Livestock Effects on Genetic Variation of Creosote Bushes in Patagonian Rangelands

2018 ◽  
Vol 46 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Cintia P. Souto ◽  
Mariana Tadey
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Native Species ◽  
Environmental Changes ◽  
Natural Populations ◽  
Raw Material ◽  
Hierarchical Regression ◽  
Evolutionary Potential ◽  
Monte Desert ◽  
Larrea Divaricata

SummaryGenetic diversity is the raw material for species’ persistence over time, providing the potential to survive stochastic events, as well as climate and/or human-induced environmental changes. Biodiversity in dry rangelands is decreasing due to intensification of livestock production, but its effects on the genetic diversity of the consumed biota have seldom been assessed. We examined livestock effects on the genetic diversity of two dominant creosote species of the Patagonian Monte Desert, Larrea divaricata and Larrea cuneifolia. We deployed competing hierarchical regression models to assess the relationship between genetic variation within natural populations as a function of increasing stocking rates on ten arid rangelands. These species exhibit similar levels and patterns of genetic structure, with high levels of both inbreeding and divergence among locations. We found that increased stocking reduces genetic variation and increases genetic subdivision between populations. Our results indicate that grazing pressures are impoverishing the gene pool of these dominant native species of the Monte Desert, decreasing the evolutionary potential of the primary plant producers and increasing the desertification risk for a vulnerable habitat. We highlight the importance of considering livestock as a major driver of genetic losses in dry rangelands under overgrazing pressure, especially given current forecasts of climate change.

Inbreeding and loss of genetic diversity increase extinction risk

2019 ◽  
pp. 31-48
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Inbreeding Depression ◽  
Environmental Changes ◽  
Extinction Risk ◽  
Raw Material ◽  
Heterozygote Advantage ◽  
Isolated Populations ◽  
Survival And Reproduction ◽  
Loss Of Genetic Diversity ◽  
Harmful Effects

Inbreeding reduces survival and reproduction (i.e. it causes inbreeding depression), and thereby increases extinction risk. Inbreeding depression is due to increased homozygosity for harmful alleles and at loci exhibiting heterozygote advantage. Inbreeding depression is nearly universal in sexually reproducing organisms that are diploid or have higher ploidies. Impacts of inbreeding are generally greater in species that naturally outbreed than those that inbreed, in stressful than benign environments, and for fitness than peripheral traits. Harmful effects accumulate across the life cycle, resulting in devastating effects on total fitness in outbreeding species.Species face ubiquitous environmental change and must adapt or they will go extinct. Genetic diversity is the raw material required for evolutionary adaptation. However, loss of genetic diversity is unavoidable in small isolated populations, diminishing their capacity to evolve in response to environmental changes, and thereby increasing extinction risk.

scholarly journals Coalescent Theory of Migration Network Motifs

2019 ◽  
Vol 36 (10) ◽  
pp. 2358-2374
Author(s):  
Nicolas Alcala ◽  
Amy Goldberg ◽  
Uma Ramakrishnan ◽  
Noah A Rosenberg
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Nucleotide Diversity ◽  
Natural Populations ◽  
Node Degree ◽  
Small Subset ◽  
Network Motifs ◽  
Coalescent Theory ◽  
Migration Networks ◽  
The Impact

Abstract Natural populations display a variety of spatial arrangements, each potentially with a distinctive impact on genetic diversity and genetic differentiation among subpopulations. Although the spatial arrangement of populations can lead to intricate migration networks, theoretical developments have focused mainly on a small subset of such networks, emphasizing the island-migration and stepping-stone models. In this study, we investigate all small network motifs: the set of all possible migration networks among populations subdivided into at most four subpopulations. For each motif, we use coalescent theory to derive expectations for three quantities that describe genetic variation: nucleotide diversity, FST, and half-time to equilibrium diversity. We describe the impact of network properties on these quantities, finding that motifs with a high mean node degree have the largest nucleotide diversity and the longest time to equilibrium, whereas motifs with low density have the largest FST. In addition, we show that the motifs whose pattern of variation is most strongly influenced by loss of a connection or a subpopulation are those that can be split easily into disconnected components. We illustrate our results using two example data sets—sky island birds of genus Sholicola and Indian tigers—identifying disturbance scenarios that produce the greatest reduction in genetic diversity; for tigers, we also compare the benefits of two assisted gene flow scenarios. Our results have consequences for understanding the effect of geography on genetic diversity, and they can assist in designing strategies to alter population migration networks toward maximizing genetic variation in the context of conservation of endangered species.

