scholarly journals Genetic differentiation in Scottish populations of the pine beauty moth, Panolis flammea (Lepidoptera: Noctuidae)

2005 ◽  
Vol 95 (6) ◽  
pp. 517-526 ◽  
Author(s):  
A.J. Lowe ◽  
B.J. Hicks ◽  
K. Worley ◽  
R.A. Ennos ◽  
J.D. Morman ◽  
...  
Keyword(s):  
Genetic Differentiation ◽  
Scots Pine ◽  
Rapd Analysis ◽  
Isolation By Distance ◽  
Long Distance ◽  
Panolis Flammea ◽  
Colonization Dynamics ◽  
Low Levels ◽  
Lepidoptera Noctuidae ◽  
Limited Exchange

AbstractPine beauty moth, Panolis flammea (Denis & Schiffermüller), is a recent but persistent pest of lodgepole pine plantations in Scotland, but exists naturally at low levels within remnants and plantations of Scots pine. To test whether separate host races occur in lodgepole and Scots pine stands and to examine colonization dynamics, allozyme, randomly amplified polymorphic DNA (RAPD) and mitochondrial variation were screened within a range of Scottish samples. RAPD analysis indicated limited long distance dispersal (FST = 0.099), and significant isolation by distance (P < 0.05); but that colonization between more proximate populations was often variable, from extensive to limited exchange. When compared with material from Germany, Scottish samples were found to be more diverse and significantly differentiated for all markers. For mtDNA, two highly divergent groups of haplotypes were evident, one group contained both German and Scottish samples and the other was predominantly Scottish. No genetic differentiation was evident between P. flammea populations sampled from different hosts, and no diversity bottleneck was observed in the lodgepole group. Indeed, lodgepole stands appear to have been colonized on multiple occasions from Scots pine sources and neighbouring populations on different hosts are close to panmixia.

scholarly journals Genetic structure and dispersal patterns of the invasive psocid Liposcelis decolor (Pearman) in Australian grain storage systems

2010 ◽  
Vol 100 (5) ◽  
pp. 521-527 ◽  
Author(s):  
K.M. Mikac ◽  
N.N. FitzSimmons
Keyword(s):  
Genetic Structure ◽  
Isolation By Distance ◽  
Geographic Distance ◽  
Allelic Diversity ◽  
Mantel Test ◽  
Null Alleles ◽  
Dispersal Patterns ◽  
Long Distance ◽  
Population Comparisons ◽  
Low Levels

AbstractMicrosatellite markers were used to investigate the genetic structure among invasive L. decolor populations from Australia and a single international population from Kansas, USA to determine patterns of dispersal. Six variable microsatellites displayed an average of 2.5–4.2 alleles per locus per population. Observed (HO) heterozygosity ranged from 0.12–0.65 per locus within populations; but, in 13 of 36 tests, HO was less than expected. Despite low levels of allelic diversity, genetic structure estimated as θ was significant for all pairwise comparisons between populations (θ=0.05–0.23). Due to suspected null alleles at four loci, ENA (excluding null alleles) corrected FST estimates were calculated overall and for pairwise population comparisons. The ENA-corrected FST values (0.02–0.10) revealed significant overall genetic structure, but none of the pairwise values were significantly different from zero. A Mantel test of isolation by distance indicated no relationship between genetic structure and geographic distance among all populations (r2=0.12, P=0.18) and for Australian populations only (r2=0.19, P=0.44), suggesting that IBD does not describe the pattern of gene flow among populations. This study supports a hypothesis of long distance dispersal by L. decolor at moderate to potentially high levels.

scholarly journals Genetic Structure of Cronartium ribicola Populations in Eastern Canada

1999 ◽  
Vol 89 (10) ◽  
pp. 915-919 ◽  
Author(s):  
K. Et-touil ◽  
L. Bernier ◽  
J. Beaulieu ◽  
J. A. Bérubé ◽  
A. Hopkin ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Genetic Differentiation ◽  
Distribution Systems ◽  
Gene Diversity ◽  
Isolation By Distance ◽  
Random Amplified Polymorphic Dna ◽  
Cronartium Ribicola ◽  
Eastern Canada ◽  
Long Distance ◽  
Evolutionary Forces

