The relative effects of pace of life and habitat characteristics on the evolution of sexual ornaments: a comparative assessment

Selection may favor greater investment into sexual ornaments when opportunities for future reproduction are limited (e.g., due to high adult mortality). However, a key driver of mortality, predation, typically selects against elaborate sexual ornaments. Here, we examine the evolution of sexual ornaments in a group of killifishes, which have marked contrasts in life-history strategy between species and inhabit environments that differ in their accessibility to aquatic predators. We first assessed if the size of sexual ornaments (unpaired fins) influenced swimming performance and found that larger fins negatively affected swimming performance. Second, we investigated whether the evolution of larger ornamental fins is driven primarily by the pace of life-history (i.e., investment into current vs future reproduction) or habitat type (as a proxy for predation risk). We found that males from species inhabiting ephemeral habitats with lower predation risk had both larger fins and more pronounc...