Mechanisms of mate recognition in the caridean shrimp Palaemonetes pugio Holthuis (Decapoda: Palaemonidae).

摘要

Intraspecific communication, i.e., mate recognition, involves a co-adapted signal/receptor system. This research examined the female signal and the male receptor of Palaemonetes pugio, a small, estuarine grass shrimp. Behavioral evidence suggests the use of contact sex pheromones in mate recognition of P. pugio. The female sex pheromone was hypothesized to be either cuticular hydrocarbons, as in insects, or surface glycoproteins, as in harpacticoid copepods. Gas chromatography-mass spectrometry (GC-MS) analysis of chloroform-methanol extracts of the cuticle of parturial females, non-parturial females, intermolt females, and postmolt males revealed the presence of 55 compounds, 12 of which were cuticular hydrocarbons. Cuticular hydrocarbons, while demonstrated to be present on the cuticle of P. pugio, have not been demonstrated to function in mate recognition. The mate recognition signal of P. pugio appears to be a surface glycoprotein. Males exposed to glucosamine copulated with females significantly less than males exposed to glucose suggesting the presence of glucosamine or an N-acetylglucosamine containing glycoprotein complemented by a lectin-like receptor on males.;The antennal flagellum of P. pugio was examined using light and scanning electron microscopy. Males had significantly more antennal setae than did females. The antennal flagellum was found to have 2 types of setae: simple and denticulate. Both setal types have apical/terminal pores, which are indicative of a chemoreceptive function. These setae are hypothesized to be bimodal, touch/taste receptors, functioning as both mechano- and chemoreceptors. When antennal setae were exposed to glucosamine, intracellular calcium levels of males and females significantly increased, although the response in females was not as strong. This suggests that males rely more heavily on chemoreception and exposure to glucosamine produces a stronger response in males than in females.;Upon contact of the antennal flagellum with the female's exoskeleton, a glucosamine containing glycoprotein binds the lectin-like receptors, causing an increase in intracellular calcium. Calcium, functioning as a second messenger, carries the signal to the brain, producing a specific behavior. Pheromones are defined as chemical compounds that elicit a particular behavior from conspecifics. In this case, glucosamine would be considered a pheromone functioning in mate recognition of P. pugio.