scholarly journals Genetic differentiation is determined by geographic distance in Clarkia pulchella

2018 ◽  
Author(s):  
Megan Bontrager ◽  
Amy L. Angert
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Geographic Distance ◽  
Geographic Range ◽  
Range Limits ◽  
North West ◽  
Range Edge ◽  
Genetic Differentiation Of Populations ◽  
Landscape Genetic ◽  
Clarkia Pulchella

AbstractBoth environmental differences and geographic distances may contribute to the genetic differentiation of populations on the landscape. Understanding the relative importance of these drivers is of particular interest in the context of geographic range limits, as both swamping gene flow and lack of genetic diversity are hypothesized causes of range limits. We investigated the landscape genetic structure of 32 populations of the annual wildflower Clarkia pulchella from across the species’ geographic range in the interior Pacific North-west. We tested whether climatic differences between populations influenced the magnitude of their genetic differentiation. We also investigated patterns of population structure and geographic gradients in genetic diversity. Contrary to our expectations, we found an increase in genetic diversity near the species’ northern range edge. We found no notable contribution of climatic differences to genetic differentiation, indicating that any processes that might operate to differentiate populations based on temperature or precipitation are not affecting the putatively neutral loci in these analyses. Rather, these results support seed and pollen movement at limited distances relative to the species’ range and that this movement and the subsequent incorporation of immigrants into the local gene pool are not influenced by temperature or precipitation similarities among populations. We found that populations in the northern and southern parts of the range tended to belong to distinct genetic groups and that central and eastern populations were admixed between these two groups. This pattern could be the result of a past or current geographic barrier associated with the Columbia Plateau, or it could be the result of spread from separate sets of refugia after the last glacial maximum.

scholarly journals Gene flow improves fitness at a range edge under climate change

2018 ◽  
Author(s):  
Megan Bontrager ◽  
Amy L. Angert
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Genetic Material ◽  
Geographic Range ◽  
Positive Effects ◽  
Range Edge ◽  
Common Gardens ◽  
Edge Populations ◽  
Clarkia Pulchella

AbstractPopulations at the margins of a species’ geographic range are often thought to be poorly adapted to their environment. According to theoretical predictions, gene flow can inhibit these range edge populations if it disrupts adaptation to local conditions. Alternatively, if range edge populations are small or isolated, gene flow can provide beneficial genetic variation, and may facilitate adaptation to environmental change. We tested these competing predictions in the annual wildflower Clarkia pulchella using greenhouse crosses to simulate gene flow from sources across the geographic range into two populations at the northern range margin. We planted these between-population hybrids in common gardens at the range edge, and evaluated how genetic differentiation and climatic differences between edge populations and gene flow sources affected lifetime fitness. During an anomalously warm study year, gene flow from populations occupying historically warm sites improved fitness at the range edge, and plants with one or both parents from warm populations performed best. The effects of the temperature provenance of gene flow sources were most apparent at early life history stages, but precipitation provenance also affected reproduction. We also found benefits of gene flow that were independent of climate: after climate was controlled for, plants with parents from different populations performed better at later lifestages than those with parents from the same population, indicating that gene flow may improve fitness via relieving homozygosity. Further supporting this result, we found that increasing genetic differentiation of parental populations had positive effects on fitness of hybrid seeds. Gene flow from warmer populations, when it occurs, is likely to contribute adaptive genetic variation to populations at the northern range edge as the climate warms. On heterogeneous landscapes, climate of origin may be a better predictor of gene flow effects than geographic proximity.Impact summaryWhat limits species’ geographic ranges on the landscape? One process of interest when trying to answer this question is gene flow, which is the movement of genetic material between populations, as might occur in plants when seeds or pollen move across the landscape. One hypothesis that has been proposed is that gene flow from populations in other environments prevents populations at range edges from adapting to their local habitats. Alternatively, it has been suggested that these populations might benefit from gene flow, as it would provide more genetic material for natural selection to act upon.We tested these predictions in an annual wildflower, Clarkia pulchella. We simulated gene flow by pollinating plants from the range edge with pollen from other populations. Then we planted the resulting seeds into common gardens in the home sites of the range edge populations and recorded their germination, survival, and reproduction. The weather during our experiment was much warmer than historic averages in our garden sites, and perhaps because of this, we found that gene flow from warm locations improved the performance of range edge populations. This result highlights the potential role of gene flow and dispersal in aiding adaptation to warming climates. We also found some positive effects of gene flow that were independent of climate. Even after we statistically controlled for adaptation to temperature and precipitation, plants that were the result of gene flow pollinations produced more seeds and fruits than plants with both parents from the same population. Rather than preventing adaptation, in our experiment, gene flow generally had positive effects on fitness.

