Patterns of Chemical Diversity in the Mediterranean Sponge Spongia lamella

Abstract

The intra-specific diversity in secondary metabolites can provide crucial information for understanding species ecology and evolution but has received limited attention in marine chemical ecology. The complex nature of diversity is partially responsible for the lack of studies, which often target a narrow number of major compounds. Here, we investigated the intra-specific chemical diversity of the Mediterranean sponge Spongia lamella. The chemical profiles of seven populations spreading over 1200 km in the Western Mediterranean were obtained by a straightforward SPE-HPLC-DAD-ELSD process whereas the identity of compounds was assessed by comparison between HPLC-MS spectra and literature data. Chemical diversity calculated by richness and Shannon indexes differed significantly between sponge populations but not at a larger regional scale. We used factor analysis, analysis of variance, and regression analysis to examine the chemical variability of this sponge at local and regional scales, to establish general patterns of variation in chemical diversity. The abundance of some metabolites varied significantly between sponge populations. Despite these significant differences between populations, we found a clear pattern of increasing chemical dissimilarity with increasing geographic distance. Additional large spatial scale studies on the chemical diversity of marine organisms will validate the universality or exclusivity of this pattern.

Relationship between genetic, chemical, and bacterial diversity in the Atlanto-Mediterranean bath sponge Spongia lamella

“…Secondary metabolites were extracted by dichloromethane/methanol (1:1) solution and extracts were analyzed by high performance liquid chromatography (HPLC) to characterize chemical profiles (Noyer, 2010;Noyer et al, 2011). In agreement with previous studies on S. agaricina secondary metabolites, chemical profiles showed two major compounds, the nitenin being the major compound, and a variety of minor metabolites belonging to the product class ''terpenes'' (Aiello et al, 1988;Rueda et al, 1998).…”

“…In agreement with previous studies on S. agaricina secondary metabolites, chemical profiles showed two major compounds, the nitenin being the major compound, and a variety of minor metabolites belonging to the product class ''terpenes'' (Aiello et al, 1988;Rueda et al, 1998). For each individual, we used Shannon indices obtained from the DIVERSE procedure (available in PRIMER v6) from the chemical SPE-ELSD-HPLC profiles (Noyer et al, 2011). Thus, chemical diversity was assessed by chemical richness as the number of compounds in an individual sample, and chemical evenness through the abundance or quantity of this compound in the sample.…”

“…For the interpopulation comparisons, we used pairwise dissimilarities from the SIMPER procedure (available in PRIMER v6). Pairwise dissimilarities were performed on 10 out of the 22 compounds that presented significant variations between sponge populations (Noyer, 2010;Noyer et al, 2011).…”

“…An additional sample was also obtained from Ceuta. All of those specimens were then freeze-dried and stored in a -20°C freezer until chemical extraction (Noyer, 2010;Noyer et al, 2011).…”

“…Genetic studies have shown strong genetic differentiation between populations of this species probably linked to the life cycle (brooding sponge with low dispersal capabilities, slow growing animal) and overexploitation (Noyer et al, 2009;Noyer, 2010). The tissues of S. lamella contain abundant bacteria (Bertrand & Vacelet, 1971) dominated by Chloroflexi and Acidobacteria communities (Noyer, 2010 and a great array of structurally diverse secondary metabolites with terpenes as mayor compounds (Cimino et al, 1975;Aiello et al, 1988;Fontana et al, 1996;Rueda et al, 1998;Noyer et al, 2011). Understanding the genetic, chemical, and bacterial diversity of this species can therefore be critical for the conservation and survival of this species.…”