High levels of male diploidy but low levels of genetic structure characterize <Emphasis Type="Italic">Bombus vosnesenskii</Emphasis> populations across the Western US

Patterns of genetic structure for some bee species suggest that gene flow may be limited across natural and human-created barriers and that local dispersal or natal site fidelity may be common. Interestingly, this past work has primarily focused on female bees, despite the fact that males may differ substantially in their dispersal processes. By examining genetic structure and diploidy in males, it is possible to gain insight into potential barriers to gene flow and drivers of inbreeding. In this study, we examine diploidy as well as regional and local spatial genetic structure using males of Bombus vosnesenskii, a stable bumble bee species found across western North America. Specifically, we investigate patterns of genetic structure in both island and mainland populations, across spatial scales, and over a range of natural and human-altered habitats. We document high levels of male diploidy, with significantly higher levels in mainland populations compared to island populations and increasing diploidy in areas with poor nesting habitat. Interestingly, we also find evidence of significant spatial genetic structure from 0 to 10 km and 0 to 5 km on island and mainland populations, respectively. Finally, we document low but significant genetic differentiation across the region (Φ_ST = 0.049). Overall, this work reveals the unique potential for biogeographic context and local habitat composition to drive male diploidy patterns in bumble bees.     

Genetic Divergence of an Avian Endemic on the Californian Channel Islands

The Californian Channel Islands are near–shore islands with high levels of endemism, but extensive habitat loss has contributed to the decline or extinction of several endemic taxa. A key parameter for understanding patterns of endemism and demography in island populations is the magnitude of inter–island dispersal. This paper estimates the extent of migration and genetic differentiation in three extant and two extinct populations of Channel Island song sparrows (Melospiza melodia graminea). Inter–island differentiation was substantial (G''''_ST: 0.14–0.37), with San Miguel Island having the highest genetic divergence and lowest migration rates. Santa Rosa and Santa Cruz Island populations were less diverged with higher migration rates. Genetic signals of past population declines were detected in all of the extant populations. The Channel Island populations were significantly diverged from mainland populations of M. m. heermanni (G''''_ST: 0.30–0.64). Ten mtDNA haplotypes were recovered across the extant and extinct Channel Island population samples. Two of the ten haplotypes were shared between the Northern and Southern Channel Islands, with one of these haplotypes being detected on the Californian mainland. Our results suggest that there is little contemporary migration between islands, consistent with early explanations of avian biogeography in the Channel Islands, and that song sparrow populations on the northern Channel Islands are demographically independent.     

Lack of sex-biased dispersal promotes fine-scale genetic structure in alpine ungulates

Identifying patterns of fine-scale genetic structure in natural populations can advance understanding of critical ecological processes such as dispersal and gene flow across heterogeneous landscapes. Alpine ungulates generally exhibit high levels of genetic structure due to female philopatry and patchy configuration of mountain habitats. We assessed the spatial scale of genetic structure and the amount of gene flow in 301 Dall’s sheep (Ovis dalli dalli) at the landscape level using 15 nuclear microsatellites and 473 base pairs of the mitochondrial (mtDNA) control region. Dall’s sheep exhibited significant genetic structure within contiguous mountain ranges, but mtDNA structure occurred at a broader geographic scale than nuclear DNA within the study area, and mtDNA structure for other North American mountain sheep populations. No evidence of male-mediated gene flow or greater philopatry of females was observed; there was little difference between markers with different modes of inheritance (pairwise nuclear DNA F _ST = 0.004–0.325; mtDNA F _ST = 0.009–0.544), and males were no more likely than females to be recent immigrants. Historical patterns based on mtDNA indicate separate northern and southern lineages and a pattern of expansion following regional glacial retreat. Boundaries of genetic clusters aligned geographically with prominent mountain ranges, icefields, and major river valleys based on Bayesian and hierarchical modeling of microsatellite and mtDNA data. Our results suggest that fine-scale genetic structure in Dall’s sheep is influenced by limited dispersal, and structure may be weaker in populations occurring near ancestral levels of density and distribution in continuous habitats compared to other alpine ungulates that have experienced declines and marked habitat fragmentation.     

