title: Effect of competitive cues on reproductive morphology and behavioral plasticity in male fruitflies.
abstract: Phenotypic plasticity will be favored whenever there are significant fitness benefits of responding to environmental variation. The extent and nature of the plasticity that evolves depends on the rate of environmental fluctuations and the capacity to track and respond to that variability. Reproductive environments represent one arena in which changes can be rapid. The finding that males of many species show morphological, physiological, and behavioral plasticity in response to premating and postmating reproductive competition (RC) suggests that plasticity is broadly beneficial. The developmental environment is expected to accurately predict the average population level of RC but to be a relatively poor indicator of immediate RC at any particular mating. Therefore, we predict that manipulation of average RC during development should cause a response in plasticity "set" during development (e.g., size of adult reproductive structures), but not in flexible plasticity determined by the immediate adult environment (e.g., behavioral plasticity in mating duration). We tested this prediction inDrosophila melanogastermales by manipulating 2 independent cues of average RC during development: 1) larval density and 2) the presence or absence of adult males within larval culture vials. Consistent with the prediction, both manipulations resulted in the development of males with significantly larger adult accessory glands (although testis size decreased when males were added to culture vials). There was no effect on adult plasticity (mating duration, extended mating in response to rivals). The results suggest that males have evolved independent responses to long- and short-term variation in RC.
authors.affiliation: School of Biology, University of Leeds , Manton Building, Leeds LS2 9JT , UK .
authors.forename: Amanda
authors.initials: A
authors.lastname: Bretman
authors.affiliation: Institute for Evolution and Biodiversity, University of Muenster , Huefferstr. 1, 48149 Muenster , Germany , and.
authors.forename: Claudia
authors.initials: C
authors.lastname: Fricke
authors.affiliation: School of Biological Sciences, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ , UK.
authors.forename: James D
authors.initials: JD
authors.lastname: Westmancoat
authors.affiliation: School of Biological Sciences, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ , UK.
authors.forename: Tracey
authors.initials: T
authors.lastname: Chapman
keywords: accessory gland; behavioral plasticity; developmental plasticity; larval density; social and sexual environment; testis.