Evidence of genetic subdivision among populations of blacklip abalone (Haliotis rubra Leach) in Tasmania

2007 ◽  
Vol 58 (8) ◽  
pp. 733 ◽  
Author(s):  
Nepelle Temby ◽  
Karen Miller ◽  
Craig Mundy
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Microsatellite Dna ◽  
Larval Dispersal ◽  
Field Experiments ◽  
Field Studies ◽  
Genetic Studies ◽  
Small Scales ◽  
Commercial Species ◽  
Haliotis Rubra

The scale over which populations exchange individuals (migration) is central to ecology, and important for understanding recruitment and connectivity in commercial species. Field studies indicate that blacklip abalone (Haliotis rubra) have localised larval dispersal. However, genetic studies show differentiation only at large scales, suggesting dispersal over more than 100 km. Most genetic studies, however, have failed to test for subdivision at scales equivalent to field experiments. We used microsatellite DNA to investigate genetic structure at small scales (100 m to 10 km) in blacklip abalone in south-east Tasmania. We found significant subdivision (FST = 0.021; P < 0.05) among sites, and hierarchical FST analysis indicated 64% of genetic variation was at the smallest scale, supporting field studies that concluded larval dispersal is less than 100m. We also tested if genetic differentiation varied predictably with wave exposure, but found no evidence that differences between adjacent sites in exposed locations varied from differences between adjacent sites in sheltered populations (mean FST = 0.016 and 0.017 respectively). Our results show the usefulness of microsatellites for abalone, but also identify sampling scales as critical in understanding gene flow and dispersal of abalone larvae in an ecologically relevant framework. Importantly, our results indicate that H. rubra populations are self-recruiting, which will be important for the management of this commercial species.

scholarly journals Seascape genomics reveals population isolation in the reef-building honeycomb worm, Sabellaria alveolata (L.)

2019 ◽  
Author(s):  
Anna P Muir ◽  
Stanislas F. Dubois ◽  
Rebecca E. Ross ◽  
Louise B. Firth ◽  
Antony M. Knights ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
North Atlantic ◽  
Larval Dispersal ◽  
Balancing Selection ◽  
Isolated Population ◽  
The North ◽  
Outlier Loci ◽  
Dispersal Potential ◽  
The North Atlantic

Abstract Background Under the threat of climate change populations can disperse, acclimatise or evolve in order to avoid fitness loss. In light of this, it is important to understand neutral gene flow patterns as a measure of dispersal potential, but also adaptive genetic variation as a measure of evolutionary potential. In order to assess genetic variation and how this relates to environment in the honeycomb worm (Sabellaria alveolata (L.)), a reef-building polychaete that supports high biodiversity, we carried out RAD sequencing using individuals from along its complete latitudinal range. Patterns of neutral population genetic structure were compared to larval dispersal as predicted by ocean circulation modelling, and outlier analyses and genotype-environment associations tests were used to attempt to identify loci under selection in relation to local temperature data. Results We genotyped 482 filtered SNPs, from 68 individuals across nine sites, 27 of which were identified as outliers using BAYESCAN and ARLEQUIN. All outlier loci were potentially under balancing selection, despite previous evidence of local adaptation in the system. Limited gene flow was observed among reef-sites (FST = 0.28 ± 0.10), in line with the low dispersal potential identified by the larval dispersal models. The North Atlantic reef emerged as an isolated population and this was linked to high local larval retention and the effect of the North Atlantic Current on dispersal. Conclusions As an isolated population, with limited potential for natural genetic or demographic augmentation from other reefs, the North Atlantic site warrants conservation attention in order to preserve not only this species, but above all the crucial functional ecological roles that are associated with their bioconstructions. Our study highlights the utility of using seascape genomics to identify populations of conservation concern.

scholarly journals Genetic Variation in The Endangered Southwestern Willow Flycatcher

The Auk ◽  
2000 ◽  
Vol 117 (3) ◽  
pp. 586-595 ◽  
Author(s):  
Joseph D. Busch ◽  
Mark P. Miller ◽  
Eben H. Paxton ◽  
Mark K. Sogge ◽  
Paul Keim
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Field Studies ◽  
Breeding Sites ◽  
Neotropical Migrant ◽  
Length Polymorphisms ◽  
Upgma Cluster Analysis ◽  
Local Breeding ◽  
Willow Flycatcher ◽  
Breeding Groups