scholarly journals Genetic diversity of African clawless otters (Aonyx capensis) occurring in urbanised areas of Gauteng, South Africa

2019 ◽  
Vol 115 (7/8) ◽  
Author(s):  
Damian W. Ponsonby ◽  
M. Thabang Madisha ◽  
Schwaibold Schwaibold ◽  
Desiré L. Dalton
Keyword(s):  
South Africa ◽  
Genetic Diversity ◽  
Gene Flow ◽  
Environmental Changes ◽  
Urban Expansion ◽  
Evolutionary Potential ◽  
Non Invasive ◽  
Faecal Samples ◽  
Physical Barriers ◽  
High Gene

Genetic diversity is the basis of the evolutionary potential of species to respond to environmental changes. However, restricting the movement of species can result in populations becoming less connected which can reduce gene flow and can subsequently result in a loss of genetic diversity. Urban expansion can lead to the fragmentation of habitats which affects the ability of species to move freely between areas. In this study, the genetic diversity of the African clawless otter (Aonyx capensis) in Gauteng (South Africa) was assessed using non-invasive sampling techniques. DNA was extracted from spraint (faecal) samples collected along nine rivers and genotyped using 10 microsatellites to assess population structure and genetic diversity. Samples were grouped based on locality and by catchment to determine whether isolated subpopulations exist. Genetic diversity of A. capensis in Gauteng was found to be low (mean observed heterozygosity (Ho)=0.309). Analysis of genetic structure provides support for the otter populations being panmictic with high gene flow between populations from different rivers. Results from the study indicate that the movement of A. capensis is not affected by physical barriers in urbanised areas. However, because the genetic diversity of the species in the study area is low, these animals may not be able to cope with future environmental changes.

scholarly journals Comparison of the effectiveness of ISJ and SSR markers and detection of outlier loci in conservation genetics ofPulsatilla patenspopulations

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2504 ◽  
Author(s):  
Katarzyna Bilska ◽  
Monika Szczecińska
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Conservation Genetics ◽  
Ssr Markers ◽  
Full Range ◽  
Mantel Test ◽  
Evolutionary Potential ◽  
Functional Variation ◽  
Genetics Research ◽  
Outlier Loci

BackgroundResearch into the protection of rare and endangered plant species involves genetic analyses to determine their genetic variation and genetic structure. Various categories of genetic markers are used for this purpose. Microsatellites, also known as simple sequence repeats (SSR), are the most popular category of markers in population genetics research. In most cases, microsatellites account for a large part of the noncoding DNA and exert a neutral effect on the genome. Neutrality is a desirable feature in evaluations of genetic differences between populations, but it does not support analyses of a population’s ability to adapt to a given environment or its evolutionary potential. Despite the numerous advantages of microsatellites, non-neutral markers may supply important information in conservation genetics research. They are used to evaluate adaptation to specific environmental conditions and a population’s adaptive potential. The aim of this study was to compare the level of genetic variation inPulsatilla patenspopulations revealed by neutral SSR markers and putatively adaptive ISJ markers (intron-exon splice junction).MethodsThe experiment was conducted on 14 Polish populations ofP. patensand threeP. patenspopulations from the nearby region of Vitebsk in Belarus. A total of 345 individuals were examined. Analyses were performed with the use of eight SSR primers specific toP. patensand three ISJ primers.ResultsSSR markers revealed a higher level of genetic variation than ISJ markers (He= 0.609,He= 0.145, respectively). An analysis of molecular variance (AMOVA) revealed that, the overall genetic diversity between the analyzed populations defined by parametersFSTand ΦPTfor SSR (20%) and ΦPTfor ISJ (21%) markers was similar. Analysis conducted in theStructureprogram divided analyzed populations into two groups (SSR loci) and three groups (ISJ markers). Mantel test revealed correlations between the geographic distance and genetic diversity of Polish populations ofP. patensfor ISJ markers, but not for SSR markers.ConclusionsThe results of the present study suggest that ISJ markers can complement the analyses based on SSRs. However, neutral and adaptive markers should not be alternatively applied. Neutral microsatellite markers cannot depict the full range of genetic variation in a population because they do not enable to analyze functional variation. Although ISJ markers are less polymorphic, they can contribute to the reliability of analyses based on SSRs.

