Low genetic connectivity in an estuarine fish with pelagic larvae

2008 ◽  
Vol 65 (2) ◽  
pp. 147-158 ◽  
Author(s):  
I R Bradbury ◽  
S E Campana ◽  
P Bentzen
Keyword(s):  
Gene Flow ◽  
Isolation By Distance ◽  
Spatial Scales ◽  
Genetic Connectivity ◽  
Estuarine Fish ◽  
Small Scale ◽  
Osmerus Mordax ◽  
Genetic Structuring ◽  
Rainbow Smelt ◽  
High Dispersal

We evaluated the spatial scale of metapopulation structure and genetic connectivity in rainbow smelt, Osmerus mordax, using eight microsatellite loci at 22 spawning locations throughout Newfoundland and Labrador. Consistent with low gene flow and limited dispersal, significant genetic structuring (FST ≈ 0.11) was present at small spatial scales (<200 km). Moreover, strong isolation by distance (IBD, P < 0.001, r2 = 0.47) was observed, which was linear at small scales and nonlinear at large distances (>200 km). We hypothesized that despite high dispersal potential associated with a pelagic larval stage, behaviours restricting gene flow may result in structuring at the estuary scale. Multidimensional scaling and neighbour-joining of multilocus genotypes indicate some bay-scale associations. However, a comparison of FST values and IBD residuals at both estuary and bay scales indicated low structure within and elevated structure among estuaries. Estuarine structuring was further supported by the presence of significant small-scale IBD within several coastal embayments (50–100 km), as well as Bayesian clustering consistent with estuarine-scale independence. Finally, estimates of dispersal based on the IBD relationship are consistent with local estuarine recruitment (<1.5 km·generation–1). We conclude that the unexpectedly high genetic structure observed is consistent with behavioral influences reducing dispersal, supporting previous work implicating active larval retention.

scholarly journals Gene-flow between populations of cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) is highly variable between years

2005 ◽  
Vol 95 (4) ◽  
pp. 381-392 ◽  
Author(s):  
K.D. Scott ◽  
K.S. Wilkinson ◽  
N. Lawrence ◽  
C.L. Lange ◽  
L.J. Scott ◽  
...  
Keyword(s):  
Gene Flow ◽  
Helicoverpa Armigera ◽  
Isolation By Distance ◽  
Resistance Management ◽  
Small Scale ◽  
Genetic Structuring ◽  
Long Distance ◽  
Helicoverpa Armígera ◽  
To Come ◽  
Average Gene

AbstractBoth large and small scale migrations of Helicoverpa armigera Hübner in Australia were investigated using AMOVA analysis and genetic assignment tests. Five microsatellite loci were screened across 3142 individuals from 16 localities in eight major cotton and grain growing regions within Australia, over a 38-month period (November 1999 to January 2003). From November 1999 to March 2001 relatively low levels of migration were characterized between growing regions. Substantially higher than average gene-flow rates and limited differentiation between cropping regions characterized the period from April 2001 to March 2002. A reduced migration rate in the year from April 2002 to March 2003 resulted in significant genetic structuring between cropping regions. This differentiation was established within two or three generations. Genetic drift alone is unlikely to drive genetic differentiation over such a small number of generations, unless it is accompanied by extreme bottlenecks and/or selection. Helicoverpa armigera in Australia demonstrated isolation by distance, so immigration into cropping regions is more likely to come from nearby regions than from afar. This effect was most pronounced in years with limited migration. However, there is evidence of long distance dispersal events in periods of high migration (April 2001–March 2002). The implications of highly variable migration patterns for resistance management are considered.

scholarly journals Genetic differentiation in an endangered and strongly philopatric, migrant shorebird

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nelli Rönkä ◽  
Veli-Matti Pakanen ◽  
Angela Pauliny ◽  
Robert L. Thomson ◽  
Kimmo Nuotio ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Environmental Changes ◽  
Isolation By Distance ◽  
Population Subdivision ◽  
Genetic Structuring ◽  
Long Distance ◽  
Mobile Species ◽  
High Dispersal ◽  
The Baltic

