Direct and indirect measures of dispersal in the fairy shrimp Branchipodopsis wolfi indicate a small scale isolation-by-distance pattern

Many animals move among habitats, and even small-scale dispersal of individuals between habitat patches may have strong implications for population dynamics and structure. Here, we use long-term mark–recapture data combined with extensive genotyping and parentage assignment to investigate the importance of small-scale location change of resident brown trout ( Salmo trutta ) in a small stream (1500 m). During the first summer, juvenile fish dispersed downstream (mean displacement 200 m), with smaller juveniles dispersing longer distances. Downstream movement was also predominant during the first winter, but older fish moved little. This limited dispersal resulted in a significant isolation-by-distance structure for ages 1 and 2, but not for older age groups or for the mature fish. Individual pairwise relatedness coefficients decreased with waterway distance for mature fish during the 2002 and 2003 spawning seasons, but only weakly. Overall, between-site genetic differentiation was stronger for the younger age classes, and the signal decayed with age, indicating that the genetic structure observed in the stream is mainly driven by spatial aggregation of close relatives.

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

Bulletin of Entomological Research ◽

10.1079/ber2005369 ◽

2005 ◽

Vol 95 (4) ◽

pp. 381-392 ◽

Cited By ~ 22

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.

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Spatial and Temporal Dynamics and Molecular Evolution of Tula orthohantavirus in German Vole Populations

Viruses ◽

10.3390/v13061132 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1132

Author(s):

Sabrina Schmidt ◽

Daniela Reil ◽

Kathrin Jeske ◽

Stephan Drewes ◽

Ulrike M. Rosenfeld ◽

...

Keyword(s):

Molecular Evolution ◽

Temporal Dynamics ◽

Isolation By Distance ◽

Common Vole ◽

Pathogen Transmission ◽

Small Scale ◽

Geographic Scale ◽

Ideal System ◽

The Common ◽

Common Voles

Tula orthohantavirus (TULV) is a rodent-borne hantavirus with broad geographical distribution in Europe. Its major reservoir is the common vole (Microtus arvalis), but TULV has also been detected in closely related vole species. Given the large distributional range and high amplitude population dynamics of common voles, this host–pathogen complex presents an ideal system to study the complex mechanisms of pathogen transmission in a wild rodent reservoir. We investigated the dynamics of TULV prevalence and the subsequent potential effects on the molecular evolution of TULV in common voles of the Central evolutionary lineage. Rodents were trapped for three years in four regions of Germany and samples were analyzed for the presence of TULV-reactive antibodies and TULV RNA with subsequent sequence determination. The results show that individual (sex) and population-level factors (abundance) of hosts were significant predictors of local TULV dynamics. At the large geographic scale, different phylogenetic TULV clades and an overall isolation-by-distance pattern in virus sequences were detected, while at the small scale (<4 km) this depended on the study area. In combination with an overall delayed density dependence, our results highlight that frequent, localized bottleneck events for the common vole and TULV do occur and can be offset by local recolonization dynamics.

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

10.26686/wgtn.17019374 ◽

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>

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Low genetic connectivity in an estuarine fish with pelagic larvae

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f07-154 ◽

2008 ◽

Vol 65 (2) ◽

pp. 147-158 ◽

Cited By ~ 25

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.

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

10.26686/wgtn.17019374.v1 ◽

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>

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Five years investigation of female and male genotypes in Périgord black truffle (Tuber melanosporum Vittad.) revealed contrasted reproduction strategies

10.1101/073650 ◽

2016 ◽

Author(s):

Herminia De la Varga ◽

Françis Le Tacon ◽

Mélanie Lagoguet ◽

Flora Todesco ◽

Torda Varga ◽

...

Keyword(s):

Isolation By Distance ◽

Genotypic Diversity ◽

Tuber Melanosporum ◽

Small Scale ◽

Black Truffle ◽

Ectomycorrhizal Symbiosis ◽

Distance Analysis ◽

Reproduction Strategy ◽

Genetic Structures ◽

Male Genotype

SummaryThe Périgord black truffle (Tuber melanosporum Vittad.) is a heterothallic ascomycete that establishes ectomycorrhizal symbiosis with trees and shrubs. Small-scale genetic structures of female genotypes in truffle orchards are known, but it has not yet been studied in male genotypes. In this study, our aim was to characterize the small-scale genetic structure of both male and female genotypes over five years in an orchard to better understand the T. melanosporum sexual reproduction strategy, male genotype dynamics, and origins. Two-hundred forty-one ascocarps, 475 ectomycorrhizas, and 20 soil cores were harvested and genotyped using microsatellites and mating type genes. Isolation by distance analysis revealed pronounced small-scale genetic structures for both female and male genotypes. The genotypic diversity was higher for male than female genotypes with numerous small size genotypes suggesting an important turnover due to ascospore recruitment. Larger and perennial female and male genotypes were also detected. Only three genotypes (1.5 %) were found as both female and male genotypes (hermaphrodites) while most were detected only as female or male genotype (dioecy). Our results suggest that germinating ascospores act as male genotypes, but we also proposed that soil mycelium could be a reservoir of male genotypes.

