speciation through asexuality in fish: postzygotic reproductive isolation may be completed in spite of fertility of hybrids
Karel
Janko1, 2*,
Jan
Paces1,
Hilde
Wilkinson Herbots3,
Rui
R.
Da Costa3,
Pavel
Drozd2,
Nataliia
Iakovenko1, 2,
Jakub
Ridl4,
Jan
Koci1, 2,
Jan
Roslein1, 5,
Radka
Reifova6 and
Lukas
Choleva1
-
1
Institute of Animal Physiology and Genetics, Czechia
-
2
University of Ostrava, Faculty of Natural Sciences, Czechia
-
3
University College London, Department of Statistical Science, United Kingdom
-
4
Institute of Molecular Genetics of the ASCR, Laboratory of Genomics and Bioinformatics, Czechia
-
5
Institute of Vertebrate Biology, AS CR, Czechia
-
6
Charles University in Prague, Faculty of Science, Czechia
Speciation process often occurs in the face of hybridisation between forming species. Hybrid genomic constitution of many clonal organisms including fish, amphibians and reptiles also indicates tight linkage between hybridization, clonality and malfunction of sex in hybrids. To address the causal links between these phenomena, we investigated the evolution of asexuality and postzygotic reproductive isolation mechanisms (postRIMs) in the Cobitis loaches, which involves three sister species (C. taenia, C. pontica and C. tanaitica) and their distant relative, C. elongatoides. Interspecific crossings revealed that initiation of asexuality is causally linked to hybridization but does not require involvement of any particular genome. Rather, it depends on genetic distance between hybridizing parental taxa: crossings of distantly related elongatoides-taenia pair produced sterile males and fertile clonal females, while crossings of closely related species, C. pontica and C. taenia, produced fertile sexually reproducing hybrids of both sexes, with only rarely occurring clonal biotypes. Previous study of elongatoides-taenia hybrid zone together with current population genetic analysis of elongatoides-tanaitica hybrid zone demonstrated the completion of speciation: no BC or F2 hybrids have been revealed and inferred F1 hybrids were clonal. However, phylogenomic analysis revealed that gene flow between these species has been quite intensive in the past, leading to massive historical introgressions.
Altogether, it appears that initiation of hybrid asexuality and the completion of speciation process through formation of postRIMs are interconnected phenomena. Both processes are linked to the genetic divergence of hybridizing taxa: initially, hybridization between little diverged species leads to recombinant and fertile hybrids allowing intensive gene flow. As the hybridizing taxa continue to diverge, clonally reproducing hybrid females and sterile males become dominant and the gene flow ceases. The speciation may therefore be completed through asexuality of hybrids
The work was supported by grant no. 13-12580S provided by the Czech Science Foundation (www.gacr.cz). Further support was provided by the Academy of Sciences of the Czech Republic (www.cas.cz) by the grant no. RVO 67985904
Keywords:
speciation,
asexual reproduction,
postzygotic isolation,
hybridization,
hybrid zones,
meiosis disturbance
Conference:
XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015.
Presentation Type:
Oral Presentation
Topic:
Phylogeny, Systematics and Genetics
Citation:
Janko
K,
Paces
J,
Wilkinson Herbots
H,
Da Costa
RR,
Drozd
P,
Iakovenko
N,
Ridl
J,
Koci
J,
Roslein
J,
Reifova
R and
Choleva
L
(2015). speciation through asexuality in fish: postzygotic reproductive isolation may be completed in spite of fertility of hybrids.
Front. Mar. Sci.
Conference Abstract:
XV European Congress of Ichthyology.
doi: 10.3389/conf.FMARS.2015.03.00241
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Received:
22 Dec 2015;
Published Online:
24 Dec 2015.
*
Correspondence:
Dr. Karel Janko, Institute of Animal Physiology and Genetics, Libechov, Czech Republic, 27721, Czechia, janko@iapg.cas.cz