Population structure in two geographically sympatric and congeneric ectoparasites (Cimex adjunctus and Cimex lectularius) in the North American Great Lakes region

Subdivided populations can be described by different models of population structure that reflect population organization, dynamics, and connectivity. We used genetic data to investigate population structure in two geographically sympatric, congeneric species of generalist ectoparasites of warm-blooded animals. We characterized the spatial genetic structure of the eastern bat bug (Cimex adjunctus Barber, 1939), an understudied and fairly abundant species, using microsatellite markers at a spatial scale representing contemporary dispersal of the species. We found seven genetic clusters, global [Formula: see text] of 0.2, 33% of genetic variation among sites, and nonsignificant isolation-by-distance. We compared these results with the common bed bug (Cimex lectularius L., 1758), a closely related but conversely well-known species, in the same geographic area. We found stronger genetic structuring in C. lectularius than in C. adjunctus, with 11 genetic clusters, [Formula: see text] of 0.7, 57% of genetic variation among sites, and significant but weak isolation-by-distance (R2 = 0.09). These results suggest that while both species can be described as having classic metapopulation structure, C. adjunctus leans more towards a patchy population and C. lectularius leans more towards a nonequilibrium metapopulation. The difference in population structure between these species may be attributable to differences in movement potential and extinction–colonization dynamics.

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Genetic structuring in Atlantic haddock contrasts with current management regimes

ICES Journal of Marine Science ◽

10.1093/icesjms/fsaa204 ◽

2020 ◽

Author(s):

Paul R Berg ◽

Per E Jorde ◽

Kevin A Glover ◽

Geir Dahle ◽

John B Taggart ◽

...

Keyword(s):

Population Structure ◽

North Atlantic ◽

Isolation By Distance ◽

Melanogrammus Aeglefinus ◽

Genetic Structuring ◽

Current Management ◽

Northeast Atlantic ◽

The North ◽

Management Regime ◽

The North Atlantic

Abstract The advent of novel genetic methods has made it possible to investigate population structure and connectivity in mobile marine fish species: knowledge of which is essential to ensure a sustainable fishery. Haddock (Melanogrammus aeglefinus) is a highly exploited marine teleost distributed along the coast and continental shelf on both sides of the North Atlantic Ocean. However, little is known about its population structure. Here, we present the first study using single-nucleotide polymorphism (SNP) markers to assess the genetic population structure of haddock at multiple geographic scales, from the trans-Atlantic to the local (fjord) level. Genotyping 138 SNP loci in 1329 individuals from 19 locations across the North Atlantic revealed three main genetic clusters, consisting of a Northwest Atlantic cluster, a Northeast Arctic cluster, and a Northeast Atlantic cluster. We also observed a genetically distinct fjord population and a pattern of isolation by distance in the Northeast Atlantic. Our results contrast with the current management regime for this species in the Northeast Atlantic, as we found structure within some management areas. The study adds to the growing recognition of population structuring in marine organisms in general, and fishes in particular, and is of clear relevance for the management of haddock in the Northeast Atlantic.

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Genetic population structure of the monogenean parasite Gyrodactylus thymalli and its host European grayling (Thymallus thymallus) in a large Norwegian lake

Hydrobiologia ◽

10.1007/s10750-020-04431-7 ◽

2020 ◽

Author(s):

Ruben Alexander Pettersen ◽

Claudia Junge ◽

Kjartan Østbye ◽

Tor Atle Mo ◽

Leif Asbjørn Vøllestad

Keyword(s):

