Species distribution
Species distribution is not to be confused with dispersal, which is the movement of individuals away from their region of origin or from a population center of high density.
Researchers from the Arctic Ocean Diversity (ARCOD) project have documented rising numbers of warm-water crustaceans in the seas around Norway's Svalbard Islands.
This study shows that as the ocean temperatures rise species are beginning to travel into the cold and harsh Arctic waters.
Biotic factors such as predation, disease, and inter- and intra-specific competition for resources such as food, water, and mates can also affect how a species is distributed.
[5] An advantage of a herd, community, or other clumped distribution allows a population to detect predators earlier, at a greater distance, and potentially mount an effective defense.
Plants are well documented as examples showing how phenology is an adaptive trait that can influence fitness in changing climates.
For example, large tankers often fill their ballasts with water at one port and empty them in another, causing a wider distribution of aquatic species.
[11] One common example of bird species' ranges are land mass areas bordering water bodies, such as oceans, rivers, or lakes; they are called a coastal strip.
In the U.S. of North America, the Sierra Nevada range in the west, and the Appalachian Mountains in the east are two examples of this habitat, used in summer, and winter, by separate species, for different reasons.
Organisms that usually serve as prey form clumped distributions in areas where they can hide and detect predators easily.
For example, the bald eagle's nest of eaglets exhibits a clumped species distribution because all the offspring are in a small subset of a survey area before they learn to fly.
African wild dogs, Lycaon pictus, use the technique of communal hunting to increase their success rate at catching prey.
Studies have shown that larger packs of African wild dogs tend to have a greater number of successful kills.
A prime example of clumped distribution due to patchy resources is the wildlife in Africa during the dry season; lions, hyenas, giraffes, elephants, gazelles, and many more animals are clumped by small water sources that are present in the severe dry season.
The reasoning behind this is that they share traits that increase vulnerability to extinction because related taxa are often located within the same broad geographical or habitat types where human-induced threats are concentrated.
This flower releases chemicals called terpenes which inhibit the growth of other plants around it and results in uniform distribution.
[18] This is an example of allelopathy, which is the release of chemicals from plant parts by leaching, root exudation, volatilization, residue decomposition and other processes.
[19] Farming and agricultural practices often create uniform distribution in areas where it would not previously exist, for example, orange trees growing in rows on a plantation.
Oyster larvae can also travel hundreds of kilometers powered by sea currents, which can result in their random distribution.
Typical statistical tests used to find the significance of the variance/mean ratio include Student's t-test and chi squared.
The hierarchical model takes into consideration the requirements, impacts or resources as well as local extinctions in disturbance factors.
Species distribution models (SDMs) can be used to assess climate change impacts and conservation management issues.
This simple SDM is often modified through the use of range data or ancillary information, such as elevation or water distance.
