Variance in Female Reproductive Success Differentially Impacts Effective Population Size in the Short-Nosed Fruit Bat, <Emphasis Type="Italic">Cynopterus sphinx</Emphasis>

Effective population size (N _e) quantifies the effects of micro-evolutionary processes and the rate of loss of genetic diversity in a population. Several demographic and mating parameters reduce N _e. Theoretical studies elucidate the impacts of various demographic and mating system parameters on N _e, while empirical studies illustrate realized N _e for species with differing life histories and mating systems. However, effect of intra-specific variation in mating system on effective size remains largely unexplored. In this paper we investigated the effect of promiscuous and polygynous mating on N _e in two wild populations of the short-nosed fruit bat, Cynopterus sphinx. N _e/N (ratio of effective population size to census size) was lower than unity in both populations, and much lower for the polygynous population compared to promiscuous population. Elasticity analyses reveal that N _e/N was sensitive to deviations in the sex ratio. Variance in female reproductive success had a higher impact on N _e compared to variance in male reproductive success in the promiscuous population. However, for the polygynous population, impact of variance in male reproductive success on N _e was higher than that of variance in female reproductive success. Our results suggest that depending on mating system, different populations of the same species could have alternate evolutionary trajectories. The rate of loss of genetic diversity would be lower for the promiscuous population compared to the polygynous population. Our study is the first to highlight which parameters would most significantly impact population specific N _e under different mating systems.     

Meta-analysis reveals asymmetric reduction in the genetic diversity of introduced populations of exotic insects

Factors promoting the invasion success of introduced populations have been receiving increased attention in studies of biological invasions. Previous reports have indicated that successful invasions may be attributable to reduced genetic diversity in the invasive species. However, there is large variation in the magnitude and direction of the impact of exotic species that have remained unexplained. Here, we present a structured meta-analysis of papers investigating the genetic diversity of native and introduced populations of exotic insects using nuclear microsatellites and mitochondrial DNA sequences. The results indicate that invasion by exotic insects had an overall reducing effect on the genetic diversity of the invading population, with nonzero effect sizes for the number of alleles (NA), observed heterozygosity (Ho), expected heterozygosity (He) and nucleotide diversity (Nd). However, when analyzing different orders (e.g., Lepidoptera, Hemiptera), the effect sizes of NA, Ho and Nd in Lepidoptera were found to bracket zero, as did the effect size of He in Hemiptera. These results suggest an asymmetric reduction in the genetic diversity of introduced populations of exotic insects, indicating diverse mechanisms underlying their successful invasion.     

Genetic assessment of <Emphasis Type="Italic">Abies koreana</Emphasis> (Pinaceae), the endangered Korean fir,and conservation implications

To establish a management plan for endangered and rare species, genetic assessment must first be conducted. The genetic characteristics of plant species are affected by demographic history, reproductive strategy, and distributional range as well as anthropological effects. Abies koreana E. H. Wilson (Pinaceae), Korean fir, is endemic to Korea and found only in sub-alpine areas of the southern Korean Peninsula and Jejudo Island. This species has been designated as critically endangered by the International Union for Conservation of Nature due to a continuous decline in its range and population fragmentation. We genotyped 176 individuals from seven natural populations and two afforested populations on the Korean Peninsula using 19 microsatellite loci. STRUCTURE analysis revealed two genetic clusters in natural populations (F _st  = 0.040 and R _st  = 0.040) despite low differentiation. We did not detect a significant reduction in genetic diversity or the signature of a genetic bottleneck despite population fragmentation and small population size. We deduced that this species exhibits a metapopulation structure, with the population on Jirisan Mountain acting as a source of genetic diversity for other local small populations on the Korean Peninsula, through contemporary asymmetric gene flow. However, the majority of afforested individuals on the Korean Peninsula originated from a different gene cluster. Thus, we recommend a conservation strategy that maintains two genetically unique clusters.     