Genetic Structure ◽

Evolutionary Biology ◽

Isolation By Distance ◽

Genetic Structuring ◽

Thymallus Thymallus ◽

Homing Behavior ◽

Genetic Population ◽

Monogenean Parasite ◽

European Grayling ◽

Genetic Clusters

Abstract Understanding how populations are structured in space and time is a central question in evolutionary biology. Parasites and their hosts are assumed to evolve together, however, detailed understanding of mechanisms leading to genetic structuring of parasites and their hosts are lacking. As a parasite depends on its host, studying the genetic structure of both parasite and host can reveal important insights into these mechanisms. Here, genetic structure of the monogenean parasite Gyrodactylus thymalli and its host the European grayling (Thymallus thymallus) was investigated in 10 tributaries draining into the large Lake Mjøsa in Norway. The population genetic structure of spawning grayling was studied using microsatellite genotyping, while G. thymalli was studied by sequencing a mitochondrial DNA gene (dehydrogenase subunit 5). Two main genetic clusters were revealed in grayling, one cluster comprising grayling from the largest spawning population, while the remaining tributaries formed the second cluster. For both taxa, some genetic differentiation was observed among tributaries, but there was no clear isolation-by-distance signature. The structuring was stronger for the host than for the parasite. These results imply that moderate to high levels of gene flow occur among the sub-populations of both taxa. The high parasite exchange among tributaries could result from a lack of strong homing behavior in grayling as well as interactions among individual fish outside of the spawning season, leading to frequent mixing of both host and parasite.

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Spatial genetic structure of the sea sandwort (<i>Honckenya peploides</i>) on Surtsey: an immigrant's journey

Biogeosciences ◽

10.5194/bg-11-6495-2014 ◽

2014 ◽

Vol 11 (22) ◽

pp. 6495-6507 ◽

Cited By ~ 3

Author(s):

S. H. Árnason ◽

Ǽ. Th. Thórsson ◽

B. Magnússon ◽

M. Philipp ◽

H. Adsersen ◽

...

Keyword(s):

Genetic Variation ◽

Genetic Structure ◽

Early Stage ◽

Isolation By Distance ◽

Spatial Genetic Structure ◽

Rapid Expansion ◽

Aflp Markers ◽

Plant Colonization ◽

Southern Coast ◽

Binary Matrix

Abstract. Sea sandwort (Honckenya peploides) was one of the first plants to successfully colonize and reproduce on the volcanic island Surtsey, formed in 1963 off the southern coast of Iceland. Using amplified fragment length polymorphic (AFLP) markers, we examined levels of genetic variation and differentiation among populations of H. peploides on Surtsey in relation to populations on the nearby island Heimaey and from the southern coast of Iceland. Selected populations from Denmark and Greenland were used for comparison. In addition, we tested whether the effects of isolation by distance could be seen in the Surtsey populations. Using two primer combinations, we obtained 173 AFLP markers from a total of 347 plant samples. The resulting binary matrix was then analysed statistically. The main results include the following: (i) Surtsey had the highest proportion of polymorphic markers as well as a comparatively high genetic diversity (55.5% proportion of polymorphic loci, PLP; 0.1974 HE) and Denmark the lowest (31.8% PLP; 0.132 HE), indicating rapid expansion during an early stage of population establishment on Surtsey and/or multiple origins of immigrants; (ii) the total genetic differentiation (FST) among Surtsey (0.0714) and Heimaey (0.055) populations was less than half of that found among the mainland populations in Iceland (0.1747), indicating substantial gene flow on the islands; (iii) most of the genetic variation (79%, p < 0.001) was found within localities, possibly due to the outcrossing and subdioecious nature of the species; (iv) a significant genetic distance was found within Surtsey, among sites, and this appeared to correlate with the age of plant colonization; and (v) the genetic structure analysis indicated multiple colonization episodes on Surtsey, whereby H. peploides most likely immigrated from the nearby island of Heimaey and directly from the southern coast of Iceland.

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

Phytopathology ◽

10.1094/phyto-05-18-0157-r ◽

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.

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Population genetic structure of European wildcats inhabiting the area between the Dinaric Alps and the Scardo-Pindic mountains

10.21203/rs.3.rs-443648/v1 ◽

2021 ◽

Author(s):

Felicita Urzi ◽

Nikica Šprem ◽

Hubert Potočnik ◽

Magda Sindičić ◽

Dean Konjević ◽

...