Effects of founder events on the genetic variation of translocated island populations: implications for conservation management of the northern quoll

Translocation is a strategy commonly used to maximize the persistence of threatened species, but it may sometimes lead to undesirable genetic consequences. The northern quoll (Dasyurus hallucatus) is a carnivorous marsupial that is critically endangered in Australia’s Northern Territory due to rapid population declines in areas recently colonized by the exotic cane toad Chaunus [Bufo] marinus. In 2003, 64 quolls were translocated to two offshore islands to establish insurance populations and reduce the species’ risk of extinction. In this study, we assessed genetic diversity at five microsatellite loci in the translocated populations, two endemic islands and three mainland populations. In the short-term (three generations), the translocated populations showed a slight but non-significant reduction in genetic diversity (A = 4.1–4.2; H _e = 0.56–0.59) compared to the mainland source populations (A = 5.0–8.4; H _e = 0.56–0.71). In comparison, high genetic erosion was observed in the endemic island populations (A = 1.5–2.9; H _e = 0.11–0.34). Genetic bottlenecks were detected on both endemic islands and in one mainland population, indicating recent reductions in population size. Our results are consistent with previous studies describing greater losses of genetic diversity on islands compared to mainland populations. Divergence from ancestral allele frequencies in the translocated populations also suggests effects due to founder events. This study, although short-term, highlights the importance of continued monitoring for detecting changes in genetic diversity over time and makes a significant contribution to our understanding of the effects of founder events on island populations.     

Insights into the biodiversity of the Succulent Karoo hotspot of South Africa: the population genetics of a rare and endemic halictid bee,Patellapis doleritica

Population genetic analyses are especially relevant for species considered threatened or highly endemic and for which other forms of biological information are lacking. Patellapis doleritica is a recently described communally nesting halictid bee of conservation concern because it is rare and endemic to the Succulent Karoo of South Africa. Moreover, its dispersal is considered to be restricted by its specialised nesting requirements and inclement weather conditions during its limited annual flight period, traits which may be common to other bee species of the region. We hypothesised that gene flow in P. doleritica was low, leading to marked genetic differentiation. Using 7 microsatellites, we investigated its mating and population genetic structure in 258 individuals (171 females and 87 males) from 7 populations spanning most of its known range. Deviation from Hardy–Weinberg equilibrium (F_IS = + 0.254) suggested P. doleritica to be inbred, as in many other communal nesting bee species. Global F_ST (0.028) and global G′_ST (0.216) revealed modest but significant differentiation between most populations, even across the very limited range of the species (ca. 25 km), with one genetically extreme outlier population. Despite inbreeding, we detected a surprisingly low frequency of diploid males (2 %). Patellapis doleritica nevertheless deserves special conservation attention since it is an endemic species with a low overall abundance and therefore possibly prone to environmental change and local extinction.     

Small-scale genetic structure in an endangered wetland specialist: possible effects of landscape change and population recovery

The effects of anthropogenic landscape change on genetic population structure are well studied, but the temporal and spatial scales at which genetic structure can develop, especially in taxa with high dispersal capabilities like birds, are less well understood. We investigated population structure in the Hawaiian gallinule (Gallinula galeata sandvicensis), an endangered wetland specialist bird on the island of O`ahu (Hawai`i, USA). Hawaiian gallinules have experienced a gradual population recovery from near extinction in the 1950s, and have recolonized wetlands on O`ahu in the context of a rapidly urbanizing landscape. We genotyped 152 Hawaiian gallinules at 12 microsatellite loci and sequenced a 520 base-pair fragment of the ND2 region of mitochondrial DNA (mtDNA) from individuals captured at 13 wetland locations on O`ahu in 2014–2016. We observed moderate to high genetic structuring (overall microsatellite F_ST?=?0.098, mtDNA F_ST?=?0.248) among populations of Hawaiian gallinules occupying wetlands at very close geographic proximity (e.g., 1.5–55 km). Asymmetry in gene flow estimates suggests that Hawaiian gallinules may have persisted in 2–3 strongholds which served as source populations that recolonized more recently restored habitats currently supporting large numbers of birds. Our results highlight that genetic structure can develop in taxa that are expanding their range after severe population decline, and that biologically significant structuring can occur over small geographic distances, even in avian taxa.     

