Evol Ecol Res 11: 1217-1233 (2009)     Full PDF if your library subscribes.

The author retracted this paper.

Morphological and dietary differences between individuals are weakly but positively correlated within a population of threespine stickleback

Daniel I. Bolnick and Jeffrey S. Paull

Section of Integrative Biology, University of Texas at Austin, Austin, Texas, USA

Correspondence: D.I. Bolnick, Section of Integrative Biology, University of Texas at Austin, One University Station C0930, Austin, TX 78712, USA.
e-mail: danbolnick@austin.utexas.edu

ABSTRACT

Background: Many theoretical models of speciation and niche evolution assume that the ecological similarity between conspecific individuals depends on their phenotypic similarity. Thus, competition between individuals is expected to depend on their phenotypic similarity. Theoretical models often assume that this intraspecific competition function is Gaussian.

Questions: Are morphological similarity and diet similarity positively correlated? If so, is this relationship non-linear?

Data: Stomach contents, stable isotope ratios (δ13C and δ15N), and trophic morphology (standard length, gape width, body width, gill raker number, and gill raker length) for 265 threespine sticklebacks (Gasterosteus aculeatus) from a single population from a lake in British Columbia.

Analysis: We calculated the diet similarity and morphological similarity between all pairs of individuals in our sample. We examined the correlation between diet and morphological similarity, and tested whether the relationship exhibits any non-linearity.

Conclusions: Similarity in trophic morphology is correlated with dietary similarity between individuals. However, both body size and trophic morphology explained remarkably small percentages of the variance in diet overlap. Also, we found no evidence of curvature in the intraspecific competition function.

Keywords: adaptive dynamics, Gasterosteus aculeatus, individual specialization, niche evolution, niche variation.

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