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Population structure and clonal prevalence of scleractinian corals (Montipora capitata and Porites compressa) in Kaneohe Bay, Oahu

10.1101/2019.12.11.860585 ◽

2019 ◽

Cited By ~ 2

Author(s):

NS Locatelli ◽

JA Drew

Keyword(s):

Population Structure ◽

Isolation By Distance ◽

Geographic Distance ◽

High Energy ◽

Small Scale ◽

Coral Host ◽

Montipora Capitata ◽

Porites Compressa ◽

Kaneohe Bay ◽

Yearly Average

AbstractAs the effects of anthropogenic climate change grow, mass coral bleaching events are expected to increase in severity and extent. Much research has focused on the environmental stressors themselves, symbiotic community compositions, and transcriptomics of the coral host. Globally, fine-scale population structure of corals is understudied. This study reports patterns of population structure and clonal prevalence found in Montipora capitata and Porites compressa in Kaneohe Bay, Oahu. Generated using ddRAD methods, genetic data reveals different patterns in each taxa despite them being exposed to the same environmental conditions. STRUCTURE and site-level pairwise FST analyses suggest population structure in M. capitata resembling isolation by distance. Mantel tests show strong, significant FST correlations in M. capitata in relation to geographic distance, water residence time, and salinity and temperature variability (range) at different time scales. STRUCTURE did not reveal strong population structure in P. compressa. FST correlation was found in P. compressa in relation to yearly average sea surface height. We also report high prevalence of clonal colonies in P. compressa in outer bay sites exposed to storms and high energy swells. Amongst only outer bay sites, 7 out of 23 sequenced individuals were clones of other colonies. Amongst all 47 sequenced P. compressa individuals, 8 were clones. Only one clone was detected in M. capitata. Moving forward, it is crucial to consider these preexisting patterns relating to genetic diversity when planning and executing conservation and restoration initiatives. Recognizing that there are differences in population structure and diversity between coral taxa, even on such small-scales, is important as it suggests that small-scale reefs must be managed by species rather than by geography.

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Conservation genomics and pollination biology of an endangered, edaphic-endemic, octoploid herb: El Dorado bedstraw (Galium californicum subsp. sierrae; Rubiaceae)

PeerJ ◽

10.7717/peerj.10042 ◽

2020 ◽

Vol 8 ◽

pp. e10042

Author(s):

Dylan Burge

Keyword(s):

Asexual Reproduction ◽

Isolation By Distance ◽

Mantel Test ◽

Pollination Biology ◽

Perennial Herb ◽

Small Scale ◽

Sampling Location ◽

Conservation Genomics ◽

Sexual And Asexual Reproduction ◽

El Dorado

El Dorado bedstraw (Galium californicum subsp. sierrae) is a federally endangered dioecious, octoploid, perennial herb found only in the Pine Hill region of El Dorado County, CA, USA. Like many species of Galium, El Dorado bedstraw is capable of both sexual and asexual reproduction, spreading via stem-layering as well as seeds. El Dorado bedstraw is also dioecious, and thus dependent on pollinators to transfer pollen from male to female stems. The capacity for asexual reproduction has conservation implications for this plant, due to the potential for populations to become dominated by a small number of clones in the absence of recruitment from seeds. No previous work has examined either the population genetics or pollination biology of this plant. Here, double-digest restriction site-associated DNA sequencing was used to develop a genetic dataset for a sample of El Dorado bedstraw (12 individuals from each of seven locations). Genomic data was used to calculate population genetic statistics and quantify the degree to which clonality affects the sampled populations. Visual observation of insect visitors at every sampling location was used to assess the potential for pollen transfer within and among locations. A total of 23 clonal colonies were detected across 82 successfully sequenced stems, consisting of an average of 2.4 individuals (range: 2–6). Significant isolation by distance among locations was detected using a Mantel test. Insect pollinators were from eleven families, consisting mainly of small species with weak flight. It is recommended that clonality and small-scale population differentiation be taken into account in conservation measures.

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