Uniform trichromacy in Alouatta caraya and Alouatta seniculus: behavioural and genetic colour vision evaluation.
Front Zool 2021;
18:36. [PMID:
34238318 PMCID:
PMC8268213 DOI:
10.1186/s12983-021-00421-0]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 06/15/2021] [Indexed: 11/25/2022] Open
Abstract
Primate colour vision depends on a matrix of photoreceptors, a neuronal post receptoral structure and a combination of genes that culminate in different sensitivity through the visual spectrum. Along with a common cone opsin gene for short wavelengths (sws1), Neotropical primates (Platyrrhini) have only one cone opsin gene for medium-long wavelengths (mws/lws) per X chromosome while Paleotropical primates (Catarrhini), including humans, have two active genes. Therefore, while female platyrrhines may be trichromats, males are always dichromats. The genus Alouatta is inferred to be an exception to this rule, as electrophysiological, behavioural and molecular analyses indicated a potential for male trichromacy in this genus. However, it is very important to ascertain by a combination of genetic and behavioural analyses whether this potential translates in terms of colour discrimination capability. We evaluated two howler monkeys (Alouatta spp.), one male A. caraya and one female A. seniculus, using a combination of genetic analysis of the opsin gene sequences and a behavioral colour discrimination test not previously used in this genus. Both individuals completed the behavioural test with performances typical of trichromatic colour vision and the genetic analysis of the sws1, mws, and lws opsin genes revealed three different opsin sequences in both subjects. These results are consistent with uniform trichromacy in both male and female, with presumed spectral sensitivity peaks similar to Catarrhini, at ~ 430 nm, 532 nm, and 563 nm for S-, M- and L-cones, respectively.
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