Home Carl People Alumni Funstuff



My research interests include the evolution of behavior; specifically in regards to understanding mechanisms of acoustic communication evolution.

The Gray Treefrog complex consists of a diploid-tetraploid cryptic species pair: Hyla chrysoscelis, the diploid progenitor, and H. versicolor, tetraploid, which arose via allo- or auto-polyploidy at least three times. Like most anuran species, male gray treefrogs produce stereotyped acoustic advertisement signals that facilitate sexual selection via female phonotaxis towards attractive mates. Both species of gray treefrogs produce trilled advertisement calls that consist of a series of amplitude modulated pulses. The main differences in male advertisement calls between the two species differ quantitatively. In H. chrysoscelis, the pulses within the advertisement call are repeated at a frequency of ~50Hz (MO populations) with a fast amplitude rise-time, whereas in H. versicolor the pulses are repeated at a frequency of ~20Hz with a slow amplitude rise-time.

Not surprisingly, females of each species prefer advertisement calls of conspecifics to heterospecifics; however, the most striking dissimilarity between the two species is the criteria by which females perceive the acoustic signals. Females of H. chrysoscelis use pulse repetition rate alone for mate choice, while those of H. versicolor use pulse repetition rate (through pulse period and interpulse duration), as well as pulse shape (the rise-time of amplitude envelope). However, female H. chrysoscelis also use pulse rise-time for discrimination, when advertisement calls consist of pulses of supernormal duration.

Polyploidy, through an effect of increases in cell size, has been shown to be responsible for changes in male advertisement calls, which result in calls that may be more salient in an acoustically-noisy environment.

I use laboratory behavioral experiments to analyze mechanisms of acoustically mediated mate-choice in an artificial lineage of induced auto-polyploid H. chrysoscelis. I use this model system to explore the mechanisms of evolution within the context of acoustic communication.