Aposematic Signal Variation Predicts Male-Male Interactions in a Polymorphic Poison Frog

Many species use conspicuous “aposematic” signals to communicate unpalatability/unprofitability to potential predators. Although aposematic traits are generally considered to be classic examples of evolution by natural selection, they can also function in the context of sexual selection, and therefore comprise exceptional systems for understanding how conspicuous signals evolve under multifarious selection. We used males from a highly territorial poison frog species in a dichotomous choice behavioral test to conduct the first examination of how aposematic signal variation influences male–male interactions. Our results reveal two behavioral patterns: (1) male dorsal brightness influences the behaviors of male conspecifics such that males approach and call to brighter males more frequently and (2) a male\u27s dorsal brightness predicts his own behavior such that bright males approach stimulus frogs faster, direct more calls to bright stimulus frogs, and exhibit lower advertising call pulse rates (a fitness‐related trait). These findings indicate the potential for sexual selection by male–male competition to impact aposematic signal evolution

Flooding Hazard in Howard County: Causes and Green Infrastructure Solutions

Final project for BSCI215: Global Sustainability (Fall 2015). University of Maryland, College Park.Howard Count

Data from: Warning signal brightness variation: sexual selection may work under the radar of natural selection in populations of a polytypic poison frog

Though theory predicts consistency of warning signals in aposematic species to facilitate predator learning, variation in these signals often occurs in nature. The strawberry poison frog, Dendrobates pumilio, is an exceptionally polytypic aposematic frog exhibiting variation in warning color and brightness. In the Solarte population, males and females both respond differentially to male brightness variation. Here, we demonstrate through spectrophotometry and visual modeling that variation in aposematic brightness within this population is likely visible to two putative predators (crabs, snakes) and conspecifics, but not to the presumed major predator (birds). This study thus suggests that signal brightness within D. pumilio populations can be shaped by sexual selection, with limited opportunity for natural selection to influence this trait due to predator sensory constraints. As changes in signal brightness can ultimately lead to changes in hue, our findings at the within-population level can provide insights into understanding this polytypism at across-population scales

Interacting selection diversifies warning signals in a polytypic frog: an examination with the strawberry poison frog

Abstract Aposematic signals represent one of the most accessible traits to evaluate the interaction of natural and sexual selection on signal evolution. Here we investigate the contributions of these two selective forces on the aposematic signal evolution of the highly polytypic strawberry poison frog, Oophaga pumilio, of Bocas del Toro, Panama. Previous research has shown that the brightness of O. pumilio warning coloration can inform predators of the toxicity levels associated with different populations of the archipelago. Other studies suggest that sexual selection may be influencing warning signal brightness within populations via female mate choice (Isla Solarte, Isla Bastimentos, and Aquacate Peninsula populations) and male-male competition (Isla Solarte). Here we present two non-exclusive scenarios for how natural and sexual selection interact to drive phenotypic variation across this archipelago: (1) predators impose a selective regime whereby populations above a toxicity-brightness threshold are at liberty to diversify via sexual selection and below which populations are constrained to maintain a stricter resemblance to a more cryptic population mean, and (2) synergistic/additive effects of inter-and intrasexual selection drive the evolution of brighter males within populations above this toxicity threshold. We investigate whether aposematic patterns of divergence across the archipelago relative to the common mainland phenotype meet these predictions using existing data on O. pumilio morph toxicity measures and overall conspicuousness estimates to an avian predator. Using standardized z-scores to evaluate the range of trait values, we find that indeed the population representative of the common mainland phenotype (Almirante) represents an intermediate level of both toxicity and conspicuousness, and that derived Bocas del Toro populations vary in each of those components in directions predicted by the proposed scenarios. Furthermore, we find greater divergence towards conspicuousness than crypsis, 123 Evol Ecol (2013) 27:693-710 DOI 10.1007 a pattern suggestive of sexual and natural selection acting synergistically in morphs with high toxicity

Reflectance and irradiance data used in analyses

Reflectance and irradiance data used in analyses. Please see ReadMe file for additional details