Levels Of Subdivision Research Articles

Genetic variation within and among naturally regenerating populations of alder (Alnus glutinosa)

To assess the inter- and intrapopulation genetic variation in the filial generation (F1) of alder (<em>Alnus glutinosa</em> (L.) Gaertn.), 11 naturally regenerated populations were analysed. Their parental populations (P), represent the whole Polish territory and belong to three phytosociological associations with alder: typical alder swamp forest <em>Carici elongatae-Alnetum</em> (Ce-A); alder riparian forest <em>Circaeo-Alnetum</em> (C-A); and ash-elm riparian forest <em>Fraxino-Ulmetum</em> (F-U). F1 populations are grown in a common-garden experiment (provenance trial). Genotyping of individual trees has been carried out by analysis in a bud tissue allele frequency in the 21 isozyme putative loci of 10 enzymes. Differences between populations in respect to the level of genetic diversity were not high. Genetic diversity measured as the number of effective alleles per locus was the highest (Ne = 1.65) in population Wińsko originating from F-U (where also the inbreeding coefficient was the highest, F = 0.429), and the lowest (Ne = 1.48) in population Sławki from Ce-A. In all investigated populations, observed heterozygosity (Ho = 20%) was lower than expected from H-W equilibrium (He = 29%). The highest genetic variation expressed as percentage of polymorphic loci (77.3%) was observed in the offspring populations from Ce-A, and the smallest (69.9%) in the populations originating from F-U. It seems that the low genetic differentiation between populations is probably connected with long-distance seed dispersal via river systems. Alder seed can be transported over long distances thanks to periodical flooding. There is some gene flow between alder populations, with about 2.5 immigrants successfully entering a population per generation (Nm = 2.55). The level of population subdivision within <em>A. glutinosa</em> was low (Fst = 0.089). There was no significant genetic differentiation between populations from different phytosociological associations. Mantel test exhibited no significant correlation (r = 0.077) between genetic and geographic distance. In the dendrogram constructed according to Nei (1972) on the basis of interpopulation genetic distances, many small groups can be observed.

Shape Optimization to Improve Energy Absorption Ability of Cylindrical Thin-Walled Origami Structure

During car frontal crash, crush energy is absorbed by the parts of front bumper, front side member, front panel member and so on. Previous research has indicated that front side member plays major role in energy absorption. For protecting the passengers, the front side member is expected to absorb crush energy as much as possible. In this study, we adopt cylindrical thin-walled structure using origami engineering as front side member instead of structure with rectangular cross section which is generally used. We develop an optimization system of the cylindrical thin-walled origami structure, in which the objective function is to maximize the energy absorption of origami structure; the design variables are structural parameter, number of divisional sections along axis, number of edges of polygonal cross section and number of subdivision levels; the weight and initial peak load of optimal structure must be less than those of structure with rectangular cross section. We then discuss the optimization results that the optimal structure is capable of absorbing energy 91% more than that of original rectangular cross sectional structure which is usually bended on the way of being crushed, 37% more than that of original structure which is ideally crushed to 70% length without bending.

Study on Crash Characteristics of Half Cut Type Vehicle Side Member Structure of Energy Absorption Ability by Using Origami Engineering

As regard to car frontal crash, previous research has indicated that front side member plays major role in energy absorption. For protecting the passengers, the front side member is expected to absorb crash energy as much as possible. In this study, we investigated the crash characteristics of half cut type side member structure by optimal design method to improve the performance for energy absorption. We developed an automatic optimal design system, in which the analysis meshes are generated with a group of design parameters and shape optimization is carried out automatically. The design variables are side member cross section shape, spot welding pitch length, divisional section number and radius difference along the axial direction, and the number of subdivision levels. As the result, the optimal side member structure with half cut type is capable of absorbing 1.44 times (1.29 times per unit mass) more energy than the original rectangular cross sectional side member structure with half cut type which is generally used.

