10-5 Thursday, Jan. 5 09:15 - 09:30 The origin of complex calls: inferences from phylogeny and function HARNESS, N*; SCHUL, J; University of Missouri; University of Missouri Harness@gmail.com
Among closely related groups meadow katydids have unusually complex calls, consisting of buzzing and ticking phrases. In some species the tick/buzz pattern is highly stereotyped, while in others it is variable both within and between males. This makes them an excellent system for a comparative study of complex call evolution. In all species tested buzzes are necessary and sufficient to attract females. In some, but not all, species the ticking phrase increases attractiveness. Here we test the importance of ticks for male-male interactions. First we compared solo and group calling: in all species tested, males produced more tick phrases while group calling. Within each group the male starting a calling bout produced a higher proportion of ticking phrases. In arena experiments males chose their calling position in the presence of a call playback. Stimulated with natural patterns, males showed significant spacing. With buzzes alone, males moved much closer to the speaker. With ticks alone, the distance increased significantly. Our findings support the hypothesis that tick phrases evolved in the context of male-male interactions and were later incorporated into male-female communication.