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>

scholarly journals Genetic structure and long-distance dispersal in populations of the wingless pest springtail, Sminthurus viridis (Collembola: Sminthuridae)

2011 ◽  
Vol 93 (1) ◽  
pp. 1-12 ◽  
Author(s):  
JOHN M. K. ROBERTS ◽  
ANDREW R. WEEKS
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
Cytochrome Oxidase ◽  
Isolation By Distance ◽  
Control Strategies ◽  
Single Species ◽  
Coi Gene ◽  
Effective Control ◽  
Long Distance Dispersal ◽  
Long Distance

SummaryThe lucerne flea, Sminthurus viridis (Collembola: Sminthuridae) (L.) is a major pest of broadacre agriculture across southern Australia. Few molecular studies have been conducted on S. viridis and none have examined its population genetics, despite the importance for developing effective control strategies. Here, we characterize the genetic structure of Australian populations using three allozyme and eight microsatellite loci, as well as sequencing a fragment of the mitochondrial DNA cytochrome oxidase I gene. We found that S. viridis in Australia are diploid, sexually reproducing and exhibit significant population structure as a result of limited gene flow. Despite significant differentiation between populations, there was very low cytochrome oxidase subunit I (COI) gene sequence variation, indicating the presence of a single species in Australia. The observed structure only marginally complied with an ‘isolation by distance’ model with human-mediated long-distance dispersal likely occurring. Allozymes and microsatellites gave very similar FST estimates, although differences found for novel alternative estimates of differentiation suggest that the allozymes did not capture the full extent of the population structure. These results highlight that control strategies may need to vary for locally adapted S. viridis populations and strategies aimed at limiting the spread of any future pesticide resistance will need to manage the effects of human-mediated dispersal.

scholarly journals Phylogeography of the oyster borer (Haustrum scobina)

2021 ◽  
Author(s):  
◽  
Sebastian Logan
Keyword(s):  
New Zealand ◽  
Dna Sequences ◽  
Population Genetic ◽  
Isolation By Distance ◽  
Haplotype Diversity ◽  
Genetic Connectivity ◽  
Long Distance Dispersal ◽  
Genetic Structuring ◽  
Long Distance ◽  
Ecological Processes

<p>An effective investigation of the underlying ecological processes that shape genetic diversity and connectivity typically requires comparisons among phylogeographic studies of multiple species. Phylogeographic studies of New Zealand’s coastal marine benthos have historically relied on post hoc speculation rather than directed research questions to investigate ecological processes. There has also been a lack of studies on direct developing marine molluscs. Direct developers are expected to have a low potential for dispersal and thus show a pattern of genetic isolation by distance across their distributions. Recent research indicates that this assumption may frequently be violated by instances of long distance dispersal/translocation. The oyster borer (Haustrum scobina) is an endemic direct-developing marine mollusc found in high abundances at rocky intertidal environments across the entirety of New Zealand. This distribution and life history makes H. scobina an ideal target to study genetic connectivity in a species expected to show low realised dispersal and high population genetic structuring. This thesis research used 379 new DNA sequences from the mitochondrial gene cytochrome c oxidase subunit 1 (COI) to investigate the phylogeography of H. scobina across the southern North Island. In addition 16 new COI sequences were inadvertently sequenced from the morphologically similar congener Haustrum albomarginatum. Results from both species support the recently proposed division of H. scobina and H. albomarginatum as separate species. H. scobina populations show significant geographic structure and a lack of haplotype diversity across the south-eastern North Island concordant with results of another previous study of a direct developer. This finding suggests that ecological processes may be producing similar population genetic structures for direct developers generally. Contrast between high and low haplotype diversities in northern and southern H. scobina populations respectively, indicates that southern H. scobina populations may have originated via recolonisation from northern populations following a range contraction during the Last Glacial Maximum. Evidence of multiple long distance dispersal/translocation events was found indicating that long distance dispersal via rafting and/or inadvertent human-mediated translocations may have occurred frequently. Results are then discussed with a view to inform further research in to New Zealand direct developers.</p>

scholarly journals Phylogeography of the oyster borer (Haustrum scobina)

