Final answer:
Peripatric speciation differs from vicariant allopatry in that it involves a small number of individuals isolating from the main population, often leading to speciation due to genetic drift, while vicariant allopatry involves the splitting of populations by geographic barriers causing independent evolution.
Step-by-step explanation:
Peripatric speciation is a specific kind of allopatric speciation that occurs when a small group of individuals becomes isolated from the main population and evolves into a new species due to its small population size and genetic drift. In contrast, vicariant allopatry, another form of allopatric speciation, refers to the separation of populations into multiple groups by geographic barriers, leading to speciation due to the independent evolution of these separated groups.
Peripatric speciation can often be caused by a founder effect, where a few individuals disperse to a new location, establishing a new population with limited genetic variation. Meanwhile, vicariant allopatry can be the result of environmental changes such as mountain building, river changes, or human activities that create barriers preventing gene flow between separated populations.
An example illustrating vicariant allopatry is the separation of the northern spotted owl from the Mexican spotted owl, potentially due to glacial activity. These subspecies have developed significant genetic and phenotypic differences, indicating speciation has occurred.