Regional genetic differentiation among populations of Cladocora caespitosa in the Western Mediterranean

Abstract

Cladocora caespitosa is the only reef-forming zooxanthellate scleractinian in the Mediterranean Sea. This endemic coral has suffered severe mortality events at different Mediterranean sites owing to anomalous summer heat waves related to global climate change. In this study, we assessed genetic structure and gene flow among four populations of this species in the Western Mediterranean Sea: Cape Palos (SE Spain), Cala Galdana (Balearic Islands), Columbretes Islands, and L'Ametlla (NE Spain). The results obtained from Bayesian approaches, F ST statistics, and Bayesian analysis of migration rates suggest certain levels of genetic differentiation driven by high levels of selfrecruitment, a fact that is supported by egg-retention mechanisms. Conversely, genetic connectivity among distant populations, even if generally low, seems to be related to sporadic dispersal events through regional surface currents linked to the spawning period that occurs at the end of summer-beginning of autumn. These features, together with a certain isolation of the Columbretes Islands, could explain the regional genetic differentiation found among populations. These results help to better understand population structure and connectivity of the species and will serve as an approach for further studies on different aspects of the biology and ecology of C. caespitosa.

Host‐targeted RAD‐Seq reveals genetic changes in the coral Oculina patagonica associated with range expansion along the Spanish Mediterranean coast

“…Aside from an environmental shift, the observed genetic break could also stem from a barrier to dispersal at the Ibiza Channel (IC; Figure ). The IC coincides with genetic breaks in other marine organisms (García‐Merchán et al., ; Mokhar‐Jamai et al., ), including the coral C. caespitosa (Casado‐Amezúa, Kersting, Templado, & Machordom, ). Circulation across the IC is often blocked by the Northern Current, which carries waters south to the IC and then diverts north‐eastward (Pinot, López‐Jurado, & Riera, ; Ruiz et al., ).…”

“…Their COI haplotypes differ by only a single SNP over 606 bp ( C. caespitosa COI accession number ), although nucleotide substitution rates tend to be very slow in coral mtDNA (Hellberg, ). Cladocora caespitosa occurs along the entire Spanish Mediterranean coast (Casado‐Amezúa et al., ) and spawns at the end of summer (August–October) in the western Mediterranean (Kersting, Casado, López‐Legentil, & Linares, ), as does O. patagonica (Fine et al., ). However, C. caespitosa is more abundant at deeper depths (>10 m) than O. patagonica (Casado‐Amezúa et al., ; Kersting & Linares, ).…”

“…Cladocora caespitosa occurs along the entire Spanish Mediterranean coast (Casado‐Amezúa et al., ) and spawns at the end of summer (August–October) in the western Mediterranean (Kersting, Casado, López‐Legentil, & Linares, ), as does O. patagonica (Fine et al., ). However, C. caespitosa is more abundant at deeper depths (>10 m) than O. patagonica (Casado‐Amezúa et al., ; Kersting & Linares, ). In addition, our sequencing of variable nuclear marker p14 (Supporting Information Figure ) found a high degree of divergence between C. caespitosa and O. patagonica individuals, including O. patagonica along the northern Spanish expansion.…”

“…While the westward expansion is similar to long-established core populations, the northern expansion (Serrano, Coma, & Marta, 2013) is genetically distinct from the core and westward expansion. The break between the two genetic clusters occurs between populations 8 and 9 (Figure 3 including the coral C. caespitosa (Casado-Amez ua, Kersting, Templado, & Machordom, 2014). Circulation across the IC is often blocked by the Northern Current, which carries waters south to the IC and then diverts north-eastward (Pinot, L opez-Jurado, & Riera, 2002;Ruiz et al, 2009).…”

Correlation between pollution and decline of Scleractinian Cladocora caespitosa (Linnaeus, 1758) in the Gulf of Gabes

“…2) (Casado-Amezúa et al, 2011; Casado-Amezúa et al, 2014; Kersting, 2013; Kersting et al, 2013a; Kersting et al, 2013b; Kersting et al, 2014a; Kersting et al, 2014b; Kersting et al, 2015; Kersting et al, 2016; Kružić and Benkovic, 2008; Kružić and Požar-Domac, 2003; Kružić and Požar-Domac, 2007; Kružić et al, 2012; Kružić et al, 2013). Some colonies in the Eastern part of the Adriatic Sea are particularly threatened by anthropogenic activities such as e.g., tuna farming (Kružić and Požar-Domac, 2007).…”