Geographic Variation and Maintainace of Polymorhism in Parasemia plantaginis (Wood Tiger Moth)
Project Number: CH-4168
||01/01/2010 - 12/31/2012 project completed
||Dr. Robert Hegna
University of Palm Beach Atlantic
901 S. Flagler Drive
West Palm Beach, FL 33401
United States of America
A central question in evolutionary biology is to understand how spatial and temporal variation in selection maintains genetic and phenotypic variation within and among populations (Conover et al. 2006). Recently, a comparative analyses in lizards suggested that species with variable color patterns have larger ranges, utilize a greater diversity of habitat types, and are underrepresented among species currently listed as threatened (Forsman & Åberg 2008). These results are consistent with the proposition that the co-occurrence of multiple color variants may promote the ecological success of populations and species. Thus, in addition to its purely intellectual endeavor, studies on color polymorphism also offer tools in following populations during the (human) induced environmental changes (Mace and Purvis 2008).
Butterflies and moths provide an ideal system for integrative research on evolution and selective pressures because of the plethora of ‘raw material’ through which evolution can act via the variability between and within species (Brakefield and French 1999, McMillan et al. 2002). The wood tiger moth (Parasemia plantaginis, family Arctiidae) occurs worldwide at northern latitudes and exhibits extensive color polymorphism. Our studies also indicate Parasemia plantaginis is aposematic (i.e., it tastes bad to predators and has a warning signal). Aposematic organisms are not predicted to be polymorphic because it would disrupt the ability for predators to form a ‘search image’, which would make it more difficult for predators to learn avoidance (Mappes et al. 2005). Therefore, P. plantaginis are not predicted to display color polymorphisms. Relaxed predation pressure, via predator generalization or less dense predator populations, can allow greater variation in warning signal because there is less need for an extremely uniform signal to lower predator education costs. Another factor besides a lack of predation that can help explain polymorphisms in aposematic organisms is trade-offs. In the alps and other high elevation locations we observe a very melanistic color morph of this species in addition to other geographic trends that result in increased melanization. Therefore, our predation study aims to address two main questions. The first is whether lower predation pressure can explain observed variability in phenotype in this aposematic moth. We are performing experiments in multiple locations this summer to address this first question. The second question in our research is whether there is a cost in terms of increased predation for individuals who are very melanistic.
Last update: 2/2/18
Source of data: ProClim- Research InfoSystem (1993-2020)
Update the data of project: CH-4168