Keyword(s):

Genetic Variation ◽

Population Genetic ◽

Allelic Richness ◽

Isolation By Distance ◽

Domestic Cats ◽

Genetic Purity ◽

Eastern Group ◽

Two Samples ◽

European Wildcat ◽

Genetic Clusters

Abstract Habitat fragmentation and loss have contributed significantly to the demographic decline of European wildcat populations and hybridization with domestic cats poses a threat to the loss of genetic purity of the species. In this study we used microsatellite markers to analyse genetic variation and structure of the wildcat populations from the area between the Dinaric Alps and the Scardo-Pindic mountains in Slovenia, Croatia, Serbia and North Macedonia. We also investigated hybridisation between populations of wildcats and domestic cats in the area. One hundred and thirteen samples from free-leaving European wildcats and thirty-two samples from domestic cats were analysed. Allelic richness across populations ranged from 3.61 to 3.98. The observed Ho values ranged between 0.57 and 0.71. The global FST value for the four populations was 0.080 (95% CI 0.056–0.109) and differed significantly from zero (P < 0.001). The highest FST value was observed between the populations North Macedonia and Slovenia and the lowest between Slovenia and Croatia. We also found a signal for the existence of isolation by distance between populations. Our results showed that wildcats are divided in two genetic clusters largely consistent with a geographic division into a genetically diverse northern group (Slovenia, Croatia) and genetically eroded south-eastern group (Serbia, N. Macedonia). Hybridisation rate between wildcats and domestic cats varied between 13% and 52% across the regions.

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Genetic structuring of the stream lily Helmholtzia glaberrima (Philydraceae) within Toolona Creek, south-eastern Queensland

Australian Journal of Botany ◽

10.1071/bt03064 ◽

2004 ◽

Vol 52 (2) ◽

pp. 201 ◽

Cited By ~ 17

Author(s):

Peter J. Prentis ◽

A. Vesey ◽

N. M. Meyers ◽

P. B. Mather

Keyword(s):

Population Structure ◽

Genetic Variation ◽

Linkage Disequilibrium ◽

Fragment Length Polymorphism ◽

Metapopulation Model ◽

Genetic Structuring ◽

Mantel Tests ◽

Riparian Species ◽

Site Diversity ◽

Non Equilibrium

The distribution of genetic variation among five isolated sites of the riparian species Helmholtzia glaberrima (J.D.Hook) was examined in Toloona Creek (28�13′S, 153�07′E) by using dominant amplified fragment length polymorphism (AFLP) markers. From the 137 fragments assessed, analysis of molecular variance (AMOVA) showed that most genetic variability occurred within sites (68%), although high (32%) variation also occurred among sites. Highly significant pairwise θ estimates among all sampled sites suggest that gene flow is restricted in H. glaberrima. Levels of within-site diversity were intermediate and significantly different across the sampled sites. Significant levels of linkage disequilibrium were detected at all sites except TC3. Differences in linkage disequilibrium and genetic diversity among the sites suggest that sites may have been founded by different numbers of colonists. Mantel tests found no correlation between geographic and genetic distance and significant levels of linkage disequilibrium were detected at the total site level, supporting a non-equilibrium model of population structure. The observed pattern of non-equilibrium population structure and genetic variation in H. glaberrima are best explained by a classical metapopulation model.

