The legacy of sexual ancestors in phenotypic variability, gene expression and homoeolog regulation of clonal fish hybrids and polyploids
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1
Institute of Animal Physiology and Genetics (ASCR), Czechia
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2
University of Wrocław, Poland
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3
Slovak Academy of Sciences (SAS), Slovakia
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4
Czech University of Life Sciences Prague, Czechia
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5
Academy of Sciences of the Czech Republic (ASCR), Czechia
Hybridization and polyploidization are important evolutionary processes whose impact ranges from alteration of gene expression and phenotypic variation to triggering of asexual reproduction. We investigated fishes of the Cobitis taenia-elongatoides hybrid complex, which allows disentangling the direct effects of both processes, due to co-occurrence of parental species with their diploid and triploid hybrids. Employing morphological, ecological and RNAseq approaches we investigated molecular determinants of hybrid and polyploid forms.
In contrast to other studies, hybridization or polyploidy induced relatively very little transgressivity. Instead, Cobitis hybrids appeared intermediate with a clear effect of genomic dose when triploids expressed higher similarity to the parent contributing two genome sets. Such dosage effect was asymmetric in the germline (oocyte gene expression), but interestingly we observed overall bias toward C. taenia in somatic traits including liver gene expression, habitat preference and morphology. At the level of individual genes, expression-level dominance vastly prevailed over additivity or transgressivity. We noticed that trans-regulation of gene expression was less efficient in diploid hybrids than in triploids, where the expression modulation of homoeologues derived from the 'haploid' parent was stronger than of those derived from the ‘diploid’ one.
Our findings suggest that apparent intermediacy of hybrid phenotypes results from combination of individual genes with dominant expression rather than from simple additivity. The efficiency of cross-talk between trans-regulatory elements further appears dosage-dependent. Important effects of polyploidization may thus stem from changes in relative concentrations of trans-regulatory elements and their binding sites between hybridizing genomes. Links between gene regulation and asexuality are discussed.
Acknowledgements
We are grateful for financial support from the Czech Academy of Sciences of the Czech Republic grant no. RVO67985904, Czech Science Foundation grant nos. 13-12580S, 17-09807S, the Ministry of Education, Youth and Sports of the Czech Republic grant EXCELLENCE CZ.02.1.01/0.0/0.0/15_003/0000460 OP RDE, 7AMB14PL
Keywords:
Gene expreesion regulation,
hybridization,
Polyploidy,
phenotype,
Genotyp x environment interaction,
Microhabitat adaptation,
Geometric morphology
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Oral
Topic:
EVOLUTIONARY GENOMICS OF FISHES
Citation:
Janko
K,
Bartoš
O,
Roslein
J,
Kotusz
J,
Pekárik
L,
Petrtýl
M and
Pačes
J
(2019). The legacy of sexual ancestors in phenotypic variability, gene expression and homoeolog regulation of clonal fish hybrids and polyploids.
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00045
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Received:
06 Jun 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
Mx. Karel Janko, Institute of Animal Physiology and Genetics (ASCR), Prague, Czechia, janko@iapg.cas.cz