In what type of evolution do organisms evolve into different forms due to geographical isolation?

The correct choice provides insight into how geographical isolation can lead to the evolution of distinct species. In allopatric speciation, a population is divided by a physical barrier, such as mountains or rivers, which prevents members of the population from mating with each other. Over time, these isolated groups experience different environmental pressures, mutations, and paths of natural selection, which can result in significant evolutionary changes. This process often leads to the development of new species that are well adapted to their particular environments, distinct from their ancestral forms.

In contrast, the other types of evolution mentioned do not specifically emphasize the impact of geographical isolation in the same way. Speciation is a broader term that refers to the formation of new species, which can occur through various mechanisms, not just geographical separation. Adaptive radiation describes the rapid evolution of diversely adapted species from a common ancestor, often in response to the creation of new ecological niches, but it may not necessarily involve isolation. Convergence, on the other hand, involves unrelated species developing similar traits due to similar environmental pressures, which does not relate to geographical isolation. Thus, allopatric speciation is the most accurate answer when discussing the influence of geographical barriers on the evolution of different forms.