Final answer:
After genetic isolation, both forms of speciation (allopatric and sympatric) are subject to reproductive isolation mechanisms, which prevent interbreeding between closely related species.
Step-by-step explanation:
After genetic isolation, both forms of speciation (allopatric and sympatric) are subject to reproductive isolation mechanisms. These mechanisms act as barriers between closely related species, preventing them from interbreeding and allowing them to diverge and exist as genetically independent species. There are two types of reproductive isolation: prezygotic barriers, which prevent reproduction prior to the formation of a zygote, and postzygotic barriers, which block reproduction after fertilization occurs.
In allopatric speciation, populations become geographically isolated, preventing gene flow between them and leading to reproductive isolation. For example, the northern spotted owl and the Mexican spotted owl are genetically and phenotypically different due to their geographic separation.
In sympatric speciation, reproductive isolation can occur within a single population without geographic isolation. This can happen through mechanisms like polyploidy, where errors in meiosis result in gametes with extra chromosomes. Autopolyploidy occurs within a single species, while allopolyploidy occurs between closely related species.