Environmental Research Institute (ERI) Seminar Series: "The hidden costs of sexually selected traits: Metabolic costs of maintenance and behaviour"
|Date||Wednesday 25 March 2020|
|Time||12pm - 1pm|
|Presenter||Dr Ummat Somjee (Smithsonian Tropical Research Institute, Panama)|
Horns in antelopes, tusks in elephants and antlers in deer are all examples of animal weapons. These structures are often used in competition for mating opportunities. In many species, larger males carry disproportionally larger sexually selected weapons (positive allometry), yet we know little about how the energetic costs of these structures relate to body size or behaviour. We examine the Heliconia bug, Leptoscelis tricolor (Hemiptera: Coriedae), where males have extremely enlarged hind legs used as weapons in male-male combat. First, we capitalize on the behaviour of this insect, which autotomizes its sexually selected weapon (without regeneration), to isolate the metabolic rate associated with the maintenance of these weapons. Second, we perform a mark-recapture study of individuals in a natural population in Panama to understand the movement rates and social associations of these insects in the wild. We find that small and large males differ in the energetic cost of their weapons; metabolic enzyme assays reveal highly metabolically active tissue within leg muscle. Males of different sizes also differed in their social associations and mating opportunities. These energetic costs remain a largely unexplored avenue to understand the forces that shape the behaviour and positive allometries associated with sexually selected weapons so ubiquitous in nature.