scholarly journals Landscape structure and the genetic effects of a population collapse

2014 ◽  
Vol 281 (1796) ◽  
pp. 20141798 ◽  
Author(s):  
Serena A. Caplins ◽  
Kimberly J. Gilbert ◽  
Claudia Ciotir ◽  
Jens Roland ◽  
Stephen F. Matter ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Landscape Structure ◽  
Isolation By Distance ◽  
Spatial Genetic Structure ◽  
Genetic Differentiation Of Populations ◽  
Patch Connectivity ◽  
Landscape Genetic ◽  
Independent Effects ◽  
Patterns And Processes

Both landscape structure and population size fluctuations influence population genetics. While independent effects of these factors on genetic patterns and processes are well studied, a key challenge is to understand their interaction, as populations are simultaneously exposed to habitat fragmentation and climatic changes that increase variability in population size. In a population network of an alpine butterfly, abundance declined 60–100% in 2003 because of low over-winter survival. Across the network, mean microsatellite genetic diversity did not change. However, patch connectivity and local severity of the collapse interacted to determine allelic richness change within populations, indicating that patch connectivity can mediate genetic response to a demographic collapse. The collapse strongly affected spatial genetic structure, leading to a breakdown of isolation-by-distance and loss of landscape genetic pattern. Our study reveals important interactions between landscape structure and temporal demographic variability on the genetic diversity and genetic differentiation of populations. Projected future changes to both landscape and climate may lead to loss of genetic variability from the studied populations, and selection acting on adaptive variation will likely occur within the context of an increasing influence of genetic drift.

scholarly journals Fine-scale genetic structure of the overwintering Chilo suppressalis in the typical bivoltine areas of northern China

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243999
Author(s):  
Ke-Xin Zhu ◽  
Shan Jiang ◽  
Lei Han ◽  
Ming-Ming Wang ◽  
Xing-Ya Wang
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Isolation By Distance ◽  
Genetic Relationships ◽  
Management Strategies ◽  
Geographic Distance ◽  
Northern China ◽  
Economic Losses ◽  
Chilo Suppressalis

The rice stem borer (RSB), Chilo suppressalis (Lepidoptera: Pyralidae), is an important agricultural pest that has caused serious economic losses in the major rice-producing areas of China. To effectively control this pest, we investigated the genetic diversity, genetic differentiation and genetic structure of 16 overwintering populations in the typical bivoltine areas of northern China based on 12 nuclear microsatellite loci. Moderate levels of genetic diversity and genetic differentiation among the studied populations were detected. Neighbour-joining dendrograms, Bayesian clustering and principal coordinate analysis (PCoA) consistently divided these populations into three genetic clades: western, eastern and northern/central. Isolation by distance (IBD) and spatial autocorrelation analyses demonstrated no correlation between genetic distance and geographic distance. Bottleneck analysis illustrated that RSB populations had not undergone severe bottleneck effects in these regions. Accordingly, our results provide new insights into the genetic relationships of overwintering RSB populations and thus contribute to developing effective management strategies for this pest.

scholarly journals The genetic diversity of Ethiopian barley genotypes in relation to their geographical origin

2021 ◽  
Author(s):  
Surafel Shibru Teklemariam ◽  
Kefyalew Negisho Bayissa ◽  
Andrea Matros ◽  
Klaus Pillen ◽  
Frank Ordon ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Geographic Distance ◽  
Snp Array ◽  
Farming Systems ◽  
Mantel Test ◽  
Snp Markers ◽  
Improvement Program ◽  
Climate Conditions ◽  
Breeding Lines

