1
|
Archetti M. Soft selection reduces loss of heterozygosity in asexual reproduction. J Evol Biol 2023; 36:1313-1327. [PMID: 37584223 DOI: 10.1111/jeb.14209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 06/27/2023] [Accepted: 07/19/2023] [Indexed: 08/17/2023]
Abstract
The adaptive value of sexual reproduction is still debated in evolutionary theory. It has been proposed that the advantage of sexual reproduction over asexual reproduction is to promote genetic diversity, to prevent the accumulation of harmful mutations or to preserve heterozygosity. Since these hypothetical advantages depend on the type of asexual reproduction, understanding how selection affects the taxonomic distribution of each type could help us discriminate between existing hypotheses. Here, I argue that soft selection, competition among embryos or offspring in selection arenas prior to the hard selection of the adult phase, reduces loss of heterozygosity in certain types of asexual reproduction. Since loss of heterozygosity leads to the unmasking of recessive deleterious mutations in the progeny of asexual individuals, soft selection facilitates the evolution of these types of asexual reproduction. Using a population genetics model, I calculate how loss of heterozygosity affects fitness for different types of apomixis and automixis, and I show that soft selection significantly reduces loss of heterozygosity, hence increases fitness, in apomixis with suppression of the first meiotic division and in automixis with central fusion, the most common types of asexual reproduction. Therefore, if sexual reproduction evolved to preserve heterozygosity, soft selection should be associated with these types of asexual reproduction. I discuss the evidence for this prediction and how this and other observations on the distribution of different types of asexual reproduction in nature is consistent with the heterozygosity hypothesis.
Collapse
Affiliation(s)
- Marco Archetti
- Department of Biology, W210 MSC, Pennsylvania State University, University Park, Pennsylvania, USA
| |
Collapse
|
2
|
Blanc C, Saclier N, Le Faou E, Marie-Orleach L, Wenger E, Diblasi C, Glemin S, Galtier N, Delattre M. Cosegregation of recombinant chromatids maintains genome-wide heterozygosity in an asexual nematode. SCIENCE ADVANCES 2023; 9:eadi2804. [PMID: 37624896 PMCID: PMC10456839 DOI: 10.1126/sciadv.adi2804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Accepted: 07/27/2023] [Indexed: 08/27/2023]
Abstract
In asexual animals, female meiosis is modified to produce diploid oocytes. If meiosis still involves recombination, this is expected to lead to a rapid loss of heterozygosity, with adverse effects on fitness. Many asexuals, however, have a heterozygous genome, the underlying mechanisms being most often unknown. Cytological and population genomic analyses in the nematode Mesorhabditis belari revealed another case of recombining asexual being highly heterozygous genome-wide. We demonstrated that heterozygosity is maintained despite recombination because the recombinant chromatids of each chromosome pair cosegregate during the unique meiotic division. A theoretical model confirmed that this segregation bias is necessary to account for the observed pattern and likely to evolve under a wide range of conditions. Our study uncovers an unexpected type of non-Mendelian genetic inheritance involving cosegregation of recombinant chromatids.
