Response to Conspecific Chemical Cues in the Fiddler Crab Uca Rapax

Abstract

Fiddler crabs are well-known for their visual displays in courtship and social interactions. However, the ability of these animals to produce and respond to chemical stimuli remains unknown. The current study investigated the existence of these cues and the information they may contain. Experiments were designed to discover any behavioral differences among populations as well as the duration of the cues. Both male and female crabs were found to be able to distinguish the size and sex of another fiddler crab by chemical cues alone, and displayed preferences for sand exposed to females and smaller crabs. Mate choice trials were conducted using crabs from a local and non-local population to determine whether these chemical cues differ among populations. Females showed a preference for males from a non-local population based on chemical cues. Larval development was studied to ascertain the duration of the planktonic larval phase as well as gain information regarding survival and development rates correlated with factors such as mother size, hatch date, and hatch size. Larval survival and duration were found to be impacted by the timing of release and the size of the mother. Population genetic analyses using cytochrome oxidase I were conducted to discover the relatedness of different populations of fiddler crabs throughout the Gulf of Mexico. Populations from Texas showed high relatedness, which may indicate high gene flow among populations.