Rhythmic Feel as Meter

This article studies the empirical structures and theoretical status of rhythmic feels in jembe music, which is a popular style of drum ensemble music from West Africa. The focus is onsystematic variations of durations(Bengtsson 1975)—that is, cyclic patterns of non-isochronous pulse streaming at the metric level of beat subdivision. Taking for example a standard piece of jembe repertoire that is set in a 4-beat/12-subpulse metric cycle (often notated as 12/8), I show that the ternary beat subdivision forms a repeated sequence of unequal (short, flexible, and long) subpulses. This stable rhythmic feel pattern, SFL, is unmistakable and non-interchangeable with a second ternary pattern, which is characterized by long, flexible, flexible subpulses (LFF) and occurs in other pieces of jembe music. As predicted in Justin London’s “hypothesis of many meters” (London 2004), these timing patterns distinguish individual meters. I further analyze how schemes of binary and ternary beat subdivisions can be synchronized to operate in parallel. Such metric nesting is based on the patterned non-isochrony of rhythmic feels. Cyclic variation of subpulse durations, I argue, is inherent in the repertoire and fundamental to the metric system of jembe music.

Extremely low genetic variability and highly structured local populations of Arabidopsis thaliana at higher latitudes

The genetic diversity and population structure of Arabidopsis thaliana populations from Norway were studied and compared to a worldwide sample of A. thaliana to investigate the demographic history and elucidate possible colonization routes of populations at the northernmost species limit. We genotyped 282 individuals from 31 local populations using 149 single nucleotide polymorphism markers. A high level of population subdivision (F(ST) = 0.85 ± 0.007) was found indicating that A. thaliana is highly structured at the regional level. Significant relationships between genetic and geographical distances were found, suggesting an isolation by distance mode of evolution. Genetic diversity was much lower, and the level of linkage disequilibrium was higher in populations from the north (65-68°N) compared to populations from the south (59-62°N); this is consistent with a northward expansion pattern. A neighbour-joining tree showed that populations from northern Norway form a separate cluster, while the remaining populations are distributed over a few minor clusters. Minimal gene flow seems to have occurred between populations in different regions, especially between the geographically distant northern and southern populations. Our data suggest that northern populations represent a homogenous group that may have been established from a few founders during northward expansions, while populations in the central part of Norway constitute an admixed group established by founders of different origins, most probably as a result of human-mediated gene flow. Moreover, Norwegian populations appeared to be homogenous and isolated compared to a worldwide sample of A. thaliana, but they are still grouped with Swedish populations, which may indicate common colonization histories.

Population genetic structure and genetic diversity of Jatropha curcas germplasm as investigated by 5′-anchored simple sequence repeat primers

Jatropha (Jatropha curcas L.) is widely distributed in the tropics with a promise for use as an oil crop for biodiesel. Understanding population genetic structure and diversity of J. curcas is important for germplasm collection and planning for breeding programs. Twelve 5′-anchored simple sequence repeat primers were selected and used for evaluation of population genetic structure and genetic diversity of J. curcas accessions collected from different regions within Thailand and introduced from other countries. A moderate level of genetic variation was found in all accessions studied. Cluster analysis did not reflect geographical distance in general as revealed by the Mantel test. An analysis of molecular variance showed that the majority (83.3%) of genetic diversity was within populations, indicating a high level of overlap and little population subdivision with respect to geographic area. An absence of subpopulation structure among neighboring regions may be caused by exchanging germplasm with vegetative propagation. This study provides a basis for breeders on selection of parental material to maximize genetic polymorphism in J. curcas breeding programs.

PHYLOGEOGRAPHIC PATTERNS INDICATE TRANSATLANTIC MIGRATION FROM EUROPE TO NORTH AMERICA IN THE RED SEAWEED CHONDRUS CRISPUS (GIGARTINALES, RHODOPHYTA)1

Inferring how the Pleistocene climate oscillations have repopulated the extant population structure of Chondrus crispus Stackh. in the North Atlantic Ocean is important both for our understanding of the glacial episode promoting diversification and for the conservation and development of marine organisms. C. crispus is an ecologically and commercially important red seaweed with broad distributions in the North Atlantic. Here, we employed both partial mtDNA Cox1 and nrDNA internal transcribed spacer region 2 (ITS2) sequences to explore the genetic structure of 17 C. crispus populations from this area. Twenty-eight and 30 haplotypes were inferred from these two markers, respectively. Analysis of molecular variance (AMOVA) and of the population statistic Theta(ST) not only revealed significant genetic structure within C. crispus populations but also detected significant levels of genetic subdivision among and within populations in the North Atlantic. On the basis of high haplotype diversity and the presence of endemic haplotypes, we postulate that C. crispus had survived in Pleistocene glacial refugia in the northeast Atlantic, such as the English Channel and the northwestern Iberian Peninsula. We also hypothesize that C. crispus from the English Channel refugium repopulated most of northeastern Europe and recolonized northeastern North America in the Late Pleistocene. The observed phylogeographic pattern of C. crispus populations is in agreement with a scenario in which severe Quaternary glaciations influenced the genetic structure of North Atlantic marine organisms with contiguous population expansion and locally restricted gene flow coupled with a transatlantic dispersal in the Late Pleistocene.