Collapse
Affiliation(s)
- Caroline Blanc
- Laboratory of Biology and Modeling of the Cell, Ecole Normale Supérieure de Lyon, CNRS UMR 5239, Inserm U1293, University Claude Bernard Lyon 1, Lyon, France
| | - Nathanaelle Saclier
- Institut des Sciences de l'Evolution, Université Montpellier, Institut de Recherche pour le Développement, 34090 Montpellier, France
| | - Ehouarn Le Faou
- University of Rennes, CNRS, ECOBIO (Ecologie, Biodiversité, Evolution)–UMR 6553, F-35000 Rennes, France
| | - Lucas Marie-Orleach
- University of Rennes, CNRS, ECOBIO (Ecologie, Biodiversité, Evolution)–UMR 6553, F-35000 Rennes, France
| | - Eva Wenger
- Laboratory of Biology and Modeling of the Cell, Ecole Normale Supérieure de Lyon, CNRS UMR 5239, Inserm U1293, University Claude Bernard Lyon 1, Lyon, France
| | - Celian Diblasi
- Institut des Sciences de l'Evolution, Université Montpellier, Institut de Recherche pour le Développement, 34090 Montpellier, France
| | - Sylvain Glemin
- University of Rennes, CNRS, ECOBIO (Ecologie, Biodiversité, Evolution)–UMR 6553, F-35000 Rennes, France
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, 75236 Uppsala, Sweden
| | - Nicolas Galtier
- Institut des Sciences de l'Evolution, Université Montpellier, Institut de Recherche pour le Développement, 34090 Montpellier, France
| | - Marie Delattre
- Laboratory of Biology and Modeling of the Cell, Ecole Normale Supérieure de Lyon, CNRS UMR 5239, Inserm U1293, University Claude Bernard Lyon 1, Lyon, France
| |
Collapse
|
3
|
Pequeno PACL, Franklin E, Norton RA. Hunger for sex: Abundant, heterogeneous resources select for sexual reproduction in the field. J Evol Biol 2022; 35:1387-1395. [PMID: 36117406 DOI: 10.1111/jeb.14091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 08/05/2022] [Accepted: 08/21/2022] [Indexed: 11/29/2022]
Abstract
Major hypotheses on sex evolution predict that resource abundance and heterogeneity should either select for or against sexual reproduction. However, seldom have these predictions been explicitly tested in the field. Here, we investigated this question using soil oribatid mites, a diverse and abundant group of soil arthropods whose local communities can be dominated by either sexual or asexual species. First, we refined theoretical predictions by addressing how the effects of resource abundance, heterogeneity and abiotic conditions could modify each other. Then, we estimated the strength of selection for sexual species in local communities while controlling for phylogeny and neutral processes (ecological drift and dispersal), and tested its relation to resource and abiotic gradients. We show that sexual species tended to be favoured with increasing litter amount, a measure of basal resource abundance. Further, there was some evidence that this response occurred mainly under higher tree species richness, a measure of basal resource heterogeneity. This response to resources is unlikely to reflect niche partitioning between reproductive modes, as sexual and asexual species overlapped in trophic niche according to a comparative analysis using literature data on stable isotope ratios. Rather, these findings are consistent with the hypothesis that sex facilitates adaptation by breaking unfavourable genetic associations, an advantage that should increase with effective population size when many loci are under selection and, thus, with resource abundance.
Collapse
Affiliation(s)
| | - Elizabeth Franklin
- Biodiversity Coordination, National Institute for Amazonia Research, Manaus, Brazil
| | - Roy A Norton
- College of Environmental Science and Forestry, State University of New York, Syracuse, New York, USA
| |
Collapse
|
4
|
Polyploidy as an Adaptation against Loss of Heterozygosity in Cancer. Int J Mol Sci 2022; 23:ijms23158528. [PMID: 35955663 PMCID: PMC9369199 DOI: 10.3390/ijms23158528] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/23/2022] [Accepted: 07/28/2022] [Indexed: 12/13/2022] Open
Abstract
Polyploidy is common in cancer cells and has implications for tumor progression and resistance to therapies, but it is unclear whether it is an adaptation of the tumor or the non-adaptive effect of genomic instability. I discuss the possibility that polyploidy reduces the deleterious effects of loss of heterozygosity, which arises as a consequence of mitotic recombination, and which in diploid cells leads instead to the rapid loss of complementation of recessive deleterious mutations. I use computational predictions of loss of heterozygosity to show that a population of diploid cells dividing by mitosis with recombination can be easily invaded by mutant polyploid cells or cells that divide by endomitosis, which reduces loss of complementation, or by mutant cells that occasionally fuse, which restores heterozygosity. A similar selective advantage of polyploidy has been shown for the evolution of different types of asexual reproduction in nature. This provides an adaptive explanation for cyclical ploidy, mitotic slippage and cell fusion in cancer cells.
Collapse
|