Macroevolutionary Constraint and Selection on Anti-Bat Moth Tails

Abstract

AbstractElaborate traits evolve via intense selective pressure, often overpowering ecological constraints. Hindwing tails that thwart bat attack have repeatedly originated in moon moths (Saturniidae), with longer tails having more pronounced anti-predator effect. Understanding the relative evolutionary balance between predation pressure and possible limiting factors requires a macroevolutionary perspective. To estimate the eco-evolutionary forces shaping tails, we conducted phylogenetically-informed linear regressions. We built a well-sampled, time-calibrated phylogeny of the entirely tailed moth group (Actias + Argema) and performed ancestral state reconstruction and biogeographical analyses. To generate metrics of evolutionary pressures, we developed estimates of bat predator abundance and estimated environmental conditions associated with individual moth wing measurements. This integrative approach reveals evidence for positive selection on hindwing tails and body size by bats and negative selective pressure from environmental factors. Our study provides insight into the tradeoffs between strong biotic selective pressures and abiotic constraints that shape elaborate traits across the tree-of-life.