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| 2. |
- Beekman, Madeleine, et al.
(författare)
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Sexual selection in hermaphrodites, sperm and broadcast spawners, plants and fungi
- 2016
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 371:1706
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Forskningsöversikt (refereegranskat)abstract
- Darwin was the first to recognize that sexual selection is a strong evolutionary force. Exaggerated traits allow same-sex individuals to compete over access to mates and provide a mechanism by which mates are selected. It is relatively easy to appreciate how inter-and intrasexual selection work in organisms with the sensory capabilities to perceive physical or behavioural traits that signal mate quality or mate compatibility, and to assess the relative quality of competitors. It is therefore not surprising that most studies of sexual selection have focused on animals with separate sexes and obvious adaptations that function in the context of reproductive competition. Yet, many sexual organisms are both male and female at the same time, often lack sexual dimorphism and never come into direct contact at mating. How does sexual selection act in such species, and what can we learn from them? Here, we address these questions by exploring the potential for sexual selection in simultaneous hermaphrodites, sperm-and broadcast spawners, plants and fungi. Our reviewreveals a range of mechanisms of sexual selection, operating primarily after gametes have been released, which are common in many of these groups and also quite possibly in more familiar (internally fertilizing and sexually dimorphic) organisms. This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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| 3. |
- Hooftman, Danny A. P., et al.
(författare)
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Introgression potential of downy mildew resistance from lettuce to Lactuca serriola and its relevance for plant fitness
- 2007
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Ingår i: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 8:2, s. 135-146
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Tidskriftsartikel (refereegranskat)abstract
- Hybridization between plant species may cause ecological changes in species, enhancing their potential to become invasive. Increasing evidence suggests that the expanding distribution of Lactuca serriola could (partly) be caused by hybridization with its closest relative, the crop plant L. sativa (lettuce). Fitness advantages in hybrids may result from heterosis and epistasis but single added traits may enhance hybrid fitness as well. Here, we study the potential for introgression of an important crop trait, downy mildew (Bremia lactucae) resistance, into L. serriola hybrids. We monitored the abundance of B. lactucae on wild L. serriola in The Netherlands to test its impact potential. We found that B. lactucae is common in The Netherlands: B. lactucae occurred in 33 of the 35 surveyed populations of L. serriola. Subsequently, under regulated conditions, using two physiotypes of B. lactucae (BL-16 and BL-18), we recorded (i) quantitative conidiophore and (ii) haustoria development in seedlings. Furthermore, we explored its effects on plant fitness. Based on the (non-) occurrence of conidiophores, genomic segments from L. sativa that include Bremia resistance are present and expressing in these hybrids for at least two hybrid generations. However, haustoria density was lower in all hybrids, irrespective of physiotype or siring cultivar. We attributed this to heterosis. Furthermore, all plants shed infected leaves, but we observed no effects of infection on reproductive fitness. We therefore suggest that when L. serriola gains resistance to B. lactucae, the fitness effects are tow. The hypothesis that the gain of B. lactucae resistance is causally related to the recent spread of L. serriola has become less Likely. If hybridization is connected to this at all, it seems through heterosis. We conclude that it is important to study fitness impacts of introgressed traits along with other ecological factors. (c) 2006 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.
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| 4. |
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| 5. |
- Nieuwenhuis, Bart P. S., et al.
