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.

scholarly journals North America Insect Invades the World: the Case of the Flood Mosquito, Aedes vexans (Diptera: Culicidae), from Mitochondrial DNA

2021 ◽  
Author(s):  
Jose Heriberto Vargas-Espinosa ◽  
Oscar Alexander Aguirre Obando
Keyword(s):  
Gene Flow ◽  
Gene Diversity ◽  
Isolation By Distance ◽  
Vector Competence ◽  
Coi Gene ◽  
West Nile Fever ◽  
Aedes Vexans ◽  
Genetic Structuring ◽  
Long Distance ◽  
Valley Fever

The flood mosquito, Aedes vexans (Diptera: Culicidae), native of Canada, and currently present in all continents, has a vector competence for 30 arboviruses, being responsible for transmitting diseases, like West Nile fever, Rift Valley fever, Saint Louis Encephalitis and Eastern Equine Encephalitis. Hence, knowing the structure and gene flow of A. vexans is important to develop adequate vector control strategies for this species. For this, from partial sequences of the mitochondrial COI gene available in Bold and GenBank, it was possible to determine the Haplotypic (Hd) and nucleotide (π) gene diversity, genetic structuring and gene flow at global, continental, and country levels. In total, 1184 sequences were recovered, distributed between America (88.60%), Europe (7.35%), Asia (3.89%), and Africa (0.17%). From these, 395 haplotypes (H) were detected without presence of pseudogenes (NUMTs), with H1 being the most frequent (24.58%) and between H12 - H395 the least frequent varying between 0.93% (H12) and 0.08% (H395). Phylogenetically, the haplotypes were grouped into six clades. Clade I grouped haplotypes from countries in America and Europe, while clades II and III presented haplotypes exclusively from Asia and Europe; clade IV grouped only one haplotype from Africa and the last ultimo clade V grouped haplotypes from America and Africa. The global Hd and π was 0.92 and 0.01, respectively. In addition, evidence was obtained of genetic structuring among continents (7.07%), countries (1.62%), and within countries (91.30%; FST = 0.08, p < 0.05) and no isolation by distance was detected (r = 0.003, p > 0.05). These results suggest that the mosquito populations that invaded other continents originate directly from the American continent, where possibly transcontinental commercial routes favored their long-distance dispersion.

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.

Genetic structure of Lycorma delicatula (Hemiptera: Fulgoridae) populations in Korea: implication for invasion processes in heterogeneous landscapes

2013 ◽  
Vol 103 (4) ◽  
pp. 414-424 ◽  
Author(s):  
Marana Park ◽  
Kyung-Seok Kim ◽  
Joon-Ho Lee
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
South Korea ◽  
Isolation By Distance ◽  
Assignment Test ◽  
Invasive Pest ◽  
Genetic Structuring ◽  
Long Distance ◽  
Heterogeneous Landscapes ◽  
Lycorma Delicatula

AbstractLycorma delicatula (White) was identified in 2004 as an invasive pest in South Korea, where it causes serious damage to vineyard crops. To investigate the population structure and dispersal pattern of L. delicatula in South Korea, we estimated the population genetic structure and gene flow among nine locations across the country using seven microsatellite markers. Although L. delicatula spread throughout most of its geographical range in South Korea within 5–7 years following invasion, its populations show evidence of genetic structuring across the range with a low but significant global FST (genetic differentiation across all populations) of 0.0474. Bayesian-based clustering analysis indicates the presence of at least three genetically unique populations in South Korea, including populations in northeastern South Korea, which show a distinct genetic background. However, isolation by distance suggests that populations in South Korea have not yet reached genetic equilibrium. Estimates of the historical rate of gene flow (Nem) indicate that relatively high rates of flow have been maintained among populations within the western region, which may indicate recent range expansion. A population assignment test using the first-generation migrant detection method suggested that long-distance dispersal of L. delicatula may have occurred over large areas of South Korea. More complex dispersal patterns may have occurred during L. delicatula invasion of heterogeneous landscapes in South Korea.

