Genomic and cytogenetic evidence for divergence and speciation in geladas
13 affiliations
- 1School of Life Sciences, Arizona State University
- 2College of Veterinary Medicine and Agriculture, Addis Ababa University
- 3Department of Biology, College of Science, Bahir Dar University
- 4Center for Evolution and Medicine, Arizona State University
- 5School of Life Sciences, University of Nevada
- 6Cologne Center for Genomics, Medical Faculty, University of Cologne
- 7NaturZoo Rheine
- 8Ethiopian Wildlife Conservation Authority
- 9Bioinnovation and Genome Sciences, The Translational Genomics Research Institute
- 10Department of Anthropology and Archaeology, University of Calgary
- 11Department of Psychology, University of Michigan
- 12Department of Anthropology, Stony Brook University
- 13Department of Biology, University of Alabama at Birmingham
Abstract
Background Chromosomal rearrangements can play an important role in shaping patterns of genomic divergence and speciation, yet their evolutionary context is still largely unclear, as such events are rare and challenging to identify in recent evolutionary history. Geladas (Theropithecus gelada) provide a unique system to investigate this process, as a novel fission on chromosome 7 has resulted in polymorphic karyotypes among gelada populations. Results We integrate new cytogenetic data from ten animals together with whole-genome sequencing from 149 individuals spanning all three extant gelada populations (northern, central, and southern). We report additional cytogenetic evidence consistent with fixation of a chromosomal fission on chromosome 7 in northern geladas, and the absence of the fission in the central population. Phylogenetic analyses reveal that the southern lineage diverged first, prior to the split between northern and central geladas, strongly suggesting that the southern population retains the ancestral karyotype. Demographic modeling further refines the timing of the northern–central split, indicating a more recent divergence (~ 160 thousand years ago) than previously estimated. We detect elevated genetic differentiation between the northern and central populations and reduced nucleotide diversity in the northern lineage on chromosome 7, which is consistent with historically suppressed recombination. These results suggest that the fission on chromosome 7 may have contributed to regional divergence by promoting recombination suppression in heterokaryotypes. Conclusions By combining cytogenetics with population genomes, these findings highlight the role of chromosomal evolution in shaping localized genomic differentiation, and its potential for reinforcing reproductive isolation. Our results also suggest that northern geladas may represent an incipient species.
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BibTeX
@article{scott2026genomic,
title = {{Genomic and cytogenetic evidence for divergence and speciation in geladas}},
author = {Brooklynn R. Scott and Ferehiwot Ayele and Alemayehu Lemma and Amera Moges and Belayneh Abebe and Ashlee Greenier and Elizabeth Slikas and Michael Blackwell and Kerstin Becker and Megan Stoltzmann and Baptiste Sadoughi and Achim Johann and Nicolas Brüning and Abebaw Azanaw Haile and Fanuel Kebede and Fekede Regassa Joka and Andrea Guarracino and Addisu Mekonnen and Allyson Hindle and Jacinta C. Beehner and India A. Schneider-Crease and Amy Lu and Thore J. Bergman and Kenneth L. Chiou and Noah Snyder-Mackler},
journal = {Genome Biology},
year = {2026},
month = jul,
doi = {10.1186/s13059-026-04143-6},
url = {https://doi.org/10.1186/s13059-026-04143-6},
note = {CC BY},
}
RIS
TY - JOUR
TI - Genomic and cytogenetic evidence for divergence and speciation in geladas
AU - Brooklynn R. Scott
AU - Ferehiwot Ayele
AU - Alemayehu Lemma
AU - Amera Moges
AU - Belayneh Abebe
AU - Ashlee Greenier
AU - Elizabeth Slikas
AU - Michael Blackwell
AU - Kerstin Becker
AU - Megan Stoltzmann
AU - Baptiste Sadoughi
AU - Achim Johann
AU - Nicolas Brüning
AU - Abebaw Azanaw Haile
AU - Fanuel Kebede
AU - Fekede Regassa Joka
AU - Andrea Guarracino
AU - Addisu Mekonnen
AU - Allyson Hindle
AU - Jacinta C. Beehner
AU - India A. Schneider-Crease
AU - Amy Lu
AU - Thore J. Bergman
AU - Kenneth L. Chiou
AU - Noah Snyder-Mackler
PY - 2026
DA - 2026/07/01
JO - Genome Biology
DO - 10.1186/s13059-026-04143-6
UR - https://doi.org/10.1186/s13059-026-04143-6
AB - Background Chromosomal rearrangements can play an important role in shaping patterns of genomic divergence and speciation, yet their evolutionary context is still largely unclear, as such events are rare and challenging to identify in recent evolutionary history. Geladas (Theropithecus gelada) provide a unique system to investigate this process, as a novel fission on chromosome 7 has resulted in polymorphic karyotypes among gelada populations. Results We integrate new cytogenetic data from ten animals together with whole-genome sequencing from 149 individuals spanning all three extant gelada populations (northern, central, and southern). We report additional cytogenetic evidence consistent with fixation of a chromosomal fission on chromosome 7 in northern geladas, and the absence of the fission in the central population. Phylogenetic analyses reveal that the southern lineage diverged first, prior to the split between northern and central geladas, strongly suggesting that the southern population retains the ancestral karyotype. Demographic modeling further refines the timing of the northern–central split, indicating a more recent divergence (~ 160 thousand years ago) than previously estimated. We detect elevated genetic differentiation between the northern and central populations and reduced nucleotide diversity in the northern lineage on chromosome 7, which is consistent with historically suppressed recombination. These results suggest that the fission on chromosome 7 may have contributed to regional divergence by promoting recombination suppression in heterokaryotypes. Conclusions By combining cytogenetics with population genomes, these findings highlight the role of chromosomal evolution in shaping localized genomic differentiation, and its potential for reinforcing reproductive isolation. Our results also suggest that northern geladas may represent an incipient species.
SN - 1474-760X
ER -