Geographical Distribution

Abstract In this chapter, Darwin explains why the same animal and plant species are often found living in many different places that are widely separated from each other, and why areas that are separated by physical barriers that prevent migration between them sometimes have similar species and sometime have different species. Darwin argues that the present geographical distribution of species is related to geological events and gradual changes in climate, along with differences in dispersal patterns and the impact of natural selection, and that these interesting species distributions make perfect sense if each species originated in a single location. Their later distributions will then be related to the ability of a given species to disperse over long distances and the amount of time that a separated population has been isolated from other members of the same species.