Genetic diversity and spatial genetic structure of Pinus strobus (Pinaceae) across an island landscape inferred from allozyme and cpDNA markers

The Beaver Island Archipelago (BIA) provides a model system to address the impact of long-term isolation on genetic diversity and gene flow. Low lake levels are assumed to have caused the BIA to be attached to mainland Michigan for at least 4000 years (10000 yr B.P.- 6000 yr B.P.), eventually, rising lake levels would have kept the islands isolated since 6000 yr B.P. If the island populations of a plant species in the BIA were indeed once continuous with the mainland of Michigan, then we would expect similar levels of genetic diversity in populations of such a species on the islands vs. the mainland. We compared levels of allozyme genetic diversity of 20 plots of Pinus strobus in the BIA with two mainland populations in northern Michigan. In addition, if pollen is a primary agent of gene flow across islands, a low degree of allozyme differentiation among the island populations of P. strobus in the BIA would be evident. Furthermore, since seed dispersal is more limited than pollen dispersal in P. strobus, a more pronounced spatial genetic structure (SGS) is expected in allozymes than in cpDNA markers. To gain insights on the pattern of seed and pollen dispersal among the 20 plots, we further analyzed spatial autocorrelation using Moran's I-statistics for both data sets [biparentally inherited, allozymes and paternally inherited, cpDNA microsatellites (cpDNA SSR)]. We found a similar level of allozyme variability in both the BIA (mean H _e = 0.080) and the two mainland populations (mean H _e = 0.078). As predicted, we observed a low but significant degree of genetic divergence among populations for allozymes (mean F _ST = 0.033 across 20 plots). Our allozyme-based SGS analysis revealed significant evidence of SGS (i.e. isolation-by-distance; slope β = ?0.194 from regression analysis of observed averaged Moran's I values against the logarithm of the upper bound of six distance classes). In contrast, little evidence of SGS was found in cpDNA SSR data across the BIA (β = 0.013). These results suggest that although gene flow via seed dispersal is somewhat limited, pollen flow has been sufficient to maintain genetic diversity and prevent differentiation across the island landscape over several thousand years of isolation.     

Within-river gene flow in the hellbender (Cryptobranchus alleganiensis) and implications for restorative release

Understanding how populations are genetically and demographically connected is beneficial for species management, since gene flow and dispersal contribute to genetic diversity and population persistence. For hellbenders (Cryptobranchus alleganiensis), an aquatic salamander species experiencing dramatic declines in population size, fine-scale (i.e. within river) patterns of genetic diversity and gene flow are not well understood. Previous findings indicate that hellbenders are habitat specialists that exhibit extreme site fidelity and low vagility, suggesting that gene flow is restricted among the several, discrete habitat patches within a river. Using 15 polymorphic microsatellite loci and 497 hellbender samples from four Missouri rivers, we assessed fine-scale patterns of genetic diversity in order to infer population connectivity and aid in population management. Results indicate moderate levels of genetic variation (H_O = 0.66–0.78) with little differentiation among habitat patches (avg. F_ST = 0.002) and no evidence of isolation by distance. Our data suggest that hellbender gene flow has been extensive even among habitat patches separated by distances greater than >100 km. These results are useful for hellbender management, especially in terms of making informed decisions regarding restorative releases of captively propagated individuals.     

