How would homologous recombination and mutations affect speciation?

Question

I'm wondering how homologous recombination and mutations can affect how speciation can occur from one species (so that 2 will be created).

I'm doing research and I found that different mutations and genetic combinations occur in two geographically separated populations which can lead to speciation.

I know recombination can result in different genetic combinations, but how does that factor into a phylogenetic tree? Wouldn't recombination technically play no role in leading to evolution?

My (sort of) guess is that say recombination creates a population with a lot of AA genes and the other population, say by chance (genetic drift), has a population with a lot of aa genes.

We know A and a differ by perhaps a few SNPs, so on average, the two populations would become slightly different from one another due to genetic drift and geographic separation.

Do I have the right idea here? I'm not 100% sure how recombination during prophase I would affect recombination. Hoping someone can clarify this for me or provide some new insights.

Thank you!

Answer 1

Recombination occurs when homologous DNA sequences pair with each other and cross over, essentially swapping genetic material. Now, say that this crossover junction is in the middle of a gene, and we have some genetic differences in the top half and some in the bottom that distinguish the two alleles. If recombination occurs in the middle of the gene, then a new combination of alleles is created that didn't exist before. This new version of the chromosome can now be passed on as a single unit via sexual reproduction.

I left out a lot of details obviously, but this is the basic idea. The reason why recombination adds to genetic diversity and can lead to speciation is because it is essentially mixing and matching existing combinations to create new alleles.