Color lightness of velvet ants (Hymenoptera: Mutillidae) follows an environmental gradient

• Published in: Journal of thermal biology Vol. 100; p. 103030
• Main Authors: Lopez, Vinicius Marques, Azevedo Tosta, Thaína Aparecida, da Silva, Guilherme Gonzaga, Bartholomay, Pedro Reck, Williams, Kevin Andrew, Guillermo-Ferreira, Rhainer
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2021; Elsevier BV
• Subjects: Adaptation, Physiological; Animals; Ants - metabolism; Ants - physiology; Aposematism; Batesian; Behavior; Bioclimatology; Biogeography; Climate change; Color; Coloration; Environmental conditions; Humidity; Hymenoptera; Hypotheses; Melanin; Melanism; Mutillidae; Müllerian; Parasitoid; Phylogeny; Pigmentation; Predators; Radiation; Species; Temperature; Ultraviolet radiation; Ultraviolet Rays; Variation; Biogeography; Climate change; Batesian; Parasitoid; Behavior; Müllerian
• ISSN: 0306-4565; 1879-0992
• DOI: 10.1016/j.jtherbio.2021.103030

Color traits are highly influenced by environmental conditions along the distributional range of many species. Studies on the variation of animal coloration across different geographic gradients are, therefore, fundamental for a better understanding of the ecological and evolutionary processes that shape color variation. Here, we address whether color lightness in velvet ants (Hymenoptera: Mutillidae) responds to latitudinal gradients and bioclimatic variations, testing three ecogeographic rules: The Thermal melanism hypothesis; the Photoprotection hypothesis; and Gloger's rule. We test these hypotheses across the New World. We used photographs of 482 specimens (n = 142 species) of female mutillid wasps and extracted data on color lightness (V). We analyzed whether variation in color is determined by bioclimatic factors, using Phylogenetic Generalized Least Square analysis. Our explanatory variables were temperature, ultraviolet radiation, humidity, and forest indicators. Our results were consistent with the Photoprotection hypothesis and Gloger's rule. Species with darker coloration occupied habitats with more vegetation, higher humidity, and UV-B radiation. However, our results refute one of the initial hypotheses suggesting that mutillids do not respond to the predictions of the Thermal melanism hypothesis. The results presented here provide the first evidence that abiotic components of the environment can act as ecological filters and as selective forces driving the body coloration of velvet ants. Finally, we suggest that studies using animals with melanin-based colors as a model for mimetic and aposematic coloration hypotheses consider that this coloration may also be under the influence of climatic factors and not only predators. [Display omitted] •We studied velvet ants from New World and analyzed whether color lightness variation is determined by environmental factors.•We tested three ecogeographic rules: The Thermal Melanism hypothesis; the Photoprotection hypothesis; and Gloger's rule.•Darker species occupied habitats with more vegetation, higher humidity, and UV-B radiation.•Results are consistent with the Photoprotection hypothesis and Gloger's rule.•Abiotic components of the environment can act as ecological filters and as selective forces on velvet ant colors.