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

This Article Full Text Free Full Text (PDF) Free 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 PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Irie, T. Articles by Morimoto, N. Search for Related Content PubMed PubMed Citation Articles by Irie, T. Articles by Morimoto, N. Related Collections Development Ecology Molluscs

Phenotypic Plasticity and Sexual Dimorphism in Size at Post-Juvenile Metamorphosis: Common-Garden Rearing of an Intertidal Gastropod With Determinate Growth

Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, Okinawa 905-0227, Japan

^* To whom correspondence should be addressed. E-mail: irie{at}bio-math10.biology.kyushu-u.ac.jp

Proximate factors of the intraspecific variation in molluscan shell morphology have long received attention in biology. The intertidal gastropod Monetaria annulus (Mollusca; Gastropoda; Cypraeidae) is particularly suitable for the study of variation in body size, because this species is a determinate grower in the sense that soft-body size shows no further increase after the juvenile stage. Cross-sectional field surveys on post-juvenile individuals have indicated that the mean body size varies widely among populations and is larger in females than in males within populations. To examine whether these patterns are due to genetic differences, we conducted a common-garden rearing experiment with juvenile individuals collected from two populations on Okinawa Island. After adjusting for among-individual differences in initial degree of development, statistical analyses revealed that this species exhibits female-biased sexual size dimorphism mediated by a longer development time rather than by faster growth rates in females. Although wild individuals show a remarkable size difference between populations, no size difference was found between the populations in the individuals reared in a common-garden condition. This result suggests that the among-population size difference does not have a genetic basis and is caused by phenotypic plasticity based on environmental heterogeneity among habitats.

Abbreviations: DD, degree of development • DTM, days to metamorphosis • IDD, initial degree of development • IW, initial shell width • JW, juvenile shell width at metamorphosis • LGR, linear growth rate • NJW, native juvenile shell width • SSD, sexual size dimorphism