Burrow ornamentation in the fiddler crab (Uca leptodactyla): female mate choice and male–male competition

Abstract

Non-biological ornamentation is found in the nests and burrows of different kinds of animals. We evaluated here whether sand hoods constructed by male fiddler crabs (Uca leptodactyla) are one of the signals used by males to attract females during courtship. We observed females when they were walking among the males, and we quantified the proportion of females that visited male burrows with and without ornamentation and the choice to stay in a male's burrow. Females visited more burrows with hoods than burrows without hoods, and they chose significantly more builder males. Male investment in ornamentation nevertheless decreased when the proportion of females increased in the area. Male investment was not correlated with the proportion of non-builder males nearby, but was positively correlated with overall density. The density sex ratio, however, was more male-biased in high-density than in low-density areas suggesting that even if building attracts females, the function could be related to male competition for mates.

How sexual and natural selection interact and shape the evolution of nests and nesting behaviour in fishes

“…Fiddler crabs (Crustacea: Ocypodidae) defend burrows in tidal zones. Males of some species build sand ornaments at the entrance of the burrows that increase their mating success but are washed away during the daily tide [ 184 ]. Austruca annulipes mates inside the male's burrow and the male leaves the burrow to the female for brooding.…”

The importance of considering small-scale variability in macrobenthic distribution: spatial segregation between two fiddler crab species (genus Leptuca) (Decapoda, Ocypodidae)

“…Leptuca leptodactyla are known to occupy areas without vegetation cover, likely due to limitations of display visibility, as this species employs visual cues for reproduction such as sand-hoods built at the burrow entrance (Christy et al, 2002;Masunari, 2012;Rodrigues et al, 2016). Leptuca leptodactyla distribution is also found to be negatively correlated with organic matter content and soil moisture (Bezerra et al, 2006).…”

Dynamics of energy reserves and the cost of reproduction in female and male fiddler crabs

“…However, the periodicity in sperm production should not significantly affect their energy reserves, since the gonadal development of male crabs shows low energetic requirements (Wu et al, 2010). The great reproductive effort of male fiddler crabs is related to courtship and territory defense behaviors, in which the enlarged cheliped plays an essential role (Christy and Salmon, 1984;Hayes et al, 2013;Ribeiro et al, 2016;Rodrigues et al, 2016). The costs of carrying such an enlarged appendage, which represents between 25 and 35% of the male's body weight (34% in L. uruguayensis [Colpo, unpublished data]), are high (Allen and Levinton, 2007;Gerald and Thiesen, 2014).…”