Female ornamentation was initially thought to reflect genetic correlation with the more elaborate male trait. However, this cannot explain female-specific ornamentation, such as the conspicuous coloration displayed by females of many species during breeding. Females may exhibit distinctive, reproductive coloration to 1) advertise receptivity and stimulate male courtship or 2) advertise nonreceptivity when gravid to reduce male courtship, harassment, and potentially costly copulations. We tested both hypotheses in the Lake Eyre dragon lizard (Ctenophorus maculosus) by quantifying female coloration, using spectroradiometry and a model of lizard color perception, and male and female behavior across the female reproductive cycle. Females develop bright orange coloration on their throat and abdomen during the breeding season, whereas males remain cryptically colored. The onset of orange coloration was associated with enlarging follicles, acceptance of copulations, and escalation of male courtship. Rather than fading once females were no longer receptive, however, the intense orange coloration remained until oviposition. Furthermore, despite maximal coloration associated with nonreceptivity, males persisted with courtship and copulation attempts, and females increased rejection behaviors comprising lateral displays and flipping onto their backs (to prevent forced intromission), both of which emphasize the conspicuous ventrolateral coloration. These apparently costly rejection behaviors did not reduce male harassment but did decrease the frequency of potentially costly copulations. These results suggest that 1) males do not determine female receptivity based on coloration alone and 2) the potentially costly rejection behaviors may have evolved to reduce the direct costs of mating.
In some species, females develop bright colouration to signal reproductive status and exhibit behavioural repertoires to incite male courtship and/or reduce male harassment and forced copulation. Sex steroids, including progesterone and testosterone, potentially mediate female reproductive colouration and reproductive behaviour. We measured associations among plasma profiles of testosterone and progesterone with variation in colour expression and reproductive behaviour, including unique courtship rejection behaviours, in female Lake Eyre dragon lizards, (Ctenophorus maculosus). At onset of breeding, progesterone and testosterone increased with vitellogenesis, coincident with colour intensification and sexual receptivity, indicated by acceptance of copulations. As steroid levels peaked around the inferred ovulation time, maximal colour development occurred and sexual receptivity declined. When females were gravid and exhibited maximal mate rejection behaviours, progesterone levels remained consistently high, while testosterone exhibited a discrete second peak. At oviposition, significant declines in plasma steroid levels, fading of colouration and a dramatic decrease in male rejection behaviours co-occurred. Our results indicate a generally concordant association among steroid levels, colouration, behaviour and reproductive events. However, the prolonged elevation in progesterone and a second peak of testosterone was unrelated to reproductive state or further colour change, possibly suggesting selection on females to retain high steroid levels for inducing rejection behaviours.
Polyandry is a commonly utilized strategy in mammalian reproductive systems, where females engage in mating with multiple males to increase either the genetic diversity or quality of their offspring. Some species also exhibit male semelparity, a peculiar life‐history trait where all or most males within a population begin to die following mating. The northern quoll (Dasyurus hallucatus) possesses both of these reproductive adaptations, and females of this species may produce up to eight young in a single litter. Here we aimed to quantify whether there was any difference in female quolls’ choice of male sires between two genetically distinct populations located in the Pilbara region of Western Australia (one mainland‐dwelling and one island‐dwelling population). The total parentage exclusion probability was 0.9999 for excluding a candidate parent from parentage, given the genotype of a known mother. Overall, we found that every litter had young resulting from multiple males. In some litters, a different male fathered every offspring. Thus, northern quolls demonstrated a greater level of polyandry than has previously been detected in marsupials. Furthermore, females from the less genetically diverse island population exercised mate choice and preferentially bred with males that were, on average, 20% smaller than a different male randomly sampled from the island. There was no detectable difference with regard to male sire body size in the mainland population, indicating a difference of selective pressures for the two populations.
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