Phylogeography of the flag cabrilla Epinephelus labriformis (Serranidae): implications for the biogeography of the Tropical Eastern Pacific and the early stages of speciation in a marine shore fish

Abstract

Aim To examine the role of previously described biogeographical boundaries in shaping phylogeographical relationships within and among two putative eastern Pacific sibling species, the flag cabrilla, Epinephelus labriformis and the Clipperton grouper, Epinephelus clippertonensis (Serranidae). Location Tropical Eastern Pacific (TEP). Methods Sequence data from the mitochondrial cytochrome b gene were obtained from samples throughout the range of the species. Coalescence analysis, mismatch distributions and an analysis of molecular variance (amova) were used to infer population differentiation. Results Overall, 49 haplotypes were found among 304 specimens, and there was significant structure corresponding to geographical locality (amova, Φct = 0.198, P < 0.001; Φst = 0.207, P < 0.001; Fst = 0.169, P < 0.001; Fct = 0.151, P = 0.036). Coalescence analysis indicates a population expansion at Clipperton Atoll during the mid‐Pleistocene. Main conclusions Our results suggest that previously described barriers to dispersal along the mainland of the TEP may not impinge on the dispersal ability of marine species, such as these groupers, that have long‐lived pelagic larvae. In contrast, gene flow between mainland and island populations of the readily distinguishable morphospecies E. labriformis and E. clippertonensis is restricted. The low level of genetic differentiation between the two species indicates that changes in external colour patterns may evolve more rapidly than genetic markers commonly used to delimit species boundaries. Thus a combination of colour differences and a lack of reciprocal monophyly may act as good indicators of incipient speciation in the marine environment.

Genetic characterisation of populations of the critically endangered Goliath grouper ( Epinephelus itajara, Serranidae) from the Northern Brazilian coast through analyses of mtDNA

“…The values recorded here for the Goliath grouper are generally lower than those recorded in studies of other grouper species -Epinephelus marginatus (Maggio et al, 2006), and Epinephelus labriformis and Epinephelus clippertonensis (Craig et al, 2006) -however, based on a marker (the mitochondrial cyt b gene) which 990 Population analysis of Epinephelus itajara evolves more slowly than the control region. Nucleotide diversity is low (0.1% to 0.5%) in all E. itajara populations, which may reflect anthropogenic pressures -not just harvesting, but also the loss of mangrove habitat -or other evolutionary process, and will be an extremely important information to plan the management and conservation of the species.…”

Genetic differentiation across eastern Pacific oceanographic barriers in the threatened seahorse Hippocampus ingens

“…This is because dynamic oceanographic processes facilitate sporadic dispersal (Jacobs et al 2004). This pattern is evidenced by the lack of genetic differentiation in wideranging reef fish species across thousands of kilometers of the mainland coast (Muss et al 2001;Craig et al 2006). In contrast to this pattern of genetic connectivity in wide ranging species along the mainland coast, genetic differentiation has been found between the mainland coast and oceanic islands east of Central America (Muss et al 2001).…”

“…Furthermore, studies of wide ranging species have been conducted exclusively in taxa with high dispersal potential. They have revealed structure only between offshore islands and the mainland coastline (Craig et al 2006;Muss et al 2001). H. ingens is unique in that it presumably has much lower dispersal potential than species previously examined, which predicts a higher degree of population structure.…”

“…On the other hand, a species with high dispersal potential would display a pattern of minimal or non-significant U ST estimates and no IBD (e.g. Epinephelus labriformis, Craig et al 2006;Ophioblennius steindachneri, Muss et al 2001). H. ingens exhibited moderate U ST estimates driven by structure across one discrete barrier, but no pattern of IBD.…”

“…Furthermore, only the minority of studies have sited barriers with potential to influence H. ingens, while most have attributed population structure to past vicariance only influential to species with more temperate distributions than H. ingens (Bernardi et al 2003;Riginos 2005;Sandoval-Castillo et al 2004), or to ecological barriers (Pfeiler et al 2008) only influential to species with more specialized habitat needs than H. ingens. Thus, the only published barriers with potential to influence H. ingens include geographic distance coupled with low dispersal ability (Craig et al 2006;Riginos and Nachman 2001), and contemporary oceanographic barriers (Bernardi et al 2003;Selkoe et al 2007;Terry et al 2000). These potential oceanographic barriers are caused by the formation of two gyres in the upper and central GOC regions (AlvarezBorrego 2002;Beier 1997;Lavin et al 1997), a persistent oceanic front in the cape of Baja region, formed by the convergence of the California Current Water, Tropical Surface Water, and the GOC Water (Castro et al 2006), and inflow of surface waters during summer months (Lavin and Marinone 2003).…”