Abstract Background Populations living in fragmented habitats may suffer from loss of genetic variation and reduced between-patch dispersal, which are processes that can result in genetic differentiation. This occurs frequently in species with reduced mobility, whereas genetic differentiation is less common among mobile species such as migratory birds. The high dispersal capacity in the latter species usually allows for gene flow even in fragmented landscapes. However, strongly philopatric behaviour can reinforce relative isolation and the degree of genetic differentiation. The Southern Dunlin (Calidris alpina schinzii) is a philopatric, long-distance migratory shorebird and shows reduced dispersal between isolated breeding patches. The endangered population of the Southern Dunlin breeding at the Baltic Sea has suffered from habitat deterioration and fragmentation of coastal meadows. We sampled DNA across the entire population and used 12 polymorphic microsatellite loci to examine whether the environmental changes have resulted in genetic structuring and loss of variation. Results We found a pattern of isolation-by-distance across the whole Baltic population and genetic differentiation between local populations, even within the southern Baltic. Observed heterozygosity was lower than expected throughout the range and internal relatedness values were positive indicating inbreeding. Conclusions Our results provide long-term, empirical evidence for the theoretically expected links between habitat fragmentation, population subdivision, and gene flow. They also demonstrate a rare case of genetic differentiation between populations of a long-distance migratory species. The Baltic Southern Dunlin differs from many related shorebird species that show near panmixia, reflecting its philopatric life history and the reduced connectivity of its breeding patches. The results have important implications as they suggest that reduced connectivity of breeding habitats can threaten even long-distance migrants if they show strong philopatry during breeding. The Baltic Southern Dunlin warrants urgent conservation efforts that increase functional connectivity and gene flow between breeding areas.

Weak genetic structuring suggests historically high genetic connectivity among recently fragmented urban populations of the scincid lizard, Ctenotus fallens

2015 ◽  
Vol 63 (4) ◽  
pp. 279 ◽  
Author(s):  
Josef Krawiec ◽  
Siegfried L. Krauss ◽  
Robert A. Davis ◽  
Peter B. S. Spencer
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Large Population ◽  
Geographic Distance ◽  
Genetic Erosion ◽  
Genetic Connectivity ◽  
Genetic Structuring ◽  
Low Genetic Diversity ◽  
Population Sizes

Populations in fragmented urban remnants may be at risk of genetic erosion as a result of reduced gene flow and elevated levels of inbreeding. This may have serious genetic implications for the long-term viability of remnant populations, in addition to the more immediate pressures caused by urbanisation. The population genetic structure of the generalist skink Ctenotus fallens was examined using nine microsatellite markers within and among natural vegetation remnants within a highly fragmented urban matrix in the Perth metropolitan area in Western Australia. These data were compared with samples from a large unfragmented site on the edge of the urban area. Overall, estimates of genetic diversity and inbreeding within all populations were similar and low. Weak genetic differentiation, and a significant association between geographic and genetic distance, suggests historically strong genetic connectivity that decreases with geographic distance. Due to recent fragmentation, and genetic inertia associated with low genetic diversity and large population sizes, it is not possible from these data to infer current genetic connectivity levels. However, the historically high levels of gene flow that our data suggest indicate that a reduction in contemporary connectivity due to fragmentation in C. fallens is likely to result in negative genetic consequences in the longer term.

