ABSTRACT
A color gamut quantitatively describes the diversity of a taxon's integumentary coloration as seen by a specific organismal visual system. We estimated the plumage color gamut of hummingbirds (Trochilidae), a family known for its diverse barbule structural coloration, using a tetrahedral avian color stimulus space and spectra from a taxonomically diverse sample of 114 species. The spectra sampled occupied 34.2% of the total diversity of colors perceivable by hummingbirds, which suggests constraints on their plumage color production. However, the size of the hummingbird color gamut is equivalent to, or greater than, the previous estimate of the gamut for all birds. Using the violet cone type visual system, our new data for hummingbirds increases the avian color gamut by 56%. Our results demonstrate that barbule structural color is the most evolvable plumage coloration mechanism, achieving unique, highly saturated colors with multi-reflectance peaks.
Subject(s)
Birds , Feathers , AnimalsABSTRACT
The true bugs, or heteropterans, are known for their widespread production of anti-predator chemicals and alarm pheromones in scent glands, a derived trait that constitutes one of the defining characters of the suborder Heteroptera and a potential novel trait that contributed to their diversification. We investigated whether symbiotic bacteria could be involved in the formation of these chemicals using Thasus neocalifornicus, a coreid bug that produces semiochemicals frequently found in other bugs. Using DNA phylogenetic methodology and experiments using antibiotics coupled with molecular techniques, we identified Wolbachia as the microorganism infecting the scent glands of this bug. Decreasing the level of Wobachia infection using antibiotics was correlated with a diminution of heteropteran production of defensive compounds and alarm pheromones, suggesting that this symbiotic bacterium might be implicated in the formation of chemicals.
