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Isolation and Identification of Bacterial Strains from Skin of Terrestrial Amphibians

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Niche conservatism drives elevational diversity patterns in Appalachian salamanders.

Kenneth H Kozak¹, John J Wiens

¹Bell Museum of Natural History and Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, Minnesota 55108, USA. kozak016@umn.edu

The American Naturalist

|May 26, 2010

Summary

Montane regions harbor high species richness at mid-elevations due to longer habitat occupation and niche conservatism. This pattern in plethodontid salamanders offers insights into elevational diversity and climate change vulnerability.

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Area of Science:

Ecology
Evolutionary Biology
Biogeography

Background:

Biodiversity hotspots are often found in montane regions.
Many species exhibit peak diversity at intermediate elevations, a pattern known as hump-shaped diversity.
Previous studies have not fully explored the ecological and evolutionary drivers of this pattern.

Purpose of the Study:

To investigate the ecological and evolutionary causes of mid-elevation species richness peaks.
To test the time-for-speciation effect and niche conservatism in North American plethodontid salamanders.
To understand the role of habitat occupancy duration and climatic niche stability in shaping diversity gradients.

Main Methods:

Utilized a near-comprehensive phylogeny of plethodontid salamanders.
Incorporated environmental data to analyze species distributions.
Developed a null model to assess the relationship between area occupancy time and species richness.
Applied a novel approach to test for long-term stasis in climatic niches (niche conservatism).

Main Results:

The mid-elevation peak in species richness is explained by the time-for-speciation effect, with longer occupation of intermediate habitats leading to higher species accumulation.
Niche conservatism was identified, where species' climatic niches remained stable over evolutionary time.
This niche conservatism constrained the dispersal of salamander lineages to lower and higher elevations, reinforcing the mid-elevation diversity peak.

Conclusions:

Ecological (time-for-speciation) and evolutionary (niche conservatism) factors jointly explain elevational diversity patterns in montane regions.
Montane biotas exhibit high species and phylogenetic diversity but are potentially vulnerable to rapid climate change.
The findings provide a framework for understanding elevational diversity gradients in other montane ecosystems globally.