Molecular genetic variation in a widespread forest tree species Eucalyptus obliqua (Myrtaceae) on the island of Tasmania

2011 ◽  
Vol 59 (3) ◽  
pp. 226 ◽  
Author(s):  
Justin A. Bloomfield ◽  
Paul Nevill ◽  
Brad M. Potts ◽  
René E. Vaillancourt ◽  
Dorothy A. Steane
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Environmental Gradients ◽  
Molecular Genetic ◽  
Continuous Distribution ◽  
Main Mode ◽  
Chloroplast Microsatellite ◽  
Eastern Australia ◽  
Nuclear Microsatellite ◽  
Microsatellite Diversity

Eucalyptus obliqua L’Hér. is widespread across south-eastern Australia. On the island of Tasmania it has a more-or-less continuous distribution across its range and it dominates much of the wet sclerophyll forest managed for forestry purposes. To understand better the distribution of genetic variation in these native forests we examined nuclear microsatellite diversity in 432 mature individuals from 20 populations of E. obliqua across Tasmania, including populations from each end of three locally steep environmental gradients. In addition, chloroplast microsatellite loci were assessed in 297 individuals across 31 populations. Nuclear microsatellite diversity values in E. obliqua were high (average HE = 0.80) and inbreeding coefficients low (average F = 0.02) within these populations. The degree of differentiation between populations was very low (FST = 0.015). No significant microsatellite differentiation could be found across three locally steep environmental gradients, even though there is significant genetic differentiation in quantitative traits. This suggests that the observed quantitative variation is maintained by natural selection. Population differentiation based on chloroplast haplotypes was high (GST = 0.69) compared with that based on nuclear microsatellites, suggesting that pollen-mediated gene flow is >150 times the level of seed-mediated gene flow in this animal-pollinated species; hence, pollen is likely to be the main mode of gene flow countering selection along local environmental gradients. Implications of these results for silvicultural practices are discussed.

scholarly journals Genetic diversity, structure and gene flow of migratory barren-ground caribou (Rangifer tarandus groenlandicus) in Canada

Rangifer ◽  
2016 ◽  
Vol 36 (1) ◽  
pp. 1 ◽  
Author(s):  
Keri McFarlane ◽  
Anne Gunn ◽  
Mitch Campbell ◽  
Mathieu Dumond ◽  
Jan Adamczewski ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Gene Flow ◽  
Rangifer Tarandus ◽  
Continuous Distribution ◽  
Effective Population ◽  
Genetic Population ◽  
Barren Ground ◽  
Cyclic Changes ◽  
Rangifer Tarandus Groenlandicus

Migratory barren-ground caribou (Rangifer tarandus groenlandicus) provide an opportunity to examine the genetic population structure of a migratory large mammal whose movements and distribution, in some instances, have not been heavily influenced by human activities that result in habitat loss or fragmentation. These caribou have likely reached large effective population sizes since their rapid radiation during the early Holocene despite cyclic changes in abundance. Migratory barren-ground caribou are managed as discrete subpopulations. We investigated genetic variation among those subpopulations to determine the patterns of genetic diversity within and among them, and the implications for long-term persistence of caribou. We identified three distinct genetic clusters across the Canadian arctic tundra: the first cluster consisted of all fully-continental migratory barren-ground subpopulations; the second cluster was the Dolphin and Union caribou; and the third cluster was caribou from Southampton Island. The Southampton Island caribou are especially genetically distinct from the other barren-ground type caribou. Gene flow among subpopulations varied across the range. Occasional gene flow across the sea-ice is likely the reason for high levels of genetic variation in the Dolphin and Union subpopulation, which experienced very low numbers in the past. These results suggest that for most migratory caribou subpopulations, connectivity among subpopulations plays an important role in maintaining natural genetic diversity. Our analyses provide insight into the levels of microsatellite genetic diversity and patterns of gene flow that may be common to large subpopulations that historically had a continuous distribution across a large continental range. These data can also be used as a benchmark to compare the effects of habitat fragmentation and bottlenecks on other large caribou populations.

scholarly journals Gene Flow and Genetic Variation Explain Signatures of Selection across a Climate Gradient in Two Riparian Species

Genes ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 579 ◽  
Author(s):  
Hopley ◽  
Byrne
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Environmental Gradients ◽  
Genetic Connectivity ◽  
Heterogeneous Environments ◽  
Climate Gradients ◽  
Climate Gradient ◽  
Riparian Species ◽  
High Gene ◽  
Signatures Of Selection

Many species occur across environmental gradients and it is expected that these species will exhibit some signals of adaptation as heterogeneous environments and localized gene flow may facilitate local adaptation. While riparian zones can cross climate gradients, many of which are being impacted by climate change, they also create microclimates for the vegetation, reducing environmental heterogeneity. Species with differing distributions in these environments provide an opportunity to investigate the importance of genetic connectivity in influencing signals of adaptation over relatively short geographical distance. Association analysis with genomic data was used to compare signals of selection to climate variables in two species that have differing distributions along a river traversing a climate gradient. Results demonstrate links between connectivity, standing genetic variation, and the development of signals of selection. In the restricted species, the combination of high gene flow in the middle and lower catchment and occurrence in a microclimate created along riverbanks likely mitigated the development of selection to most climatic variables. In contrast the more widely distributed species with low gene flow showed a stronger signal of selection. Together these results strengthen our knowledge of the drivers and scale of adaptation and reinforce the importance of connectivity across a landscape to maintain adaptive potential of plant species.