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The potential impact of mining on population genetic variation in the Banded Ironstone Formation endemic Tetratheca erubescens (Elaeocarpaceae)

Australian Journal of Botany ◽

10.1071/bt18054 ◽

2019 ◽

Vol 67 (3) ◽

pp. 172 ◽

Cited By ~ 2

Author(s):

Siegfried L. Krauss ◽

Janet M. Anthony

Keyword(s):

Genetic Variation ◽

Population Genetic ◽

Allelic Variation ◽

Continuous Distribution ◽

Genetic Structuring ◽

Expected Heterozygosity ◽

Spatial Structuring ◽

Genetic Clusters ◽

Population Genetic Variation ◽

Entire Distribution

Tetratheca erubescens is a narrowly endemic species including ~6300 plants restricted to a 2-km2 distribution on the south Koolyanobbing Range Banded Ironstone Formation (BIF) in Western Australia. A key objective of the present study was to characterise population genetic variation, and its spatial structuring across the entire distribution of T. erubescens, to enable a quantification of genetic variation that may be affected by proposed mining of the BIF. In total, 436 plants (~30 at each of 14 sites) from across the entire distribution were sampled, genotyped and scored for allelic variation at 11 polymorphic microsatellite loci. Fifty-nine alleles were detected (mean alleles per locus=5.36, range 2–10), and observed heterozygosity was low to moderate and typically lower than expected heterozygosity across all loci (mean observed heterozygosity (Ho)=0.41, mean expected heterozygosity (He)=0.48). Given the restricted distribution of T. erubescens, overall genetic structuring was surprisingly strong (overall FST=0.098). A range-wide spatial autocorrelation analysis indicated a significant positive genetic correlation at distances up to 450m, largely corresponding to the scale of more-or-less continuous distribution within each of two geographic clusters. In support, a STRUCTURE analysis identified an optimal number of genetic clusters as K=2, with assignment of individuals to one of two genetic clusters corresponding with the main geographic clusters. The genetic impact of proposed mining on T. erubescens was assessed on the basis of identifying plants within the proposed mine footprint (all plants from 4 of 14 sites). Repeating analyses of genetic variation after removal of these samples, and comparing to the complete dataset adjusted for sample size, resulted in the loss of one (very rare: overall frequency=0.001) allele (i.e. 58 of 59 alleles (98.3%) were recovered). All other parameters of genetic variation (mean Na, Ne, I, Ho, He, F) were unaffected. Consequently, although up to 22% of all plants fall within the mine footprint and, therefore, may be lost, <2% of alleles detected will be lost, and other genetic parameters remained unaffected. Although these results suggest that the proposed mining will result in a negligible impact on the assessed genetic variation and its spatial structuring in T. erubescens, further research on impacts to, and management of, quantitative genetic variation and key population genetic processes is required.

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Isonymy and population structure of Irish isolates during the 1890s

Journal of Biosocial Science ◽

10.1017/s002193200001405x ◽

1982 ◽

Vol 14 (2) ◽

pp. 241-247 ◽

Cited By ~ 14

Author(s):

John H. Relethford

Keyword(s):

Population Structure ◽

Genetic Variation ◽

Isolation By Distance ◽

Breeding Population ◽

Isolated Populations ◽

Estimated Parameters ◽

Distance Model ◽

Local Breeding ◽

And Migration ◽

Close Fit

SummaryThe estimation of genetic similarity from correspondence of surnames (isonymy) allows investigation of historical population structure. This study uses surname data from seven isolates located along the west coast of Ireland during the 1890s to assess geographic and historic influences on population structure. Observed genetic variation among populations shows a close fit with the expected isolation by distance model, with estimated parameters of isolation and migration being similar to those obtained in other studies of isolated populations. Local genetic variation appears to be due primarily to the size of the local breeding population, with deviations being explained in terms of recent emigration.

