Frontiers in Marine Science (Oct 2015)
Population aspects of Sphoeroides testudineus (Tetraodontiformes: Tetraodontidae)
Abstract
The Tetraodontidae contains about 184 species (Matsuura, 2014), but recent studies have shown the existence of complex and new species in this fishes (Moura e Castro, 2002; Walker and Bussing, 1996; Amaral et al., 2013; Kottelat et al., 2013). Preliminary genetic analysis of Sphoeroides testudineus were conducted with mitochondrial genes ATPase 6-8, cytochrome oxidase c subunit I (COI) and control region, concatenated, from Brazilian northern and southern population samples. The haplotype (h) and nucleotide diversities (p); the pairwise fixation index (Fst); Tajima’s (1989) and Fu’s (1997) test and an analysis of molecular variance (AMOVA; Excoffier et al. 1992) were estimated using the software Arlequin 3.5 (Excoffier et al., 2005). Neighbour-Joining (using the Kimura 2-parameter distance model; Kimura, 1980) and likelihood (ML) trees were constructed with the program Mega 6.06 (Tamura et al., 2013) e PhyML 3.1 (Guidon et al. 2010), respectively; the choice of the better molecular substitution model was made by the software jModeltest (Posada, 2008). The haplotype networks was built with the software Haplowier (Barrett et al., 2005). The star shape of the haplotype network and the great distance between the two clades resulted on it; the two clades obtained in phylogenetics trees and the high and significant Fst values together with the high haplotype diversity values and the low nucleotide diversity, suggest the genetic structure and expansion of S. testudineus in the range this study, that is coincident with the geographical distribution, even if the percentage of variation between the groups (59,7%) resulted of AMOVA was not significant, unlike of percentage of variation among groups (41,54%). However, this data doesn't permit assert whether the two clades are distinct enough to characterize a species complex.
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