Developmental Plasticity in the Shell of the Queen Conch Strombus Gigas

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. To evaluate the developmental plasticity of shell morphology in the queen conch Strombus gigas, we conducted transplant experiments at five sites in the Exuma Cays, Bahamas. Juvenile conchs from a sixth site were placed in cages at three sites, in an open cage at a fourth site, and in a naturally confined area at a fifth site. All animals spent 8 mo in the field. At the end of the experiments, the morphology of their shells was quantified by means of univariate and multivariate analyses of size and shape as advocated by Mosimann and James (1979). Comparisons were made within and among experimental groups at the first three sites, between groups at the fourth and fifth sites, and between experimental groups and naturally occurring animals at all six sites.Although the experiments extended over only 20% of the juvenile growth period, analyses showed that experimental animals at three of the sites differed significantly in the shapes of their shells. The shapes of these shells were also significantly different from those of the long-spined, bulky shells of naturally occurring animals of similar age at the source site. The greatest change in shape and growth rate occurred at the fifth site, where the rapidly growing uncaged experimental animals developed relatively slender, short-spined shells with large apertures and short spires. These changes were clearly in the direction of the size and shape of unmanipulated animals in the foster population. The results of these experiments, when combined with those of others, suggest that, although variation in the morphology of marine gastropods can have a genetic basis and can be influenced by natural selection, direct environmental induction can be the dominant process underlying patterns of local among-population differentiation. We recommend (1) that the morphometric methods used here to investigate the complex consequences of variation in the size and shape of organisms be applied in other taxa and (2) that the extent to which among-population patterns of geographic variation are directly induced by the environment be given more attention.

What can aquatic gastropods tell us about phenotypic plasticity? A review and meta-analysis

“…Soft-bottom taxa are mostly absent (but see Martín-Mora et al, 1995 andDelgado et al, 2002 for examples of a species found on both rocky and softbottom substrates), as are studies involving predators that use methods other than shell breakage (but see Bourdeau, 2009 for exceptions). It is possible that gastropods living in softsediment habitats or those preyed on mainly by slow-moving shellentry predators (for example, seastars) may rely chiefly on plastic avoidance and/or escape behaviour as their antipredator defense, rather than plastic morphological defenses.…”

“…We are aware of only one tropical species in which shell plasticity has been demonstrated. The queen conch (Strombus gigas) shows marked developmental plasticity in shell shape (Martín-Mora et al, 1995) and predator-induced plasticity in behaviour, growth and shell thickness (Delgado et al, 2002). We need many more studies on tropical marine and freshwater gastropods, as it would be interesting to know whether shell plasticity is a general phenomenon in tropical gastropods and to test whether patterns of variation in shell plasticity in temperate and tropical aquatic snails reflect differences in environmental variation between temperate and tropical zones.…”

Sclerochronology – a highly versatile tool for mariculture and reconstruction of life history traits of the queen conch,Strombus gigas(Gastropoda)

“…Estimated life spans for the queen conch vary between six (Berg 1976) and 26 years (Coulston et al 1989). In particular, local habitat characteristics, food availability and temperature each exert a strong control on longevity and growth rate (Alcolado 1976;Martín-Mora et al 1995;Stoner et al 1996). Shell morphology and size-at-age may vary greatly among different localities (e.g., slim shell = fast growth; short, bulky shell = slow growth; Martín-Mora et al 1995).…”

Cryptic Species: A Mismatch between Genetics and Morphology in <i>Millepora</i>

“…The number of dactylopores associated with each gastropore also was recorded. Variable numbers of indiv idual gastropores (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) and dactylopores (27-129) were measured fro m each grid. Total nu mber o f grids measured was determined by the surface area of the hydrozoan present on each thin section.…”

“…Hence, a given species may exh ibit different phenotypes depending on the environ ment. Plasticity has been described in many marine taxa including corals [8][9], sponges [10], fish [11], barnacles [12], and mo llusks [13]. The presence and range of taxa shown to exh ibit phenotypic plasticity must be taken into consideration when applying morphological characters to define species.…”