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Population genetic structure of the Gulf of St. Lawrence aster, Symphyotrichum laurentianum (Asteraceae), a threatened coastal endemic

Botany ◽

10.1139/b09-068 ◽

2009 ◽

Vol 87 (11) ◽

pp. 1089-1095 ◽

Cited By ~ 5

Author(s):

Stephen B. Heard ◽

Linley K. Jesson ◽

Kirby Tulk

Keyword(s):

Genetic Variation ◽

Genetic Structure ◽

Threatened Species ◽

Population Genetic Structure ◽

Population Genetic ◽

Isolation By Distance ◽

Spatial Genetic Structure ◽

Population Decline ◽

Allelic Diversity ◽

Magdalen Islands

The Gulf of St. Lawrence aster ( Symphyotrichum laurentianum (Fernald) G.L. Nesom) is an endemic annual of saline habitats in the southern Gulf of St. Lawrence. It is listed as a threatened species, and has recently experienced population declines in much of its range. We used 11 allozyme markers to assay population genetic variation in six wild populations of S. laurentianum from the Magdalen Islands, Quebec (QC), the only remaining wild population from Prince Edward Island National Park (PEI), and a greenhouse population founded in 1999 with seed collected from PEI. Symphyotrichum laurentianum harbours moderate genetic diversity (Ps = 0.36, As = 1.54), with only modest spatial genetic structure (pairwise FST < 0.15) and no significant isolation by distance. The PEI population had greatly reduced allelic diversity compared with the populations from the Magdalen Islands, which likely act as a reservoir of genetic variation in S. laurentianum. Recent loss of alleles during population decline in PEI is suggested by the retention of greater allelic diversity in the greenhouse population. Estimates of breeding structure suggest small but nonzero rates of outcross pollination (FIS = 0.73, 95% CI = 0.48–0.97; outcrossing rate ∼16%). Population genetic structure in S. laurentianum can inform those forming and carrying out conservation and recovery plans for this threatened species.

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Stable genetic structure and connectivity in pollution-adapted and nearby pollution-sensitive populations of Fundulus heteroclitus

Royal Society Open Science ◽

10.1098/rsos.171532 ◽

2018 ◽

Vol 5 (5) ◽

pp. 171532 ◽

Cited By ~ 1

Author(s):

Joaquin C. B. Nunez ◽

Leann M. Biancani ◽

Patrick A. Flight ◽

Diane E. Nacci ◽

David M. Rand ◽

...

Keyword(s):

Population Structure ◽

Genetic Variation ◽

Fundulus Heteroclitus ◽

Isolation By Distance ◽

Spatial Scales ◽

Purifying Selection ◽

Spatial Distance ◽

Estuarine Fish ◽

Synonymous Mutations ◽

Microsatellite Analyses

Populations of the non-migratory estuarine fish Fundulus heteroclitus inhabiting the heavily polluted New Bedford Harbour (NBH) estuary have shown inherited tolerance to local pollutants introduced to their habitats in the past 100 years. Here we examine two questions: (i) Is there pollution-driven selection on the mitochondrial genome across a fine geographical scale? and (ii) What is the pattern of migration among sites spanning a strong pollution gradient? Whole mitochondrial genomes were analysed for 133 F. heteroclitus from seven nearby collection sites: four sites along the NBH pollution cline (approx. 5 km distance), which had pollution-adapted fish, as well as one site adjacent to the pollution cline and two relatively unpolluted sites about 30 km away, which had pollution-sensitive fish. Additionally, we used microsatellite analyses to quantify genetic variation over three F. heteroclitus generations in both pollution-adapted and sensitive individuals collected from two sites at two different time points (1999/2000 and 2007/2008). Our results show no evidence for a selective sweep of mtDNA in the polluted sites. Moreover, mtDNA analyses revealed that both pollution-adapted and sensitive populations harbour similar levels of genetic diversity. We observed a high level of non-synonymous mutations in the most polluted site. This is probably associated with a reduction in N e and concomitant weakening of purifying selection, a demographic expansion following a pollution-related bottleneck or increased mutation rates. Our demographic analyses suggest that isolation by distance influences the distribution of mtDNA genetic variation between the pollution cline and the clean populations at broad spatial scales. At finer scales, population structure is patchy, and neither spatial distance, pollution concentration or pollution tolerance is a good predictor of mtDNA variation. Lastly, microsatellite analyses revealed stable population structure over the last decade.

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