What is the most likely explanation for how speciation occurs? need asap

Speciation is most likely to occur when populations become geographically isolated from one another, and come to inhabit environments that differ significantly from one another.

hope this helped

Allopatric speciation, the most common form of speciation, occurs when populations of a species become geographically isolated. When populations become separated, gene flow between them ceases.

thinking it would be physical characteristics