2021 ◽  
Author(s):  
◽  
Sebastian Logan
Keyword(s):  
New Zealand ◽  
Dna Sequences ◽  
Population Genetic ◽  
Isolation By Distance ◽  
Haplotype Diversity ◽  
Genetic Connectivity ◽  
Long Distance Dispersal ◽  
Genetic Structuring ◽  
Long Distance ◽  
Ecological Processes

<p>An effective investigation of the underlying ecological processes that shape genetic diversity and connectivity typically requires comparisons among phylogeographic studies of multiple species. Phylogeographic studies of New Zealand’s coastal marine benthos have historically relied on post hoc speculation rather than directed research questions to investigate ecological processes. There has also been a lack of studies on direct developing marine molluscs. Direct developers are expected to have a low potential for dispersal and thus show a pattern of genetic isolation by distance across their distributions. Recent research indicates that this assumption may frequently be violated by instances of long distance dispersal/translocation. The oyster borer (Haustrum scobina) is an endemic direct-developing marine mollusc found in high abundances at rocky intertidal environments across the entirety of New Zealand. This distribution and life history makes H. scobina an ideal target to study genetic connectivity in a species expected to show low realised dispersal and high population genetic structuring. This thesis research used 379 new DNA sequences from the mitochondrial gene cytochrome c oxidase subunit 1 (COI) to investigate the phylogeography of H. scobina across the southern North Island. In addition 16 new COI sequences were inadvertently sequenced from the morphologically similar congener Haustrum albomarginatum. Results from both species support the recently proposed division of H. scobina and H. albomarginatum as separate species. H. scobina populations show significant geographic structure and a lack of haplotype diversity across the south-eastern North Island concordant with results of another previous study of a direct developer. This finding suggests that ecological processes may be producing similar population genetic structures for direct developers generally. Contrast between high and low haplotype diversities in northern and southern H. scobina populations respectively, indicates that southern H. scobina populations may have originated via recolonisation from northern populations following a range contraction during the Last Glacial Maximum. Evidence of multiple long distance dispersal/translocation events was found indicating that long distance dispersal via rafting and/or inadvertent human-mediated translocations may have occurred frequently. Results are then discussed with a view to inform further research in to New Zealand direct developers.</p>

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.

Managing Spread from Rhizome Fragments is Key to Reducing Invasiveness in Miscanthus × giganteus

2014 ◽  
Vol 7 (3) ◽  
pp. 517-525 ◽  
Author(s):  
Natalie M. West ◽  
David P. Matlaga ◽  
Adam S. Davis
Keyword(s):  
Agricultural Landscape ◽  
Propagule Pressure ◽  
Ecological Integrity ◽  
Low Risk ◽  
Small Scale ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Biofuel Crops ◽  
Combining Data ◽  
Field Edge

AbstractMiscanthus × giganteus, a widely planted biofeedstock, is generally regarded as a relatively low invasion concern. As a seed-infertile species, it lacks a consistent mechanism of long-distance dispersal, a key contributor to invasion rate, and constitutes a low risk for cultivation escape. However, agricultural production shelters plants from stochasticity and increases propagule pressure, enhancing the potential for low-risk species to take advantage of rare dispersal opportunities. Weed risk assessments of M. × giganteus assume the rarity of events such as scouring and flooding that would facilitate secondary dispersal of vegetative rhizome fragments and the long-term sexual inviability of escapes. Combining data from small-scale rhizome fragmentation and movement experiments, and estimates from the literature, we parameterized an individual-based model to examine M. × giganteus spread given three dispersal scenarios. We further evaluated our estimates in response to different field edge buffer widths and monitoring intensities, two key strategies advised for containing biofuel crops. We found that clonal expansion from the field edge alone was sufficient to allow the crop to outgrow buffers of 3 m or less within 11 to 15 yr with low monitoring intensities. Further, models that included the possibility of rhizome dispersal from fields and scouring at field edges demonstrate the potential for long-distance dispersal and establishment with inadequate management. Our study highlights the importance of considering minimum enforced management guidelines for growers to maintain the ecological integrity of the agricultural landscape.