Schistosome genetic diversity: the implications of population structure as detected with microsatellite markers

Parasitology ◽  
2002 ◽  
Vol 125 (7) ◽  
pp. S51-S59 ◽  
Author(s):  
J. CURTIS ◽  
R. E. SORENSEN ◽  
D. J. MINCHELLA
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Molecular Markers ◽  
Microsatellite Markers ◽  
Natural Populations ◽  
Mitochondrial Marker ◽  
Tropical Regions ◽  
Blood Flukes

Blood flukes in the genus Schistosoma are important human parasites in tropical regions. A substantial amount of genetic diversity has been described in populations of these parasites using molecular markers. We first consider the extent of genetic variation found in Schistosoma mansoni and some factors that may be contributing to this variation. Recently, though, attempts have been made to analyze not only the genetic diversity but how that diversity is partitioned within natural populations of schistosomes. Studies with non-allelic molecular markers (e.g. RAPDs and mtVNTRs) have indicated that schistosome populations exhibit varying levels of gene flow among component subpopulations. The recent characterization of microsatellite markers for S. mansoni provided an opportunity to study schistosome population structure within a population of schistosomes from a single Brazilian village using allelic markers. Whereas the detection of population structure depends strongly on the type of analysis with a mitochondrial marker, analyses with a set of seven microsatellite loci consistently revealed moderate genetic differentiation when village boroughs were used to define parasite subpopulations and greater subdivision when human hosts defined subpopulations. Finally, we discuss the implications that such strong population structure might have on schistosome epidemiology.

Genetic diversity and differentiation in populations of Japanese stone pine (Pinuspumila) in Japan

1996 ◽  
Vol 26 (8) ◽  
pp. 1454-1462 ◽  
Author(s):  
Naoki Tani ◽  
Nobuhiro Tomaru ◽  
Masayuki Araki ◽  
Kihachiro Ohba
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Differentiation ◽  
Phylogenetic Trees ◽  
Genetic Relationships ◽  
Natural Populations ◽  
Group Method ◽  
Stone Pine ◽  
Arithmetic Means ◽  
Pair Group

Japanese stone pine (Pinuspumila Regel) is a dominant species characteristic of alpine zones of high mountains. Eighteen natural populations of P. pumila were studied in an effort to determine the extent and distribution of genetic diversity. The extent of genetic diversity within this species was high (HT = 0.271), and the genetic differentiation among populations was also high (GST = 0.170) compared with those of other conifers. In previous studies of P. pumila in Russia, the genetic variation within the species was also high, but the genetic differentiation among populations was low. We infer that this difference originates from differences in geographic distribution and ecological differences between the two countries. The genetic variation within each population tended, as a whole, to be smaller within marginal southern populations than within northern populations. Genetic relationships among populations reflect the geographic locations, as shown by unweighted pair-group method with arithmetic means and neighbor-joining phylogenetic trees.

