Male mate choice and male–male competition in the hermit crab Pagurus nigrofascia: importance of female quality

Abstract

Male mate choice has recently been reported in some animals with male-male competition. In the laboratory, we examined whether males choose their mates based on female quality that was indicated by body size and/or days to prenuptial molt, and the effects of female quality on malemale competition in the hermit crab Pagurus nigrofascia. We collected samples from April to May 2009 at an intertidal shore in Hokkaido, Japan (41°N, 140°E). When a male simultaneously encountered two receptive females in the mate choice experiment, males chose females which require less time to molt. When a male guarding a female with less time to molt was challenged by an intruder, the guarding male defended the female for a longer period and was more likely to win the contest. These results indicate that male P. nigrofascia use time to molt to discriminate between females.3

The smell of moulting:N-acetylglucosamino-1,5-lactone is a premoult biomarker and candidate component of the courtship pheromone in the urine of the blue crab,Callinectes sapidus

“…In such species with precopulatory mate guarding, males may choose females that are close to moulting in order to maximize their mating success during a limited reproductive season by mating more often and with a relatively short mateguarding time period. For example, males of the hermit crab Pagurus nigrofascia prefer females that are closest to their pubertal moult (Suzuki et al, 2012). For these reasons, sex pheromones of mate-guarding crustaceans have sometimes been thought to be moulting-related metabolites.…”

Reason for being single: some males do not guard receptive females in the hermit crab Pagurus filholi

“…Since males primarily use their left minor chela to pick up food, they have reduced opportunities to feed during guarding (Yoshii, Takeshita, & Wada, 2009). When a solitary male encounters a guarding pair, a maleemale contest often occurs between the two males in Pagurus middendorffii (Wada et al, 1999; and Pagurus nigrofascia (Suzuki, Yasuda, Takeshita, & Wada, 2012;Yasuda et al, 2011), and the larger males or the guarding males are in the advantageous position in these contests Yasuda et al, 2012). Guarding males of Pagurus filholi and P. nigrofascia often climb up onto fronds of algae (Y. Hasaba, C. I. Yasuda, & S. Wada, personal observation) to sequester females from intruders and avoid maleemale contests (Kawaminami & Goshima, 2015), suggesting that guarding would be a beneficial behaviour for ensuring a mating opportunity.…”

Regeneration of major cheliped after the mating season in the hermit crab <i>Pagurus middendorffii</i>

“…Kendall & Wolcott (1999) suggest that once males initiate their interest in mating, their physiological status might change causing a reduction of interest in molting to continue mating behavior. In P. middendorffii and P. nigrofascia, their mating seasons are limited to about one month and females produce only one clutch per year (Wada et al, 1995;Goshima et al, 1996), and almost all males immediately guard receptive females Suzuki et al, 2012). On the other hand, P. filholi have a longer reproductive season (about 8 months) with laying several clutches (Goshima et al, 1998), and males do not guard receptive females especially when the males would molt within 5 days (Hasaba et al, 2015).…”