The genetic structure of populations of Cronartium ribicola was studied by sampling nine populations from five provinces in eastern Canada and generating DNA profiles using nine random amplified polymorphic DNA markers. Most of the total gene diversity (Ht = 0.386) was present within populations (Hw = 0.370), resulting in a low level of genetic differentiation among populations in northeastern North America (Fst = 0.062). A hierarchical analysis of genetic structure using an analysis of molecular variance (AMOVA) revealed no statistically significant genetic differentiation among provinces or among regions. Yet, genetic differentiation among populations within regions or provinces was small (AMOVA φst = 0.078) but statistically significant (P < 0.001) and was several orders of magnitude larger than differentiation among provinces. This is consistent with a scenario of subpopulations within a metapopulation, in which random drift following migration and new colonization are major evolutionary forces. A phenetic analysis using genetic distances revealed no apparent correlation between genetic distance and the province of origin of the populations. The hypothesis of isolation-by-distance in the eastern populations of C. ribicola was rejected by computing Mantel correlation coefficients between genetic and geographic distance matrices (P > 0.05). These results show that eastern Canadian provinces are part of the same white pine blister rust epidemiological unit. Nursery distribution systems are controlled provincially, with virtually no seedling movement among provinces; therefore, infected nursery material may not play an important role in the dissemination of this disease. Long-distance spore dispersal across provincial boundaries appears to be an epidemiologically important factor for this pathogen.

Genetic diversity and structure of the treeManilkara zapotain a naturally fragmented tropical forest

2017 ◽  
Vol 33 (4) ◽  
pp. 285-294 ◽  
Author(s):  
Daniela A. Martínez-Natarén ◽  
Víctor Parra-Tabla ◽  
Miguel A. Munguía-Rosas
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Tropical Forest ◽  
Isolation By Distance ◽  
Allelic Diversity ◽  
Long Distance ◽  
Population Genetic Differentiation ◽  
Continuous Forest ◽  
Genetic Diversity And Structure ◽  
Degree Of Isolation

Abstract:Forest fragmentation, habitat loss and isolation may have a strong effect on biodiversity in tropical forests. This can include modification of the genetic diversity and structure of plant populations. In this study, we assessed the genetic diversity and structure of the treeManilkara zapotain 15 naturally formed fragments of semi-evergreen tropical forest, as well as in an adjacent continuous forest for comparison. Forest fragments were scattered within a matrix of wetlands and were highly variable in terms of size and degree of isolation. The naturally fragmented populations ofM.zapotahad slightly less allelic diversity (Ar: 3.4) than those of the continuous forest (Ar: 3.6), when corrected for sample size. However, populations in the fragments and continuous forest had very similar heterozygosity levels (HE: 0.59 in both cases). Low levels of genetic differentiation were observed among populations (FST: 0.026) and genetic structure was not consistent with isolation by distance, indicating high levels of gene flow. Genetic diversity was not explained by fragment size or degree of isolation. The relatively high genetic diversity and low inter-population genetic differentiation observed inM. zapotamay be the result of long-distance pollen and seed dispersal, as well as the high proximity among patches.

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 Crawling to connectivity? The direct-developing journey of the spotted whelk (Cominella maculosa)

2021 ◽  
Author(s):  
◽  
Melanie Dohner
Keyword(s):  
Genetic Differentiation ◽  
Isolation By Distance ◽  
Alternative Methods ◽  
Coi Gene ◽  
Genetic Connectivity ◽  
Small Scale ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Ecological Scale ◽  
Genetic Patterns

