Niche conservatism, niche evolution, and species coexistence in lungless salamanders

Background/Question/Methods

The niche is often separated into two different dimensions: Grinellian and Eltonian.  The Grinellian niche encompasses the environmental conditions that determine a species' large scale geographic distribution.  The Eltonian niche is characterized by factors related to biotic interactions and consumer-resource dynamics, which are often more important in facilitating species coexistence at local scales.  In species-rich communities composed of lineages exhibiting conservatism of the Grinellian niche, more rapid evolution of the Eltonian niche might be required in order to achieve high local species richness.  Using the world's diverse lungless salamander fauna as a case study, we test whether the Eltonian niche evolves more rapidly than the Grinnellian niche.  We use phylogenetic comparative methods and a suite of niche variables to estimate and compare the rates of climatic niche (Grinellian niche) and body-size evolution (Eltonian niche).

Results/Conclusions

Preliminary analyses suggest that rates of climatic-niche evolution and body-size evolution did not differ substantially.  Thus, Grinnellian and Eltonian niches have seemingly evolved at similar rates in lungless salamanders.  The similar rates of evolution in these niche dimensions suggest that evolution in both the Grinnellian and Eltonian niche has been important in the coexistence of species.