Evol Ecol Res 9: 843-854 (2007)     Full PDF if your library subscribes.

Bioclimatic modelling, morphology, and behaviour reveal alternative mechanisms regulating the distributions of two parapatric salamander species

Saad Arif,1* Dean C. Adams2 and Jill A. Wicknick3

1Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY 11794-5245, 2Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA 50011 and  3Department of Biology, University of Montevallo, Montevallo, AL 35115, USA

Author to whom all correspondence should be addressed.
e-mail: sarif@life.bio.sunysb.edu

ABSTRACT

Question: What ecological and evolutionary processes are important in maintaining parapatric distributions of sibling species?

Hypotheses: Previous research has suggested that competition is a likely factor limiting species distributions and maintaining parapatric distributions. Alternatively, abiotic restrictions such as climatic factors and local adaptation can also limit species’ ranges.

Organisms: Plethodon hubrichti, a mountaintop endemic salamander, has an extremely limited geographic range that is entirely surrounded by the widespread Plethodon cinereus. Previous studies have suggested that P. hubrichti may be geographically restricted as a result of interspecific competition with P. cinereus.

Methods: We studied the relationship between trophic morphology and diet in allopatric and sympatric populations to examine the effect of exploitative competition on geographic distribution. Behavioural experiments were conducted in the laboratory to determine the effects of interference competition. We complemented these analyses with bioclimatic modelling of species’ ranges and climate–phenotype correlations to examine the abiotic impact.

Results: Our results suggest that aggressive interactions with P. hubrichti restrict the distribution of P. cinereus and not the converse, whereas P. hubrichti appears to be limited by abiotic climatic factors.

Keywords: aggression, geometric morphometrics, interspecific competition, Plethodon, species’ distributions.

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