Presentation Detail

Behavior and Social Evolution

Xu, Mingzi [1], Fincke, Ola [1].

Honest signal of male quality in the territorial contests of a Neotropical giant damselfly.

In species whose males defend territories to attract females, competing males frequently challenge residents over the ownership. Signals that correlate with male quality, hence, can be used to predict contest outcomes are beneficial because they reduce the costs and risks associated with actual fights. However, a challenge to the use of signals of male quality in resolving the contests is that males may exaggerate their signals. Such dishonest signals can undermine the stability of a signaling system. One of the common resolutions to the problem is to involve condition dependent costs in the production or the efficacy of the signals. In the Neotropical giant damselfly Megaloprepus caerulatus, males defend water-filled tree holes to attract females, who lay their eggs in the tree holes. Previous work has suggested that a male's white wing patches, made of nano wax-structures, are a signal assessed by contesting rivals. However, the honesty of this signal and the male traits it reflects remain unclear. We hypothesized that the wing patch indicates (1) body size, (2) fat reserves used in fights, or (3) flight muscle mass that provides power and agility. Furthermore, if the patch honestly signals male quality, we expect that (4) the wing patch exhibits higher allometry and variation than non-signaling traits, and that (5) the production cost is condition dependent. To test these hypotheses, we conducted a rearing experiment that manipulated food availability of full-sib larvae. After adults emerged, we measured the size, reflectance and fat content of the wing patch, and the potential underlying male qualities (body size, fat reserves and flight muscle mass). The results suggested that the wing patch was indicative of both body size and fat reserves, but not flight muscle mass. As predicted for honest signals, the wing patch showed a higher isometric scaling and greater variation relative to homologous, non-signaling traits in both males and females. Additionally, the proportion of total fat allocated to develop the wing patch decreased with body condition as measured by size-corrected fat reserve, suggesting that condition-dependent production cost of the signal was a possible, if not the only, mechanism for maintaining the honesty of the male quality signal in this species.

1 - University of Oklahoma, Department of Biology, 730 Van Vleet Oval, Norman, OK, 73019, USA

Keywords:
honesty signaling
condition dependence
territorial contest
fighting ability
Megaloprepus.

Presentation Type: Regular Oral Presentation
Session: 46
Location: Peruvian B/Snowbird Center
Date: Saturday, June 22nd, 2013
Time: 4:15 PM
Number: 46004
Abstract ID:873
Candidate for Awards:W.D. Hamilton Award for Outstanding Student Presentation