Population Dynamics and Gene Flow of Helicoverpa armigera (Lepidoptera: Noctuidae) on Cotton and Grain Crops in the Murrumbidgee Valley, Australia

2006 ◽  
Vol 99 (1) ◽  
pp. 155-163 ◽  
Author(s):  
Leon J. Scott ◽  
Nicole Lawrence ◽  
Corinna L. Lange ◽  
Glenn C. Graham ◽  
Scott Hardwick ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Gene Flow ◽  
Helicoverpa Armigera ◽  
Grain Crops ◽  
Helicoverpa Armígera ◽  
Lepidoptera Noctuidae

scholarly journals Spatial population genomics of a recent mosquito invasion

2020 ◽  
Author(s):  
Thomas L Schmidt ◽  
T. Swan ◽  
Jessica Chung ◽  
Stephan Karl ◽  
Samuel Demok ◽  
...  
Keyword(s):  
Gene Flow ◽  
Population Genomics ◽  
Isolation By Distance ◽  
Spatial Genetic Structure ◽  
Nucleotide Polymorphisms ◽  
Discrete Events ◽  
Long Distance ◽  
Population Genomic ◽  
Asian Tiger ◽  
Study Designs

AbstractPopulation genomic approaches can characterise dispersal across a single generation through to many generations in the past, bridging the gap between individual movement and intergenerational gene flow. These approaches are particularly useful when investigating dispersal in recently altered systems, where they provide a way of inferring long-distance dispersal between newly established populations and their interactions with existing populations. Human-mediated biological invasions represent such altered systems which can be investigated with appropriate study designs and analyses. Here we apply temporally-restricted sampling and a range of population genomic approaches to investigate dispersal in a 2004 invasion of Aedes albopictus (the Asian tiger mosquito) in the Torres Strait Islands (TSI) of Australia. We sampled mosquitoes from 13 TSI villages simultaneously and genotyped 373 mosquitoes at genome-wide single nucleotide polymorphisms (SNPs): 331 from the TSI, 36 from Papua New Guinea (PNG), and 4 incursive mosquitoes detected in uninvaded regions. Within villages, spatial genetic structure varied substantially but overall displayed isolation by distance and a neighbourhood size of 232–577. Close kin dyads revealed recent movement between islands 31–203 km apart, and deep learning inferences showed incursive Ae. albopictus had travelled to uninvaded regions from both adjacent and non-adjacent islands. Private alleles and a coancestry matrix indicated direct gene flow from PNG into nearby islands. Outlier analyses also detected four linked alleles introgressed from PNG, with the alleles surrounding 12 resistance-associated cytochrome P450 genes. By treating dispersal as both an intergenerational process and a set of discrete events, we describe a highly interconnected invasive system.

scholarly journals Pollen-mediated gene flow ensures connectivity among spatially discrete sub-populations of Phalaenopsis pulcherrima, a tropical food-deceptive orchid

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Zhe Zhang ◽  
Stephan W. Gale ◽  
Ji-Hong Li ◽  
Gunter A. Fischer ◽  
Ming-Xun Ren ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Polynomial Regression ◽  
Genetic Erosion ◽  
Population Level ◽  
Hainan Island ◽  
Paternity Analysis ◽  
Genetic Structuring ◽  
Long Distance ◽  
High Genetic Diversity

Abstract Background Gene flow in plants via pollen and seeds is asymmetrical at different geographic scales. Orchid seeds are adapted to long-distance wind dispersal but pollinium transfer is often influenced by pollinator behavior. We combined field studies with an analysis of genetic diversity among 155 physically mapped adults and 1105 F1 seedlings to evaluate the relative contribution of pollen and seed dispersal to overall gene flow among three sub-populations of the food-deceptive orchid Phalaenopsis pulcherrima on Hainan Island, China. Results Phalaenopsis pulcherrima is self-sterile and predominantly outcrossing, resulting in high population-level genetic diversity, but plants are clumped and exhibit fine-scale genetic structuring. Even so, we detected low differentiation among sub-populations, with polynomial regression analysis suggesting gene flow via seed to be more restricted than that via pollen. Paternity analysis confirmed capsules of P. pulcherrima to each be sired by a single pollen donor, probably in part facilitated by post-pollination stigma obfuscation, with a mean pollen flow distance of 272.7 m. Despite limited sampling, we detected no loss of genetic diversity from one generation to the next. Conclusions Outcrossing mediated by deceptive pollination and self-sterility promote high genetic diversity in P. pulcherrima. Long-range pollinia transfer ensures connectivity among sub-populations, offsetting the risk of genetic erosion at local scales.

