The Genetic Differentiation of Pyrrhulina (Teleostei, Characiformes) Species is Likely Influenced by Both Geographical Distribution and Chromosomal Rearrangements

Abstract

Allopatry is generally considered to be one of the main contributors to the remarkable Neotropical biodiversity. However, the role of chromosomal rearrangements including neo-sex chromosomes for genetic diversity is still poorly investigated and understood. Here, we assess the genetic divergence in five Pyrrhulina species using population genomics and combined the results with previously obtained cytogenetic data, highlighting that molecular genetic diversity is consistent with their chromosomal features. The results of a principal coordinate analysis (PCoA) indicated a clear difference among all species while showing a closer relationship of the ones located in the same geographical region. This was also observed in genetic structure analyses that only grouped P. australis and P. marilynae, which were also recovered as sister species in a species tree analysis. We observed a contradictory result for the relationships among the three species from the Amazon basin, as the phylogenetic tree suggested P. obermulleri and P. semifasciata as sister species, while the PCoA showed a high genetic difference between P. semifasciata and all other species. These results suggest a potential role of sex-related chromosomal rearrangements as reproductive barriers between these species.

Chromosomes of Asian Cyprinid Fishes: Genomic Differences in Conserved Karyotypes of ‘Poropuntiinae’ (Teleostei, Cyprinidae)

“…The presence of karyotypes composed primarily of mono-armed chromosomes (acrocentric) appears to be a feature of most derived fish clades, whereas the basal ones exhibit primarily biarmed ones (meta-, submetacentric) [ 74 ]. Aside from the differences found in fish phylogeny between basal and derived orders, the tendency towards chromosome acrocentrization appears to occur even within groups at the family level, as seem in some Neotropical and marine groups [ 15 , 75 ]. Considering the diversity of freshwater fishes, Cypriniformes can only be considered a basal clade when compared to Characiformes, Siluriformes and Gymnotiformes, but not within Acipenseriformes and Osteoglossomorpha [ 76 ].…”

“…On other hand, Labeoninae, ‘Poropuntiinae’, Acrossocheilinae and most Smiliogastrinae are strictly composed by diploid species. Examining cytogenetic information from species with significant chromosomal rearrangements can help us understand their evolution and diversification [ 15 ]. Nonetheless, only research on diploid numbers and karyotype composition is now available for the ‘Poropuntiinae’ [ 16 ].…”