Wing pigmentation, immune ability, fat reserves and territorial status in males of the rubyspot damselfly, Hetaerina americana

Abstract

An explanation for courting traits is that they convey information about the bearer's condition to conspecifics, more specifically immune ability. Here we test a series of immune-based assumptions in the territorial damselfly Hetaerina americana, whose males bear wing pigmentation patterns, which are maintained via male-male competition. H. americana males emerge and take some time to mature sexually, after which, depending on their fat reserves, may start defending territories where females arrive at for copulation. Territorial males are eventually defeated and lose their territories. This loss is a consequence of a reduction in muscular fat reserves. We tested whether: (a) territorial males had more pigmented wings, more intense melaninebased immune response (encapsulation response to a nylon filament implant) and higher fat reserves than nonterritorial males; (b) pigmentation is related to immunity and fat reserves; (c) the immune response held constant in two different episodes (3 days between each) in the same male during territorial tenure; and (d) immune response and fat reserves decreased after experimentally simulated fighting event. Our results agree with current views of immune ability and courting traits: (1) territorial males had more wing pigmentation, higher immune responses and fat reserves than non-territorial males; (2) pigmentation was also correlated with immunity and fat reserves; and (3) immune response was similarly intense in the two episodes during territorial tenure. However, this response and fat reserves were considerably lower after fighting compared to that of territorial males and non-territorial males. Our work points out a link between fat reserves and immune ability which agree with previous studies in insects. Given, however, that in this species the use of wing pigmentation via male-male competition is more likely to provide information about current fat reserves than immunity, it is suggested that immune ability is only indirectly selected and may not be the information that pigmentation would convey to conspecifics.

Predation selects for increased immune function in male damselflies,Calopteryx splendens

“…However, we found no difference in wing-spot size between territorial and nonterritorial males. Likewise, in contrast to previous studies on C. splendens [13,14] and other damselflies ( [58,59]; see also [53]), we found no significant relationship between wing-spot size and immune response. This is the first study to measure selection via a known agent, predation, on any aspect of immune function at the individual level in a wild animal population.…”

Resource Defense Polygyny by Hetaerina rosea Selys (Odonata: Calopterygidae): Influence of Age and Wing Pigmentation

“…It has been demonstrated that in Hetaerina, the size of the pigmented area of the wings is under selection, mainly with respect to male-male agonistic displays (Grether 1996a, Serrano-Meneses et al 2007. The size of these pigmented areas are positively correlated with thoracic fat reserves (Contreras-Garduño et al 2006, SerranoMeneses et al 2007, Contreras-Garduño et al 2008, which are used as fuel to light (Marden & Waage 1990). Our results showed that males with a larger pigmented area won more contests, independently of body size (but see also Serrano-Meneses et al 2007).…”

“…Johnson 1962, Waage 1973, Alcock 1982, Lefevre & Muehter 2004, Günther 2006. The outcomes of these contests are in luenced mainly by thoracic fat reserves (Marden & Waage 1990, Plaistow & Siva-Jothy 1996, Serrano-Meneses et al 2007, which are correlated with wing pigmentation (Córdoba-Aguilar 2002, Contreras-Garduño et al 2006, Serrano-Meneses et al 2007. Recently, males with larger pigmented wing areas were shown to win most contests (Contreras-Graduño et al 2008).…”

Effects of Natural and Sexual Selection on Adaptive Population Divergence and Premating Isolation in a Damselfly

“…In general, secondary traits would give information about the bearer's physical condition (Andersson 1994). In this family, some of the secondary sexual traits seem to be clearly dependent on the male condition (Grether 1996b) and are related to greater sexual fitness in different aspects (Grether 1996a, b;Rantala et al 2000;Siva-Jothy 2000;Córdoba-Aguilar 2002;Contreras-Garduño et al 2006. In fact, sexual selection processes in secondary sexual traits play a major role in specific divergence (Svensson et al 2006).…”