Mite load predicts the quality of sexual color and locomotor performance in a sexually dichromatic lizard

Abstract

Since Darwin, the maintenance of bright sexual colors has recurrently been linked to mate preference. However, the mechanisms underpinning such preferences for bright colors would not be resolved for another century. Likely, the idea of selection for colors that could decrease the chances of survival (e.g., flashy colors that can inadvertently attract predators) was perceived as counterintuitive. It is now widely accepted that these extreme colors often communicate to mates the ability to survive despite a “handicap” and act as honest signals of individual quality when they are correlated with the quality of other traits that are directly linked to individual fitness. Sexual colors in males are frequently perceived as indicators of infection resistance, in particular. Still, there remains considerable discord among studies attempting to parse the relationships between the variables associating sexual color and infection resistance, such as habitat type and body size. This discord may arise from complex interactions between these variables. Here, we ask if sexual color in male Florida scrub lizards (Sceloporus woodi) is an honest signal of resistance to chigger mite infection. To this end, we use linear modeling to explore relationships between mite load, different components of sexual color, ecological performance, body size, and habitat type. Our data show that that the brightness of sexual color in scrub lizards is negatively associated with the interaction between mite load and body size, and scrub lizards suffer decreased endurance capacity with increases in mite load. Our data also indicate that mite load, performance, and sexual color in male scrub lizards can vary between habitat types. Collectively, these results suggest that sexual color in scrub lizards is an honest indicator of individual quality and further underscore the importance of considering multiple factors when testing hypotheses related to the maintenance of sexual color.

Using Delaunay triangulation to sample whole‐specimen color from digital images

“…Image segmentation approaches have been useful in addressing many questions. For example, ImageJ has been used for counting pixels within a specified color range to identify diseased tissue (Hadi et al., 2011 ; Papadopulos et al., 2007 ; Schindelin et al., 2015 ), patternize was used to compare the similarity of distributions of three discrete color categories among species of reef fish (Hemingson et al., 2019 ), and colordistance was used to visualize badge color differences between two lizard populations (Orton et al., 2019 ). In certain applications, the use of digital photography, along with computer software to group pixels into categories of color, has decreased subjectivity of color classification and increased the accuracy and reproducibility of color data collection (e.g., Laurinaviciene et al., 2011 ; Rizzardi et al., 2016 ).…”

Seasonal changes in color patches and parasite load of male torquate lizards (Sceloporus torquatus)

“…The torquate lizard shows sexual dichromatism; only the males of this species present blue patches on the venter and the throat (Smith 1936). We assume a similar structure of its blue color patches as in other close-related lizards of the genus (i.e., Quinn and Hews 2003) and, due to evolutionary inertia within sceloporine lizards, we also hypothesize a similar evolution as intraspeci c signals of quality (e.g., Megía-Palma et al 2018b; Orton et al 2019;Megía-Palma et al, 2022). The aim of this study is to investigate whether (i) the re ectance of the structural-based coloration varies across seasons, (ii) there is a relationship between this re ectance and parasite load or the in ammatory response to the injection of an innocuous mitogen (IRM), and (iii) these relationships change across seasons.…”

“…Color patches of animals can re ect trade-offs in resource allocation between important functions, including immunocompetence and reproduction (Zahavi 1975;Václav et al 2007; Orton et al 2019). Hamilton and Zuk (1982) studied bird communities to propose that the full expression of their sexual ornaments can be limited by parasite infections because the latter damage tissues and draw resources from their hosts, compromising the host's energy allocation into signal production.…”