Abstract The Southwestern Willow Flycatcher (Empidonax traillii extimus) is an endangered Neotropical migrant that breeds in isolated remnants of dense riparian habitat in the southwestern United States. We estimated genetic variation at 20 breeding sites of the Southwestern Willow Flycatcher (290 individuals) using 38 amplified fragment length polymorphisms (AFLPs). Our results suggest that considerable genetic diversity exists within the subspecies and within local breeding sites. Statistical analyses of genetic variation revealed only slight, although significant, differentiation among breeding sites (Mantel's r = 0.0705, P < 0.0005; θ = 0.0816, 95% CI = 0.0608 to 0.1034; ΦST = 0.0458, P < 0.001). UPGMA cluster analysis of the AFLP markers indicates that extensive gene flow has occurred among breeding sites. No one site stood out as being genetically unique or isolated. Therefore, the small level of genetic structure that we detected may not be biologically significant. Ongoing field studies are consistent with this conclusion. Of the banded birds that were resighted or recaptured in Arizona during the 1996 to 1998 breeding seasons, one-third moved between breeding sites and two-thirds were philopatric. Low differentiation may be the result of historically high rangewide diversity followed by recent geographic isolation of breeding sites, although observational data indicate that gene flow is a current phenomenon. Our data suggest that breeding groups of E. t. extimus act as a metapopulation.

scholarly journals Seascape genomics reveals population isolation in the reef-building honeycomb worm, Sabellaria alveolata (L.)

2020 ◽  
Author(s):  
Anna P Muir ◽  
Stanislas F. Dubois ◽  
Rebecca E. Ross ◽  
Louise B. Firth ◽  
Antony M. Knights ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Larval Dispersal ◽  
Balancing Selection ◽  
The North ◽  
Outlier Loci ◽  
Dispersal Potential ◽  
The North Atlantic

Abstract Background: Under the threat of climate change populations can disperse, acclimatise or evolve in order to avoid fitness loss. In light of this, it is important to understand neutral gene flow patterns as a measure of dispersal potential, but also adaptive genetic variation as a measure of evolutionary potential. In order to assess genetic variation and how this relates to environment in the honeycomb worm (Sabellaria alveolata (L.)), a reef-building polychaete that supports high biodiversity, we carried out RAD sequencing using individuals from along its complete latitudinal range. Patterns of neutral population genetic structure were compared to larval dispersal as predicted by ocean circulation modelling, and outlier analyses and genotype-environment association tests were used to attempt to identify loci under selection in relation to local temperature data. Results: We genotyped 482 filtered SNPs, from 68 individuals across nine sites, 27 of which were identified as outliers using BAYESCAN and ARLEQUIN. All outlier loci were potentially under balancing selection, despite previous evidence of local adaptation in the system. Limited gene flow was observed among reef-sites (FST= 0.28 ± 0.10), in line with the low dispersal potential identified by the larval dispersal models. The North Atlantic reef emerged as a distinct population and this was linked to high local larval retention and the effect of the North Atlantic Current on dispersal. Conclusions: As an isolated population, with limited potential for natural genetic or demographic augmentation from other reefs, the North Atlantic site warrants conservation attention in order to preserve not only this species, but above all the crucial functional ecological roles that are associated with their bioconstructions. Our study highlights the utility of using seascape genomics to identify populations of conservation concern.

scholarly journals Lack of spatial genetic variation in the edible crab (Cancer pagurus) in the Kattegat–Skagerrak area

2009 ◽  
Vol 66 (3) ◽  
pp. 462-469 ◽  
Author(s):  
Anette Ungfors ◽  
Niall J. McKeown ◽  
Paul W. Shaw ◽  
Carl André
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Larval Dispersal ◽  
Power Analysis ◽  
Norwegian Sea ◽  
Cancer Pagurus ◽  
Genotype Frequencies ◽  
Contemporary Gene Flow ◽  
Large Populations ◽  
Spatial Genetic Variation

