Selfing is the safest sex for Caenorhabditis tropicalis

Mating systems have profound effects on genetic diversity and compatibility. The convergent evolution of self-fertilization in three Caenorhabditis species provides a powerful lens to examine causes and consequences of mating system transitions. Among the selfers, C. tropicalis is the least genetically diverse and most afflicted by outbreeding depression. We generated a chromosomal-scale genome for C. tropicalis and surveyed global diversity. Population structure is very strong, and islands of extreme divergence punctuate a genomic background that is highly homogeneous around the globe. Outbreeding depression in the laboratory is caused largely by multiple Medea-like elements, genetically consistent with maternal toxin/zygotic antidote systems. Loci with Medea activity harbor novel and duplicated genes, and their activity is modified by mito-nuclear background. Segregating Medea elements dramatically reduce fitness, and simulations show that selfing limits their spread. Frequent selfing in C. tropicalis may therefore be a strategy to avoid Medea-mediated outbreeding depression.

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Selfing is the safest sex for Caenorhabditis tropicalis

10.1101/2020.08.07.242032 ◽

2020 ◽

Author(s):

Luke M. Noble ◽

John Yuen ◽

Lewis Stevens ◽

Nicolas Moya ◽

Riaad Persaud ◽

...

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Convergent Evolution ◽

Mating Systems ◽

Outbreeding Depression ◽

Duplicated Genes ◽

Gene Drive ◽

Multiple Gene ◽

Nuclear Background ◽

Self Fertilization

AbstractMating systems have profound effects on genetic diversity and compatibility. The convergent evolution of self-fertilization in three Caenorhabditis species provides a powerful lens to examine causes and consequences of mating system transitions. Among the selfers, C. tropicalis is the least genetically diverse and most afflicted by outbreeding depression. We generated a chromosomal-scale genome for C. tropicalis and surveyed global diversity. Population structure is very strong, and islands of extreme divergence punctuate a genomic background that is highly homogeneous around the globe. Outbreeding depression in the laboratory is caused largely by multiple gene drive elements, genetically consistent with maternal toxin/zygotic antidote systems. Driver loci harbor novel and duplicated genes, and their activity is modified by mito-nuclear background. Segregating drivers dramatically reduce fitness, and simulations show that selfing limits their spread. Frequent selfing in C. tropicalis may therefore be a strategy to avoid drive-mediated outbreeding depression.

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Study of genetic differences among Slovak Tsigai populations using microsatellite markers

Czech Journal of Animal Science ◽

10.17221/1670-cjas ◽

2009 ◽

Vol 54 (No. 10) ◽

pp. 468-474 ◽

Cited By ~ 3

Author(s):

S. Kusza ◽

E. Gyarmathy ◽

J. Dubravska ◽

I. Nagy ◽

A. Jávor ◽

...

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Genetic Distance ◽

Microsatellite Markers ◽

Mating System ◽

Population Differentiation ◽

Genetic Relationships ◽

The Other ◽

Potential Risks ◽

Substantial Degree

In this study genetic diversity, population structure and genetic relationships of Tsigai populations in Slovakia were investigated using microsatellite markers. Altogether 195 animals from 12 populations were genotyped for 16 microsatellites. 212 alleles were detected on the loci. The number of identified alleles per locus ranged from 11 to 35. In the majority of the populations heterozygosity deficiency and potential risks of inbreeding could be determined. High values of <I>F</I><sub>ST</sub> (0.133) across all the loci revealed a substantial degree of population differentiation. The estimation of genetic distance value showed that the Slovak Vojin population was the most different from the other populations. The 12 examined populations were able to group into 4 clusters. With this result our aim is to help the Slovak sheep breeders to establish their own mating system, to avoid genetic loss and to prevent diversity of Tsigai breed in Slovakia.

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Pollen dispersal, pollen immigration, mating and genetic diversity in restoration of the southern plains Banksia

Biological Journal of the Linnean Society ◽

10.1093/biolinnean/blaa003 ◽

2020 ◽

Vol 129 (4) ◽

pp. 773-792

Author(s):

Melissa A Millar ◽

David J Coates ◽

Margaret Byrne ◽

Siegfried L Krauss ◽

Matthew R Williams ◽

...

Keyword(s):

Genetic Diversity ◽

Genetic Differentiation ◽

Mating System ◽

Mating Systems ◽

Pollen Dispersal ◽

Floral Display ◽

Molecular Tools ◽

Plant Populations ◽

Southern Plains ◽

Population Fitness

Abstract Evaluation of patterns of pollen dispersal, mating systems, population fitness, genetic diversity and differentiation in restoration and remnant plant populations can be useful in determining how well restoration activities have achieved their objectives. We used molecular tools to assess how well restoration objectives have been met for populations of Banksia media in the biodiversity hotspot of south-west Western Australia. We characterized patterns of pollen dispersal within, and pollen immigration into, two restoration populations. We compared mating system parameters, population fitness via seed weight, genetic diversity and genetic differentiation for restoration and associated reference remnant populations. Different patterns of pollen dispersal were revealed for two restoration sites that differed in floral display, spatial aggregation of founders and co-planted species. Proximity to remnant native vegetation was associated with enhanced immigration and more short-range pollen dispersal when other population variables were constant. Greater seed weights at remnant compared to restoration populations were not related to outcrossing rate. Equivalent mating system and genetic diversity parameters and low to moderate levels of genetic differentiation between restoration and remnant populations suggest pollinator services have been restored in genetically diverse restoration populations of local provenance B. media as early as four years from planting.