Population structure and demographic history of Genypterus blacodes using microsatellite loci

Three loci microsatellites were used to determine genetic variability and population structure at 15 locations within three zones where Genypterus blacodes is being fully exploited in Chilean waters. A total of 209 individuals were used: 77 from Cuadra Meulin (CM), 65 from the northern Magellan Strait (NMS), and 67 from the southern Magellan Strait (SMS). The genetic variability found, measured as observed heterozygosity, was Ho = 0.841 ± 0.016. The levels of population subdivision found were F st = 0.0032 ( p = 0.687 ± 0.004) and R st = 0.0059 ( p = 0.160 ± 0.003). Both the F st and R st values were near zero, with non-significant probability values, indicating that the three studied zones were not significantly different. The demographic history analyses did not exhibit significant differences between the observed and expected diversity, under a scenario of reduced effective population size. Therefore, the results obtained in the present study show that there was no population level genetic differentiation of G. blacodes between the analyzed zones in austral Chilean waters (between 41 and 57° S), confirming the presence of a single genetic stock. This result should be included in the management strategy by which harvest quotas are set, and used to improve the application of government management policies, with the aim of increasing the sustainability of this important fishery resource.

Effect of Watershed Subdivision and Filter Width on SWAT Simulation of a Coastal Plain Watershed1

Cho, Jaepil, Richard R. Lowrance, David D. Bosch, Timothy C. Strickland, Younggu Her, and George Vellidis, 2010. Effect of Watershed Subdivision and Filter Width on SWAT Simulation of a Coastal Plain Watershed. Journal of the American Water Resources Association (JAWRA) 46(3):586‐602. DOI: 10.1111/j.1752‐1688.2010.00436.xAbstract: The Soil and Water Assessment Tool (SWAT) does not fully simulate riparian buffers, but has a simple filter function that is responsive to filter strip width (FILTERW). The objectives of this study were to (1) evaluate SWAT hydrology and water quality response to changes in watershed subdivision levels and different FILTERW configurations and (2) provide guidance for selecting appropriate watershed subdivision for model runs that include the riparian buffer feature through the FILTERW parameter. Watershed subdivision level is controlled by the critical source area (CSA) which defines the minimum drainage area required to form the origin of a stream. SWAT was calibrated on a 15.7 km2 subdrainage within the Little River Experimental Watershed, Georgia. The calibrated parameter set was applied to 32 watershed configurations consisting of four FILTERW representations for each of eight CSA levels. Streamflow predictions were stable regardless of watershed subdivision and FILTERW configuration. Predicted sediment and nutrient loads from upland areas decreased as CSA increased when spatial variations of riparian buffers are considered. Sediment and nutrient yield at the watershed outlet was responsive to different combinations of CSA and FILTERW depending on selected in‐stream processes. CSA ranges which provide stable sediment and nutrient yields at the watershed outlet was suggested for avoiding significant modifications in selected parameter set.

Genetic diversity of the Plasmodium vivax merozoite surface protein-5 locus from diverse geographic origins

Plasmodium vivax merozoite surface protein-5 (PvMsp-5), a potential vaccine candidate, is encoded by a two-exon single copy gene. We have conducted a comprehensive analysis of PvMsp-5 by sequencing the entire gene of four parasite populations from northwestern Thailand ( n = 73), southern Thailand ( n = 53), Indonesia ( n = 25) and Brazil ( n = 24), and five isolates from other endemic areas. Results reveal that exon I exhibits a significantly higher level of nucleotide diversity at both synonymous and nonsynonymous sites than exon II ( p < 0.01). Neutrality tests based on both intraspecific and interspecific nucleotide polymorphism have detected a signature of positive selection in exon I of all populations while substitutions in exon II mainly followed neutral expectation except that three residues in exon II of northwestern Thailand population appear to be positively selected using the Bayes Empirical Bayes method. Short imperfect repeats were identified in exon I at an equivalent region to its orthologue in P. knowlesi, supporting their close genetic relatedness. Significant levels of population subdivision were detected among most populations including those between northwestern and southern Thailand ( p < 10 − 5 ), implying absent or minimal gene flow between these populations. Importantly, evidences for intragenic recombination in PvMsp-5 were found in most populations except that from southern Thailand in which haplotype diversity and nucleotide diversity were exceptionally low. Results from Fu and Li's D*, F* and D and F tests suggested that PvMsp-5 of most P. vivax populations have been maintained by balancing selection whereas southern Thailand population could have gone through recent bottleneck events. These findings are concordant with a substantial reduction in the number of P. vivax cases in southern Thailand during the past decade, followed by a very recent population expansion. Therefore, spatio-temporal monitoring of parasite population genetics provides important implications for disease control.

