New model for studying species distributions and the mid-domain effect developed

Understanding why some parts of the world sustain more species than others is one of the most enigmatic problems in ecology. One particularly common pattern is a “hump-shaped” biodiversity gradient: for example, biodiversity peaks near the equator and declines going either north or south.


Historically, explanations for such gradients invoked coincident geographical variation in environmental factors hypothesized to reduce extinction rates or promote the evolution of new species.

Recently, however, random re-arrangements (“randomizations”) of species’ distributions in geographical space have been shown to reproduce these hump-shaped gradients (termed “mid-domain effects”).

Because randomizations do not explicitly include environmental factors, some have argued that such factors may be less important for biodiversity than previously thought. However, randomization analyses are controversial: critics argue that they are devoid of any ecological processes (not just environmental gradients), and thus have no explanatory utility.

Addressing this criticism requires models that make explicit biological assumptions about how species’ distributional limits are determined, consistent with a particular hypothesized cause of biodiversity gradients.

In an article in the July 2005 issue of The American Naturalist, Sean R. Connolly (James Cook University) develops a general framework for such models and analyzes specific models that omit roles for variation in the quality of environmental conditions.

Under a very general set of conditions, these models are shown to produce mid-domain effects. These are qualitatively similar in shape, but of substantially lower magnitude, compared to randomization analyses. These results reveal that the mid-domain effect is likely to be a real phenomenon, and thus cannot be ignored, but that comparing real biodiversity patterns to those produced by randomizations may be misleading. They also identify an alternative way forward: formulating process-oriented models of species distributions and testing them directly against empirical data.

Media Contact

Carrie Olivia Adams EurekAlert!

More Information:

http://www.uchicago.edu

All latest news from the category: Life Sciences and Chemistry

Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to home

Comments (0)

Write a comment

Newest articles

Perovskite solar cells soar to new heights

Metal halide perovskites have been under intense investigation over the last decade, due to the remarkable rise in their performance in optoelectronic devices such as solar cells or light-emitting diodes….

Blue hydrogen can help protect the climate

An international group of researchers led by the Paul Scherrer Institute and the Heriot-Watt University has carried out in-depth analyses of the climate impact of blue hydrogen. This is produced…

Genes associated with hearing loss visualised in new study

Researchers from Uppsala University have been able to document and visualise hearing loss-associated genes in the human inner ear, in a unique collaboration study between otosurgeons and geneticists. The findings…

Partners & Sponsors