Color variation in signal crayfish Pacifastacus leniusculus

Abstract

External colouration in animals depends on the interaction of several different factors including the genetics and epigenetics processes that underlie the colour expression, the mechanisms of colour perception, and the general mechanisms controlling colour evolution and function. Among all, camouflage from predators and conspicuousness are of particular interest since pose animal to choose between opposite adjustment in colouration. The external colouration of crustaceans is mainly due to the accumulation of carotenoids in the exoskeleton and the epidermal layer, and the trade-off between camouflage and communication had lead to a variety of responses, involving signal partitioning, spectral sensibility, changing colouration or signalling behaviour. Here, we used digital images to explore intrapopulation variability of the external colouration of Pacifastacus leniusculus among body regions within an individual and between sexes. We found that i) ventral colouration of claws are more saturated and brilliant than upperparts, ii) males express a more saturated and brightness colouration than females, especially on the lower portion of claws, iii) colour intensity and brightness increases with size differently in different body regions, and iv) brightness is more variable in males than in females. All the above patterns support the hypothesis that colour in this species could be the result of a compromise between camouflage from predators and conspicuousness for communication. The results of this study suggest that carotenoid might have something to do with intraspecific communication and perform more complex functions than that of a simple pigment.

Patterns of variations in dorsal colouration of the Italian wall lizard Podarcis siculus

“…Colour variation in the Italian wall lizards was assessed in a three-step analysis ( Sacchi et al, 2021 ). First, we generated the individuals’ frequency distributions of hue, saturation, and brightness by using values computed on the whole samples of pixels selected for each individual (HSV colour spectrum).…”

Color Perspectives in Aquatic Explorations: Unveiling Innate Color Preferences and Psychoactive Responses in Freshwater Crayfish

“…Similarly, crayfish are also under intense sexual selection pressure in their mating systems. Their mating selection is also affected by the color of exoskeleton and claws [55]. Despite their picky selection, which involves coloration, individual male or female crayfish showed no different color preference when introduced to the novel environment.…”

Haemosporidian infections in wild populations of Podarcis muralis from the Italian Peninsula

“…To account for seasonal variation of parasites, we used multiple-components cosinor models (Halberg et al ., 1967 ; Cornelissen, 2014 ; Sacchi et al ., 2021 ; Storniolo et al ., 2021 for details on the method), which use linear combinations of cosine functions to assess the amplitude ( A ) and phase ( φ ) of seasonal rhythms around the average value [i.e. the midline estimating statistic of rhythm (MESOR)] over the period ( τ ).…”

“…Sex, body size (standardized SVL, by subtracting the mean and dividing by standard deviation) and latitude (standardized UTM coordinate) also entered the models as fixed effects. We also added the cosinor × sex, cosinor × body size and cosinor × latitude interactions to account for possible sex, size and geographical specific patterns in circannual rhythms on parasite occurrence and parasite load.The population entered the models as a random intercept to account for unexplained variation at the population level (σ 2 pop ) when controlling for the explanatory variables(Sacchi et al, 2021).…”