scholarly journals Measuring recent effective gene flow among large populations in Pinus sylvestris: Local pollen shedding does not preclude substantial long-distance pollen immigration

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255776
Author(s):  
Azucena Jiménez-Ramírez ◽  
Delphine Grivet ◽  
Juan José Robledo-Arnuncio
Keyword(s):  
Gene Flow ◽  
Pinus Sylvestris ◽  
Molecular Genetic ◽  
Natural Populations ◽  
Common Garden ◽  
Long Distance ◽  
Chloroplast Microsatellite ◽  
Flow Rates ◽  
Recent Gene Flow ◽  
Large Tree

The estimation of recent gene flow rates among vast and often weakly genetically differentiated tree populations remains a great challenge. Yet, empirical information would help understanding the interaction between gene flow and local adaptation in present-day non-equilibrium forests. We investigate here recent gene flow rates between two large native Scots pine (Pinus sylvestris L.) populations in central Iberian Peninsula (Spain), which grow on contrasting edaphic conditions six kilometers apart from each other and show substantial quantitative trait divergence in common garden experiments. Using a sample of 1,200 adult and offspring chloroplast-microsatellite haplotypes and a Bayesian inference model, we estimated substantial male gametic gene flow rates (8 and 21%) between the two natural populations, and even greater estimated immigration rates (42 and 64%) from nearby plantations into the two natural populations. Our results suggest that local pollen shedding within large tree populations does not preclude long-distance pollen immigration from large external sources, supporting the role of gene flow as a homogenizing evolutionary force contributing to low molecular genetic differentiation among populations of widely distributed wind-pollinated species. Our results also indicate the high potential for reproductive connectivity in large fragmented populations of wind-pollinated trees, and draw attention to a potential scenario of adaptive genetic divergence in quantitative traits under high gene flow.

Genetic differentiation of Sorbus torminalis in Eastern Europe as determined by microsatellite markers

Biologia ◽  
2010 ◽  
Vol 65 (5) ◽  
Author(s):  
Veronika Kučerová ◽  
Martin Honec ◽  
Ladislav Paule ◽  
Petar Zhelev ◽  
Dušan Gömöry
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Bayesian Methods ◽  
Isolation By Distance ◽  
General Pattern ◽  
The Other ◽  
Hand Model ◽  
Sorbus Torminalis ◽  
Nuclear Microsatellite

AbstractThe genetic variation in fourteen Sorbus torminalis (L.) Crantz. populations distributed over the eastern and south-eastern part of its range was studied using seven nuclear microsatellite loci. The differentiation level was relatively high (F ST = 0.228), as expected for a species with a fragmented range. The distance-based approach to the analysis of differentiation patterns (neighbour-joining tree based on pairwise coefficients of differentiation) did not reveal a clear geographical structure. On the other hand, model-based Bayesian methods (BAPS and STRUCTURE) gave geographically continuous clusters of populations. The occurrence of populations deviating strongly from the general pattern is attributed to founder effect. In spite of a generally high differentiation, a significant isolation-by-distance pattern was found, which might be a consequence of postglacial migration and gene flow among descendants of different refugia.

scholarly journals Evolutionary history and genetic connectivity across highly fragmented populations of an endangered daisy

Heredity ◽  
2021 ◽  
Author(s):  
Yael S. Rodger ◽  
Alexandra Pavlova ◽  
Steve Sinclair ◽  
Melinda Pickup ◽  
Paul Sunnucks
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Evolutionary History ◽  
Livestock Grazing ◽  
Genetic Connectivity ◽  
Evolutionary Divergence ◽  
Common Component ◽  
A Genome ◽  
Eastern Australia

AbstractConservation management can be aided by knowledge of genetic diversity and evolutionary history, so that ecological and evolutionary processes can be preserved. The Button Wrinklewort daisy (Rutidosis leptorrhynchoides) was a common component of grassy ecosystems in south-eastern Australia. It is now endangered due to extensive habitat loss and the impacts of livestock grazing, and is currently restricted to a few small populations in two regions >500 km apart, one in Victoria, the other in the Australian Capital Territory and nearby New South Wales (ACT/NSW). Using a genome-wide SNP dataset, we assessed patterns of genetic structure and genetic differentiation of 12 natural diploid populations. We estimated intrapopulation genetic diversity to scope sources for genetic management. Bayesian clustering and principal coordinate analyses showed strong population genetic differentiation between the two regions, and substantial substructure within ACT/NSW. A coalescent tree-building approach implemented in SNAPP indicated evolutionary divergence between the two distant regions. Among the populations screened, the last two known remaining Victorian populations had the highest genetic diversity, despite having among the lowest recent census sizes. A maximum likelihood population tree method implemented in TreeMix suggested little or no recent gene flow except potentially between very close neighbours. Populations that were more genetically distinctive had lower genetic diversity, suggesting that drift in isolation is likely driving population differentiation though loss of diversity, hence re-establishing gene flow among them is desirable. These results provide background knowledge for evidence-based conservation and support genetic rescue within and between regions to elevate genetic diversity and alleviate inbreeding.

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