Evol Ecol Res 10: 197-212 (2008)     Full PDF if your library subscribes.

An ecological twist on the morphology–performance–fitness axis

Ryan Calsbeek*

Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA

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ABSTRACT

Hypothesis: Natural selection shapes correlations between morphology and performance through variation in ecology (habitat use).

Organism: Anolis sagrei lizards (the brown anole).

Field site: A small offshore island near Great Exuma, Bahamas.

Methods: I measured morphology, physiological performance [e.g. sprint speed, sprint sensitivity (the change in speed on broad versus narrow surfaces), running endurance], and habitat use (perching diameter) in natural populations of male and female lizards. I released lizards to their original sites of capture and measured differences in survival (natural selection) in each sex as a function of morphology, performance, and estimates of habitat use. Survival differences were recorded over 4 months (June–September), a period that includes the greater part of the breeding season.

Results: Natural selection acted on correlations between morphology and performance that were associated with differences in habitat use among males. In most cases, selection acted on trait correlations despite the lack of any measurable selection on individual morphological or performance traits. However, morphology and performance were not correlated in females, nor did selection operate on performance variables or most morphological traits in females. Thus, hypotheses concerning selection on morphology, performance, and habitat use were supported by data for males but not females.

Keywords: anole, island, lizard, locomotor performance, selection.

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        © 2008 Ryan Calsbeek. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

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