Call synchrony and the evolutionary origins of leader preference in Neoconocephalus ensiger katydids /

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Many species of acoustically communicating insects and anurans display a female preference for males producing their calls just ahead of those of their neighbors. The evolutionary origin of these preferences is unclear. We test whether leader preference is adaptive in Neoconocephalus katydids. The ability to produce leading calls was not correlated with male quality in a species with leader preference or two closely related species without the preference. However, in N. ensiger, the species with the preference, females mating with leaders produced higher quality offspring than those mating with followers. This suggested that leader preference is adaptive and selected for in this species. The ability to produce leading calls was not heritable, meaning that the preference cannot have an evolutionary effect on the male trait and they will not become coupled. Male N. ensiger adjust the timing of their chirps relative to their neighbors, which leads to synchrony within a chorus. The mechanism used by N. ensiger males differs from that of all previously described species with acoustic synchrony. Neoconocephalus ensiger males adjust their actual intrinsic chirp rate to match that of other males. The characteristics that determine a male's ability to produce leading calls and the specific source of the female fitness benefit are yet unknown.