Association of Coloration Mode with Population Declines and Endangerment in Australian Frogs

Abstract

Successful protection of biodiversity requires increased understanding of the ecological characteristics that predispose some species to endangerment. Theory posits that species with polymorphic or variable coloration should have larger distributions, use more diverse resources, and be less vulnerable to population declines and extinctions, compared with taxa that do not vary in color. We used information from literature on 194 species of Australian frogs to search for associations of coloration mode with ecological variables. In general, species with variable or polymorphic color patterns had larger ranges, used more habitats, were less prone to have a negative population trend, and were estimated as less vulnerable to extinction compared with nonvariable species. An association of variable coloration with lower endangerment was also evident when we controlled statistically for the effects of range size. Nonvariable coloration was not a strong predictor of endangerment, and information on several characteristics is needed to reliably identify and protect species that are prone to decline and may become threatened by extinction in the near future. Analyses based on phylogenetic-independent contrasts did not support the hypothesis that evolutionary transitions between nonvariable and variable or polymorphic coloration have been accompanied by changes in the ecological variables we examined. Irrefutable demonstration of a role of color pattern variation in amphibian decline and in the dynamics and persistence of populations in general will require a manipulative experimental approach.

Effects of genotypic and phenotypic variation on establishment are important for conservation, invasion, and infection biology

“…It is particularly promising that diversity seems to contribute to successful establishment most strongly in experiments performed under natural conditions in the wild, because in those studies the fate of the introduced individuals and their progeny may be influenced by a plethora of abiotic factors and biotic interactions beyond the control of the experimenter, as in reintroduction and translocation programs. Further support for the pivotal role of diversity for population fitness comes from comparative studies across different species, indicating that greater variability in morphological, life history, and color pattern traits buffers against extinction in bivalves, ostracods, frogs, snakes, lizards, birds, and mammals (24,(40)(41)(42)(43)(44). The results reported here also support the notion that founder diversity is potentially important in biological invasions (3,25).…”

Diversity and Relatedness Enhance Survival in Colour Polymorphic Grasshoppers

“…This supports the proposition that negative effects associated with competition are less manifest in groups of individuals with different capabilities, requirements and tolerances that enable temporal and micro-spatial subdivision of resources, and corroborates one of the mechanisms envisaged to promote the ecological success of polymorphic populations [3], [4], [7], [9]. It is encouraging that the strength in diversity demonstrated in pygmy grasshoppers at the scale of experimental cages mirror associations of variable coloration with endangerment seen at the continent scale across species of lizards and snakes [39] and frogs [40]. Perhaps the most exiting outcome of our study is the demonstration of conflicting selection for and against genetic similarity occurring simultaneously, a finding of importance for models of the evolution of female multi-male mating behaviour [15], [16], [17], [26].…”

Variation in founder groups promotes establishment success in the wild

“…Our results also have implications for conservation biology, since taking variation into consideration may improve the success of reintroduction and translocation projects aiming to protect endangered populations, species and communities [4,5,14]. In this context, it is interesting that species with variable colour patterns have larger geographical range distributions and occupy more diverse habitat types compared with less variable species [44,45]. Finally, that some of the most well-known invasive species (e.g.…”