Ontogeny Versus Phylogeny in Determining Patterns of Chemoreception: Initial Studies with Fiddler Crabs

Area of Science:

• Marine Biology
• Chemical Ecology
• Crustacean Research

Background:

• Chemosensitivity is crucial for crustaceans to find food and mates.
• Life-history stages often have different ecological niches and dietary requirements.

Purpose of the Study:

• To investigate and compare the chemosensory responses of larval and adult fiddler crabs (Uca longisignalis) to amino acids and sugars.
• To determine the correlation between chemosensitivity patterns across different life stages within a species and between related species.

Main Methods:

• Assayed behavioral responses of first-stage zoea and adult Uca longisignalis to 16 amino acids and sugars.
• Utilized computer-video motion analysis for larval swimming behavior.
• Determined adult feeding responses to chemical stimuli.

Main Results:

• Adult Uca longisignalis chemosensitivity patterns strongly correlate with those of adult Uca pugilator, suggesting shared trophic ecology.
• No significant correlation was found between larval and adult chemosensitivity in U. longisignalis.
• Both stages responded most strongly to substances in potential prey, but larval and adult prey differed.
• Larvae responded to adult prey substances, while adults were insensitive to larval-specific food cues.

Conclusions:

• Dietary differences between larval and adult stages are the primary driver for the lack of correlation in chemosensitivity.
• Developmental constraints, where early life stages adapt to the requirements of later stages, influence chemosensory abilities.
• Both ecological context and developmental factors shape chemosensitivity patterns in fiddler crabs.