<p>The exchange of individuals between populations influences demographic connectivity on the ecological scale and genetic connectivity on the evolutionary scale. In some circumstances there are similarities between demographic and genetic connectivity, but in others there are differences. Whenever genetic differentiation is found between populations demographic uncoupling can also be inferred, but when gene flow is found there is uncertainty about whether populations are demographically connected or not. Marine invertebrates typically have large population sizes and many opportunities for dispersal. However, species that have limited planktonic dispersal power are often characterized by genetically and demographically discrete populations that exhibit an isolation-by-distance (IBD) pattern of gene distribution. Alternative methods of dispersal, such as rafting or drifting, produce departures from this expected pattern for species lacking planktonic larvae. Examining genetic patterns at fine geographic scales can identify key dispersal barriers and may give clues to alternative dispersal methods influencing large scale processes.  The endemic, direct-developing spotted whelk, Cominella maculosa, is found in the intertidal rocky shores throughout most of New Zealand. This distribution makes it ideal for studying a species expected to exhibit low realized dispersal by crawling and is unlikely to experience dispersal by rafting. The first aim of this study was to investigate genetic patterns between two genetically distinct populations along the Wairarapa Coast of the North Island to determine if a barrier to dispersal was present or if the expected IBD pattern was observed. The second aim was to determine the likelihood of individual hatchlings undertaking long distance dispersal by drifting in the water column. The mitochondrial DNA COI gene was sequenced using 324 whelk samples collected at seven sites along 125 km of Wairarapa shoreline. No significant level of genetic isolation-by-distance or discontinuity in haplotype distribution was observed. Instead, two sites in the middle of the region form a contact area where the dominant northern and southern haplotypes coexist. To investigate dispersal by drifting in the water, three experimental trials were conducted with hatchlings obtained from field-collected egg capsules. When subjected to wave forces, or deposited directly in flow, hatchlings remained suspended and were carried a short distance. However, hatchlings circulated in currents and left for a longer period (12 hours) were rarely found drifting after this period. These trials indicate that wave dislodgement and local flow regime may result in small-scale displacement of hatchlings, but long-distance dispersal by drift is unlikely. Plankton sampling was also conducted at two sites with four nearshore traps. The rare capture of a related Cominella virgata hatchling supports the finding that hatchlings can be dislodged, but prolonged drift cannot be inferred. The findings from this study support the assumption that crawling is the dominant dispersal mechanism for C. maculosa. Crawling between sites best explains the blending of haplotypes in the middle of the Wairarapa and the genetic differentiation between populations. Crawling-mediated connectivity is unlikely to occur at the ecological scale; therefore populations are expected to be demographically isolated. The results of this research support the general findings in the literature that populations of direct developing species are often demographically isolated and have low levels of genetic connectivity.</p>

scholarly journals Crawling to connectivity? The direct-developing journey of the spotted whelk (Cominella maculosa)

2021 ◽  
Author(s):  
◽  
Melanie Dohner
Keyword(s):  
Genetic Differentiation ◽  
Isolation By Distance ◽  
Alternative Methods ◽  
Coi Gene ◽  
Genetic Connectivity ◽  
Small Scale ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Ecological Scale ◽  
Genetic Patterns

<p>The exchange of individuals between populations influences demographic connectivity on the ecological scale and genetic connectivity on the evolutionary scale. In some circumstances there are similarities between demographic and genetic connectivity, but in others there are differences. Whenever genetic differentiation is found between populations demographic uncoupling can also be inferred, but when gene flow is found there is uncertainty about whether populations are demographically connected or not. Marine invertebrates typically have large population sizes and many opportunities for dispersal. However, species that have limited planktonic dispersal power are often characterized by genetically and demographically discrete populations that exhibit an isolation-by-distance (IBD) pattern of gene distribution. Alternative methods of dispersal, such as rafting or drifting, produce departures from this expected pattern for species lacking planktonic larvae. Examining genetic patterns at fine geographic scales can identify key dispersal barriers and may give clues to alternative dispersal methods influencing large scale processes.  The endemic, direct-developing spotted whelk, Cominella maculosa, is found in the intertidal rocky shores throughout most of New Zealand. This distribution makes it ideal for studying a species expected to exhibit low realized dispersal by crawling and is unlikely to experience dispersal by rafting. The first aim of this study was to investigate genetic patterns between two genetically distinct populations along the Wairarapa Coast of the North Island to determine if a barrier to dispersal was present or if the expected IBD pattern was observed. The second aim was to determine the likelihood of individual hatchlings undertaking long distance dispersal by drifting in the water column. The mitochondrial DNA COI gene was sequenced using 324 whelk samples collected at seven sites along 125 km of Wairarapa shoreline. No significant level of genetic isolation-by-distance or discontinuity in haplotype distribution was observed. Instead, two sites in the middle of the region form a contact area where the dominant northern and southern haplotypes coexist. To investigate dispersal by drifting in the water, three experimental trials were conducted with hatchlings obtained from field-collected egg capsules. When subjected to wave forces, or deposited directly in flow, hatchlings remained suspended and were carried a short distance. However, hatchlings circulated in currents and left for a longer period (12 hours) were rarely found drifting after this period. These trials indicate that wave dislodgement and local flow regime may result in small-scale displacement of hatchlings, but long-distance dispersal by drift is unlikely. Plankton sampling was also conducted at two sites with four nearshore traps. The rare capture of a related Cominella virgata hatchling supports the finding that hatchlings can be dislodged, but prolonged drift cannot be inferred. The findings from this study support the assumption that crawling is the dominant dispersal mechanism for C. maculosa. Crawling between sites best explains the blending of haplotypes in the middle of the Wairarapa and the genetic differentiation between populations. Crawling-mediated connectivity is unlikely to occur at the ecological scale; therefore populations are expected to be demographically isolated. The results of this research support the general findings in the literature that populations of direct developing species are often demographically isolated and have low levels of genetic connectivity.</p>

