A Mismatch between the Perceived Fighting Signal and Fighting Ability Reveals Survival and Physiological Costs for Bearers

Abstract

Signals of fighting indicate an animal's intention to attack and so they serve to prevent costly aggressive encounters. However, according to theory, a signal that is different in design (i.e. a novel signal) but that fails to inform fighting intentions will result in negative fitness consequences for the bearer. In the present study we used males of the territorial damselfly Hetaerina americana, which have a red wing spot during territory defense that has evolved as a signal of fighting ability. By producing a novel signal (covering the red spot with blue ink) in territory owners, we investigated: a) the behavioral responses by conspecific males; b) survival cost and c) three physiological mediators of impaired survival: muscular fat reserves, muscle mass and immune ability. We predicted that males with the novel signal would be attacked more often by conspecifics as the former would fail to convey fighting ability and intentions adequately. This will result in lower survival and physiological condition for the novel signal bearers. We found that, compared to control males (males whose red spot was not changed), experimental males had reduced survival, were less able to hold a territory, and had a reduced muscle mass. It seems that spot modified males were not able to effectively communicate their territory tenancy, which may explain why they lost their defended sites. Our results provide support for theoretical models that a novel signal that fails to informing fighting ability may lead to a fitness cost for bearers.

The Role of Wing Coloration in Sex Recognition and Competitor Recognition in Rubyspot Damselflies (Hetaerina spp.)

“…This may explain why, in a previous study, covering the red spots of male H. americana with blue ink reduced their territory holding ability (González‐Santoyo et al. ).…”

Sexual signals reveal males’ oxidative stress defences: Testing this hypothesis in an invertebrate

“…Although the size of the red wing spot in H. americana has been related to the immune response in males within and between populations (Contreras‐Garduño et al., ; Contreras‐Garduño, Lanz Mendoza, et al., ; Contreras‐Garduño et al., , ), it is also possible that it evolved as a correlated trait of males’ general condition (Contreras‐Garduño et al., ) such as muscle mass and fat load (Contreras‐Garduño et al., ; Contreras‐Garduño et al., , ; González‐Santoyo et al., ; Raihani et al., ), amount of food (Álvarez et al., ; Jiménez‐Cortés et al., ) and oxidative defences (this study). This notion is consistent with models that suggest that SSC are signals of general health and condition, not of the immune response or parasite resistance specifically (Adamo & Spiteri, , ).…”

“…Wing spot size is positively correlated with male mating success and territory acquisition (Grether, ; Raihani, Serrano‐Meneses, & Córdoba‐Aguilar, ; Serrano‐Meneses et al., ), and spot size appears to be a signal of male immunity (Contreras‐Garduño, Buzatto, Abundis, et al., ; Contreras‐Garduño, Buzatto, Serrano‐Meneses, Nájera‐Cordero, & Córdoba‐Aguilar, ; Contreras‐Garduño et al., , ). However, it is very likely that wing spots represent not only signals of a male's immune response but also his general condition (Contreras‐Garduño et al., ), since wing spot size correlates with fat reserves and muscle mass (Contreras‐Garduño et al, ; Contreras‐Garduño et al., , ; González‐Santoyo, González‐Tokman, Munguía‐Steyer, & Córdoba‐Aguilar, ; Raihani et al., ), as well as the amount of food ingested in the larval and teneral stages (Álvarez, Serrano‐Meneses, Reyes‐Márquez, Jiménez‐Cortés, & Córdoba‐Aguilar, ; Jiménez‐Cortés, Serrano‐Meneses, & Córdoba‐Aguilar, ).…”

Physiological condition and wing pigmentation expression in a damselfly with seasonal polyphenism

“…More remarkable than colour, in some genera of the Calopterygidae family, such as Calopteryx , Hetaerina and Mnais , spot size shows large inter‐ and intraspecific variation (Hooper et al ., ; Anderson, & Grether , b; Outomuro et al ., ; Drury et al ., ), with very consistent hyper‐allometric patterns (Outomuro et al ., ) for which size is positively related to mating success (Córdoba‐Aguilar & Cordero‐Rivera, ; Córdoba‐Aguilar & González‐Tokman, ). Different sources indicate that these wing spots are ‘honest’, condition‐dependent traits because individuals with a larger expression of spots survive for longer (Grether, ; González‐Santoyo et al ., ) and respond more strongly to immune challenges (Siva‐Jothy, ; Rantala et al ., ; Koskimäki et al ., ; Contreras‐Garduño et al ., , ) and diet stress (Álvarez et al ., ) than males with smaller wing spots.…”