Geographical variation in male advertisement calls and female preference of the wide-ranging canyon treefrog, Hyla arenicolor

Abstract

We surveyed the geographical variation in male advertisement calls of the wide-ranging canyon treefrog, Hyla arenicolor, and found large call differences among geographically distant lineages that had been characterized by a recent phylogeographical study. To test whether these call differences were biologically relevant and could allow reproductive isolation of different lineages should they come into secondary contact, we assessed female preference in a lineage occurring in southern Utah and north-western Arizona, USA. These females exhibited a strong preference for their own lineage's call type over the calls of two Mexican lineages, but not over the calls from the geographically nearest lineage. We also identified traits that female frogs probably use to discriminate between lineage-specific advertisement calls. Our behavioural results, together with recent molecular estimates of phylogenetic relationships among lineages, will guide future work addressing the evolutionary forces that have led to this biologically significant variation in male sexual signals.