Contrasting spatial genetic structure in Annona crassiflora populations from fragmented and pristine savannas

In continuous populations, fine-scale genetic structure tends to be stronger in species with restricted pollen and seed dispersal. However, habitat fragmentation and disturbances can affect genetic diversity and spatial genetic structure due to disruption in ecological processes, such as plant reproduction and seed dispersal. In this study, we compared the genetic diversity and fine-scale spatial genetic structure (SGS) in two populations of Annona crassiflora (Annonaceae) in a pristine savanna Reserve (ESECAE) and in a fragmented disturbed savanna area (PABE), both in Cerrado biome in Central Brazil. The analyses were based on the polymorphism at 10 microsatellite loci. Our working hypothesis was that SGS is stronger and genetic diversity is lower in population at fragmented area (PABE) than at pristine area (ESECAE). Both populations presented high levels of polymorphism and genetic diversity and showed no sign of bottleneck for both Wilcoxon sign-rank test for heterozygosity excess (p > 0.05) and coalescent analyses (growth parameter g not different from zero), but population at fragmented area showed higher fixation index and stronger SGS. Besides, populations are significantly differentiated (F _ST = 0.239, R _ST = 0.483, p < 0.001 for both). Coalescent analyses showed high historical effective population sizes for both populations, high gene flow between ESECAE and PABE and recent time to most recent common ancestor (~37 k year BP). Our results suggest that despite the high genetic diversity, fragmentation and disturbance may have been affecting populations of this species increasing mating between closely related individuals leading to high fixation index and strong SGS.     

Contemporary human‐altered landscapes and oceanic barriers reduce bumble bee gene flow

Much of the world's terrestrial landscapes are being altered by humans in the form of agriculture, urbanization and pastoral systems, with major implications for biodiversity. Bumble bees are one of the most effective pollinators in both natural and cultivated landscapes, but are often the first to be extirpated in human‐altered habitats. Yet, little is known about the role of natural and human‐altered habitats in promoting or limiting bumble bee gene flow. In this study, I closely examine the genetic structure of the yellow‐faced bumble bee, Bombus vosnesenskii, across the southwestern US coast and find strong evidence that natural oceanic barriers, as well as contemporary human‐altered habitats, limit bee gene flow. Heterozygosity and allelic richness were lower in island populations, while private allelic richness was higher in island populations compared to mainland populations. Genetic differentiation, measured for three indices across the 1000 km study region, was significantly greater than the null expectation (F_ST = 0.041, F’_ST = 0.044 and D_est = 0.155) and correlated with geographic distance. Furthermore, genetic differentiation patterns were most strongly correlated with contemporary (2011) not past (2006, 2001) resistance maps calibrated for high dispersal limitation over oceans, impervious habitat and croplands. Despite the incorporation of dramatic elevation gradients, the analyses reveal that oceans and contemporary human land use, not mountains, are the primary dispersal barriers for B. vosnesenskii gene flow. These findings reinforce the importance of maintaining corridors of suitable habitat across the distribution range of native pollinators to promote their persistence and safeguard their ability to provide essential pollination services.     

Rangewide genetic analysis of Lesser Prairie-Chicken reveals population structure,range expansion,and possible introgression

The distribution of the Lesser Prairie-Chicken (Tympanuchus pallidicinctus) has been markedly reduced due to loss and fragmentation of habitat. Portions of the historical range, however, have been recolonized and even expanded due to planting of conservation reserve program (CRP) fields that provide favorable vegetation structure for Lesser Prairie-Chickens. The source population(s) feeding the range expansion is unknown, yet has resulted in overlap between Lesser and Greater Prairie-Chickens (T. cupido) increasing the potential for hybridization. Our objectives were to characterize connectivity and genetic diversity among populations, identify source population(s) of recent range expansion, and examine hybridization with the Greater Prairie-Chicken. We analyzed 640 samples from across the range using 13 microsatellites. We identified three to four populations corresponding largely to ecoregions. The Shinnery Oak Prairie and Sand Sagebrush Prairie represented genetically distinct populations (F _ST > 0.034 and F _ST > 0.023 respectively). The Shortgrass/CRP Mosaic and Mixed Grass ecoregions appeared admixed (F _ST = 0.009). Genetic diversity was similar among ecoregions and N _e ranged from 142 (95 % CI 99–236) for the Shortgrass/CRP Mosaic to 296 (95 % CI 233–396) in the Mixed Grass Prairie. No recent migration was detected among ecoregions, except asymmetric dispersal from both the Mixed Grass Prairie and to a lesser extent the Sand Sagebrush Prairie north into adjacent Shortgrass/CRP Mosaic (m = 0.207, 95 % CI 0.116–0.298, m = 0.097, 95 % CI 0.010–0.183, respectively). Indices investigating potential hybridization in the Shortgrass/CRP Mosaic revealed that six of the 13 individuals with hybrid phenotypes were significantly admixed suggesting hybridization. Continued monitoring of diversity within and among ecoregions is warranted as are actions promoting genetic connectivity and range expansion.     

