scholarly journals Variable opportunities for outcrossing result in hotspots of novel genetic variation in a pathogen metapopulation

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Anna-Liisa Laine ◽  
Benoit Barrès ◽  
Elina Numminen ◽  
Jukka P Siren
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Structure ◽  
Fungal Pathogen ◽  
Population Genetic ◽  
Reproductive Strategies ◽  
Natural Populations ◽  
Pathogen Population ◽  
To Come ◽  
Pathogen Populations

Many pathogens possess the capacity for sex through outcrossing, despite being able to reproduce also asexually and/or via selfing. Given that sex is assumed to come at a cost, these mixed reproductive strategies typical of pathogens have remained puzzling. While the ecological and evolutionary benefits of outcrossing are theoretically well-supported, support for such benefits in pathogen populations are still scarce. Here, we analyze the epidemiology and genetic structure of natural populations of an obligate fungal pathogen, Podosphaera plantaginis. We find that the opportunities for outcrossing vary spatially. Populations supporting high levels of coinfection –a prerequisite of sex – result in hotspots of novel genetic diversity. Pathogen populations supporting coinfection also have a higher probability of surviving winter. Jointly our results show that outcrossing has direct epidemiological consequences as well as a major impact on pathogen population genetic diversity, thereby providing evidence of ecological and evolutionary benefits of outcrossing in pathogens.

Genetic Diversity and Population Genetic Structure in the Rare Chittering Grass Wattle, Acacia anomala Court

1988 ◽  
Vol 36 (3) ◽  
pp. 273 ◽  
Author(s):  
DJ Coates
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Genetic System ◽  
Small Population ◽  
Vegetative Multiplication ◽  
The Mean ◽  
Allozyme Loci

There are 10 known populations of Acacia anomala occurring in two small disjunct groups some 30 km apart. The Chittering populations reproduce sexually whereas the Kalamunda populations appear to reproduce almost exclusively by vegetative multiplication. The level and distribution of genetic variation were studied at 15 allozyme loci. Two loci were monomorphic in all populations. In the Chittering populations the mean number of alleles per locus was 2.0 and the expected panmictic heterozygosity (genetic diversity) 0.209. In the Kalamunda populations the mean number of alleles per locus was 1.15 and the expected panmictic heterozygosity 0.079, although the observed heterozygosity of 0.150 was only marginally less than the Chittering populations (0.177). These data support the contention that the Chittering populations are primarily outcrossing whereas the Kalamunda populations are clonal, with each population consisting of individuals with identical and, in three of the four populations, heterozygous, multilocus genotypes. The level of genetic diversity within the Chittering populations is high for plants in general even though most populations are relatively smsll and isolated. It is proposed that either the length of time these populations have been reduced in size and isolated is insufficient for genetic diversity to be reduced or the genetic system of this species is adapted to small population conditions. Strategies for the adequate conservation of the genetic resources of Acacia anomala are discussed.

Genetic diversity and population genetic structure in fragmented Allocasuarina verticillata (Allocasuarinaceae) – implications for restoration

2011 ◽  
Vol 59 (8) ◽  
pp. 770 ◽  
Author(s):  
Linda M. Broadhurst
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Gene Diversity ◽  
Natural Populations ◽  
Long Distance ◽  
Study Region ◽  
Allocasuarina Verticillata ◽  
Seed Crops

Vegetation restoration in fragmented regions is constrained by limited supplies of high quality seed and an understanding of the scale over which seed can be moved without causing negative outcomes. ‘Local’ seed is often prescribed for restoration but in fragmented landscapes this restricts collecting to small, inbred populations. Six polymorphic microsatellites were used to examine genetic diversity and population genetic structure in seed collected from 18 fragmented natural populations and three restored populations of the wind-pollinated and dispersed tree Allocasuarina verticillata, a key restoration species. Smaller populations produced seed crops with significantly fewer alleles, lower allelic richness and less gene diversity. Most of the populations assessed, including the restored sites, produce genetically diverse seed crops suitable for restoration but smaller populations (<30 plants) should be augmented with seed from larger populations. Principal coordinate analysis, graph-theory and Bayesian analyses found little evidence of spatially predictable genetic structure across the study region, which probably reflects long distance gene dispersal preventing the development of strong spatial structure. The absence of strong spatial patterns suggests that seed can be moved beyond current 5–50-km limits while being mindful of strong selection gradients or conditions that might indicate locally adapted populations.

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