Abstract
The endangered species Strombus gigas is a marine gastropod of significant economic importance through the Greater Caribbean region. In contrast to phenotypic plasticity, the role of genetics on shell variations in S. gigas has not been addressed so far, despite its importance in evolution, management and conservation of this species. This work used geometric morphometrics to investigate the phenotypic variation of 219 shells of S. gigas from eight sites of the Colombian Southwest Caribbean. Differences in mean size between sexes and among sites were contrasted by analysis of variance. Allometry was tested by multivariate regression and the hypothesis of common slope was contrasted by covariance multivariate analysis. Differences in the shell shape among sites were analyzed by principal component analysis. Sexual size dimorphism was not significant, whereas sexual shape dimorphism was significant and variable across sites. Differences in the shell shape among sites were concordant with genetic differences based on microsatellite data, supporting its genetic background. Besides, differences in the shell shape between populations genetically similar suggest a role of phenotypic plasticity in the morphometric variation of the shell shape. These outcomes evidence the role of genetic background and phenotypic plasticity in the shell shape of S. gigas. Thus, geometric morphometrics of shell shape may constitute a complementary tool to explore the genetic diversity of this species.
Highlights
The queen conch Strombus gigas Linnaeus, 1758 is a large marine gastropod of significant economic importance through the Greater Caribbean region (Theile, 2005)
Nonsignificant sexual size dimorphism of S. gigas found in this work contrasts with previous studies of this species in other Caribbean regions (Randall, 1964; Avila-Poveda & BaqueiroCárdenas, 2006; Galindo-Pérez, 2009) but it is concordant with results found in S. pugilis (Galindo-Pérez, 2009)
This suggests that the sexual size dimorphism may vary among sites, corroborating that the degree of sexual size dimorphism in gastropods may differ among localities as well as found in S. gibberulus and S. flammeus from Indo-Pacific (Abbott, 1949)
Summary
The queen conch Strombus gigas Linnaeus, 1758 is a large marine gastropod of significant economic importance through the Greater Caribbean region (Theile, 2005). The plastic responses to environmental variations have been found in other snail species (Pascoal et al, 2012; Kistner & Dybdahl, 2013; Gustafson, Kensinger, Bolek, & Luttbeg, 2014; Solas, Hughes, Márquez, & Brante, 2015) During ontogeny, these plastic responses to environmental heterogeneity constitute a key factor in the potential of species to colonize, survive and reproduce; abilities that allow them to persist under diverse environmental conditions and expand its distribution range (Stearns, 1989). In this work, geometric morphometric analysis was used to address the effect of genetics and geographic origin on S. gigas shell size and shape across a broad area in the Colombian Southwestern Caribbean (San Andrés archipelago) In this area, the spatial phenotypic variation of S. gigas shell is unknown, this information may complement the genetic studies in this region (Márquez et al, 2013). Both the bathymetry of San Andrés archipelago (Andrade, 2001) that limit the queen conch dispersion among sites, as well as the environmental and fishing variable conditions, may induce phenotypic differences in the queen conch shells
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