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.

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 Limited long-distance dispersal success in a Western European fairy shrimp evidenced by nuclear and mitochondrial lineage structuring

2019 ◽  
Vol 66 (3) ◽  
pp. 227-237
Author(s):  
Paula C Rodríguez-Flores ◽  
Ernesto Recuero ◽  
Yolanda Jiménez-Ruiz ◽  
Mario García-París
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Iberian Peninsula ◽  
Isolation By Distance ◽  
Local Scale ◽  
Long Distance Dispersal ◽  
Evolutionary Potential ◽  
Long Distance ◽  
Widespread Species ◽  
Spatio Temporal

Abstract Anostraca are known by their ability for long-distance dispersal, but the existence in several species of deep, geographically structured mtDNA lineages suggests their populations are subjected to allopatric differentiation, isolation, and prevalence of local scale dispersion. Tanymastix stagnalis is one of the most widespread species of Anostraca and previous studies revealed an unclear geographical pattern of mtDNA genetic diversity. Here, we analyze populations from the Iberian and Italian Peninsulas, Central Europe, and Scandinavia, with the aim to characterize the patterns of genetic diversity in a spatio-temporal framework using mtDNA and nuclear markers to test gene flow among close populations. For these aims we built a time-calibrated phylogeny and carried out Bayesian phylogeographic analyses using a continuous diffusion model. Our results indicated that T. stagnalis presents a deeply structured genetic diversity, including 7 ancient lineages, some of them even predating the Pleistocene. The Iberian Peninsula harbors high diversity of lineages, with strong isolation and recent absence of gene flow between populations. Dispersal at local scale seems to be the prevailing dispersal mode of T. stagnalis, which exhibits a pattern of isolation-by-distance in the Iberian Peninsula. We remark the vulnerability of most of these lineages, given the limited known geographic distribution of some of them, and the high risk of losing important evolutionary potential for the species.

scholarly journals High genetic connectivity in a gastropod with long-lived planktonic larvae

2019 ◽  
Vol 86 (1) ◽  
pp. 42-55 ◽  
Author(s):  
Fabio Crocetta ◽  
Luigi Caputi ◽  
Sofia Paz-Sedano ◽  
Valentina Tanduo ◽  
Angelo Vazzana ◽  
...  
Keyword(s):  
Dna Sequence ◽  
Dna Sequences ◽  
Sequence Data ◽  
Isolation By Distance ◽  
Gross Anatomy ◽  
Coi Gene ◽  
Genetic Connectivity ◽  
Extrinsic Factors ◽  
Dna Sequence Data ◽  
Pelagic Larvae

Abstract Genetic connectivity plays a crucial role in shaping the geographic structure of species. Our aim in this study was to explore the pattern of genetic connectivity in Bursa scrobilator, an iconic marine caenogastropod with long-lived pelagic larvae. Our study was based on the analysis of DNA sequence data for the 658-bp barcoding fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene. This is the largest DNA sequence dataset assembled to date for B. scrobilator. These data confirm that the two recently described subspecies B. scrobilator scrobilator (Linnaeus, 1758), from the Mediterranean and Macaronesia, and B. s. coriacea (Reeve, 1844), from West Africa, constitute two evolutionarily significant units (ESUs). We found that for the nominal subspecies, the variation in morphology (shell, radula and gross anatomy) and DNA sequences was not geographically structured, and this agrees with what we would expect in a species with high connectivity at the larval stage. The divergence between the two subspecies cannot be easily explained by isolation by distance, and we would argue that one or more extrinsic factors may have played a role in isolating the two ESUs and maintaining that isolation.

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