Washington, June 1 (ANI): The distribution of species in space and time changes continually across the globe, according to a new study.
Janne Soininen of the University of Helsinki explores a number of recent studies on the topic, synthesizing conclusions from thousands of observations.
The study explains how proportion of species present in two samples differ - either depending on the distance between them or with the time separating two samplings of the species present at one place.
Opposite to trends in small areas, turnover of species is more in the tropics than closer to the poles - a square kilometre or less-or at periods of less than about a year.
Studies that look at very large areas, or at multi-year changes, often find the opposite effect: turnover of species is higher close to the poles than in the tropics.
Soininen's surveys imply that species turnover does not change in a straightforward way over distance and time, perhaps because of different interactions between the species that make up different ecosystems.
Further and more detailed work on the study could shed light on the fundamental processes that assemble ecosystems, according to her.
The study is published in the June 2010 issue of BioScience.(ANI)