<P> Species distribution is the manner in which a biological taxon is spatially arranged . Species distribution is not to be confused with dispersal, which is the movement of individuals away from their area of origin or from centers of high on density . A similar concept is the species range . A species range is often represented with a species range map . Biogeographers try to understand the factors determining a species' distribution . The pattern of distribution is not permanent for each species . Distribution patterns can change seasonally, in response to the availability of resources, and also depending on the scale at which they are viewed . Dispersion usually takes place at the time of reproduction . Populations within a species are translocated through many methods, including dispersal by people, wind, water and animals . Humans are one of the largest distributors due to the current trends in globalization and the expanse of the transportation industry . 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 . </P> <P> Biogeography is the study of the distribution of biodiversity over space and time . It is very useful in understanding species distribution through factors such as speciation, extinction, continental drift, glaciation, variation of sea levels, river capture and available resources . This branch of study not only gives a description of the species distribution, but also a geographical explanation for the distribution of particular species . The traditional biogeographic regions were first modeled by Alfred Wallace in The Geographical Distribution of Animals (1876). These were based on the work of Sclater's terrestrial biogeographic regions . Wallace's system was based on both birds and vertebrates, including non-flying mammals, which better reflect the natural divisions of the Earth due to their limited dispersal abilities . </P> <P> Clumped distribution is the most common type of dispersion found in nature . In clumped distribution, the distance between neighboring individuals is minimized . This type of distribution is found in environments that are characterized by patchy resources . Animals need certain resources to survive, and when these resources become rare during certain parts of the year animals tend to "clump" together around these crucial resources . Individuals might be clustered together in an area due to social factors such as selfish herds and family groups . Organisms that usually serve as prey form clumped distributions in areas where they can hide and detect predators easily . </P> <P> Other causes of clumped distributions are the inability of offspring to independently move from their habitat . This is seen in juvenile animals that are immobile and strongly dependent upon parental care . 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 . Clumped distribution can be beneficial to the individuals in that group . However, in some herbivore cases, such as cows and wildebeests, the vegetation around them can suffer, especially if animals target one plant in particular . </P>

What are the 3 types of population distribution