(författare)
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Evolution of uni- and bifactorial sexual compatibility systems in fungi
- 2013
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Ingår i: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 111:6, s. 445-455
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Forskningsöversikt (refereegranskat)abstract
- Mating systems, that is, whether organisms give rise to progeny by selfing, inbreeding or outcrossing, strongly affect important ecological and evolutionary processes. Large variations in mating systems exist in fungi, allowing the study of their origin and consequences. In fungi, sexual incompatibility is determined by molecular recognition mechanisms, controlled by a single mating-type locus in most unifactorial fungi. In Basidiomycete fungi, however, which include rusts, smuts and mushrooms, a system has evolved in which incompatibility is controlled by two unlinked loci. This bifactorial system probably evolved from a unifactorial system. Multiple independent transitions back to a unifactorial system occurred. It is still unclear what force drove evolution and maintenance of these contrasting inheritance patterns that determine mating compatibility. Here, we give an overview of the evolutionary factors that might have driven the evolution of bifactoriality from a unifactorial system and the transitions back to unifactoriality. Bifactoriality most likely evolved for selfing avoidance. Subsequently, multiallelism at mating-type loci evolved through negative frequency-dependent selection by increasing the chance to find a compatible mate. Unifactoriality then evolved back in some species, possibly because either selfing was favoured or for increasing the chance to find a compatible mate in species with few alleles. Owing to the existence of closely related unifactorial and bifactorial species and the increasing knowledge of the genetic systems of the different mechanisms, Basidiomycetes provide an excellent model for studying the different forces that shape breeding systems.
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| 6. |
- Nieuwenhuis, Bart P. S., et al.
(författare)
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On the asymmetry of mating in natural populations of the mushroom fungus Schizophyllum commune
- 2013
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Ingår i: Fungal Genetics and Biology. - : Elsevier BV. - 1087-1845 .- 1096-0937. ; 56, s. 25-32
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Tidskriftsartikel (refereegranskat)abstract
- Before a mycelium of a mushroom-forming basidiomycete develops mushrooms, the monokaryotic mycelium needs to become fertilized. Although the mechanistic details of mating in mushrooms have been studied thoroughly in laboratory research, very little is known on mating patterns in nature. In this study, we performed fine-scale analyses of three populations of Schizophyllum commune from their natural substrate (i.e. dead beech branches). From the three branches, 24, 12, and 24 fruiting bodies were isolated and for each mushroom, the origins of its nuclei and cytoplasm were reconstructed using DNA markers. Nuclear genotypes were determined using sequencing data and mating types, and mitochondrial haplotypes using SNP markers. From these combined data we reconstructed colonization and mating patterns of the mycelia. On each branch, we found multiple dikaryons (3, 3, and 8, respectively); in two instances one nuclear haplotype was shared between two dikaryons and in two other cases a nuclear haplotype was shared between three dikaryons. Each dikaryon always had a single mitochondrial haplotype. These findings indicate that mating usually is not symmetrical and that a monokaryon is most likely fertilized by a small monokaryon, a spore or a dikaryon. Sharing of nuclear haplotype between different dikaryons resulted either from multiple fertilizations of a single monokaryon, if the dikaryons had identical mitochondrial haplotypes, or, if the dikaryons had different mitochondria] haplotypes, most likely from secondary matings between a monokaryon and a dikaryon (Buller phenomenon). We conclude that mating in S. commune between same-sized monokaryons with reciprocal migration, as generally described in textbooks, is rare in nature. We discuss the implications of non-symmetric mating for basidiomycete evolution.
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| 7. |
- Nieuwenhuis, Bart P. S., et al.
(författare)
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Repeated evolution of self-compatibility for reproductive assurance
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Sexual reproduction in eukaryotes requires the fusion of two compatible gametes of opposite sexes or mating types. To meet the challenge of finding a mating partner with compatible gametes, evolutionary mechanisms such as hermaphroditism and self-fertilization have repeatedly evolved. Here, by combining the insights from comparative genomics, computer simulations and experimental evolution in fission yeast, we shed light on the conditions promoting separate mating types or self-compatibility by mating-type switching. Analogous to multiple independent transitions between switchers and non-switchers in natural populations mediated by structural genomic changes, novel switching genotypes readily evolved under selection in the experimental populations. Detailed fitness measurements accompanied by computer simulations show the benefits and costs of switching during sexual and asexual reproduction, governing the occurrence of both strategies in nature. Our findings illuminate the trade-off between the benefits of reproductive assurance and its fitness costs under benign conditions facilitating the evolution of self-compatibility.
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| 8. |
- Nieuwenhuis, Bart P. S., et al.