Divergent selection maintains adaptive differentiation despite high gene flow between sympatric rainbow smelt ecotypes (Osmerus mordax Mitchill)

2003 ◽  
Vol 12 (2) ◽  
pp. 315-330 ◽  
Author(s):  
Robert Saint-Laurent ◽  
Michel Legault ◽  
Louis Bernatchez
Keyword(s):  
Gene Flow ◽  
Divergent Selection ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
High Gene Flow ◽  
High Gene ◽  
Adaptive Differentiation

scholarly journals Living on the edge: how philopatry maintains adaptive potential

2013 ◽  
Vol 280 (1763) ◽  
pp. 20130305 ◽  
Author(s):  
Victor A. Stiebens ◽  
Sonia E. Merino ◽  
Christian Roder ◽  
Frédéric J. J. Chain ◽  
Patricia L. M. Lee ◽  
...  
Keyword(s):  
Gene Flow ◽  
Positive Association ◽  
Sea Turtle ◽  
Genetic Connectivity ◽  
Small Scale ◽  
Adaptive Potential ◽  
Loggerhead Sea Turtle ◽  
Local Adaptations ◽  
Population Sizes ◽  
Genomic Regions

Without genetic variation, species cannot cope with changing environments, and evolution does not proceed. In endangered species, adaptive potential may be eroded by decreased population sizes and processes that further reduce gene flow such as philopatry and local adaptations. Here, we focused on the philopatric and endangered loggerhead sea turtle ( Caretta caretta ) nesting in Cape Verde as a model system to investigate the link between adaptive potential and philopatry. We produced a dataset of three complementary genomic regions to investigate female philopatric behaviour (mitochondrial DNA), male-mediated gene flow (microsatellites) and adaptive potential (major histocompatibility complex, MHC). Results revealed genetically distinct nesting colonies, indicating remarkably small-scale philopatric behaviour of females. Furthermore, these colonies also harboured local pools of MHC alleles, especially at the margins of the population's distribution, which are therefore important reserves of additional diversity for the population. Meanwhile, directional male-mediated gene flow from the margins of distribution sustains the adaptive potential for the entire rookery. We therefore present the first evidence for a positive association between philopatry and locally adapted genomic regions. Contrary to expectation, we propose that philopatry conserves a high adaptive potential at the margins of a distribution, while asymmetric gene flow maintains genetic connectivity with the rest of the population.

scholarly journals Population structure and dispersal across small and large spatial scales in a direct developing marine isopod

2020 ◽  
Author(s):  
William S. Pearman ◽  
Sarah J. Wells ◽  
Olin K. Silander ◽  
Nikki E. Freed ◽  
James Dale
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Population Genetic ◽  
Isolation By Distance ◽  
Spatial Scales ◽  
Population Connectivity ◽  
Clear Pattern ◽  
Small Spatial Scale ◽  
Cook Strait ◽  
Genetic Break

AbstractMarine organisms generally exhibit one of two developmental modes: biphasic, with distinct adult and larval morphology, and direct development, in which larvae resemble adults. Developmental mode is thought to significantly influence dispersal, with direct developers expected to have much lower dispersal potential. However, in contrast to our relatively good understanding of dispersal and population connectivity for biphasic species, comparatively little is known about direct developers. In this study, we use a panel of 8,020 SNPs to investigate population structure and gene flow for a direct developing species, the New Zealand endemic marine isopod Isocladus armatus. On a small spatial scale (20 kms), gene flow between locations is extremely high and suggests an island model of migration. However, over larger spatial scales (600km), populations exhibit a clear pattern of isolation-by-distance. Because our sampling range is intersected by two well-known biogeographic barriers (the East Cape and the Cook Strait), our study provides an opportunity to understand how such barriers influence dispersal in direct developers. Our results indicate that I. armatus exhibits significant migration across these barriers, and suggests that ocean currents associated with these locations do not present a barrier to dispersal. Interestingly, we do find evidence of a north-south population genetic break occurring between Māhia and Wellington, two locations where there are no obvious biogeographic barriers between them. We conclude that developmental life history largely predicts dispersal in intertidal marine isopods. However, localised biogeographic processes can disrupt this expectation.

