University of Oulu

Lukhtanov VA, Dincă V, Friberg M, Vila R and Wiklund C (2020) Incomplete Sterility of Chromosomal Hybrids: Implications for Karyotype Evolution and Homoploid Hybrid Speciation. Front. Genet. 11:583827. doi: 10.3389/fgene.2020.583827

Incomplete sterility of chromosomal hybrids : implications for karyotype evolution and homoploid hybrid speciation

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Author: Lukhtanov, Vladimir A.1; Dincă, Vlad2,3; Friberg, Magne4;
Organizations: 1Department of Karyosystematics, Zoological Institute of Russian Academy of Sciences, Saint Petersburg, Russia
2Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
3Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Spain
4Biodiversity Unit, Department of Biology, Lund University, Lund, Sweden
5Department of Zoology, Stockholm University, Stockholm, Sweden
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 5.1 MB)
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Language: English
Published: Frontiers Media, 2020
Publish Date: 2021-02-04


Heterozygotes for major chromosomal rearrangements such as fusions and fissions are expected to display a high level of sterility due to problems during meiosis. However, some species, especially plants and animals with holocentric chromosomes, are known to tolerate chromosomal heterozygosity even for multiple rearrangements. Here, we studied male meiotic chromosome behavior in four hybrid generations (F1–F4) between two chromosomal races of the Wood White butterfly Leptidea sinapis differentiated by at least 24 chromosomal fusions/fissions. Previous work showed that these hybrids were fertile, although their fertility was reduced as compared to crosses within chromosomal races. We demonstrate that (i) F1 hybrids are highly heterozygous with nearly all chromosomes participating in the formation of trivalents at the first meiotic division, and (ii) that from F1 to F4 the number of trivalents decreases and the number of bivalents increases. We argue that the observed process of chromosome sorting would, if continued, result in a new homozygous chromosomal race, i.e., in a new karyotype with intermediate chromosome number and, possibly, in a new incipient homoploid hybrid species. We also discuss the segregational model of karyotype evolution and the chromosomal model of homoploid hybrid speciation.

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Series: Frontiers in genetics
ISSN: 1664-8021
ISSN-E: 1664-8021
ISSN-L: 1664-8021
Volume: 11
Article number: 583827
DOI: 10.3389/fgene.2020.583827
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Funding: Support for this research was provided by the Russian Science Foundation No. 19-14-00202 to VL, by the Academy of Finland to VD (decision no. 328895), by the Royal Swedish Academy of Sciences to MF, and by the Spanish AEI/FEDER, UE (CGL2016-76322-P and PID2019-107078GB-I00) to RV.
Academy of Finland Grant Number: 328895
Detailed Information: 328895 (Academy of Finland Funding decision)
Copyright information: © 2020 Lukhtanov, Dincă, Friberg, Vila and Wiklund. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.