Cryptic Speciation Within the Neotropical CichlidGeophagus brasiliensis(Quoy & Gaimard, 1824) (Teleostei Cichlidae): A New Paradigm in Karyotypical and Molecular Evolution

Abstract

The family Cichlidae is one of the most species-rich taxa in the Neotropics. However, the factors that determine these high levels of biodiversity remain unexplored. We have analyzed the morphological, cytogenetic, and molecular data from 62 specimens of a widespread cichlid, Geophagus brasiliensis, from three adjacent basins in southeastern Brazil. Morphological analyses did not show differences among specimens. The cytogenetic data indicate the occurrence of multiple nucleolar organizer regions and four sympatric karyotypes that differ in the first pair of chromosome morphology, in the Doce River Basin; whereas the karyotype from the Paraíba do Sul Basin is widely divergent. The molecular data--616 bp fragment of cytochrome oxidase subunit I--revealed two haplogroups with the deepest genetic divergence (6.4%) ever reported within a nominal species in the Neotropical Region: One of the haplogroups is restricted to the quaternary lakes in the middle portion of the Doce Basin and the Mucuri River, whereas the other haplogroup is composed of haplotypes from elsewhere in the Doce Basin and the Paraíba do Sul Basin. These patterns suggest that G. brasiliensis undergoes a cryptic speciation process involving three major lineages that differ from the African explosive cichlid radiation.

Mapping the hidden diversity of the Geophagus sensu stricto species group (Cichlidae: Geophagini) from the Amazon basin

“…This is also consistent with the study of Melo et al (2021) , who studied patterns of diversification of Characoid fishes, and identified a burst of diversification in Anostomidae, Serrasalmidae and Characidae families. DNA-based species discovery analyses focusing on lower taxonomic units such as genera of cichlids, also discovered multiple divergent evolutionary lineages ( e.g ., Astronotus Swainson, 1839 ( Colatreli et al, 2012 ); Apistogramma Regan, 1913 ( Tougard et al, 2017 ); Gymnogeophagus Miranda-Ribeiro, 1918 ( Říčan et al, 2018 ); Australoheros Říčan & Kullander, 2006 ( Ottoni et al, 2019 ); and Geophagus Heckel, 1840 ( Alves-Silva & Dergam, 2014 ; Carvalho et al, 2018 ; Argolo et al, 2020 )) suggesting cryptic diversity and, possibly, undescribed species.…”

Identification of a New Mullet Species Complex Based on an Integrative Molecular and Cytogenetic Investigation of Mugil hospes (Mugilidae: Mugiliformes)

“…On the other hand, the utility of molecular markers in this family to identify the species, better define the genera, and reconstruct their phylogenetic relationships, is well-represented by the huge amount of literature on this topic published in the last 15 years (see Rossi et al, 2016 for a review and Durand et al, 2017 ). In addition, molecular phylogenetic analyses have been used successfully in the investigation of chromosome evolution in some fish groups as those of the genus Characidium ( Pansonato-Alves et al, 2014 ) and Triportheus ( Yano et al, 2014 ), and in Geophagus brasiliensis ( Alves-Silva and Dergam, 2015 ).…”