Nematode population genetics

1998 ◽  
Vol 72 (4) ◽  
pp. 281-283 ◽  
Author(s):  
M.E. Viney
Keyword(s):  
Population Genetics ◽  
Genetic Structure ◽  
Population Genetic ◽  
Genetic Relationships ◽  
Parasitic Nematodes ◽  
Important Group ◽  
Nematode Parasites ◽  
Genetic Patterns ◽  
Patterns And Processes ◽  
Epidemiological Information

Population genetics seeks to understand the genetic relationships within and between populations of a species and the processes that generate these patterns. Little is known about the population genetics of parasitic nematodes. This is a notable gap in our knowledge since understanding the population genetic patterns and processes of parasitic nematodes has profound implications for our ability to fully understand this important group of pathogens. For example, it is only possible to begin to understand how a parasite population will respond to an imposed selection pressure (such as an anthelmintic drug, a vaccine, or resistant hosts) when the population genetic structure and patterns of gene flow of that population is known. Equally, the epidemiology of many nematode parasites is well known empirically and theoretically, yet this epidemiological information is of limited use without a good understanding of the genetic structure of those populations (Anderson & May, 1992).

Significant genetic differences among Heterodera schachtii populations within and among sugar beet production areas

Nematology ◽  
2020 ◽  
Vol 22 (2) ◽  
pp. 165-177 ◽  
Author(s):  
Rasha Haj Nuaima ◽  
Johannes Roeb ◽  
Johannes Hallmann ◽  
Matthias Daub ◽  
Holger Heuer
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Spatial Scales ◽  
Geographic Distance ◽  
Heterodera Schachtii ◽  
Parasitic Nematodes ◽  
Neutral Genetic Variation ◽  
Production Areas

Summary Characterising the non-neutral genetic variation within and among populations of plant-parasitic nematodes is essential to determine factors shaping the population genetic structure. This study describes the genetic variation of the parasitism gene vap1 within and among geographic populations of the beet cyst nematode Heterodera schachtii. Forty populations of H. schachtii were sampled at four spatial scales: 695 km, 49 km, 3.1 km and 0.24 km. DGGE fingerprinting showed significant differences in vap1 patterns among populations. High similarity of vap1 patterns appeared between geographically close populations, and occasionally among distant populations. Analysis of spatially sampled populations within fields revealed an effect of tillage direction on the vap1 similarity for two of four studied fields. Overall, geographic distance and similarity of vap1 patterns of H. schachtii populations were negatively correlated. In conclusion, the population genetic structure was shaped by the interplay between the genetic adaptation and the passive transport of this nematode.

scholarly journals The influence of gene flow and drift on genetic and phenotypic divergence in two species of Zosterops in Vanuatu

2010 ◽  
Vol 365 (1543) ◽  
pp. 1077-1092 ◽  
Author(s):  
Sonya M. Clegg ◽  
Albert B. Phillimore
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Bird Species ◽  
Dispersal Ability ◽  
Phenotypic Divergence ◽  
Genetic Patterns ◽  
Changing Patterns ◽  
Regional Population

Colonization of an archipelago sets the stage for adaptive radiation. However, some archipelagos are home to spectacular radiations, while others have much lower levels of diversification. The amount of gene flow among allopatric populations is one factor proposed to contribute to this variation. In island colonizing birds, selection for reduced dispersal ability is predicted to produce changing patterns of regional population genetic structure as gene flow-dominated systems give way to drift-mediated divergence. If this transition is important in facilitating phenotypic divergence, levels of genetic and phenotypic divergence should be associated. We consider population genetic structure and phenotypic divergence among two co-distributed, congeneric (Genus: Zosterops ) bird species inhabiting the Vanuatu archipelago. The more recent colonist, Z. lateralis , exhibits genetic patterns consistent with a strong influence of distance-mediated gene flow. However, complex patterns of asymmetrical gene flow indicate variation in dispersal ability or inclination among populations. The endemic species, Z. flavifrons , shows only a partial transition towards a drift-mediated system, despite a long evolutionary history on the archipelago. We find no strong evidence that gene flow constrains phenotypic divergence in either species, suggesting that levels of inter-island gene flow do not explain the absence of a radiation across this archipelago.

scholarly journals Genetic structure of Trypanosoma cruzi in American continents: special emphasis on sexual reproduction in Central America