Ethiopia is recognized as a center of diversity for barley, and its landraces are known for the distinct genetic features compared to other barley collections. The genetic diversity of Ethiopian barley likely results from the highly diverse topography, altitude, climate conditions, soil types, and farming systems. To get detailed information on the genetic diversity a panel of 260 accessions, comprising 239 landraces and 21 barley breeding lines, obtained from the Ethiopian biodiversity institute (EBI) and the national barley improvement program, respectively were studied for their genetic diversity using the 50k iSelect single nucleotide polymorphism (SNP) array. A total of 983 highly informative SNP markers were used for structure and diversity analysis. Three genetically distinct clusters were obtained from the structure analysis comprising 80, 71, and 109 accessions, respectively. Analysis of molecular variance (AMOVA) revealed the presence of higher genetic variation (89%) within the clusters than between the clusters (11%), with moderate genetic differentiation (PhiPT=0.11) and adequate gene flow (Nm=2.02). The Mantel test revealed that the genetic distance between accessions is poorly associated with their geographical distance. Despite the observed weak correlation between geographic distance and genetic differentiation, for some regions like Gonder, Jimma, Gamo-Gofa, Shewa, and Welo, more than 50% of the landraces derived from these regions are assigned to one of the three clusters.

GENETIC DIFFERENTIATION BY STR-MARKERS AND PRODUCTIVITY TRAITS OF KARACHAEV GOATS FROM DIFFERENT BREEDING ZONES

2021 ◽  
Vol 1 (19) ◽  
pp. 349-352
Author(s):  
A.M. Aibazov ◽  
T.V. Mamontova ◽  
V.R. Kharzinova ◽  
N.A. Zinovieva
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Live Weight ◽  
Mountain Area ◽  
Str Markers ◽  
Genetic Differentiation Of Populations ◽  
High Level

Data have been obtained indicating differences by the live weight and exterior appearance of Karachaev goats bred in the mountain area, foothill, and plain-hill zone. A high level of genetic diversity and a clear genetic differentiation of populations from different breeding zones on the basis of STR-markers have been established.

scholarly journals Genetic Divergence of Two Sitobion avenae Biotypes on Barley and Wheat in China

Insects ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 117
Author(s):  
Da Wang ◽  
Xiaoqin Shi ◽  
Deguang Liu ◽  
Yujing Yang ◽  
Zheming Shang
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Host Plant ◽  
Genetic Divergence ◽  
Isolation By Distance ◽  
Critical Role ◽  
Geographic Distance ◽  
Sitobion Avenae ◽  
Insect Populations

Host plant affinity and geographic distance can play critical roles in the genetic divergence of insect herbivores and evolution of insect biotypes, but their relative importance in the divergence of insect populations is still poorly understood. We used microsatellite markers to test the effects of host plant species and geographic distance on divergence of two biotypes of the English grain aphid, Sitobion avenae (Fabricius). We found that clones of S. avenae from western provinces (i.e., Xinjiang, Gansu, Qinghai and Shaanxi) had significantly higher genetic diversity than those from eastern provinces (i.e., Anhui, Henan, Hubei, Zhejiang and Jiangsu), suggesting their differentiation between both areas. Based on genetic diversity and distance estimates, biotype 1 clones of eastern provinces showed high genetic divergence from those of western provinces in many cases. Western clones of S. avenae also showed higher genetic divergence among themselves than eastern clones. The Mantel test identified a significant isolation-by-distance (IBD) effect among different geographic populations of S. avenae, providing additional evidence for a critical role of geography in the genetic structure of both S. avenae biotypes. Genetic differentiation (i.e., FST) between the two biotypes was low in all provinces except Shaanxi. Surprisingly, in our analyses of molecular variance, non-significant genetic differentiation between both biotypes or between barley and wheat clones of S. avenae was identified, showing little contribution of host-plant associated differentiation to the divergence of both biotypes in this aphid. Thus, it is highly likely that the divergence of the two S. avenae biotypes involved more geographic isolation and selection of some form than host plant affinity. Our study can provide insights into understanding of genetic structure of insect populations and the divergence of insect biotypes.