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

2018 ◽  
Vol 5 (5) ◽  
pp. 171532 ◽  
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.

scholarly journals Resolving natal tags using otolith geochemistry in an estuarine fish, rainbow smelt Osmerus mordax

2011 ◽  
Vol 433 ◽  
pp. 195-204 ◽  
Author(s):  
IR Bradbury ◽  
C DiBacco ◽  
SR Thorrold ◽  
PVR Snelgrove ◽  
SE Campana
Keyword(s):  
Estuarine Fish ◽  
Osmerus Mordax ◽  
Rainbow Smelt

scholarly journals Phylogeography of the Pacific Blueline Surgeonfish,Acanthurus nigroris, Reveals High Genetic Connectivity and a Cryptic Endemic Species in the Hawaiian Archipelago

2011 ◽  
Vol 2011 ◽  
pp. 1-17 ◽  
Author(s):  
Joseph D. DiBattista ◽  
Christie Wilcox ◽  
Matthew T. Craig ◽  
Luiz A. Rocha ◽  
Brian W. Bowen
Keyword(s):  
Gene Flow ◽  
Marine Protected Areas ◽  
Population Genetic ◽  
Spatial Scales ◽  
Genetic Connectivity ◽  
Species Pair ◽  
Hawaiian Archipelago ◽  
National Monument ◽  
Hawaiian Species ◽  
The Pacific

Understanding genetic connectivity is fundamental to the design of marine protected areas in the service of ecosystem-scale management. Here we evaluate such trends for a Pacific surgeonfish (Acanthurus nigroris;N=544) at two spatial scales: (1) within the Hawaiian archipelago, and (2) across the entire species range from the central to southwest Pacific. The mtDNA cytochromebdata reveal genetic divergence (d=0.041) between Hawaii and the rest of the Pacific range indicating a cryptic species pair, with one taxon endemic to Hawaii. Johnston Atoll, 1400 km SW of Hawaii, also has the Hawaiian species but is distinct from most Hawaiian locations in population genetic comparisons, indicating the limits of gene flow for this widespread reef species. No consistent population genetic differences were observed among Hawaiian sites or among the other Pacific island sites. We also detected a modest bias in gene flow from the southeast towards the northwest islands of the Hawaiian Archipelago, indicating that the Papahānaumokuākea Marine National Monument may be a recipient, rather than a source of propagules to replenish reef resources.

Landscape structure and climatic variation determine Atlantic salmon genetic connectivity in the Northwest Atlantic

2014 ◽  
Vol 71 (2) ◽  
pp. 246-258 ◽  
Author(s):  
Ian R. Bradbury ◽  
Lorraine C. Hamilton ◽  
Martha J. Robertson ◽  
Chuck E. Bourgeois ◽  
Atef Mansour ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Spatial Structure ◽  
Genetic Drift ◽  
Isolation By Distance ◽  
Spatial Scales ◽  
Spatial Diversity ◽  
Genetic Connectivity ◽  
Stepwise Multiple Regression ◽  
Adaptive Divergence ◽  
Management And Conservation

The identification of landscape or climatic correlates of genetic connectivity can reveal the processes that regulate spatial diversity and inform the management and conservation of exploited or endangered species. Increasingly, the role of local adaptation in regulating spatial structure is gaining recognition, though disentangling its influence from that of dispersal and genetic drift remains challenging. We examined genetic connectivity using 15 microsatellite loci in 3546 Atlantic salmon (Salmo salar) from 47 locations in Newfoundland and Labrador. Cluster analysis revealed regional associations, but examples of unexpectedly high divergence over small spatial scales (<50 km) or low divergence over large scales (>500 km) were common with little evidence of isolation by distance (R2 = 0.04). We evaluated the hypothesis that spatial structure is less influenced by straying and more by adaptation and (or) drift using sample-associated data on 22 landscape and climate variables and both stepwise multiple regression and redundancy analysis. Landscape variables explained ∼40% of the variation in spatial structure with freshwater habitat area as the largest determinant. Linkages were also observed with water chemistry and winter severity, supporting hypotheses of adaptive divergence. Overall, the results suggest Atlantic salmon populations are structured by extensive genetic drift and low rates of effective straying and demonstrate how a landscape genetics approach can inform wildlife management and conservation.

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