Doppler-shift compensation behavior (DSC) is a highly specialized vocal response displayed by bats that emit pulses with a prominent constant frequency (CF) component and adjust the frequency of their CF component to compensate for flight-speed induced Doppler shifts in the frequency of the returning echoes. DSC has only been observed in one member of the Neotropical Mormoopidae, a family of bats that use pulses with prominent CF components, leading researchers to suspect that DSC is a uniquely derived trait in the single species Pteronotus parnellii. Yet recent phylogenetic data indicate that the lineage of P. parnellii originates from the most basal node in the evolutionary history of the genus Pteronotus. DSC behavior was investigated in another member of this family, Pteronotus personatus, because molecular data indicated that this species stems from the second most basal node in Pteronotus. DSC was tested for by swinging the bats on a pendulum. P. personatus performed DSC as well as P. parnellii under identical conditions. Two other closely related mormoopids, Pteronotus davyi and Mormoops megalophylla, were also tested and neither shifted the peak frequency of their pulses. These results shed light on the evolutionary history of DSC among the mormoopids.