Section 1. The Australian insecticide resistance management strategy

1993 ◽  
Vol 1 ◽  
pp. 1-4 ◽  
Author(s):  
Neil W. Forrester ◽  
Matthew Cahill ◽  
Lisa J. Bird ◽  
Jacquelyn K. Layland
Keyword(s):  
Insecticide Resistance ◽  
Helicoverpa Armigera ◽  
Pyrethroid Resistance ◽  
Resistance Management ◽  
Grain Legumes ◽  
Pest Species ◽  
Insecticide Resistance Management ◽  
Eastern Australia ◽  
Helicoverpa Armígera ◽  
Chemical Groups

SummaryIn response to field pyrethroid failures against Helicoverpa armigera (Hübner) in early 1983, an insecticide resistance management (IRM) strategy was introduced for insect control in summer crops in eastern Australia. The aims of this strategy were to contain the pyrethroid resistance problem, to prevent re-selection of historical endosulfan resistance (both curative IRM) and to avoid any future problems with organophosphate/carbamate resistance (preventative IRM). An alternation strategy was adopted which was based on the rotation of unrelated chemical groups on a per generation basis, along with a strong recommendation for the use of ovicidal mixtures. These chemical countermeasures were then integrated with other non-chemical control methods (biological and cultural) into a workable integrated pest management programme. The restrictions were applied to all Helicoverpa armigera susceptible crops (including cereals, oilseeds, grain legumes, tomatoes, tobacco and cotton) and even to other co-incident pest species. From its inception, compliance with the voluntary strategy has been exceptional.

scholarly journals Evidence for facultative migratory flight behavior in Helicoverpa armigera (Noctuidae: Lepidoptera) in India

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245665
Author(s):  
Patil Jyothi ◽  
Prabhuraj Aralimarad ◽  
Vijaya Wali ◽  
Shivansh Dave ◽  
M. Bheemanna ◽  
...  
Keyword(s):  
Helicoverpa Armigera ◽  
Significant Proportion ◽  
Danaus Plexippus ◽  
Flight Behavior ◽  
Wing Loading ◽  
Long Distance ◽  
Migratory Flight ◽  
Helicoverpa Armígera ◽  
Single Night ◽  
Polyphagous Insect

Despite its deleterious impact on farming and agriculture, the physiology and energetics of insect migration is poorly understood due to our inability to track their individual movements in the field. Many insects, e.g. monarch butterflies, Danaus plexippus (L.), are facultative migrants. Hence, it is important to establish whether specific insect populations in particular areas migrate. The polyphagous insect, Helicoverpa armigera (Hübner), is especially interesting in this regard due to its impact on a variety of crops. Here, we used a laboratory-based flight mill assay to show that Helicoverpa armigera populations clearly demonstrate facultative migration in South India. Based on various flight parameters, we categorized male and female moths as long, medium or short distance fliers. A significant proportion of moths exhibited long-distance flight behavior covering more than 10 km in a single night, averaging about 8 flight hours constituting 61% flight time in the test period. The maximum and average flight speeds of these long fliers were greater than in the other categories. Flight activity across sexes also varied; male moths exhibited better performance than female moths. Wing morphometric parameters including forewing length, wing loading, and wing aspect ratio were key in influencing long-distance flight. Whereas forewing length positively correlated with flight distance and duration, wing loading was negatively correlated.

Do lowland habitats represent barriers to dispersal for a rainforest mayfly, Bungona narilla, in south-east Queensland?

2008 ◽  
Vol 59 (9) ◽  
pp. 761 ◽  
Author(s):  
Alison J. McLean ◽  
Daniel J. Schmidt ◽  
Jane M. Hughes
Keyword(s):  
Gene Flow ◽  
Aquatic Insect ◽  
Restricted Gene Flow ◽  
Long Distance Dispersal ◽  
Genetic Structuring ◽  
Long Distance ◽  
Heterogeneous Landscapes ◽  
Insect Populations ◽  
Dispersal Events ◽  
The Relationship

Long-distance dispersal might be an important mechanism for the maintenance of aquatic insect populations in heterogeneous landscapes. However, these events can be difficult to measure by direct observation because the techniques can be time-consuming, expensive and technically difficult. When dispersal results in gene flow within and between populations, patterns of variation can be detected by genetic methods. The levels of population genetic structuring and the relationship between gene flow and geographical distance were assessed in the mayfly species Bungona narilla (Harker, 1957) in rainforest streams in south-east Queensland that are separated by lowland habitats. An analysis of molecular variance based on mitochondrial DNA data, using a fragment of the cytochrome oxidase I gene, revealed significant differentiation between regions, suggesting that maternal gene flow was restricted. A nested clade analysis revealed patterns of historical (contiguous) range expansions and recent restricted gene flow along with some long-distance dispersal events. Our analyses have shown that populations of B. narilla are significantly structured throughout the species range in south-east Queensland and that the low elevation habitats separating the northern and southern populations are restricting gene flow to some extent.

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