Repetitive DNA Dynamics, Phylogenetic Relationships and Divergence Times in Andean Ctenomys (Rodentia: Ctenomyidae)
1
Unidad de Producción Acuícola, Universidad de Los Lagos, Osorno 5290000, Chile
2
Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
3
Leibniz Institute for the Analysis of Biodiversity Change, Museum Koenig, 53113 Bonn, Germany
4
Instituto de Ciencias Naturales, Facultad de Medicina Veterinaria y Agronomía, Universidad de las Américas, Concepción 4030000, Chile
*
Author to whom correspondence should be addressed.
Biology 2025, 14(12), 1776; https://doi.org/10.3390/biology14121776
Submission received: 8 October 2025
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Revised: 31 October 2025
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Accepted: 11 November 2025
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Published: 12 December 2025
(This article belongs to the Section Evolutionary Biology)
Simple Summary
This study aimed to determine the distribution and variation of repetitive DNA sequences in two closely related Andean Ctenomys species with different diploid numbers (2n = 26 and 2n = 28) using molecular cytogenetic approaches. Phylogenetic analyses were employed to infer the direction and timing of the detected chromosomal changes. The results suggest a reduction in repetitive DNA associated with chromosomal fission events that led to an increase in diploid number, with no evidence of recent major sequence turnover.
Abstract
The genus Ctenomys comprises a group of rodents with remarkable karyotypic variability linked to the distribution of repetitive sequences and rearrangements. We analyzed the distribution and variation of repetitive DNA in two parapatric Andean species from Chile: Ctenomys maulinus brunneus (2n = 26; FNa = 48) and Ctenomys sp. (2n = 28; FNa = 50). Self-genomic in situ hybridization (Self-GISH), whole comparative genomic hybridization (W-CGH), and fluorescent in situ hybridization (FISH) using a telomeric probe were performed. Phylogenetic relationships and divergence times based on cytochrome b sequences helped infer the direction and timing of cytogenetic changes. Self-GISH revealed the absence of highly repetitive sequences in four chromosome pairs of C. m. brunneus and nine in Ctenomys sp. W-CGH showed no differential expansion of species-specific repeats, suggesting no recent major sequence turnover. FISH detected signals exclusively in telomeres. Phylogenetic analyses indicate that C. m. maulinus (2n = 26) diverged from the clade formed by C. m. brunneus and Ctenomys sp. during the Late Pleistocene, supporting, together with cytogenetic data, a loss of repetitive sequences associated with fission events from 2n = 26 to 28. These findings highlight the evolutionary significance of repetitive DNA and reinforce Ctenomys as a model for studying chromosomal evolution.