Abstract Ungfors, A., McKeown, N. J., Shaw, P. W., and André, C. 2009. Lack of spatial genetic variation in the edible crab (Cancer pagurus) in the Kattegat–Skagerrak area. – ICES Journal of Marine Science, 66: 462–469. The stock structure of the edible crab (Cancer pagurus L.) in the Kattegat and Skagerrak was investigated using eight microsatellite DNA loci. Replicate samples, collected 4–6 years apart, were derived from the Kattegat (Grove Bank, 57°N) and the Skagerrak (Lunneviken, 59°N), plus a geographical outgroup sample from the Norwegian Sea (Midsund, 62°N). Genetic differentiation among samples, estimated as global FST = 0.002, was significant (p = 0.03) when the statistical test was based on allele frequencies, but not when based on genotype frequencies. Moreover, all single- and multilocus pairwise tests between samples were non-significant. An analysis of molecular variance, AMOVA, did not reveal significant differentiation between spatial (Kattegat vs. Skagerrak) or temporal (2001/2002 vs. 2006/2007) groups of samples. Power analysis suggested that the loci and sample sizes employed conferred a power of >90% of detecting even low (true FST = 0.002) levels of population structure. Low spatial and temporal genetic structure might be explained by either or both of (i) high levels of contemporary gene flow in the area attributable to adult migration or larval dispersal or both factors taken together, and (ii) patterns of historical gene flow persisting among recently founded large populations.

Genetically defining populations is of limited use for evaluating and managing human impacts on gene flow

2012 ◽  
Vol 39 (4) ◽  
pp. 290 ◽  
Author(s):  
Adam J. Stow ◽  
William E. Magnusson
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Human Impacts ◽  
Statistical Tests ◽  
In Situ Conservation ◽  
Spatially Explicit ◽  
Genetic Studies ◽  
Genetic Detection ◽  
Sampling Procedures

Partitioning genetic variation into panmictic units is one of the most commonly used techniques in genetic studies of wild organisms. For conservation, the rationale is to identify units for management, most often referred to as populations. Describing these populations provides a measure of genetic differentiation, but they are only management units in relation to specific objectives. In situ conservation activities are mostly constrained to landscape (or ‘seascape’) units. With continuing habitat fragmentation, maintaining gene flow and genetic variation is an underlying objective for many conservation activities. Spatially explicit genetic approaches can describe how gene flow varies across a landscape, but the popular approach of identifying populations has limited and specific application. The statistical tests and sampling procedures used seldom allow for the spatial extent of genetic panmixia to be precisely defined. Gene flow, genetic variation and genetic detection of individual movements can be estimated without reference to populations. Furthermore, the term ‘population’ is used inconsistently in the literature and is often poorly defined. Formulating appropriate questions for management requires that the unit of study is clearly described, and often this could be organisms inhabiting defined areas of the landscape. Resources for conservation management are limited, so geneticists working on gene flow in wild organisms need to frame questions relevant to specific management needs and carefully consider the language and approaches employed.

Differentiation and Interrelations of Two Representatives of Laudakia stellio Complex (Reptilia: Agamidae) in Israel

2011 ◽  
Vol 4 (2) ◽  
pp. 102-114 ◽  
Author(s):  
Evgenyi N. Panov ◽  
Larissa Yu. Zykova
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Habitat Preference ◽  
Additional Data ◽  
Near East ◽  
Field Studies ◽  
Subspecies Level ◽  
Limited Gene Flow ◽  
Study Sites ◽  
And Behavior

Field studies were conducted in Central Negev within the breeding range of Laudakia stellio brachydactyla and in NE Israel (Qyriat Shemona) in the range of an unnamed form (tentatively “Near-East Rock Agama”), during March – May 1996. Additional data have been collected in Jerusalem at a distance of ca. 110 km from the first and about 170 km from the second study sites. A total of 63 individuals were caught and examined. The animals were marked and their subsequent movements were followed. Social and signal behavior of both forms were described and compared. Lizards from Negev and Qyriat Shemona differ from each other sharply in external morphology, habitat preference, population structure, and behavior. The differences obviously exceed the subspecies level. At the same time, the lizards from Jerusalem tend to be intermediate morphologically between those from both above-named localities, which permits admitting the existence of a limited gene flow between lizard populations of Negev and northern Israel. The lizards from NE Israel apparently do not belong to the nominate subspecies of L. stellio and should be regarded as one more subspecies within the species.

