Biogeography is a synthetic science, bringing in aspects of many other types of science. Within a species individuals from more humid habitats tend to be darker in color than those from drier habitats 2. Dispersal of Species Dispersal is the capacity of organisms to move from their birthplace to a new site. Dispersal is an ecological process that is part of the life history of every species. Without dispersal, genetic interchange is limited, and species do not have a chance to adapt to a new environment.
Dispersal is an important part of the process of evolution.
Animals achieve dispersal by walking, swimming, flying. There are many barriers to dispersal . Without these barriers, every species would be everywhere. A vast body of water can be a significant barrier to a land dweller, but none at all to a fish. Physiological barriers are those so different from that of the original environment that a species can't survive in them for very long.