折紙工学援用による半割り型自動車サイドメンバーの衝突圧潰エネルギー吸収性能に関する研究

As regard to car frontal crash, previous researches have indicated that the front side member plays a major role in energy absorption. For protecting the passengers, the front side member is expected to absorb crash energy as much as possible. In this study, we investigated the crash characteristics of half cut type side member structure by optimal design method to improve energy absorption ability. We developed an automatic optimal design system, in which the analysis meshes are generated with a group of design parameters and shape optimization is carried out automatically, The design variables are side member cross section shape, spot welding pitch length, divisional section numbers and radius difference along the axial direction, and the number of subdivision levels. As the result, the optimal side member structure with half cut type is capable of absorbing 1.44 times (1.29 times per unit mass) more energy than the original rectangular cross sectional side member structure with half cut type which is generally used.

Are differences in fitness traits related to genetic clusters? An empirical test on the European tree frog

Microsatellites are one of the preferred marker types to estimate the level of genetic diversity and subdivision in natural populations of endangered species. Many studies thereby attempted to identify genetically defined management units for conservation by applying a variety of genetic clustering methods. It is not clear, however, whether genetic clusters inferred from neutral molecular markers reflect differences in fitness or adaptation. In this study, I conducted a common garden experiment on the endangered European tree frog ( Hyla arborea) to clarify whether fitness-related traits of larval development differed between three genetic groups defined by Bayesian clustering analysis. I reared larvae under semi-natural conditions and measured growth and developmental rates as well as survival at five larval stages from eclosion to completion of metamorphosis. Nested general and generalized linear models showed significant cluster differences for several variables in terms of smaller growth rates and body sizes at early larval stages. These differences were, however, probably not linked to adaptive divergence among clusters but rather to neutral genetic processes in the breeding sites of one cluster, which were spatially isolated and subject of recent bottlenecks. Hence, a genetic load effect (e.g. inbreeding depression) may have acted on the populations of this particular cluster. I advise studies aiming to define management units for conservation to not only use genetic clustering methods but to complement their findings with experimental approaches on fitness-related traits.

Later-Life Migrations in Canada in 2001: A Multilevel Approach

Canada is an aging society; with over 13% of the population 65 and over in 2008 and with this population growing at a rate more than double the overall population. Moreover, the aging of the Canada population varies geographically across the nation. Using data drawn from the 2001 Census of Canada Master files (20% sample), the objectives of this analysis are twofold. First, the analysis examines the internal migration behavior of the older population, distinguishing between the native-born and foreign-born. Second, the analysis examines how residential attributes at the census subdivision (CSD) and census metropolitan levels influence the migration decision. This analysis examines the later-life migrations of Canada’s older population at the census subdivision level in 2001.

High levels of population subdivision in a morphologically conserved Mediterranean toad (Alytes cisternasii) result from recent, multiple refugia: evidence from mtDNA, microsatellites and nuclear genealogies

Pleistocene glaciations often resulted in differentiation of taxa in southern European peninsulas, producing the high levels of endemism characteristic of these regions (e.g. the Iberian Peninsula). Despite their small ranges, endemic species often exhibit high levels of intraspecific differentiation as a result of a complex evolutionary history dominated by successive cycles of fragmentation, expansion and subsequent admixture of populations. Most evidence so far has come from the study of species with an Atlantic distribution in northwestern Iberia, and taxa restricted to Mediterranean-type habitats remain poorly studied. The Iberian Midwife toad (Alytes cisternasii) is a morphologically conserved species endemic to southwestern and central Iberia and a typical inhabitant of Mediterranean habitats. Applying highly variable genetic markers from both mitochondrial and nuclear genomes to samples collected across the species' range, we found evidence of high population subdivision within A. cisternasii. Mitochondrial haplotypes and microsatellites show geographically concordant patterns of genetic diversity, suggesting population fragmentation into several refugia during Pleistocene glaciations followed by subsequent events of geographical and demographic expansions with secondary contact. In addition, the absence of variation at the nuclear beta-fibint7 and Ppp3caint4 gene fragments suggests that populations of A. cisternasii have been recurrently affected by episodes of extinction and recolonization, and that documented patterns of population subdivision are the outcome of recent and multiple refugia. We discuss the evolutionary history of the species with particular interest in the increasing relevance of Mediterranean refugia for the survival of genetically differentiated populations during the Pleistocene glaciations as revealed by studies in co-distributed taxa.