(författare)
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The evolution of mating-type switching for reproductive assurance
- 2016
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Ingår i: Bioessays. - : Wiley. - 0265-9247 .- 1521-1878. ; 38:11, s. 1141-1149
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Forskningsöversikt (refereegranskat)abstract
- Alternative ways to ensure mate compatibility, such as hermaphroditism and the breakdown of self-incompatibility, evolved repeatedly when finding a mating partner is difficult. In a variety of microorganisms where compatibility is determined by mating-types, a highly regulated form of universal compatibility system called mating-type switching has evolved several times. This sophisticated system allows for the genetic adjustment of the mating type during asexual growth, and it most likely evolved for reproductive assurance of immotile species under low densities. In this review, we compare the switching strategy to other universal compatibility systems such as unisexual mating and homothallism. We identify the costs of switching, including genome instability, and mechanistic costs, as well as the benefits, mainly the maintenance of important mating-type functions. Given the potential benefits of mating-type switching, we speculate that switching is likely to have evolved many times independently, and may be more common in groups where genetic mating types regulate mate compatibility than assumed so far.
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| 9. |
- Nieuwenhuis, Bart P. S., et al.
(författare)
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The frequency of sex in fungi
- 2016
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 371:1706
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Forskningsöversikt (refereegranskat)abstract
- Fungi are a diverse group of organisms with a huge variation in reproductive strategy. While almost all species can reproduce sexually, many reproduce asexually most of the time. When sexual reproduction does occur, large variation exists in the amount of in- and out-breeding. While budding yeast is expected to outcross only once every 10 000 generations, other fungi are obligate outcrossers with well-mixed panmictic populations. In this review, we give an overview of the costs and benefits of sexual and asexual reproduction in fungi, and the mechanisms that evolved in fungi to reduce the costs of either mode. The proximate molecular mechanisms potentiating outcrossing and meiosis appear to be present in nearly all fungi, making them of little use for predicting outcrossing rates, but also suggesting the absence of true ancient asexual lineages. We review how population genetic methods can be used to estimate the frequency of sex in fungi and provide empirical data that support a mixed mode of reproduction in many species with rare to frequent sex in between rounds of mitotic reproduction. Finally, we highlight how these estimates might be affected by the fungus-specific mechanisms that evolved to reduce the costs of sexual and asexual reproduction. This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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| 10. |
- Tusso, Sergio, et al.
(författare)
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Ancestral admixture is the main determinant of global biodiversity in fission yeast
- 2019
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Ingår i: Molecular biology and evolution. - : Oxford University Press. - 0737-4038 .- 1537-1719. ; 36:9, s. 1975-1989
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Tidskriftsartikel (refereegranskat)abstract
- Mutation and recombination are key evolutionary processes governing phenotypic variation and reproductive isolation. We here demonstrate that biodiversity within all globally known strains of Schizosaccharomyces pombe arose through admixture between two divergent ancestral lineages. Initial hybridization was inferred to have occurred similar to 20-60 sexual outcrossing generations ago consistent with recent, human-induced migration at the onset of intensified transcontinental trade. Species-wide heritable phenotypic variation was explained near-exclusively by strain-specific arrangements of alternating ancestry components with evidence for transgressive segregation. Reproductive compatibility between strains was likewise predicted by the degree of shared ancestry. To assess the genetic determinants of ancestry block distribution across the genome, we characterized the type, frequency, and position of structural genomic variation using nanopore and single-molecule real-time sequencing. Despite being associated with double-strand break initiation points, over 800 segregating structural variants exerted overall little influence on the introgression landscape or on reproductive compatibility between strains. In contrast, we found strong ancestry disequilibrium consistent with negative epistatic selection shaping genomic ancestry combinations during the course of hybridization. This study provides a detailed, experimentally tractable example that genomes of natural populations are mosaics reflecting different evolutionary histories. Exploiting genome-wide heterogeneity in the history of ancestral recombination and lineage-specific mutations sheds new light on the population history of S. pombe and highlights the importance of hybridization as a creative force in generating biodiversity.
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