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.
Highlights
Reef regions are home to a huge diversity of fish (Bezerra and Silva, 2011), among which Epinephelidae stand out for their exceptional diversity
Eight species belonging to three Epinephelidae genera, Epinephelus Bloch, 1793: E. itajara (Lichtenstein, 1822), E. adscensionis (Osbeck, 1765), E. coeruleopunctatus (Bloch, 1790), E. erythrurus (Valenciennes, 1828), and E. sexfasciatus (Valenciennes, 1828); Cephalopholis Bloch and Schneider, 1801: C. fulva (Linnaeus, 1758) and C. formosa (Shaw, 1812); and Rypticus Cuvier, 1829: R. saponaceus (Bloch and Schneider, 1801) were analyzed
In E. adscensionis, E. coeruleopunctatus, E. erythrurus, E. sexfasciatus, and C. fulva, they were localized in the acrocentric pair 24 (Figure 2), while were localized in the submetacentric pair 1 of E. itajara and C. formosa, and in the acrocentric pair 20 of R. saponaceus (Figure 3)
Summary
Reef regions are home to a huge diversity of fish (Bezerra and Silva, 2011), among which Epinephelidae (groupers) stand out for their exceptional diversity. Some biological characteristics contribute to the low restoration of their populations such as slow growth, late maturation, high longevity (i.e., almost 40 years of life), and formation of large agglomerations during the reproductive period (Craig et al, 2011; Santos et al, 2019). Some species such as the Atlantic goliath grouper (Epinephelus itajara) have responded to conservation measures (Giglio et al, 2014)
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