Michael L. Rosenzweig
Prof. Ecology & Evolutionary Biology

Photo by Bert Lippel
Nothing influences species diversities more than the amount of area available to life. Area works at several scales and is controlled by several processes. At the dominant scale, the entire biogeographical province, diversity is set by the dynamics of speciation and extinction. Other scales echo this one. The large areas of tropical provinces are a major reason the tropics have so many species.
     Unlike other scales, provincial area shows a linear relationship to species diversity. This is profoundly troubling for the future of diversity, it predicts that a severe mass extinction is under way, one much more severe than is predicted by smaller scales (such as the island scale). Preventing this mass extinction will require a sea change in our conservation strategies. Through our initiative in reconciliation ecology, we are helping to plan and deploy that change.
     Understanding the scales of the species-area relationship helps us to investigate other variables that influence diversity, such as productivity (i.e., ecological energy flow). We have also replaced the mathematical theory that underlies the most often seen species-area data type (small to regional areas). And we are working toward an efficient formula for estimating diversity from relatively small surveys.

In our experimental work with Zvika Abramsky (in the Negev Desert, Israel), we pursue the dream of understanding species interactions as the result of optimal behavior of individuals. We built theories to make this possible and we have been testing them successfully in the field. Two common Negev gerbil species are the centerpiece of those tests. The habitat use of these gerbils responds in optimal ways to changes in their population sizes. Our theory also predicts significant non-linearities in population dynamics that are confirmed by the field experiments. Recently, we have used trained barn owls to add predation to the mixture of interactions. Gerbils have reacted much more strongly to predation than to competition. They have also given us the first experimental field evidence for predator-mediated mutualism in small populations of victims. Our most recent investigations explore the gerbils' abilities to combine different foraging opportunities and costs in order to behave optimally.


  Have you been reading Evolutionary Ecology Research?

Having our land and sharing it, too: Win-Win Ecology
      Discover how reconciliation ecology is designing new habitats to save the Earth's species.

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