scholarly journals Genetic variation of seed phosphorus concentration in winter oilseed rape and development of a NIRS calibration

Euphytica ◽  
2021 ◽  
Vol 217 (4) ◽  
Author(s):  
Jakob Eifler ◽  
Jürgen Enno Wick ◽  
Bernd Steingrobe ◽  
Christian Möllers
Keyword(s):  
Genetic Variation ◽  
Field Experiments ◽  
Seed Quality ◽  
Rapeseed Meal ◽  
Quality Analysis ◽  
Phosphorus Concentration ◽  
Genotypic Differences ◽  
Organic P ◽  
P Concentration ◽  
Total P

AbstractPhytic acid is the major organic phosphorus storage compound in rapeseed. Following oil extraction, the defatted meal is used in feed mixtures for livestock. However, monogastric pigs and chickens can only poorly metabolize phytate. Hence, their excrements are rich in phosphorus (P), which when applied as manure may lead to eutrophication of surface waters. The aim of the present study was to analyze the genetic variation for total and organic P concentration (i.e. mainly phytate) in rapeseed and to compare the results with soybean. Two sets of rapeseed material were tested in field experiments in different environments with varying soil P levels and harvested seeds were used for seed quality analysis. Results revealed significant genotypic differences in total seed P concentration, which ranged from 0.47 to 0.94%. Depending on the experiment, the heritability for total P concentration ranged from 52 to 93%. The organic P portion of total P concentration was above 90% for current rapeseed hybrids. In both sets, there was a significant positive correlation between seed protein and P concentration. A NIRS calibration for total P concentration in intact seeds showed in cross validation a standard error of 0.05% and a coefficient of determination of R2 = 0.83. Total P concentration of soybean seeds and meal was between 0.55 and 0.65%, and around 1.1% for rapeseed meal. Rapeseed meal had a twofold higher ratio of total P to nitrogen concentration as compared to soybean which could be considered adverse when the meal is used for feeding livestock.

scholarly journals Evaluating the Impact of Two Generalist Predators on the Leafhopper Erasmoneura vulnerata Population Density

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 321
Author(s):  
Stefan Cristian Prazaru ◽  
Giulia Zanettin ◽  
Alberto Pozzebon ◽  
Paola Tirello ◽  
Francesco Toffoletto ◽  
...  
Keyword(s):  
Field Experiments ◽  
Field Studies ◽  
Generalist Predators ◽  
Predator Species ◽  
Potted Plants ◽  
Naturally Occurring ◽  
Orius Majusculus ◽  
Limited Effectiveness ◽  
Pest Outbreaks ◽  
The Impact

Outbreaks of the Nearctic leafhopper Erasmoneura vulnerata represent a threat to vinegrowers in Southern Europe, in particular in North-eastern Italy. The pest outbreaks are frequent in organic vineyards because insecticides labeled for organic viticulture show limited effectiveness towards leafhoppers. On the other hand, the naturally occurring predators and parasitoids of E. vulnerata in vineyards are often not able to keep leafhopper densities at acceptable levels for vine-growers. In this study, we evaluated the potential of two generalist, commercially available predators, Chrysoperla carnea and Orius majusculus, in suppressing E. vulnerata. Laboratory and semi-field experiments were carried out to evaluate both species’ predation capacity on E. vulnerata nymphs. The experiments were conducted on grapevine leaves inside Petri dishes (laboratory) and on potted and caged grapevines (semi-field); in both experiments, the leaves or potted plants were infested with E. vulnerata nymphs prior to predator releases. Both predator species exhibited a remarkable voracity and significantly reduced leafhopper densities in laboratory and semi-field experiments. Therefore, field studies were carried out over two growing seasons in two vineyards. We released 4 O. majusculus adults and 30 C. carnea larvae per m2 of canopy. Predator releases in vineyards reduced leafhopper densities by about 30% compared to the control plots. Results obtained in this study showed that the two predators have a potential to suppress the pest density, but more research is required to define appropriate predator–prey release ratios and release timing. Studies on intraguild interactions and competition with naturally occurring predators are also suggested.

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