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Assessing the genetic structure of Oryza glumaepatula populations with isozyme markers

Brazilian Archives of Biology and Technology ◽

10.1590/s1516-89132008000500001 ◽

2008 ◽

Vol 51 (5) ◽

pp. 873-882 ◽

Cited By ~ 4

Author(s):

Elizabeth Ann Veasey ◽

Daruska Cardin ◽

Rainério Meireles Silva ◽

Eduardo de Andrade Bressan ◽

Roland Vencovsky

Keyword(s):

Genetic Diversity ◽

Genetic Structure ◽

Genetic Differentiation ◽

Mating System ◽

Outcrossing Rate ◽

Structure Parameters ◽

Mato Grosso ◽

Isozyme Markers ◽

Self Fertilization ◽

Oryza Glumaepatula

To assess the genetic diversity and genetic structure parameters, nine populations of Oryza glumaepatula from the Amazon biome, four from the Pantanal biome, and one collected at Rio Xingu, Mato Grosso, totaling 14 populations and 333 individuals were studied with isozyme markers. Six loci were evaluated showing a moderate allozyme variability (A = 1.21, P = 20.7%, Ho = 0.005, He = 0.060). The populations from the Pantanal biome showed higher diversity levels than the Amazon biome. High genetic differentiation among the populations, expected for self-fertilizing species, was observed (F ST=0.763), with lower differentiation found among the Pantanal populations (F ST=0.501). The average apparent outcrossing rate was higher for the Pantanal populations (t a = 0.092) than for the Amazonian populations (t a = 0.003), while the average for the 14 populations was 0.047, in accordance with a self-fertilization mating system.

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Canine echinococcosis: genetic diversity of Echinococcus granulosus sensu stricto (s.s.) from definitive hosts

Journal of Helminthology ◽

10.1017/s0022149x15000395 ◽

2015 ◽

Vol 89 (6) ◽

pp. 689-698 ◽

Cited By ~ 18

Author(s):

B. Boufana ◽

W. Lett ◽

S. Lahmar ◽

A. Griffiths ◽

D.J. Jenkins ◽

...

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Genetic Variation ◽

Echinococcus Granulosus ◽

Population Expansion ◽

Sensu Stricto ◽

Geographical Regions ◽

Self Fertilization ◽

Adult Tapeworm ◽

Asymptomatic Disease

AbstractCanids, particularly dogs, constitute the major source of cystic echinococcosis (CE) infection to humans, with the majority of cases being caused by Echinococcus granulosus (G1 genotype). Canine echinococcosis is an asymptomatic disease caused by adult tapeworms of E. granulosus sensu lato (s.l.). Information on the population structure and genetic variation of adult E. granulosus is limited. Using sequenced data of the mitochondrial cytochrome c oxidase subunit 1 (cox1) we examined the genetic diversity and population structure of adult tapeworms of E. granulosus (G1 genotype) from canid definitive hosts originating from various geographical regions and compared it to that reported for the larval metacestode stage from sheep and human hosts. Echinococcus granulosus (s.s) was identified from adult tapeworm isolates from Kenya, Libya, Tunisia, Australia, China, Kazakhstan, United Kingdom and Peru, including the first known molecular confirmation from Gaza and the Falkland Islands. Haplotype analysis showed a star-shaped network with a centrally positioned common haplotype previously described for the metacestode stage from sheep and humans, and the neutrality indices indicated population expansion. Low Fst values suggested that populations of adult E. granulosus were not genetically differentiated. Haplotype and nucleotide diversities for E. granulosus isolates from sheep and human origin were twice as high as those reported from canid hosts. This may be related to self-fertilization of E. granulosus and/or to the longevity of the parasite in the respective intermediate and definitive hosts. Improved nuclear single loci are required to investigate the discrepancies in genetic variation seen in this study.

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Estimating Long-Term Mating Systems Using DNA Sequences

Genetics ◽

10.1093/genetics/142.2.619 ◽

1996 ◽

Vol 142 (2) ◽

pp. 619-627 ◽

Cited By ~ 3

Author(s):

Brook G Milligan

Keyword(s):

Mating System ◽

Population Size ◽

Inbreeding Depression ◽

Dna Sequences ◽

Mating Systems ◽

Natural Populations ◽

Self Fertilization ◽

Plant Mating Systems ◽

The Relationship

Abstract Plant mating systems often involve a mixture of self fertilizations and outcross fertilizations. The degree of selfing has a large impact on the genetic composition of natural populations and on the evolution of the mating system itself in response to such factors as inbreeding depression. This paper describes a means of estimating the long-term rate of self-fertilization from samples of alleles taken from individuals in a population. Use is made of the genealogy of pairs of alleles at a locus within individuals and pairs between individuals. The degree of selfing is closely related to the extent to which the number of nucleotide sites differing within an individual is reduced relative to the number differing between individuals. Importantly, the estimate of long-term selfing is largely independent of population size and is not affected by historical fluctuations in population size; instead it responds directly to the mating system itself. The approach outlined here is most appropriate to evolutionary problems in which the long-term nature of the mating system is of interest, such as to determine the relationship between prior inbreeding and inbreeding depression.

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