scholarly journals Selection, Linkage, and Population Structure Interact To Shape Genetic Variation Among Threespine Stickleback Genomes

Genetics ◽  
2019 ◽  
Vol 212 (4) ◽  
pp. 1367-1382 ◽  
Author(s):  
Thomas C. Nelson ◽  
Johnathan G. Crandall ◽  
Catherine M. Ituarte ◽  
Julian M. Catchen ◽  
William A. Cresko
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Threespine Stickleback

Selection, linkage, and population structure interact to shape genetic variation among threespine stickleback genomes

2018 ◽  
Author(s):  
Thomas C. Nelson ◽  
Johnathan G. Crandall ◽  
Catherine M. Ituarte ◽  
Julian M Catchen ◽  
William A. Cresko
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Low Frequency ◽  
Threespine Stickleback ◽  
Divergent Selection ◽  
Genetic Maps ◽  
Freshwater Habitats ◽  
Freshwater Stickleback ◽  
Combine Population ◽  
Stickleback Genome

AbstractThe outcome of selection on genetic variation depends on the geographic organization of individuals and populations as well as the syntenic organization of loci within the genome. Spatially variable selection between marine and freshwater habitats has had a significant and heterogeneous impact on patterns of genetic variation across the genome of threespine stickleback fish. When marine stickleback invade freshwater habitats, more than a quarter of the genome can respond to divergent selection, even in as little as 50 years. This process largely uses standing genetic variation that can be found ubiquitously at low frequency in marine populations, can be millions of years old, and is likely maintained by significant bidirectional gene flow. Here, we combine population genomic data of marine and freshwater stickleback from Cook Inlet, Alaska, with genetic maps of stickleback fish derived from those same populations to examine how linkage to loci under selection affects genetic variation across the stickleback genome. Divergent selection has had opposing effects on linked genetic variation on chromosomes from marine and freshwater stickleback populations: near loci under selection, marine chromosomes are depauperate of variation while these same regions among freshwater genomes are the most genetically diverse. Forward genetic simulations recapitulate this pattern when different selective environments also differ in population structure. Lastly, dense genetic maps demonstrate that the interaction between selection and population structure may impact large stretches of the stickleback genome. These findings advance our understanding of how the structuring of populations across geography influences the outcomes of selection, and how the recombination landscape broadens the genomic reach of selection.

scholarly journals Determining Whether Geographic Origin and Potato Genotypes Shape the Population Structure of Phytophthora infestans in the Central Region of Colombia

2019 ◽  
Vol 109 (1) ◽  
pp. 145-154
Author(s):  
Sandra Catalina Chaves ◽  
María Camila Rodríguez ◽  
María Fernanda Mideros ◽  
Florencia Lucca ◽  
Carlos E. Ñústez ◽  
...  
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Phytophthora Infestans ◽  
Central Region ◽  
Geographic Origin ◽  
Geographic Area ◽  
Potato Cultivars ◽  
Clonal Lineage ◽  
Host Genotype ◽  
Genetic Population

Pathogen variation plays an important role in the dynamics of infectious diseases. In this study, the genetic variation of 279 Phytophthora infestans isolates was assessed using a combination of 12 microsatellite simple-sequence repeat markers. Isolates were collected from 11 different potato cultivars in 11 different geographic localities of the central region of Colombia. The objective of this study was to determine whether populations were differentiated by host genotype or geographic origin. Within a single clonal lineage, EC-1, 76 genotypes were detected. An analysis of molecular variance attributed most of the variation to differences within host genotypes rather than among the host genotypes, suggesting that host cultivars do not structure the populations of the pathogen. Furthermore, the lack of a genetic population structure according to the host cultivar was confirmed by all of the analyses, including the Bayesian clustering analysis and the minimum spanning network that used the Bruvo genetic distance, which suggested that there are no significant barriers to gene flow for P. infestans among potato cultivars. According to the geographic origin, the populations of P. infestans were also not structured, and most of the variation among the isolates was attributed to differences within localities. Only some but not all localities in the north and west of the central region of Colombia showed some genetic differentiation from the other regions. The absence of sexual reproduction of this pathogen in Colombia was also demonstrated. Important insights are discussed regarding the genetic population dynamics of the P. infestans populations of the central region of Colombia that were provided by the results. In Colombia, there is a high genetic variation within the EC-1 clonal lineage with closely related genotypes, none dominant, that coexist in a wide geographic area and on several potato cultivars.

scholarly journals Genetic Variation and Population Structure of the White Rhinoceros

2012 ◽  
Vol 11 (2) ◽  
pp. 241-244
Author(s):  
Guanyu Hou ◽  
Hongpu Zeng ◽  
Dongjin Wang ◽  
Hanlin Zhou
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
White Rhinoceros
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