scholarly journals GENETIC DIVERSITY AMONG NATURAL POPULATIONS OF Keteleeria evelyniana Mast. IN CENTRAL HIGLANDS OF VIETNAM USING SSR MARKERS

2018 ◽  
Vol 56 (3) ◽  
pp. 275
Author(s):  
Tran Thi Lieu ◽  
Dinh Thi Phong ◽  
Vu Thi Thu Hien
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Similarity ◽  
Natural Populations ◽  
Similarity Coefficient ◽  
Similarity Matrix ◽  
Analysis Of Molecular Variance ◽  
Molecular Variance ◽  
Private Alleles ◽  
Softwood Species

Keteleeria evelyniana Mast. is a big softwood species with high economic values. Therefore, the number of these trees are rapidly decreasing due to rampant exploitation as well as its habitat loss and recently, the species is considered vulnerablein Vietnam. In this study, we assessed the genetic variation among seventy K. evelyniana samples of three natural populations in Lam Dong, Dak Lak and Kon Tum using 16 microsatellite markers. The results showed that thirteen markers were polymorphic. A total 39 DNA fragments were amplified, among them, thirty – five were polymorphic (accounting for 89.74%). Among studied populations, the level of genetic diversity at Lam Dong (Na = 2.063; Ne = 1.730; Ap = 0.375; I = 0.558; Ho = 0.459 and He = 0.367) was the highest. Analysis of molecular variance (AMOVA) showed that the total level of molecular changes between populations was 34.65% and between individuals in the same population was 65.35%. Private alleles (Ap) and inbreeding values (Fis) of K. evelyniana species were founded of all three populations in Lam Dong, Dak Lak and Kon Tum (0.375 and -0.234; 0.188 and -0.065; 0.063 and -0.047, respectively). The gene flow (Nm) also occurred among the K. evelyniana populations with the average of Nm = 5.423. A dendrogram (UPGMA) constructed based on the similarity matrix of 70 K. evelyniana samples divided into two main groups with their genetic similarity coefficient ranged from 76.5% (Ke26 and Ke44) to 99% (Ke23 and Ke25). The obtained results indicated the importance of conserving the genetic resources of K. evelyniana species in Tay Nguyen.

scholarly journals Genotyping-by-sequencing reveals the effects of riverscape, climate and interspecific introgression on the genetic diversity and local adaptation of the endangered Mexican golden trout (Oncorhynchus chrysogaster)

2018 ◽  
Author(s):  
Marco A. Escalante ◽  
Charles Perrier ◽  
Francisco J. García-De León ◽  
Arturo Ruiz-Luna ◽  
Enrique Ortega-Abboud ◽  
...  
Keyword(s):  
Climate Change ◽  
Genetic Diversity ◽  
Genetic Variation ◽  
Local Adaptation ◽  
Population Genomics ◽  
Landscape Heterogeneity ◽  
Genotyping By Sequencing ◽  
Anthropogenic Factors ◽  
Nucleotide Polymorphisms ◽  
Evolutionary Potential

AbstractHow environmental and anthropogenic factors influence genetic variation and local adaptation is a central issue in evolutionary biology. The Mexican golden trout (Oncorhynchus chrysogaster), one of the southernmost native salmonid species in the world, is susceptible to climate change, habitat perturbations and the competition and hybridization with exotic rainbow trout (O. mykiss). The present study aimed for the first time to use genotyping-by-sequencing to explore the effect of genetic hybridization with O. mykiss and of riverscape and climatic variables on the genetic variation among O. chrysogaster populations. Genotyping-by-sequencing (GBS) was applied to generate 9767 single nucleotide polymorphisms (SNPs), genotyping 272 O. chrysogaster and O. mykiss. Population genomics analyses were combined with landscape ecology approaches into a riverine context (riverscape genetics). The clustering analyses detected seven different genetic groups (six for O. chrysogater and one for aquaculture O. mykiss) and a small amount of admixture between aquaculture and native trout with only two native genetic clusters showing exotic introgression. Latitude and precipitation of the driest month had a significant negative effect on genetic diversity and evidence of isolation by river resistance was detected, suggesting that the landscape heterogeneity was preventing trout dispersal, both for native and exotic individuals. Moreover, several outlier SNPs were identified as potentially implicated in local adaptation to local hydroclimatic variables. Overall, this study suggests that O. chrysogater may require conservation planning given i) exotic introgression from O. mykiss locally threatening O. chrysogater genetic integrity, and ii) putative local adaptation but low genetic diversity and hence probably reduced evolutionary potential especially in a climate change context.