Parasitology ◽  
2000 ◽  
Vol 121 (4) ◽  
pp. 403-408 ◽  
Author(s):  
H. HIGO ◽  
T. YANAGI ◽  
V. MATTA ◽  
T. AGATSUMA ◽  
A. CRUZ-REYES ◽  
...  
Keyword(s):  
Population Genetics ◽  
Genetic Structure ◽  
Trypanosoma Cruzi ◽  
Central America ◽  
Population Genetic ◽  
Geographical Area ◽  
Genetic Exchange ◽  
South American ◽  
Gene Exchange ◽  
Clinical Syndromes

Isozyme analysis (12 enzymes: 14 loci) was conducted on 99 isolates of Trypanosoma cruzi: 77 from Guatemala, 5 from Mexico and 17 from South American countries. Analyses of 4 population-genetic indices were undertaken to assess the possibility of genetic exchange occurring among Guatemalan isolates. The results provide evidence for a degree of genetic exchange occurring among isolates from this relatively small geographical area. Previous studies of population genetics on T. cruzi might have failed to detect this phenomenon because they tended to use isolates originating far from one another, rendering gene exchange unlikely for geographical reasons. Phylogenetic data, presented here, show considerable differences in genetic structure between Central and South American isolates, suggesting that different biological and clinical properties might be expected. For example, there are differences in clinical syndromes between Central and South America, a situation discussed further here.

scholarly journals High genetic diversity and strong genetic structure of Strongyllodes variegatus (Coleoptera: Nitidulidae) demonstrate the genetic mechanism of its distribution in oilseed rape production areas in China

2020 ◽  
Author(s):  
HaiXia Zhan ◽  
ZhongPing Hao ◽  
JingJiang Zhou ◽  
Rui Tang ◽  
LiNi Zhu ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Genetics ◽  
Gene Flow ◽  
Genetic Structure ◽  
Oilseed Rape ◽  
Population Genetic ◽  
Distribution Analysis ◽  
Geographical Regions ◽  
Genetic Diversity And Structure ◽  
Production Areas

Abstract Background : Strongyllodes variegatus (Fairmaire) is a major insect pest of oilseed rape in China. Despite its economic importance, the population genetics of this pest contributing to the development of suitable management and control strategies is poorly known. To understand the population genetics and assess the geographical patterns and genetic structure of S. variegates in China. Using mitochondrial DNA cytochrome c oxidase subunit I and cytochrome b region sequences as genetic markers, we analyzed population genetic diversity and structure from 437 individuals collected in 15 S. variegates populations located in different oilseed rape production areas in China. In addition, we estimated the demographic history using neutrality test and mismatch distribution analysis. Results : The high level of genetic diversity was detected among the mtDNA region sequences of S. variegates . The population structure analysis strongly suggested that three genetic and geographical regions occur with limited gene flow. The Mantel test showed that the genetic distance was greatly influenced by geographical distance. The demographic analyses showed that S. variegates experienced population fluctuation during the Pleistocene, which was likely to be related to the climatic changes. Conclusion : Overall, these results demonstrated that the strong population genetic structure of this beetle may attribute to the geographical barriers and subsequently adapt to the regional ecological conditions for the distribution of S. variegates in China. Keywords : Gene flow, Genetic differentiation, Haplotype, Oilseed rape, Population genetic pattern, Strongyllodes variegates

scholarly journals Interplay between historical and current features of the cityscape in shaping the genetic structure of the house mouse (Mus musculus domesticus) in Dakar (Senegal, West Africa)

2019 ◽  
Author(s):  
Claire Stragier ◽  
Sylvain Piry ◽  
Anne Loiseau ◽  
Mamadou Kane ◽  
Aliou Sow ◽  
...  
Keyword(s):  
Genetic Structure ◽  
House Mouse ◽  
Population Genetic Structure ◽  
Mus Musculus ◽  
Population Genetic ◽  
Management Strategies ◽  
Mus Musculus Domesticus ◽  
Model Free ◽  
Genetic Patterns ◽  
Commensal Rodents

