No evidence for accumulation of deleterious mutations and fitness degradation in clonal fish hybrids: Abandoning sex without regrets

0531707 - ÚŽFG 2021 RIV GB eng J - Journal Article
Kočí, Jan - Röslein, Jan - Pačes, Jan - Kotusz, J. - Halačka, Karel - Koščo, J. - Fedorčák, J. - Iakovenko, Nataliia - Janko, Karel
No evidence for accumulation of deleterious mutations and fitness degradation in clonal fish hybrids: Abandoning sex without regrets.
Molecular Ecology. Roč. 29, č. 16 (2020), s. 3038-3055. ISSN 0962-1083. E-ISSN 1365-294X
R&D Projects: GA ČR GA13-12580S; GA MŠMT(CZ) LM2015047; GA MŠMT EF15_003/0000460
Institutional support: RVO:67985904 ; RVO:68081766
Keywords : asexuality * clonal decay * exome capture * fitness * Muller´s ratchet * mutation load
OECD category: Biology (theoretical, mathematical, thermal, cryobiology, biological rhythm), Evolutionary biology; Ecology (UBO-W)
Impact factor: 6.185, year: 2020
Method of publishing: Open access
https://onlinelibrary.wiley.com/doi/full/10.1111/mec.15539?af=R

Despite its inherent costs, sexual reproduction is ubiquitous in nature, and the mechanisms to protect it from a competitive displacement by asexuality remain unclear. Popular mutation-based explanations, like the Muller's ratchet and the Kondrashov's hatchet, assume that purifying selection may not halt the accumulation of deleterious mutations in the nonrecombining genomes, ultimately leading to their degeneration. However, empirical evidence is scarce and it remains particularly unclear whether mutational degradation proceeds fast enough to ensure the decay of clonal organisms and to prevent them from outcompeting their sexual counterparts. To test this hypothesis, we jointly analysed the exome sequences and the fitness-related phenotypic traits of the sexually reproducing fish species and their clonal hybrids, whose evolutionary ages ranged from F1 generations to 300 ky. As expected, mutations tended to accumulate in the clonal genomes in a time-dependent manner. However, contrary to the predictions, we found no trend towards increased nonsynonymity of mutations acquired by clones, nor higher radicality of their amino acid substitutions. Moreover, there was no evidence for fitness degeneration in the old clones compared with that in the younger ones. In summary, although an efficacy of purifying selection may still be reduced in the asexual genomes, our data indicate that its efficiency is not drastically decreased. Even the oldest investigated clone was found to be too young to suffer fitness consequences from a mutation accumulation. This suggests that mechanisms other than mutation accumulation may be needed to explain the competitive advantage of sex in the short term.
Permanent Link: http://hdl.handle.net/11104/0310322