Microsatellite‐based Analysis of Tobacco (Nicotiana tabacum L.) Genetic Resources

ABSTRACTLittle is currently known about the genetic variation within diverse gene pools of cultivated tobacco (Nicotiana tabacum L.). Knowledge in this area could aid in future germplasm maintenance activities, provide additional information in the area of N. tabacum population genetics, and assist in selection of materials for breeding or genetic investigations. To this end, 702 N. tabacum accessions from the U.S. Nicotiana Germplasm Collection were genotyped with 70 microsatellite markers. A total of 1031 alleles were detected, with an average of 14.7 alleles per marker. Average gene diversity was quite large (0.7362) and was three times the value for a diverse population of U.S. flue‐cured tobacco. Cluster analysis using various distance coefficients generated seven consistent groups. Patterns of geographic‐specific clustering were frequent but not universal. An analysis of molecular variance for tobacco collected from Central and South America revealed that 92% of the total genetic variation among samples could be attributed to country‐specific subpopulations. There was also a significant level of population subdivision between country‐specific subpopulations, however. Tobacco samples collected from Peru had both the largest average gene diversity and the largest mean genetic distance, although N. tabacum collected from Mexico had the greatest allelic richness. Tobacco samples collected from Argentina were the most divergent subpopulation.

Supercubes: A High-Level Primitive for Diamond Hierarchies

Volumetric datasets are often modeled using a multiresolution approach based on a nested decomposition of the domain into a polyhedral mesh. Nested tetrahedral meshes generated through the longest edge bisection rule are commonly used to decompose regular volumetric datasets since they produce highly adaptive crack-free representations. Efficient representations for such models have been achieved by clustering the set of tetrahedra sharing a common longest edge into a structure called a diamond. The alignment and orientation of the longest edge can be used to implicitly determine the geometry of a diamond and its relations to the other diamonds within the hierarchy. We introduce the supercube as a high-level primitive within such meshes that encompasses all unique types of diamonds. A supercube is a coherent set of edges corresponding to three consecutive levels of subdivision. Diamonds are uniquely characterized by the longest edge of the tetrahedra forming them and are clustered in supercubes through the association of the longest edge of a diamond with a unique edge in a supercube. Supercubes are thus a compact and highly efficient means of associating information with a subset of the vertices, edges and tetrahedra of the meshes generated through longest edge bisection. We demonstrate the effectiveness of the supercube representation when encoding multiresolution diamond hierarchies built on a subset of the points of a regular grid. We also show how supercubes can be used to efficiently extract meshes from diamond hierarchies and to reduce the storage requirements of such variable-resolution meshes.

Effective size of the hierarchically structured populations of the agent of malaria: a coalescent-based model

Using the coalescence theory, we derived a simple expression for the asymptotic inbreeding effective population size of Plasmodium falciparum, the most malignant agent of malaria, in relationship to F-statistics at different hierarchical levels. We consider the effective size of malaria parasites, both for the intrinsic interest of the result for the study of this medically important organism and as an example illustrating general arguments that should clarify effective size calculations in a wide range of organisms with complex life cycles and a hierarchical population structure. We consider in this study a model with four hierarchical levels (villages, oocyst infrapopulations, oocysts within infrapopulations and the oocyst). The derived expression is applicable to both island and isolation by distance models and is a function of three F-statistics: the genetic differentiation among villages (F(VT)), the genetic differentiation among oocyst infrapopulations (F(MV)) and, finally, the departure from panmixia (F(IM)) within oocyst infrapopulations. The logic of the derivation of effective size presented in this study is applicable to any organism showing the same levels of subdivision.