AbstractPopulation genetic approaches may be used to investigate dispersal patterns of species living in highly urbanized environment in order to improve management strategies for biodiversity conservation or pest control. However, in such environment, population genetic structure may reflect both current features of the cityscape and urbanization history. This can be especially relevant when focusing on exotic commensal rodents that have been introduced in numerous primary colonial European settlements. Accounting for spatial and temporal cityscape heterogeneity to determine how past and recent demographic events may interplay to shape current population genetic structure of synanthropic rodents may provide useful insights to manage their populations. In this study, we addressed these issues by focusing on the house mouse, Mus musculus domesticus, in Dakar, Senegal, where the species may have been introduced as soon as Europeans settled in the middle of the nineteenth century. We examined genetic variation at one mitochondrial locus and 15 nuclear microsatellite markers from individuals sampled in 14 sampling sites representing different stages of urbanization history and different socio-economic environments in Dakar. We used various approaches, including model-based genetic clustering and model-free smoothing of pairwise genetic estimates. We further linked observed spatial genetic patterns to historical and current features of Dakar cityscape using random forest and Bayesian conditional autoregressive models. Results are consistent with an introduction of the house mouse at colonial time and the current genetic structure exhibits a gradient-like pattern reflecting the historical process of spatially continuous expansion of the city from the first European settlement. The genetic patterns further suggest that population dynamics of the house mouse is also driven by the spatial heterogeneity of the current cityscape, including socio-economics features, that translate in habitat quality. Our results highlight the potential importance of accounting for past demographic events to understand spatial genetic patterns of nonnative invasive commensal rodents in highly urbanized environment.

Selection and evolution of virulence in bacteria: an ecumenical excursion and modest suggestion

Parasitology ◽  
1990 ◽  
Vol 100 (S1) ◽  
pp. S103-S115 ◽  
Author(s):  
B.R. Levin ◽  
C. Svanborg Edén
Keyword(s):  
Population Genetics ◽  
Genetic Structure ◽  
General Theory ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Evolutionary Ecology ◽  
Bacterial Virulence ◽  
Medical Microbiology ◽  
Evolution Of Virulence ◽  
Made In

SummaryWhy do parasites kill their hosts? During this past decade, research in three different areas; evolutionary ecology, medical microbiology, and population genetics has provided theory and data that address this and related questions of selection and the evolution and maintenance of parasite virulence. A general theory of parasite–host coevolution and the conditions for selection to favour parasite virulence has been put forth. Considerable advances have been made in elucidating the mechanisms of pathogenicity and inheritance of virulence in bacteria. The population genetic structure and the relation ship between pathogenic and non-pathogenic forms has been determined for a number of species of bacteria. We critically review these developments and their implications for questions of selection and the evolution and maintenance of virulence in bacteria. We postulate how selection may operate on specific types of bacterial virulence and present a general protocol to experimentally test hypotheses concerning selection and the evolution of virulence in bacteria.

scholarly journals Application of genome-wide insertion/deletion markers on genetic structure analysis and identity signature of Malus accessions

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Xuan Wang ◽  
Fei Shen ◽  
Yuan Gao ◽  
Kun Wang ◽  
Ruiting Chen ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Structure Analysis ◽  
Genetic Relationships ◽  
Indel Markers ◽  
Genome Wide ◽  
Genetic Patterns ◽  
Golden Delicious ◽  
Unique Identity ◽  
High Level ◽  
Cultivation History

Abstract Background Apple (Malus ssp.), one of the most important temperate fruit crops, has a long cultivation history and is economically important. To identify the genetic relationships among the apple germplasm accessions, whole-genome structural variants identified between M. domestica cultivars ‘Jonathan’ and ‘Golden Delicious’ were used. Results A total of 25,924 insertions and deletions (InDels) were obtained, from which 102 InDel markers were developed. Using the InDel markers, we found that 942 (75.3%) of the 1251 Malus accessions from 35 species exhibited a unique identity signature due to their distinct genotype combinations. The 102 InDel markers could distinguish 16.7–71.4% of the 331 bud sports derived from ‘Fuji’, ‘Red Delicious’, ‘Gala’, ‘Golden Delicious’, and other cultivars. Five distinct genetic patterns were found in 1002 diploid accessions based on 78 bi-allele InDel markers. Genetic structure analysis indicated that M. domestica showed higher genetic diversity than the other species. Malus underwent a relatively high level of wild-to-crop or crop-to-wild gene flow. M. sieversii was closely related to both M. domestica and cultivated Chinese cultivars. Conclusions The identity signatures of Malus accessions can be used to determine distinctness, uniformity, and stability. The results of this study may also provide better insight into the genetic relationships among Malus species.

Sign in / Sign up

Export Citation Format

Share Document