Distribution and polymorphism of Mariner-like elements in the Bambusoideae subfamily

Picea omorika (Pan?.) Purk. is a relict from the Arcto-Tertiary flora with its entire current natural range confined to an area of only 10,000 km² within the Balkans, a region well known as a Quaternary refugium. We have amplified the second intron of the mitochondrial NADH dehydrogenase subunit1 gene in 200 trees originating from ten natural populations to assess the phylogeographic structure and history of this conifer. Five haplotypes harbouring different numbers of 34-bp minisatellites were detected, revealing haplotypic richness of 3.007 and gene diversities H _S = 0.075 and H _T = 0.225. More interestingly, despite the very small distribution range of P. omorika and its dispersal by wind, non-random distribution of haplotypes was observed, resulting in an unexpectedly high estimate of population differentiation (G _ST = 0.668), and 56.8% of molecular variation assigned to variation among populations. Those findings suggest substantial isolation of populations and their partitioning into two gene pools characterized by different history and levels of genetic diversity, and very limited seed flow in this species (Nm = 0.25). They support the hypothesised early arrival of P. omorika in the Balkan region, and residence within this refugium during several ice ages at least. We demonstrate that the assessment of genetic diversity and structuring are not straightforward in species confined to refugial regions, and that past microvicariance might bias formal phylogeographic (G _ST = N _ST = 0.668) and isolation-by-distance analysis (r = 0.028, P > 0.05).     

Unspecific histological and hematological alterations in anadromous and resident <Emphasis Type="Italic">Salvelinus malma</Emphasis> induced by volcanogenic pollution

Knowledge of larval dispersal and connectivity in coral reef species is crucial for understanding population dynamics, resilience, and evolution of species. Here, we use ten microsatellites and one mitochondrial marker (cytochrome b) to investigate the genetic population structure, genetic diversity, and historical demography of the powder-blue tang Acanthurus leucosternon across more than 1000 km of the scarcely studied Eastern African region. The global AMOVA results based on microsatellites reveal a low but significant F _ST value (F _ST = 0.00252 P < 0.001; D _EST = 0.025 P = 0.0018) for the 336 specimens sampled at ten sample sites, while no significant differentiation could be found in the mitochondrial cytochrome b dataset. On the other hand, pairwise F _ST, PCOA, and hierarchical analysis failed to identify any genetic breaks among the Eastern African populations, supporting the hypothesis of genetic homogeneity. The observed genetic homogeneity among Eastern African sample sites can be explained by the lengthy post-larval stage of A. leucosternon, which can potentiate long-distance dispersal. Tests of neutrality and mismatch distribution signal a population expansion during the mid-Pleistocene period.     

Population genetic structure of the endangered Eastern Bristlebird, Dasyornis brachypterus; implications for conservation

For species that are habitat specialists or sedentary, population fragmentation may lead to genetic divergence between populations and reduced genetic diversity within populations, with frequent inbreeding. Hundreds of kilometres separate three geographical regions in which small populations of the endangered Eastern Bristlebird, Dasyornis brachypterus, a small, ground-dwelling passerine that occurs in fire-prone bushland in eastern Australia, are currently found. Here, we use mitochondrial and microsatellite DNA markers to: (i) assess the sub-specific taxonomy designated to northern range-edge, and central and southern range-edge D. brachypterus, respectively, and (ii) assess levels of standing genetic variation and the degree of genetic subdivision of remnant populations. The phylogenetic relationship among mtDNA haplotypes and their spatial distribution did not support the recognised subspecies boundaries. Populations in different regions were highly genetically differentiated, but in addition, the two largest, neighboring populations (located within the central region and separated by ~50 km) were moderately differentiated, and thus are likely closed to migration (microsatellites, F _ST = 0.06; mtDNA, F _ST = 0.12, ?? _ST = 0.08). Birds within these two populations were genotypically diverse and apparently randomly mating. A long-term plan for the conservation of D. brachypterus??s genetic diversity should consider individual populations as separate management units. Moreover, managers should avoid actively mixing birds from different populations or regions, to conserve the genetic integrity of local populations and avoid outbreeding depression, should further translocations be used as a recovery tool for this species.     

