Color Variation:
NOTE: COVID-19 has unfortunately delayed some aspects of our work in color variation. Specifically, a planned collaboration with Dr. Speiser of USC to study differences in color vision within the band-winged grasshoppers has been delayed because of space and travel restrictions. For now, we still don't have accurate measurements of what colors these animals see despite all their colorful appearances!
Many humans appreciate the variety of colors that fill our natural world, but what selective pressures have led to the variation that we see? Although basic evolutionary theory suggests that dull colors = camouflage and bright colors = communication, reality is much more complicated. Differences in sensory physiology (between and within species), variable environments (in lighting and background), and constraints on color production all require that work on animal coloration take the perspective of the relevant natural parameters.
Current work in the lab seeks to explain two aspects of color variation in band-winged grasshoppers: 1) their hindwings (that vary between species), and 2) their body colorations (that vary within a population). In both cases students use a variety of approaches including non-human visual modeling, phylogenetic reconstruction, and behavioral work in both the lab and field.
Ultimately, seeking to understand this variation from both a functional and evolutionary perspective is a long term goal of the lab.
Current Color Variation Projects:
1) What evolutionary, ecological, and morphological factors have lead to variation in hindwing coloration between band-winged grasshopper species?
2) Does body coloration in the Carolina grasshopper differ because of variable environments?
3) How is variation in band-wing coloration perceived by conspecifics?
4) The interaction between colors, motion, and receiver vision.
Multiple aspects of coloration vary within band-winged grasshoppers.
A) Hindwing coloration in band-winged grasshoppers varies between species in hue, transparency, shape, and patterning. The color may function as a protean defense to confuse predators and/or a signal to conspecifics. B) The Carolina Grasshopper also varies in body coloration with appearances spanning from grey to reddish brown. Work in the lab has suggested this variation is continuous in nature, but we still don't understand what --- if any --- advantage different colorations may provide. Photos by former undergraduate students Brae Salazar (A) and Erick Gilbert (B).
In addition I'm always happy to support student-driven coloration projects in other animals.
Relevant Papers:
Martin E., H.L. Steinmetz, S.Y. Baek, F.R. Gilbert and N.C. Brandley (2022). Rapid Shifts in Visible Carolina Grasshopper (Dissosteira carolina) Coloration During Flights. Frontiers in Ecology & Evolution 10.
Note: these are in different study systems but provide an idea of the approaches we use.
Brandley N.C., M. Johnson, and S. Johnsen (2016). Aposematic signals in North American black widows are more conspicuous to predators than to prey. Behavioral Ecology 27: 1104-1112
Brandley N.C., D.I. Speiser, and S. Johnsen (2013). Eavesdropping on visual secrets. Evolutionary Ecology 27:1045–1068