Genetic diversity of Juglans sigillata Dode germplasm in Yunnan Province, China, as revealed by SSRs

2020 ◽  
pp. 1-10
Author(s):  
Shaoyu Chen ◽  
Tao Wu ◽  
Liangjun Xiao ◽  
Delu Ning ◽  
Li Pan
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Yunnan Province ◽  
Allelic Richness ◽  
Geographic Distance ◽  
Group Method ◽  
Pair Group ◽  
Ssr Loci ◽  
Juglans Sigillata ◽  
High Level

Abstract Iron walnut, Juglans sigillata Dode, restricted to southwestern China, has its centre of distribution in Yunnan Province which has a varied climate, geography and rich plant diversity. Yunnan contains abundant J. sigillata germplasm. In this study, a provincial-scale set of walnut germplasm resources (14 populations comprising 1122 individuals) was evaluated for genetic diversity based on 20 simple sequence repeat (SSR) loci. The number of SSR alleles per locus ranged from 7 to 27, with an average of 17.55. Mean allelic richness and mean private allelic richness ranged from 3.40 to 4.62 and 0.11 to 0.36, with average of 3.93 and 0.30, respectively. Expected heterozygosity (He) varied from 0.26 to 0.78, with an average of 0.57. Polymorphism information content ranged from 0.22 to 0.79, with an average of 0.57. Genetic differentiation (FST) was 0.05, indicating that only 5% of total genetic variability was inter-populational, a finding supported by an analysis of molecular variance and STRUCTURE analysis. Relatively high gene flow (Nm = 6.70) was observed between populations. A unweighted pair-group method with arithmetic analysis classified the 14 populations into two major groups. Mantel testing uncovered a significant correlation between geographic distance and genetic distance (r = 0.33, P = 0.04). Overall, the research revealed a moderately high level of genetic diversity in the germplasm and low genetic differentiation among populations, which showed great potential for further development and exploitation of this resource.

scholarly journals Genetic landscapes reveal how human genetic diversity aligns with geography

2017 ◽  
Author(s):  
Benjamin Marco Peter ◽  
Desislava Petkova ◽  
John Novembre
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Differentiation ◽  
Rare Variants ◽  
Disease Risk ◽  
Geographic Distance ◽  
Population History ◽  
Human Populations ◽  
Complex Processes ◽  
Scale Population

Geographic patterns in human genetic diversity carry footprints of population history1,2 and provide insights for genetic medicine and its application across human populations3,4. Summarizing and visually representing these patterns of diversity has been a persistent goal for human geneticists5–10, and has revealed that genetic differentiation is frequently correlated with geographic distance. However, most analytical methods to represent population structure11–15 do not incorporate geography directly, and it must be considered post hoc alongside a visual summary. Here, we use a recently developed spatially explicit method to estimate “effective migration” surfaces to visualize how human genetic diversity is geographically structured (the EEMS method16). The resulting surfaces are “rugged”, which indicates the relationship between genetic and geographic distance is heterogenous and distorted as a rule. Most prominently, topographic and marine features regularly align with increased genetic differentiation (e.g. the Sahara desert, Mediterranean Sea or Himalaya at large scales; the Adriatic, interisland straits in near Oceania at smaller scales). In other cases, the locations of historical migrations and boundaries of language families align with migration features. These results provide visualizations of human genetic diversity that reveal local patterns of differentiation in detail and emphasize that while genetic similarity generally decays with geographic distance, there have regularly been factors that subtly distort the underlying relationship across space observed today. The fine-scale population structure depicted here is relevant to understanding complex processes of human population history and may provide insights for geographic patterning in rare variants and heritable disease risk.

