“Microhabitat and climatic niche change explain patterns of diversification among frog families”

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Daniel S. Moen and John J. Wiens

A new study of frogs shows that the fine-scale habitats where species live are the most important factors explaining patterns of evolution and biodiversity

Hypsiboas dentei is an arboreal frog of the family Hylidae. This photo of a breeding pair in amplexus (male on left; female on right) was taken at the beginning of the wet season in French Guiana, near Cayenne.
(Credit: Daniel S. Moen)

Different groups of animals and plants can have very different numbers of species. In frogs, for example, a family can contain anywhere from a single species (like the Mexican burrowing frog) to nearly a thousand (like treefrogs). The importance of different factors that explain this diversity has remained an unresolved mystery in many groups of organisms.

In a new study appearing in The American Naturalist, researchers have now revealed these factors in frogs. Previous studies suggested that patterns of diversity among frog families were explained primarily by the rapid proliferation of species in the tropics, or by rapid proliferation in groups that occurred in many different environments. Surprisingly, the new study reveals that in frogs, the most important factor explaining their patterns of species proliferation and diversity is actually their fine-scale habitat. For example, they find that groups that live mostly in trees have higher rates of species proliferation than those that primarily live on the ground, underground, or in water. Although the effects of climates where species occurred were also significant, they were far less important than these fine-scale habitats. In fact, these fine-scale habitats were nearly three times as important for explaining biodiversity patterns as the large-scale climates where species lived.

This study may be the first to directly compare the effects of fine-scale habitat and large-scale climate on patterns of biodiversity and species proliferation. The authors suggest that the pattern found in frogs may apply to many other organisms as well.

The authors also find that the rate at which species adapt or adjust to different climates is also a key to explaining their patterns of species diversity and proliferation. Thus, groups that have been able to adapt to different climates more quickly have been more successful over tens of millions of years, in terms of having more species today. This may have important implications for how present climate change may influence long-term patterns of biodiversity in frogs and other organisms.

The authors, Daniel Moen and John Wiens, are at Oklahoma State University and the University of Arizona, respectively. Read the Article