scholarly journals Regional genetic diversity in circadian period in Boechera stricta populations is high relative to the global range of diversity in Arabidopsis

2021 ◽  
Author(s):  
Robby McMinn ◽  
Matti Salmela ◽  
Cynthia Weinig
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Significant Proportion ◽  
Natural Populations ◽  
Elevational Gradient ◽  
Environmental Data ◽  
Population Variation ◽  
Circadian Period ◽  
In The Wild ◽  
Boechera Stricta

Circadian clocks manifest adaptations to predictable 24-h fluctuations in the exogenous environment, but it has yet to be determined why the endogenous circadian period length in the wild varies genetically around the hypothesized optimum of 24 h. We quantified genetic variation in circadian period in leaf movement in 30 natural populations of the Arabidopsis relative Boechera stricta sampled within only 1° of latitude but across an elevational gradient spanning 2460−3300 m in the Rocky Mountains. Measuring over 3800 plants from 473 maternal families (7−20 per population), we found genetic variation that was of similar magnitude among vs. within populations, with population means varying between 21.9−24.9 h and maternal family means within populations varying by up to ~6 h. After statistically factoring out spatial autocorrelation at the habitat extremes, we found that elevation explained a significant proportion of genetic variation in circadian period such that higher-elevation populations had shorter mean period lengths and less within-population variation. Environmental data indicate that these spatial trends could be related to steep regional climatic gradients in temperature, precipitation, and their intra-annual variability. Our findings provide evidence that spatially fine-grained environmental heterogeneity contributes to naturally occurring genetic diversity in circadian traits in wild populations.

scholarly journals Quantifying multivariate genotype-by-environment interactions, evolutionary potential and its context-dependence in natural populations of the water flea, Daphnia magna

2020 ◽  
Author(s):  
Franziska S. Brunner ◽  
Alan Reynolds ◽  
Ian W. Wilson ◽  
Stephen Price ◽  
Steve Paterson ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Daphnia Magna ◽  
Natural Populations ◽  
Thermal Adaptation ◽  
Plastic Response ◽  
Evolutionary Potential ◽  
Genotype By Environment Interactions ◽  
Additive Genetic Variation ◽  
Genotype By Environment ◽  
Plastic Responses

ABSTRACTGenotype-by-environment interactions (G x E) underpin the evolution of plastic responses in natural populations. Theory assumes that G x E interactions exist but empirical evidence from natural populations is equivocal and difficult to interpret because G x E interactions are normally univariate plastic responses to a single environmental gradient. We compared multivariate plastic responses of 43 Daphnia magna clones from the same population in a factorial experiment that crossed temperature and food environments. Multivariate plastic responses explained more than 30% of the total phenotypic variation in each environment. G x E interactions were detected in most environment combinations irrespective of the methodology used. However, the nature of G x E interactions was context-dependent and led to environment-specific differences in additive genetic variation (G-matrices). Clones that deviated from the population average plastic response were not the same in each environmental context and there was no difference in whether clones varied in the nature (phenotypic integration) or magnitude of their plastic response in different environments. Plastic responses to food were aligned with additive genetic variation (gmax) at both temperatures, whereas plastic responses to temperature were not aligned with additive genetic variation (gmax) in either food environment. These results suggest that fundamental differences may exist in the potential for our population to evolve novel responses to food versus temperature changes, and challenges past interpretations of thermal adaptation based on univariate studies.

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