Parturition Signaling by Visual Cues in Female Marmosets (Callithrix jacchus)

Abstract

New World monkeys have polymorphic color vision, in which all males and some females are dichromats, while most females are trichromats. There is little consensus about which selective pressures fashioned primate color vision, although detection of food, mates and predators has been hypothesized. Behavioral evidence shows that males from different species of Neotropical primates seem to perceive the timing of female conception and gestation, although, no signals fulfilling this function have been identified. Therefore, we used visual models to test the hypothesis that female marmosets show chromatic and/or achromatic cues that may indicate the time of parturition for male and female conspecifics. By recording the reflectance spectra of female marmosets’ (Callithrix jacchus) sexual skin, and running chromatic and achromatic discrimination models, we found that both variables fluctuate during the weeks that precede and succeed parturition, forming “U” and inverted “U” patterns for chromatic and achromatic contrast, respectively. We suggest that variation in skin chroma and luminance might be used by female helpers and dominant females to identify the timing of birth, while achromatic variations may be used as clues by potential fathers to identify pregnancy stage in females and prepare for paternal burdens as well as to detect oestrus in the early post-partum period.

The common marmoset: An overview of its natural history, ecology and behavior

“…Thus, common marmosets can perceive the face and body changes of other individuals and adjust their behavior accordingly; this is not a simple task (Mitchell and Leopold, ; e.g., Mitchell et al, ). Indeed, such a remarkable capacity for visually processing information of social relevance has been already suggested to be used to infer about the pregnancy stage and post‐partum estrus (Moreira et al, ) as well as for learning foraging skills (Schiel and Huber, ).…”

“…The tail of an adult individual can reach 28 cm and helps the monkey to balance itself when locomoting on tree branches (Stevenson and Rylands, ). Common marmosets possess visual polymorphism, where females can be dichromats or trichromats, while all males are dichromatic (Moreira et al, ). They also have claws on all digits (except the opposable hallux), which results in the ability to easily climb tree trunks (Nash, ; Garber, ).…”

Platyrrhine color signals: New horizons to pursue

“…However, comparative studies of platyrrhine coloration are almost absent in the literature. The only study investigating intraspecific skin color variation in platyrrhines demonstrates that female genital skin color (luminance and hue) varies across pregnancy and parturition in common marmosets ( Callithrix jacchus ) . It is possible that this color variation is a nonadaptive by‐product of hormonal variation with no signaling purpose .…”

The Genetic and Evolutionary Drives behind Primate Color Vision

“…Color modeling studies have predicted that trichromats should outperform dichromats when discriminating socio-sexual signals (Sumner and Mollon, 2003;Changizi et al, 2006) and predators (Pessoa et al, 2014). The influence of color vision on sexual selection and social dynamics have been studied in Old World primates (Waitt et al, 2003;Changizi et al, 2006;Setchell et al, 2009;Gerald et al, 2010) and, to a lesser extent, in prosimians (Clough et al, 2009) and New World primates Surridge et al, 2005;Moreira et al, 2015). However, many studies may have overestimated animal color variation, by using subjective human perception when investigating other primate socio-reproductive signals (Higham et al, 2010).…”

“…However, many studies may have overestimated animal color variation, by using subjective human perception when investigating other primate socio-reproductive signals (Higham et al, 2010). The few visual modeling studies that have considered the visual system of certain primate species indicate that chromatic cues might not be essential for socio-reproductive signaling, and that dichromacy should be sufficient (Higham et al, 2010;Moreira et al, 2015).…”