Allometric plasticity in a polyphenic beetle

Publication Type:Journal Article
Year of Publication:2002
Authors:A. P. Moczek
Journal:Ecological Entomology
Date Published:Feb
Accession Number:ISI:000174361200008
Keywords:adaptive phenotypic plasticity, allometric plasticity, alternative reproductive, alternative tactics, developmental threshold, horn polyphenism, male, Onthophagus, onthophagus-acuminatus coleoptera, status-dependent selection, tactics, threshold evolution

1. Environmental conditions. such as variation in nutrition. commonly contribute to morphological variation among individuals by affecting body size and the expression of certain morphological traits however the scaling relationship between a morphological trait and body size over a range of body sizes is generally assumed not to change in response to environmental fluctuation (allometric plasticity), but instead to be constant and diagnostic for a particular trait and species or Population. The work reported here examined diet- induced allometric plasticity in the polyphenic beetle Onthophagus taurus Schreber (1759) (Coleoptera: Scarabaeidae). 2. Male O. taurus vary in body size depending on larval nutrition, Only males above a critical body size threshold express fully developed horns: males smaller than this threshold develop only rudirrientary horns or no horns at all. 3. Field populations that naturally utilise two different resources for feeding larvae (horse dung vs. cow manure) exhibited significant differences in the average scaling relationship between body size and male horn length over the same range of body sizes. Males collected from cow manure populations expressed consistently longer horns for a given body size than males collected from horse dung Populations. 4. Males reared in the laboratory on horse dung or cow manure also exhibited significant differences in the average scaling relationship between body size and horn length. Differences between laboratory populations reared on horse dung or cow manure were of the same kind and magnitude as differences between field populations that utilise these different resources naturally. 5. These findings suggest that between- population differences in scaling relationships between horn length and body size can be the product of differences in the quality of resources available to developing larvae. Results are discussed in the context of onthophagine mating systems and recent insights in the developmental and endocrine control of horn polyphenisms.

URL:<Go to ISI>://000174361200008
Alternate Journal:Ecol. Entomol.
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith