Deleterious effects of recombination and possible nonrecombinatorial advantages of sex in a fungal model

López‐Villavicencio, Manuela; Debets, A.J.M.; Slakhorst, M.; Giraud, Tatiana; Schoustra, Sijmen E.

doi:10.1111/jeb.12196

Cited by 16 publications

(14 citation statements)

References 41 publications

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“…Lichens often spread asexually by symbiotic propagules (isidia or soredia). In the course of mitotic divisions due to growth or the production of asexual spores, spontaneous mutations are expected to appear regularly (López‐Villavicencio et al, 2013). Dal Grande et al (2012) found that 15% of the fungal genetic diversity detected in 62 populations of L. pulmonaria is generated by somatic mutations.…”

Section: Discussionmentioning

confidence: 99%

Multi‐gene phylogeny of the genus Lobaria: Evidence of species‐pair and allopatric cryptic speciation in East Asia

Cornejo

Scheidegger

2015

American J of Botany

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Phylogenetic analyses confirmed the monophyly of the genus Lobaria, including L. anomala. Within Lobaria, three major clades were found. These clades associate with different photobionts and comprise 18 known species and 5 undescribed species. Several chemical compounds were found to be neither stable nor invariant characters. Some taxa of the L. meridionalis-group appear to be monophyletic but remain as allopatric cryptic species. In three clades, this study found evidence for diversification processes between isidiate and nonisidiate specimens (species-pair). These findings are discussed in the context of evolutionary hypotheses for speciation processes.

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Section: Discussionmentioning

confidence: 99%

Multi‐gene phylogeny of the genus Lobaria: Evidence of species‐pair and allopatric cryptic speciation in East Asia

Cornejo

Scheidegger

2015

American J of Botany

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“…This zygote multiplies through a series of mitoses, after which each zygote goes through meiosis. This results in sexual fruiting bodies containing up to 10 6 sexual spores (ascospores) representing all possible recombinants of meiosis [29,50,51]. Among the progeny, we expect two parental and two recombinant classes (i.e.…”

Section: Experimental Methodsmentioning

confidence: 99%

Diminishing-returns epistasis among random beneficial mutations in a multicellular fungus

et al. 2016

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Adaptive evolution ultimately is fuelled by mutations generating novel genetic variation. Non-additivity of fitness effects of mutations (called epistasis) may affect the dynamics and repeatability of adaptation. However, understanding the importance and implications of epistasis is hampered by the observation of substantial variation in patterns of epistasis across empirical studies. Interestingly, some recent studies report increasingly smaller benefits of beneficial mutations once genotypes become better adapted (called diminishing-returns epistasis) in unicellular microbes and single genes. Here, we use Fisher's geometric model (FGM) to generate analytical predictions about the relationship between the effect size of mutations and the extent of epistasis. We then test these predictions using the multicellular fungus Aspergillus nidulans by generating a collection of 108 strains in either a poor or a rich nutrient environment that each carry a beneficial mutation and constructing pairwise combinations using sexual crosses. Our results support the predictions from FGM and indicate negative epistasis among beneficial mutations in both environments, which scale with mutational effect size. Hence, our findings show the importance of diminishing-returns epistasis among beneficial mutations also for a multicellular organism, and suggest that this pattern reflects a generic constraint operating at diverse levels of biological organization.

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“…However, given that same-clone mating incurs costs of sex without some of the major benefits of recombination, heterothallism may be favoured by selection for increasing the chance to produce recombinant offspring when there is limited haploid dispersal (15, 79). Nevertheless, same-clone mating may allow benefit from indirect advantages of the sexual cycle without breaking apart beneficial allelic combinations (180, 181). Such advantages include the production of resistant sexual spores as a life history constraint, changes in ploidy level and physiology, virus elimination, and genome defenses that depend upon the sexual cycle, such as repeat-induced point mutation (182) or meiotic silencing of unpaired DNA(183).…”

Section: Breeding Systems In the Basidiomycotamentioning

confidence: 99%

Fungal Sex: The Basidiomycota

et al. 2017

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SUMMARY Fungi of the Basidiomycota, representing major pathogen lineages and mushroom-forming species, exhibit diverse means to achieve sexual reproduction, with particularly varied mechanisms to determine compatibilities of haploid mating partners. For species that require mating between distinct genotypes, discrimination is usually based on both the reciprocal exchange of diffusible mating pheromones, rather than sexes, and the interactions of homeodomain protein signals after cell fusion. Both compatibility factors must be heterozygous in the product of mating, and genetic linkage relationships of the mating pheromone/receptor and homeodomain genes largely determine the complex patterns of mating-type variation. Independent segregation of the two compatibility factors can create four haploid mating genotypes from meiosis, referred to as tetrapolarity. This condition is thought to be ancestral to the basidiomycetes. Alternatively, co-segregation by linkage of the two mating factors, or in some cases the absence of the pheromone-based discrimination, yields only two mating types from meiosis, referred to as bipolarity. Several species are now known to have large and highly rearranged chromosomal regions linked to mating-type genes. At the population level, polymorphism of the mating-type genes is an exceptional aspect of some basidiomycete fungi, where selection under outcrossing for rare, intercompatible allelic variants is thought to be responsible for mating types that may number several thousand. Advances in genome sequencing and assembly are yielding new insights by comparative approaches among and within basidiomycete species, with the promise to resolve the evolutionary origins and dynamics of mating compatibility genetics in this major eukaryotic lineage.

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Deleterious effects of recombination and possible nonrecombinatorial advantages of sex in a fungal model

Cited by 16 publications

References 41 publications

Multi‐gene phylogeny of the genus Lobaria: Evidence of species‐pair and allopatric cryptic speciation in East Asia

Multi‐gene phylogeny of the genus Lobaria: Evidence of species‐pair and allopatric cryptic speciation in East Asia

Diminishing-returns epistasis among random beneficial mutations in a multicellular fungus

Fungal Sex: The Basidiomycota

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