Evol Ecol Res 2: 593-612 (2000)     Full PDF if your library subscribes.

Experimental analyses of body size, flight and survival in pierid butterflies

Joel G. Kingsolver and Robert B. Srygley‡

Department of Zoology, Box 351800, University of Washington, Seattle, WA 98195, USA

Author to whom all correspondence should be addressed.
e-mail: jgking@u.washington.edu

ABSTRACT

To explore the consequences of allocation of body mass for flight and fitness in butterflies, we experimentally increased body weight and measured the effects on flight activity and survival in the field for two co-occurring pierid species (Pontia occidentalis and Colias philodice) that differ in palatability, mass allocation and flight speed. We predicted that increasing body weight would reduce flight activity in both Pontia and Colias, but that reductions in survival would be greater in the more palatable Colias than in the less palatable Pontia. Behavioural observations during three mark–recapture experiments showed that weighted butterflies flew less frequently than control butterflies in both Pontia and Colias. Adding weights significantly reduced survival in one study with Pontia, but not in a second study. Contrary to our predictions, adding weights had no significant effects on survival in the more palatable Colias. In combination with previous experimental manipulations of wing area, these results support the hypothesis that flight muscle ratio – the ratio of thoracic flight muscle to total body mass – is an important determinant of flight frequency in these species. However, the results do not indicate that flight muscle ratio is important for predator escape by these butterflies at our study sites. Different aspects of body size and shape may affect different components of butterfly flight, and seasonal variation in predation at our sites may modulate any relationship between flight and survival.

Keywords: body size, butterflies, flight, flight muscle ratio, mark–recapture, survival.

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        © 2000 Joel G. Kingsolver. 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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