Color variation and visual modeling provide no support for adaptive coloration in a blue crayfish

The adaptationist dogma among research on animal colors has recently come into question, as several studies have suggested that bright, conspicuous colors in animals are not always adaptive, but evolutionarily neutral. However, demonstrating that a color trait is evolutionarily neutral is complicated—there is no consensus as to what qualifies as sufficient evidence for a color trait to be considered neutral. Our study discusses these issues while investigating the function of coloration in a conspicuously colored blue crayfish, Cambarus monongalensis, which inhabits semi-terrestrial burrows and rarely interacts with the surface. By correlating sex and size with color variables, we found that three body regions of C. monongalensis do not vary in color with respect to sex or size, thereby rejecting two of our adaptive hypotheses. Additionally, visual models of crayfish and predators suggest that crayfish may not be able to distinguish body colors across the body and against backgrounds, b..., , # Color variation and visual modeling provide no support for adaptive coloration in a blue crayfish

Dataset DOI: [10.5061/dryad.8w9ghx3zs](10.5061/dryad.8w9ghx3zs)

## Description of the data and file structure

This dataset was collected as part of a study investigating color variation in the Blue Crawfish, *Cambarus monongalensis*, and how these colors may be perceived by both conspecifics and potential predators. In March and April 2024, 88 adult crayfish were collected from a population in Claysville, Pennsylvania, using daytime burrow excavation and nighttime hand collection during surface activity following rainfall. Each individual was sexed and measured for carapace length as an indicator of body size. Juveniles (carapace length <15 mm) were excluded to avoid ontogenetic variation.

Reflectance spectra were measured using an Ocean Optics Jaz UV/VIS spectrometer from three body regions: the dorsal carapace, the dorsal claw (manus), and the pollex. Four key colorimetric variables...,