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The absence of reproductive isolation between non-sister and deeply diverged mitochondrial lineages of the black-throated tit (Aegithalos concinnus) revealed by a multilocus genetic analysis in a contact zone

BACKGROUND: A deep divergence of mitochondrial DNA is common in species delimitated by morphological traits. Several hypotheses can explain such variations, such as cryptic species, introgression, allopatric divergence and ancestral lineage. The black-throated tit harbors several deeply divergent mi...

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Autores principales: Dai, Chuanyin, Hao, Yan, He, Yong, Lei, Fumin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5738821/
https://www.ncbi.nlm.nih.gov/pubmed/29262786
http://dx.doi.org/10.1186/s12862-017-1114-9
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author Dai, Chuanyin
Hao, Yan
He, Yong
Lei, Fumin
author_facet Dai, Chuanyin
Hao, Yan
He, Yong
Lei, Fumin
author_sort Dai, Chuanyin
collection PubMed
description BACKGROUND: A deep divergence of mitochondrial DNA is common in species delimitated by morphological traits. Several hypotheses can explain such variations, such as cryptic species, introgression, allopatric divergence and ancestral lineage. The black-throated tit harbors several deeply divergent mitochondrial lineages. Two lineages with 5% divergence, but having a high level of gene flow, have been detected in its subspecies, A. C. concinnus and A. c. talifuenses. In this study, we conducted a genetic analysis at a contact zone of these two lineages to identify whether these lineages either reflect a high level of intraspecific variation in mitochondrial loci or represent incipient speciation. Mitochondrial ND2 and 11 microsatellite loci were used to conduct phylogenetic and population structure analyses. RESULTS: ND2 haplotypes actually diverged into two groups within subspecies A. c. talifuenses; however, they formed a non-sister relationship when including all available GenBank ND2 sequences. Analyses of microsatellite data indicated no existing population structure and showed a pattern of isolation by distance. Individuals sampled at the contact zone were almost identified as F2 hybrids. CONCLUSIONS: Isolation for 2.4 Ma, as suggested by a previous study, appeared to be insufficient to develop robust reproductive barriers. Reproductive barriers were weak, or even absent between the divergent lineages, highlighting that incipient speciation was unlikely to be the case. Considering the results from previous studies, the divergent lineages may be better explained by secondary contact after allopatric isolation because of Pleistocene climate changes, but other hypotheses cannot be definitively ruled out because of the lack of representative samples from the other distribution region and its relatives. Considering that divergence in morphology was hardly observed and the particular split in genetics, the two subspecies might be better merged. The current findings also highlight the likely contribution of male-biased dispersal to male-biased gene flow among mitochondrial lineages; more efforts are needed to illustrate the evolutionary history of the black-throated tit. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi: 10.1186/s12862-017-1114-9) contains supplementary material, which is available to authorized users.
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spelling pubmed-57388212018-01-02 The absence of reproductive isolation between non-sister and deeply diverged mitochondrial lineages of the black-throated tit (Aegithalos concinnus) revealed by a multilocus genetic analysis in a contact zone Dai, Chuanyin Hao, Yan He, Yong Lei, Fumin BMC Evol Biol Research Article BACKGROUND: A deep divergence of mitochondrial DNA is common in species delimitated by morphological traits. Several hypotheses can explain such variations, such as cryptic species, introgression, allopatric divergence and ancestral lineage. The black-throated tit harbors several deeply divergent mitochondrial lineages. Two lineages with 5% divergence, but having a high level of gene flow, have been detected in its subspecies, A. C. concinnus and A. c. talifuenses. In this study, we conducted a genetic analysis at a contact zone of these two lineages to identify whether these lineages either reflect a high level of intraspecific variation in mitochondrial loci or represent incipient speciation. Mitochondrial ND2 and 11 microsatellite loci were used to conduct phylogenetic and population structure analyses. RESULTS: ND2 haplotypes actually diverged into two groups within subspecies A. c. talifuenses; however, they formed a non-sister relationship when including all available GenBank ND2 sequences. Analyses of microsatellite data indicated no existing population structure and showed a pattern of isolation by distance. Individuals sampled at the contact zone were almost identified as F2 hybrids. CONCLUSIONS: Isolation for 2.4 Ma, as suggested by a previous study, appeared to be insufficient to develop robust reproductive barriers. Reproductive barriers were weak, or even absent between the divergent lineages, highlighting that incipient speciation was unlikely to be the case. Considering the results from previous studies, the divergent lineages may be better explained by secondary contact after allopatric isolation because of Pleistocene climate changes, but other hypotheses cannot be definitively ruled out because of the lack of representative samples from the other distribution region and its relatives. Considering that divergence in morphology was hardly observed and the particular split in genetics, the two subspecies might be better merged. The current findings also highlight the likely contribution of male-biased dispersal to male-biased gene flow among mitochondrial lineages; more efforts are needed to illustrate the evolutionary history of the black-throated tit. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi: 10.1186/s12862-017-1114-9) contains supplementary material, which is available to authorized users. BioMed Central 2017-12-20 /pmc/articles/PMC5738821/ /pubmed/29262786 http://dx.doi.org/10.1186/s12862-017-1114-9 Text en © The Author(s). 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Dai, Chuanyin
Hao, Yan
He, Yong
Lei, Fumin
The absence of reproductive isolation between non-sister and deeply diverged mitochondrial lineages of the black-throated tit (Aegithalos concinnus) revealed by a multilocus genetic analysis in a contact zone
title The absence of reproductive isolation between non-sister and deeply diverged mitochondrial lineages of the black-throated tit (Aegithalos concinnus) revealed by a multilocus genetic analysis in a contact zone
title_full The absence of reproductive isolation between non-sister and deeply diverged mitochondrial lineages of the black-throated tit (Aegithalos concinnus) revealed by a multilocus genetic analysis in a contact zone
title_fullStr The absence of reproductive isolation between non-sister and deeply diverged mitochondrial lineages of the black-throated tit (Aegithalos concinnus) revealed by a multilocus genetic analysis in a contact zone
title_full_unstemmed The absence of reproductive isolation between non-sister and deeply diverged mitochondrial lineages of the black-throated tit (Aegithalos concinnus) revealed by a multilocus genetic analysis in a contact zone
title_short The absence of reproductive isolation between non-sister and deeply diverged mitochondrial lineages of the black-throated tit (Aegithalos concinnus) revealed by a multilocus genetic analysis in a contact zone
title_sort absence of reproductive isolation between non-sister and deeply diverged mitochondrial lineages of the black-throated tit (aegithalos concinnus) revealed by a multilocus genetic analysis in a contact zone
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5738821/
https://www.ncbi.nlm.nih.gov/pubmed/29262786
http://dx.doi.org/10.1186/s12862-017-1114-9
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