Convergence as an Evolutionary Trade-off in the Evolution of Acoustic Signals: Echolocation in Horseshoe Bats as a Case Study

The evolution of novel acoustic signals that are optimal for a particular function or habitat may restrict distinct lineages to the same ecological niche resulting in convergence of phenotypic traits. Such convergence could represent an evolutionary trade-off. The evolution of flutter detection may have restricted horseshoe bats (Rhinolophus) to similar foraging modes resulting in the convergence of phenotypic traits across different lineages. We investigated convergence in African rhinolophids using several phenotypic features. There was pronounced convergence between distantly related lineages including R. damarensis and R. darlingi, and between R. simulator and R. blasii. However, phenotypic divergence, notably in body size and resting frequency, was also evident amongst close relatives of R. damarensis and R. darlingi. These relatives diverged from both the ancestral character state and R. damarensis and R. darlingi. Such divergence suggests that an evolutionary trade-off associated with flutter detection is probably not the cause of convergence in these bats.