Low genetic diversity and high levels of inbreeding in the Sinai primrose (Primula boveana), a species on the brink of extinction

The Sinai primrose (Primula boveana) is one of the most endangered plant species worldwide, with less than 200 wild individuals surviving in the Sinai mountains of Egypt. There has been a decline in both the number and size of its populations in recent times, possibly caused by threats that include habitat aridification and the impact of human activities. Studying the standing genetic variation and extent of inbreeding of P. boveana is necessary for the design of appropriate conservation strategies for this species. In the present work, we used a set of seven, recently developed, polymorphic microsatellite markers to characterize the genetic variation and levels of inbreeding of the extant populations of P. boveana. We found low levels of genetic variation (H _T = 0.470), high differentiation between populations (F _ST = 0.737, R _ST = 0.935), and very elevated levels of inbreeding (F = 0.862) due to recurrent selfing. These results may be the reflection of low levels of genetic variation and high levels of inbreeding over a long evolutionary period, suggesting that the current genetic pool of the species may enable P. boveana to persist in a habitat where water availability and pollinator services are restricted. Nevertheless, in sight of its rapidly dwindling abundance, it seems prudent to adopt swift measures, including habitat restoration and ex-situ conservation, to prevent the impending extinction of this emblematic species.     

Population genetic structure of wild daffodils (Narcissus pseudonarcissus L.) at different spatial scales

We studied the population genetic and clonal structure of the endangered long-lived perennial plant Narcissus pseudonarcissus using random amplified polymorphic markers. Estimates for mean gene diversity within 15 populations of N. pseudonarcissus of three neighbouring geographical regions were high in comparison to other long-lived perennials (H _eN = 0.33). The genetic diversity of the two smallest populations (<200 plants) was significantly reduced, indicating loss of genetic variability due to drift. The analysis of the population genetic structure revealed a significant genetic differentiation both between regions (Φ_ST = 0.06) and between populations within regions (Φ_ST = 0.20). However, there was incomplete correspondence between geographical regions and the population genetic structure. In order to preserve the overall genetic variation in wild populations of N. pseudonarcissus, management measures should thus aim to protect many populations in each region. The spatial genetic structure within populations of N. pseudonarcissus was in agreement with an isolation by distance model indicating limited gene flow due to pollinator behaviour and restricted seed dispersal. The very restricted spatial extent of clonal growth (<5 cm) and the high level of clonal diversity indicate that clonal growth in N. pseudonarcissus is not an important mode of propagation and that management measures should favour sexual reproduction in order to avoid further reductions in the size and number of populations.     

Signatures of adaptation and genetic structure among the mainland populations of Pinus radiata (D. Don) inferred from SNP loci

Insights into the relative contributions of locus specific and genome-wide effects on population genetic diversity can be gained through separation of their resulting genetic signals. Here we explore patterns of adaptive and neutral genetic diversity in the disjunct natural populations of Pinus radiata (D. Don) from mainland California. A first-generation common garden of 447 individuals revealed significant differentiation of wood phenotypes among populations (P _ST), possibly reflecting local adaptation in response to environment. We subsequently screened all trees for genetic diversity at 149 candidate gene single nucleotide polymorphism (SNP) loci for signatures of adaptation. Ten loci were identified as being possible targets of diversifying selection following F _ST outlier tests. Multivariate canonical correlation performed on a data set of 444 individuals identified significant covariance between environment, adaptive phenotypes and outlier SNP diversity, lending support to the case for local adaptation suggested from F _ST and P _ST tests. Covariation among discrete sets of outlier SNPs and adaptive phenotypes (inferred from multivariate loadings) with environment are supported by existing studies of candidate gene function and genotype–phenotype association. Canonical analyses failed to detect significant correlations between environment and 139 non-outlier SNP loci, which were applied to estimate neutral patterns of genetic differentiation among populations (F _ST 4.3 %). Using this data set, significant hierarchical structure was detected, indicating three populations on the mainland. The hierarchical relationships based on neutral SNP markers (and SSR) were in contrast with those inferred from putatively adaptive loci, potentially highlighting the independent action of selection and demography in shaping genetic structure in this species.     

