with individuals in the middle of QLD. Technically, east and west populations would be isolated from each other, yet there is still gene flow because they are still one unified population spread over a wide geographic range.
It appears everyone else settled for allopatric speciation
which makes me think I am wrong, because yea, it makes sense if you assume that eventually the gene flow completely stops, but at that point in time, there was still gene flow.
I think I’m just gonna have to accept that I looked too much into it
.
If the question stated,
If speciation occurred during time period 3..... it would be parapatric
But if it stated,
If speciation occurred in future time periods.... it would have been allopatric because as you said, the reduced gene flow would have eventually stopped