Hierarchical Spatial Genetic Structure of Common Eiders (Somateria mollissima) Breeding along a Migratory Corridor

Documentation of spatial genetic discordance among breeding populations of Arctic-nesting avian species is important, because anthropogenic change is altering environmental linkages at micro- and macrogeographic scales. We estimated levels of population subdivision within Pacific Common Eiders (Somateria mollissima v-nigrum) breeding on 12 barrier islands in the western Beaufort Sea, Alaska, using molecular markers and capture—mark—recapture (CMR) data. Common Eider populations were genetically structured on a microgeographic scale. Regional comparisons between populations breeding on island groups separated by 90 km (Mikkelsen Bay and Simpson Lagoon) revealed structuring at 14 microsatellite loci (FST = 0.004, P < 0.01), a nuclear intron (FST = 0.022, P = 0.02), and mitochondrial DNA (ΦST = 0.082, P < 0.05). The CMR data (n = 34) did not indicate female dispersal between island groups. Concordance between genetic and CMR data indicates that females breeding in the western Beaufort Sea are strongly philopatric to island groups rather than to a particular island. Despite the apparent high site fidelity of females, coalescence-based models of gene flow suggest that asymmetrical western dispersal occurs between island groups and is likely mediated by Mikkelsen Bay females stopping early on spring migration at Simpson Lagoon to breed. Alternatively, late-arriving females may be predisposed to nest in Simpson Lagoon because of the greater availability and wider distribution of nesting habitat. Our results indicate that genetic discontinuities, mediated by female philopatry, can exist at microgeographic scales along established migratory corridors.

Genetic Structure of Populations of the Rice-Infecting Pathogen Rhizoctonia solani AG-1 IA from China

ABSTRACT Sheath blight disease (SBD) on rice, caused by Rhizoctonia solani AG-1 IA, is one of the most devastating rice diseases on a global basis, including China (in Eastern Asia), the world's largest rice-growing country. We analyzed the population genetics of nine rice-infecting populations from China using nine microsatellite loci. One allopatric population from India (Southern Asia) was included in the analyses. In total, 300 different multilocus genotypes were found among 572 fungal isolates. Clonal fractions within rice fields were 16 to 95%, suggesting that sclerotia were a major source of primary inoculum in some fields. Global Phi(ST) statistics (Phi(ST) = 42.49; P </= 0.001) were consistent with a relatively high level of differentiation among populations overall; however, pairwise comparisons gave nonsignificant R(ST) values, consistent with contemporary gene flow among five of the populations. Four of these populations were located along the Yangtze River tributary network. Gene flow followed an isolation-by-distance model consistent with restricted long-distance migration. Historical migration rates were reconstructed and yielded values that explained the current levels of population subdivision. Except for one population which appeared to be strictly clonal, all populations showed evidence of a mixed reproductive mode, including both asexual and sexual reproduction. One population had a strictly recombining structure (all loci were in Hardy-Weinberg equilibrium) but the remaining populations from China and the one from India exhibited varying degrees of sexual reproduction. Six populations showed significant F(IS) values consistent with inbreeding.

Genetic diversity and connectivity in a brooding reef coral at the limit of its distribution

Remote populations are predicted to be vulnerable owing to their isolation from potential source reefs, and usually low population size and associated increased extinction risk. We investigated genetic diversity, population subdivision and connectivity in the brooding reef coral Seriatopora hystrix at the limits of its Eastern Australian (EA) distribution and three sites in the southern Great Barrier Reef (GBR). Over the approximately 1270 km survey range, high levels of population subdivision were detected (global F(ST) = 0.224), with the greatest range in pairwise F(ST) values observed among the three southernmost locations: Lord Howe Island, Elizabeth Reef and Middleton Reef. Flinders Reef, located between the GBR and the more southerly offshore reefs, was highly isolated and showed the signature of a recent bottleneck. High pairwise F(ST) values and the presence of multiple genetic clusters indicate that EA subtropical coral populations have been historically isolated from each other and the GBR. One putative first-generation migrant was detected from the GBR into the EA subtropics. Occasional long-distance dispersal is supported by changes in species composition at these high-latitude reefs and the occurrence of new species records over the past three decades. While subtropical populations exhibited significantly lower allelic richness than their GBR counterparts, genetic diversity was still moderately high. Furthermore, subtropical populations were not inbred and had a considerable number of private alleles. The results suggest that these high-latitude S. hystrix populations are supplemented by infrequent long-distance migrants from the GBR and may have adequate population sizes to maintain viability and resist severe losses of genetic diversity.