Genetic diversity within and among populations of the endangered and endemic species Primula merrilliana in China

Primula merrilliana Schltr. is an endangered and narrowly-distributed endemic species of southern Anhui Province in China. In this study, the level of genetic variation and the pattern of genetic structure in six natural populations of P. merrilliana were assessed by using ISSR (inter-simple sequence repeats) markers. Based on ten primers, 137 clear and reproducible DNA fragments were generated, of which 109 were polymorphic. The statistical results indicated that there was a relatively low genetic diversity within populations, and a high genetic differentiation among populations (G_ST = 0.53, Φ_ST = 0.49). The level of population genetic diversity was correlated to habitat type and the gene flow (N_m) was low with only 0.45. The unexpected genetic structure of P. merrilliana may be explained by limited gene flow that was caused by habitat fragmentation and limited seeds and pollen dispersal ability, self-compatible breeding system and biennial life form.     

Two decades of genetic consistency in a reproductive population in the face of exploitation: patterns of adult and larval walleye (<Emphasis Type="Italic">Sander vitreus</Emphasis>) from Lake Erie’s Maumee River

Analyses of genetic variability and allelic composition in a species exhibiting reproductive fidelity to natal sites may provide important ecological indication of temporal population dynamics, facilitating understanding responses to past disturbances and future climate change. The walleye is an ecologically and economically valuable species, whose largest fishery centers in Lake Erie of the Laurentian Great Lakes; it exhibits reproductive site fidelity, despite otherwise wide-ranging dispersal. We tested whether genetic composition and diversity have remained temporally stable in Lake Erie’s Maumee River, which is the largest and most highly fished spawning run. This population has experienced over a century of exploitation, habitat alterations, and pollution, which may have affected genetic structure and might influence future sustainability. Fourteen nuclear DNA microsatellite loci were analyzed from 744 spawning run walleye to test genetic patterns across: (1) years (N = 12, spanning 1995–2013), (2) birth year cohorts, (3) the sexes, (4) those reproducing earlier (ages 2–6) versus later (7 or older) in life, and (5) the adults versus larvae. Results indicated stability in genetic diversity levels (mean H _O = 0.76 ± 0.03) and allelic composition across years (F _ST = 0.000–0.006, NS), cohorts (F _ST = 0.000–0.013, NS), sexes (F _ST = 0.000, NS), earlier versus later reproduction (F _ST = 0.000, NS), and between the larvae and adults (F _ST = 0.000–0.004, NS). Number of breeders and effective population size were substantial and consistent. This reproductive population thus has maintained genetic stability and high diversity, despite intensive anthropogenic pressures.     

Population genetics and fine-scale genetic structure of Rhizopogon roseolus in the Tottori sand dune

We investigated the population genetics and fine-scale genetic structure of Rhizopogon roseolus. A total of 173 R. roseolus sporocarps were collected from two stands in the Tottori sand dune. We developed and applied five novel polymorphic microsatellite (SSR; simple sequence repeat) markers for sporocarp genotyping. In total, we identified 110 genets, most of which were small in size. Spatial autocorrelation analyses revealed a significantly positive genetic structure in short-distance classes. The inbreeding coefficient value was significant in both stands (F_IS = 0.18), while the F_ST value (F_ST = 0.020) indicated little genetic differentiation between the two populations. The majority of alleles were distributed in both stands with similar frequencies. These results suggest that short-distance spore dispersal plays a dominant role in generating new genets, and eventually increases the frequency of inbreeding in the Tottori sand dune, whereas rare gene flow between the two stands, possibly associated with spore dispersal by mycophagous animals, could reduce genetic differentiation.