Chromosomal complements of some Atlantic Blennioidei and Gobioidei species (Perciformes)

Abstract

A remarkable degree of chromosomal conservatism (2n=48, FN=48) has been identified in several families of Perciformes. However, some families exhibit greater karyotypic diversity, although there is still scant information on the Atlantic species. In addition to a review of karyotypic data available for representatives of the suborders Blennioidei and Gobioidei, we have performed chromosomal analyses on Atlantic species of the families Blenniidae, Ophioblennius trinitatis Miranda-Ribeiro, 1919 (2n=46; FN=64) and Scartella cristata (Linnaeus, 1758)(2n=48; FN=50), Labrisomidae, Labrisomus nuchipinnis (Quoy & Gaimard, 1824)(2n=48; FN=50) and Gobiidae, Bathygobius soporator (Valenciennes, 1837)(2n=48; FN=56). Besides variations in chromosome number and karyotype formulas, Ag-NOR sites, albeit unique, were located in different positions and/or chromosome pairs for the species analyzed. On the other hand, the heterochromatic pattern was more conservative, distributed predominantly in the centromeric/pericentromeric regions of the four species. Data already available for Gobiidae, Blenniidae and Labrisomidae show greater intra- and interspecific karyotypic diversification when compared to other groups of Perciformes, where higher uniformity is found for various chromosome characteristics. Evolutionary dynamism displayed by these two families is likely associated with population fractionation resulting from unique biological characteristics, such as lower mobility and/or specific environmental requirements.

Chromosomal and morphological divergences in Atlantic populations of the frillfin goby Bathygobius soporator (Gobiidae, Perciformes)

“…A similar condition has been reported in other Gobiidae species, such as Potamoschistus minutus, P. pictus, P. marmoratus (Caputo, 1998;Klinkhardt, 1992). In fact, at least six different arrangement patterns for nucleolar organizer regions have been recorded among Gobiidae (Galvão et al, 2011). An association between NORs and CMA 3 + heterochromatin, as observed in the population investigated, is often found among fish (Almeida-Toledo et al, 1996;Amemiya and Gold, 1986), which may favor rearrangements involving chromosomes carrying these sites (Vicari et al, 2003).…”

“…Genus Bathygobius contains 28 species (Eschmeyer, 2011), of which only three have cytogenetic descriptions: B. soporator from the Brazilian coast (Cipriano et al, 2008;Galvão et al, 2011), B. fuscus (Arai and Sawada, 1975), and B. stellatus (Vasil'ev, 1985). The diploid number 2n = 48 chromosomes is considered basal for Perciformes (Galetti et al, 2000).…”

“…However, some groups, such as the family Gobiidae, have very diverse karyotypes (Caputo, 1998;Ene, 2003;Galvão et al, 2011) and an apparent relationship between chromosomal rearrangements and the speciation process. Some species of this family show great potential for population stratification and cytogenetic diversification (Amores et al, 1990), primarily those inhabiting large geographical areas.…”

Evolutionary diversification of Western Atlantic Bathygobius species based on cytogenetic, morphologic and DNA barcode data

“…In Gobiidae, the intense dynamism of karyotypic macrostructure (Caputo et al 1997;Galvão et al 2011) and of specific sequences on chromosomes is possibly related to the high level of speciation found in this family (Lima-Filho et al 2012). The karyotypic differences observed herein do not represent transient polymorphisms as in other species of the family (Thode et al 1988;Amores et al 1990), but on the contrary, reveal fixed patterns, leaving almost no doubt that they represent distinct species.…”

“…Recent cytogenetic and molecular analyses showed distinct patterns between continental and insular individuals from Rocas Atoll, previously identified as B. soporator (Lima et al 2005;Lima-Filho et al 2012). When compared to other marine groups within the Percomorphaceae and Eupercaria (sensu Betancur-R et al 2013), which present high uniformity in karyotypic macrostructure, gobiids show highly variable karyotypes (Galetti et al 2000;Galvão et al 2011). The high chromosomal evolutionary dynamics in this family (Molina et al 2014) supports a close relationship between chromosomal rearrangements and speciation processes.…”