A new view on the scenario of karyotypic stasis in Epinephelidae fish: Cytogenetic, historical, and biogeographic approaches

Abstract

Epinephelidae (groupers) is an astonishingly diverse group of carnivorous fish widely distributed in reef environments around the world, with growing economic importance. The first chromosomal inferences suggested a conservative scenario for the family. However, to date, this has not been validated using biogeographic and phylogenetic approaches. Thus, to estimate karyotype diversification among groupers, eight species from the Atlantic and Indian oceans were investigated using conventional cytogenetic protocols and fluorescence in situ hybridization of repetitive sequences (rDNA, microsatellites, transposable elements). Despite the remarkable persistence of some symplesiomorphic karyotype patterns, such as all species sharing 2n=48 and most preserve a basal karyotype (2n=48 acrocentrics), the chromosomal diversification in the family revealed an unsuspected evolutionary dynamic, where about 40% of the species escape from the ancestral karyotype pattern. These karyotype changes showed a relation with the historical biogeography, likely as a byproduct of the progressive occupancy of new areas (huge diversity of adaptive and speciation conditions). In this context, oceanic regions harboring more recent clades such as those of the Indo-Pacific, exhibited a higher karyotype diversity. Therefore, the karyotype evolution of Epinephelidae fits well with the expansion and geographic contingencies of its clades, providing a more complex and diverse scenario than previously assumed.

The genomic study of repetitive elements in Solea senegalensis reveals multiple impacts of transposable elements in the evolution and architecture of Pleuronectiformes chromosomes

“…These chromosomes were 1, 2 and 4 where, based on BAC clone synteny studies, other pericentric rearrangements (inversions), that have occurred during the evolution of these chromosomes were described (Rodrıǵuez et al, 2019, Rodrıǵuez et al, 2021Ramıŕez et al, 2022). There is evidence to support that inversions, as well as other chromosomal rearrangements, are involved in the adaptation of species to the environment and that polymorphisms associated with these inversions are related to geographic distributions (Wellenreuther and Bernatchez, 2018;Amorim et al, 2021). TEs are considered key elements in this chromosomal rearrangement process (Feschotte and Pritham, 2007).…”

Integration of Maps Enables a Cytogenomics Analysis of the Complete Karyotype in Solea senegalensis

“…Inversions are important rearrangements that lead to polymorphism maintenance events in populations through balancing selection and are also important in the speciation process [49,50]. In addition, there is much evidence to support the view that inversions are involved in the environmental adaptation of species and that inversion polymorphisms within a species are related geographically [51,52].…”

Karyotypic stasis and its implications for extensive hybridization events in corallivores species of butterflyfishes (Chaetodontidae)

“…Integrative cytogenetic approaches in marine fish groups have indicated that specific biological aspects and historical contingency can act together as causal effects of chromosomal changes [ [1] , [2] , [3] ]. Marine fishes display contrasting karyotype evolution patterns, which can vary from high dynamic rates to stasis, a process in which chromosomal change rates are absent or slow, allowing chromosomal patterns to persist for long periods of time [ 4 , 5 ].…”

“…[ 12 , 43 ]). Repeated sequences, such as rDNA, have been linked to mechanisms that promote chromosomal rearrangements [ 16 , 44 , 45 ], interpopulation variations [ 1 , 46 ], karyotypic diversification [ 12 , 47 , 48 ], or serve as markers to track karyotypic trends in broader biogeographical contexts [ 1 , 3 ].…”