Intra- and interspecific allozyme variation in eucalypts from the spotted gum group, Corymbia, section 'Politaria' (Myrtaceae)

2000 ◽  
Vol 13 (4) ◽  
pp. 491 ◽  
Author(s):  
M. W. McDonald ◽  
P. A. Butcher ◽  
J. C. Bell ◽  
J. S. Larmour
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Differentiation ◽  
Related Species ◽  
Allozyme Variation ◽  
Geographic Range ◽  
Breeding Systems ◽  
Closely Related Species ◽  
Tropical Regions ◽  
Corymbia Citriodora

The distribution of genetic variation within and among species inCorymbia section‘Politaria’ was examined using allozymes.This section consists of four species,Corymbia citriodora (Hook.) K.D.Hill & L.A.S.Johnson, C. maculata (Hook.) K.D.Hill & L.A.S.Johnson, C. henryi (Blake) K.D.Hill & L.A.S.Johnson and C. variegata (F.Muell.) K.D.Hill & L.A.S.Johnson, which are of commercial interest for plantation and farmforestry. Thirty populations representing the species’ range-widedistributions were studied, extending from upland tropical regions of northQueensland, south to eastern Victoria. Despite relatively low allozymedivergence between species, there was a relationship between geographicdistribution patterns of populations and allozyme variation. The section wasshown to comprise very closely related species with only 15% of thetotal genetic diversity attributed to differences between species. Twodistinct genetic alliances were evident:C. maculata–C. henryi andC. citriodora–C. variegata.Corymbia citriodora andC. variegata, however, could not be distinguished bytheir allozyme profiles. The lack of genetic differentiation between thesetaxa suggests that they represent one species composed of two chemical races.Corymbia maculata and C. henryiwere shown to be closely allied but genetically distinct.Corymbia henryi had the highest genetic diversity in thegroup and lowest differentiation among populations, whileC. maculata had the lowest diversity but the highestgenetic differentiation among populations. There was evidence ofisolation-by-distance among populations ofC. citriodora, C. maculata andC. variegata but not in C. henryi,which has a smaller geographic range. The inclusion in the study ofC. torelliana (F.Muell.) K.D.Hill & L.A.S.Johnson asan outgroup accentuated the small genetic differences between species in thegroup. The patterns of genetic diversity are discussed in relation to thespecies’ taxonomic relationships, breeding systems and utilisation.

Genetic impacts of habitat loss on the rare Banded Ironstone Formation endemic Ricinocarpos brevis (Euphorbiaceae)

2019 ◽  
Vol 67 (3) ◽  
pp. 183 ◽  
Author(s):  
Siegfried L. Krauss ◽  
Janet Anthony
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Isolation By Distance ◽  
Spatial Genetic Structure ◽  
Geographic Distance ◽  
Mining Operations ◽  
Analysis Of Molecular Variance ◽  
Mantel Tests ◽  
Tests Of Association ◽  
Potential Impact

Ricinocarpos brevis (Euphorbiaceae) is a declared rare species currently known from only three Banded Ironstone Formation (BIF) ranges (Perrinvale, Johnston and Windarling Ranges) in the Yilgarn region of Western Australia. The present study assessed the potential impact of proposed mining on genetic diversity within R. brevis. Approximately 30 plants were sampled from each of 14 sites across the known distribution of R. brevis. Genetic variation and its spatial structure was assessed with 144 polymorphic AFLP markers that were generated by two independent primer pairs: M-CTG/P-AC (81 markers) and M-CTA/P-AC (63 markers). Hierarchical spatial genetic structure was assessed by an analysis of molecular variance (AMOVA), Mantel tests of association between genetic- and geographic-distance and ordination. Specific attention was given to the extent of genetic differentiation of the three populations on the Windarling Range W4 deposit, which was proposed for mining operations. Strong genetic differentiation (ΦPT=0.186–0.298) among the three ranges was found. Genetic differentiation of the Johnston Range populations from Windarling and Perrinvale was greater than expected under isolation by distance predictions, suggesting adaptive genetic differentiation driven by site environmental differences, reflected by differences in plant community, substrate and landscape features. In contrast, genetic differentiation among the three Windarling Range regions (W2, W3, W4) was weaker (ΦPT=0.055–0.096). Mean pairwise ΦPT=0.078 for the 10 Windarling sites, which was unchanged with the removal of the W4 populations. In addition, none of the markers scored were unique to the W4 populations. Thus, for this set of markers, the removal of plants on the Windarling Range W4 deposit had little impact on genetic diversity within R. brevis. Strong concordance in results from the independent datasets generated by the two AFLP primer pairs provides overall support for the conclusions drawn.

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