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Hello everyone. I wrote this ideas paper on exaggerated sexually selected traits and energetics, out now in #BioEssays… Here is a short summary..a thread @AnimBehSociety @SSEgrad @EEOEvolution https://onlinelibrary.wiley.com/doi/10.1002/bies.202000183
The smallest deer species, the pudú, is about the size of a small dog & has tiny antlers that account for ~ 0.1% of its body mass. The largest deer species we know to have ever existed the Irish elk had massive antlers accounting for ~10% of its body mass
This positive allometry arises in diverse taxa. It is found in elk antlers, but also the antlers of tiny antlered flies, in the tusks of elephants, the horns of prehistoric rhinos, and even the ornaments of canopy dwelling mosquitoes…
Trait exaggeration and positive allometry have long been puzzles. Why do only relatively few species have large sexually selected traits (SSTs)? Why can larger animals sometimes invest relatively more in SSTs compared to smaller ones?
As these animals get larger they may get disproportionately larger SSTs, but their per-gram energy use gets more efficient too. Larger animals pay relatively lower energy costs for maintenance and locomotion.
Many studies have looked at the energetic cost of growth, contest/signaling behavior or locomotion with SSTs… but these costs may be very different depending on the specific animal groups studied, but the cost of maintaining tissue is almost always lower for larger animals
Animals can also use physiological ‘tricks’ to reduce the energetic costs of SSTs. Bone in antlers, keratin in horns and feathers & insect cuticle all have relatively low maintenance costs & It turns out a peacock's train does not measurably increase energy costs of locomotion!
This energetic perspective allows us to develop hypotheses and testable predictions. Animals that are energy-limited may have developed cost-saving ‘tricks’ to keep their big SSTs. We should also pay more attention to metabolically active tissue associated with SSTs
I learned so much and got a lot of really helpful input and advice for this really broad exploratory paper… thank you @MMayDixon @JJinsing @cpaintingnz @insectecophys @j_welklin @nushiamme @ginnygreenway
