Comparative Cytogenetics Analysis Among Peckoltia Species (Siluriformes, Loricariidae): Insights on Karyotype Evolution and Biogeography in the Amazon Region.

Kevin Santos Da Silva,Marcelo Ricardo Vicari,Renata Coelho Rodrigues Noronha,Ananda Marques Pety,Julio Cesar Pieczarka,Augusto Cesar Paes De Souza,Cleusa Yoshiko Nagamachi

doi:10.3389/fgene.2021.779464

Abstract

Peckoltia is widely distributed genus in the Amazon and Orinoco basins and the Guiana Shield, containing 18 valid species, and distinct morphotypes still needing description in the scientific literature due to its great taxonomic complexity. This study performed a comparative chromosomal analysis of two undescribed Peckoltia species (Peckoltia sp. 3 Jarumã and Peckoltia sp. 4 Caripetuba) from the Brazilian Amazon using conventional chromosome bands methods and in situ localization of the repetitive DNA (5S and 18S rRNA and U1 snRNA genes and telomeric sequences). Both species presented 2n = 52 but differed in their karyotype formula, probably due to inversions or translocations. The nucleolus organizer regions (NORs) showed distal location on a probably homeologous submetacentric pair in both species, besides an extra signal in a subtelocentric chromosome in Peckoltia sp. 4 Caripetuba. Heterochromatin occurred in large blocks, with different distributions in the species. The mapping of the 18S and 5S rDNA, and U1 snDNA showed differences in locations and number of sites. No interstitial telomeric sites were detected using the (TTAGGG)n probes. Despite 2n conservationism in Peckoltia species, the results showed variation in karyotype formulas, chromosomal bands, and locations of repetitive sites, demonstrating great chromosomal diversity. A proposal for Peckoltia karyotype evolution was inferred in this study based on the diversity of location and number of chromosomal markers analyzed. A comparative analysis with other Peckoltia karyotypes described in the literature, their biogeography patterns, and molecular phylogeny led to the hypothesis that the derived karyotype was raised in the left bank of the Amazon River.

Highlights

The Loricariidae is one of the most specious family of catfish within the order Siluriformes, containing 1,016 valid species (Fricke et al, 2021)
According to phylogenetic analyzes proposed for Loricariidae, Peckoltia genus receive strong support as monophyletic lineage (Lujan et al, 2015; Lujan et al, 2017; Roxo et al, 2019); a complex taxonomic identification procedure at a specific level related to a wide geographic distribution and morphological similarity is observed for these species (Armbruster et al, 2015; Armbruster and Lujan, 2016)
In Peckoltia sp. 3 Jarumã, heterochromatin occurred in the interstitial region of the short arm (p) of pairs 1p, 5p and 11p; in large blocks in the long arm (q) in pairs 9q with size heteromorphism and 12q; and in the pericentromeric and interstitial region of the 24q pair (Figure 2B)

Summary

Introduction

The Loricariidae is one of the most specious family of catfish within the order Siluriformes, containing 1,016 valid species (Fricke et al, 2021). Peckoltia Miranda Ribeiro, 1912 (sensu Lujan et al, 2015), comprises 18 valid species, in addition to distinct morphotypes that still lack description in the scientific literature. They are widely distributed in the Amazon and Orinoco basins and the Guiana Shield (Armbruster et al, 2015; Lujan et al, 2015; Armbruster and Lujan, 2016). Representatives of Peckoltia vittate (the type species of the genus) collected in the Amazon region (Xingu, Madeira and Orinoco rivers) presented polyphyletic lineages in molecular phylogeny by Lujan et al (2015)

Methods

Results

Conclusion