Species Distribution

Species distribution describes the pattern in which species disperse over a region. Crows, for instance, have a wide distribution across most continents. Conversely, narrow distribution occurs when a species lives only in a small area, such as manatees in the waters of central and south Florida.

Distribution comprises two additional characteristics: evenness and dominance. An even distribution results when a similar number of individuals live in different areas. Species that live in social structures (herds, packs, flocks, schools, etc.) tend to travel as groups, and so they do not have evenness, but rather live in a clumped distribution. Groups such as these protect their members against predation, aid in hunting, and help in breeding and raising young. The second type of distribution comes from dominance. Dominance occurs when biologists see more individuals of a species than expected. Dominance may be an indication of an imbalanced ecosystem. Dominance may also arise from temporary conditions due to
fire, flooding, or a sudden influx of people into a habitat.

Species distribution consists of many aspects that scientists understand and likely some aspects that are not yet understood. A brief list of the factors that influence species distribution are the following, all topics that have been discussed in this book: biome characteristics, climate change, ecosystem health, habitat status, invasive species, competition and adaptation, status of migration corridors, vulnerability of species to illegal killing and trade, urbanization, and special protections for endangered and threatened species.