How many species of goliath grouper are there? Cryptic genetic divergence in a threatened marine fish and the resurrection of a geopolitical species

Abstract

The goliath grouper Epinephelus itajara (Epinephelidae) is an exceptionally large marine fish that inhabits sub-tropical and tropical waters of the Americas and western Africa. Due to a lack of readily observable morphological variation in specimens across its range, the goliath grouper has been regarded as a single species. We tested the hypothesis that Pacific and West Atlantic populations constitute a single species by analyzing nuclear and mitochondrial DNA sequence data. We found numerous fixed genetic differences for mitochondrial loci between Pacific and West Atlantic goliath grouper (genetic distance D ≈ 3.5% at 16S and D ≈ 6% at cytochrome b; ϕ st = 0.98 [p < 0.001] for 16S and ϕ st = 0.98 [p < 0.001] for cytochrome b). The nuclear S7 intron showed 3 fixed nucleotide differences between Pacific and West Atlantic populations. Within the West Atlantic, we found few absolute genetic differences (D < 0.01 at 16S and D < 0.02 at cytochrome b), but statistically significant population structure based on haplotype frequency data (ϕ st = 0.04 [p = 0.05] at 16S; ϕ st = 0.14 [p < 0.001] at cytochrome b). These data indicate that (1) goliath grouper in the West Atlantic are subdivided into discrete populations, (2) goliath grouper populations in the Pacific and western Atlantic represent 2 (or more) distinct species, and (3) these distinct populations/species require separate management and conservation strategies. We resurrect the species Epinephelus quinquefasciatus (Bocourt 1868) for Pacific goliath grouper. KEY WORDS: Epinephelus itajara · Epinephelus quinquefasciatus · Phylogeography · EpinephelidaeResale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESS Contribution to the Theme Section 'Range-wide status and conservation of the goliath grouper'Endang Species Res: 7: 167-174, 2009 tinue to be at the forefront of conservation efforts. Surprisingly, this basic information is lacking in many areas, despite its obvious importance for conservation measures.In the marine environment, biodiversity inventories often reflect the fact that marine species tend to be more broadly distributed than their terrestrial counterparts, with some organisms ranging more than 10 000 km (Jablonski & Lutz 1983). With the now widespread use of molecular genetic techniques, it has become clear that cryptic genetic diversity may confound estimates of both species ranges and biodiversity (reviewed in Bickford et al. 2006). Species once thought to be distributed over immense oceanic expanses are now known to be comprised of discreet lineages that may or may not occur in sympatry (reviewed in Rocha et al. 2007). Although this phenomenon was thought to occur most commonly in small or difficult-to-study organisms, recent evidence shows that these cryptic genetic lineages also occur amongst Earth's largest and most well-studied marine animals (e.g. Bass et al. 2005, Quattro et al. 2006, Vianna et al. 2006. In addition, these genetic studies often elucidate genetic patterns that reflect...

Molecular Characteristics of Batanghari, Tambago, Orange, and Mandiangin Giant Gourami Strains

“…This condition might be due to no genetic exchange between those two islands because seeds transportation mainly tends to occur on the island. This result was also similar to another part of Craig et al (2007) and Craig et al (2009) studies in two reef fish species where significant genetic differences were found among large geographically separated populations. Moreover, strong genetic structures were also observed among geographically separated cyprinids populations (Durand et al, 2002) and among Orizyas latipes populations Takehana et al (2003).…”

“…This value indicates that the used marker has a low level of polymorphisms. Low genetic polymorphisms were also observed in Myripristis berndti (Craig et al, 2007) and in Ephinepenlus itijara (Craig et al, 2009). This similar result indicates that low level of genetic polymorphisms can be observed in the broad scope of fish species.…”

“…Our result was different to Santos et al (2003) study which found high genetic distances in cyt b gene of geographically separated Macrodon ancylodon populations and Craig et al (2009) which also observed a high genetic difference among goliath grouper (Epinephelus itajara) populations. The differences between our result and the study from Santos et al (2003) and Craig et al (2009) might due to we used a different source of populations. In one hand, we used cultivated populations which might be under similar selecti-on pressure from breeder to develop high-quality strains.…”

“…Complete data on haplotype and nucleotide diversity are presented in Table 1. Craig et al (2007) in twenty populations of coral reef fish Myripristis berndti (h= 0.286-0.829) from geographic widely separated populations, and Craig et al (2009) in goliath grouper Ephinepenlus itijara from Panama, Bezile, Brazil, and Florida populations (h=0.324-0.684). According to our result in giant gourami and those previous studies, it is likely that moderate haplotype diversity is rather common in cyt b gene of fish taxa.…”

Mitochondrial DNA evidences reflect an incipient population structure in Atlantic goliath grouper (<em>Epinephelus itajara</em>, Epinephelidae) in Brazil

“…It was subsequently determined that goliath groupers in the Pacific constitute a cryptic species (E. quinquefasciatus) in comparison with the populations of the Atlantic (E. itajara), as demonstrated by their cytochrome B sequences (Craig et al 2009). Silva-Oliveira et al (2012), Seyoum et al (2013) and Silva-Oliveira et al (2014) developed specific markers for E. itajara to establish a more effective database for population studies with evolutionary models aimed specifically at the protection of the species.…”