Invited Speakers

Molly Cummings earned her BA at Stanford University in Human Biology; a Post-Graduate Diploma in Marine Sciences at James Cook University in North Queensland, Australia; and her PhD in Evolutionary Biology at the University of California at Santa Barbara.  She completed a short PostDoc at the University of Texas at Austin, and has been an Assistant Professor at UT Austin since 2004.  Her research focuses on external and internal processes shaping animal communication via three avenues of research:  (1) Sensory Ecology:  quantitatively characterizing environmental, visual, and signaling features involved in sexual communication.  (2) Evolution of aposematic signals (warning colors) in poison frogs: employing predator learning experiments, toxicity assays, visual pigment expression, and mate choice experiments to identify factors driving signal variation. (3)  Internal mechanisms of mate choice behavior in fish: investigating how the CNS regulates female responses during mate choice using brain-specific microarrays, qPCR and in situ hybridizations.

Abstract

SENSORY ECOLOGY OF KELP FOREST FISHES OR (WHAT CAN WE LEARN ABOUT VISUAL DETECTION BY STUDYING EVOLUTION)

Molly Cummings, Section of Integrative Biology, University of Texas, Austin,TX 78712 

A spectrally variable environment can tell us much about the ideal design for visual detection and visual communication.  It is under such constrained environments that selection acts directionally on traits.  I examine the evolutionary solutions to the problem of target detection and signal design in an optically variable environment by studying a group of closely related fish (surfperch: Embiotocidae) that inhabit the California kelp forest.  Using species-specific measurements of habitat spectral irradiances collected over 3 years, visual pigment absorptances, and foraging target and color pattern reflectances along with simple visual detection models, I evaluate the direction of visual evolution in this system.  The results show that photoreceptor peak sensitivity covaries with changes in optical habitat and that this divergence produces detectional biases.  The evolutionary divergence in visual detection performance across this group of dichromats suggest that some species favor luminance contrast detection while others favor chromatic contrast.  Divergence in sensory biases follows divergence in habitat optical properties—specifically the variation in signal:to:noise in particular detection channels.  Signal design properties and display behaviors also show parallel divergence to exploit receiver biases, with signal design divergence observed across three different chromatophore types favoring species-specific biases.