Pollen as an Indicator of Long-distance Movement of Heliothis zea (Lepidoptera: Noctuidae)

1987 ◽  
Vol 16 (5) ◽  
pp. 1148-1151 ◽  
Author(s):  
W. H. Hendrix ◽  
T. F. Mueller ◽  
J. R. Phillips ◽  
O. K. Davis
Keyword(s):  
Heliothis Zea ◽  
Long Distance ◽  
Long Distance Movement ◽  
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 Population genetic structure and variability in Lindera glauca (Lauraceae) indicates low levels of genetic diversity and skewed sex ratios in natural populations in mainland China

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8304 ◽  
Author(s):  
Biao Xiong ◽  
Limei Zhang ◽  
Shubin Dong ◽  
Zhixiang Zhang
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Isolation By Distance ◽  
Sex Ratios ◽  
Mainland China ◽  
Small Sample ◽  
Chloroplast Microsatellites ◽  
Wild Populations ◽  
Haplotype Networks ◽  
Low Levels

Lindera glauca (Lauraceae) is a tree of economic and ecological significance that reproduces sexually and asexually via apomictic seeds. It is widely distributed in the low-altitude montane forests of East Asia. Despite the potential implications of a mixed reproductive system in terms of genetic diversity, few studies have focused on this aspect. In this study, the genetic structure of wild populations of L. glauca was investigated via genetic analyses. Overall, 13 nuclear microsatellites (nSSRs) and five chloroplast microsatellites (cpSSRs) were used to genotype 300 individual plants, taken from 20 wild populations (a small sample size in some wild populations is due to the limitation of its specific reproduction, leading to certain limitations in the results of this study) and two cultivated populations ranging across nearly the entire natural distribution of mainland China. The populations exhibited low levels of genetic diversity (nSSR: AR = 1.75, Ho = 0.32, He = 0.36; cpSSR: Nb = 2.01, Hrs = 0.40), and no significant effect of isolation by distance between populations existed, regardless of marker type (nSSR: R2 = 0.0401, P = 0.068; cpSSR: R2 = 0.033, P = 0.091). Haplotype networks showed complex relationships among populations, and the H12 haplotype was predominant in most populations. Analyses of molecular variance obtained with nuclear markers (Fsc = 0.293, FST = 0.362) and chloroplast markers (Fsc = 0.299, FST = 0.312) were similar. The migration ratio of pollen flow versus seed flow in this study was negative (r = −1.149). Results suggest that weak barriers of dispersal between populations and/or the similarity of founders shared between neighbors and distant populations are indicative of the gene flow between populations more likely involving seeds. Wild L. glauca in mainland China was inferred to have highly skewed sex ratios with predominant females. In addition, some populations experienced a recent bottleneck effect, especially in Gujianshan, Chongqing, and southwest China (population GJS). It is suggested that few wild male individuals should be conserved in order to maintain overall genetic diversity in the wild populations of this species. These findings provide important information for the sustainable utilization and preservation of the overall genetic diversity of L. glauca.

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