HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (36) Citing Articles via Google Scholar Google Scholar Articles by Rondeau, A. Articles by Sainte-Marie, B. Search for Related Content PubMed PubMed Citation Articles by Rondeau, A. Articles by Sainte-Marie, B. Related Collections Ecology Evolution Reproduction Behavior Crustaceans

Variable Mate-Guarding Time and Sperm Allocation by Male Snow Crabs (Chionoecetes opilio) in Response to Sexual Competition, and their Impact on the Mating Success of Females

Amélie Rondeau^1,* and Bernard Sainte-Marie^2,

¹ Institut des sciences de la mer de Rimouski (ISMER), Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L 3A1, Canada
² Division des invertébrés et de la biologie expérimentale, Institut Maurice-Lamontagne, Pêches et Océans Canada, 850 route de la Mer, C.P. 1000, Mont-Joli, Québec G5H 3Z4, Canada

To whom correspondence should be addressed. E-mail: Sainte-MarieB{at}dfo-mpo.gc.ca

Two laboratory experiments investigated mate guarding and sperm allocation patterns of adult males with virgin females of the snow crab, Chionoecetes opilio, in relation to sex ratio. Although females outnumbered males in treatments, operational sex ratios were male-biased because females mature asynchronously and have a limited period of sexual attractiveness after their maturity molt. Males guarded females significantly longer as the sex ratio increased: the mean time per female was 2.9 d in a 2:20 treatment compared to 5.6 d in a 6:20 treatment. Female injury and mortality scaled positively to sex ratio. Males that guarded for the greatest number of days were significantly larger, and at experiment’s end had significantly smaller vasa deferentia, suggesting greater sperm expense, than males that guarded for fewer days. In both experiments, the spermathecal load (SL)—that is, the quantity of ejaculate stored in a female’s spermatheca—was independent of molt date, except in the most female-biased treatment, where it was negatively related. The SL increased as the sex ratio increased, mainly because females accumulated more ejaculates. However, similarly sized males had smaller vasa deferentia and passed smaller ejaculates, such that, at a given sex ratio, the mean SL was 55% less in one experiment than in the other. Some females extruded clutches with few or no fertilized eggs, and their median SL (3–4 mg) was one order of magnitude smaller than that of females with well-fertilized clutches (31–50 mg), indicating sperm limitation. Males economized sperm: all females irrespective of sex ratio were inseminated, but to a varying extent submaximally; each ejaculate represented less than 2.5% of male sperm reserves; and no male was fully exhausted of sperm. Sperm economy is predicted by sperm competition theory for species like snow crab in which polyandry exists, mechanisms of last-male sperm precedence are effective, and the probability that one male fertilizes a female’s lifetime production of eggs is small.

Abbreviations: CW, carapace width • GT, guarding time per female • ESR, effective sex ratio • OSR, operational sex ratio • SL, spermathecal load • VDW, vasa deferentia weight

This article has been cited by other articles:

				A. Corgos and J. Freire Morphometric and gonad maturity in the spider crab Maja brachydactyla: a comparison of methods for estimating size at maturity in species with determinate growth ICES J. Mar. Sci., January 1, 2006; 63(5): 851 - 859. [Abstract] [Full Text] [PDF]