Patterns of population genetic structure and diversity across bumble bee communities in the Pacific Northwest

Patterns of genetic structure and diversity are largely mediated by a species’ ecological niche and sensitivity to climate variation. Some species with narrow ecological niches have been found to exhibit increased population differentiation, limited gene flow across populations, and reduced population genetic diversity. In this study, we examine patterns of population genetic structure and diversity of four bumble bee species that are broadly sympatric, but do not necessarily inhabit the same ecological niche in the Pacific Northwest of the United States. Testing for the effect of isolation by geographic distance (IBD) with linearized F _st and D _est found that Bombus sylvicola and B. mixtus exhibited significant IBD across populations. In contrast, both B. melanopygus and B. flavifrons, two species that are distributed across a broad elevation gradient, exhibited no IBD, a result further corroborated by Bayesian a priori population assignment tests. Furthermore, we discovered that B. sylvicola populations distributed on the Olympic Peninsula have significantly less average allelic diversity than populations distributed in the Cascade Mountains. Our results suggest that populations distributed in the Olympic Mountains represent a distinct genetic cluster relative to the Cascade Mountains, with B. sylvicola and B. mixtus likely experiencing the greatest degree of population genetic differentiation relative to B. flavifrons and B. melanopygus. While bumble bees are known to co-exist across a diversity of habitats, our results demonstrate that underlying population genetic structure and diversity may not necessarily be similar across species, and are largely governed by their respective niches.     

Influences of the genetic neighborhood on ramet reproductive success in a clonal desert cactus

Clonal structure in clonal plants can affect sexual reproduction. Individual ramets can decrease reproduction if their neighbors are ramets of the same genet due to inbreeding depression or self-incompatibility. We assessed ramet reproductive success in the partial self-incompatible Ferocactus robustus (Cactaceae) as a function of floral display size in focal ramets and floral display size and clonal structure of their reproductive neighborhoods. Ramets were labeled, sized in number of stems, mapped and genetically identified through RAPD markers in one population. A pollen dispersal area of 15-m radius was established for each ramet to determine the clonal diversity in the neighborhoods. Flower production and fruit set were counted on a monthly basis during one reproductive season as a surrogate of ramet fitness. We expected a decrease in individual ramet reproductive success as a function of the number of reproductive ramets of the same genet in the neighborhood. A total of 272 sampled ramets revealed 116 multilocus genotypes, showing high clonal diversity in the population (G/N = 0.43, D = 0.98). Clonal diversity of neighborhoods ranged from 0.06 to 1 and fruit set varied from 0 to 76.9%. Individual ramet reproductive success was influenced by (1) mate availability, (2) floral display size of a genet within the reproductive neighborhood, and (3) the proportion of distinguishable genotypes. Floral display size of genets and ramets coupled with the genetic diversity within the reproductive neighborhood determines the low sexual reproduction in F. robustus.     

Co-occurring patterns of endophyte infection and genetic structure in the alpine grass, <Emphasis Type="Italic">Festuca eskia</Emphasis>: implications for seed sourcing in ecological restoration

Choosing the provenance of seed used in ecological restoration could entail its success. An alternative approach to examine local adaptation in seed sourcing is the assessment of genetic structure and diversity based on molecular markers. These types of analyses focus on the genetics of the target plant itself and eliminate the genetic influence of associated organisms, such as Epichloë/Neotyphodium endophytes in grasses. By impacting the fitness of their host, such symbionts may influence population genetic structure and diversity. Therefore, seed sourcing for grasses must consider the influence of their endophytes to increase seed translocation success and minimize the risks associated with this practice. To delineate seed zones for restoration of the alpine fescue Festuca eskia Ramond ex. DC. (Poaceae), we assessed population genetic differentiation and diversity patterns in the species including endophyte occurrence along altitudinal and longitudinal gradients in the Pyrenees Mountains. Twenty-three populations were analysed for endophyte status, and three STS and one SSR marker were used to examine genetic differentiation and diversity patterns. Results showed that F. eskia hosts an asexual form of Epichloë and infection frequency within populations decreased from East to West (100 vs. 8–25%). Molecular markers separated F. eskia into two East and West groups, and endophyte infection and genetic patterns were congruent with molecular data. Little evidence for genetic differentiation or difference in endophyte occurrence associated with altitude was detected. Little variation was found in within population diversity, regardless of provenance altitude and site, and/or endophyte infection frequency. The results of this study suggested the establishment of two distinct management units for F. eskia seed sourcing restoration.     

Genetic diversity and population structure of Chinese <Emphasis Type="Italic">Lentinula edodes</Emphasis> revealed by InDel and SSR markers

Genetic diversity and population structure of 88 Chinese Lentinula edodes strains belonging to four geographic populations were inferred from 68 Insertion-Deletion (InDel) and two simple sequence repeat (SSR) markers. The overall values of Shannon’s information index and gene diversity were 0.836 and 0.435, respectively, demonstrating a high genetic diversity in Chinese L. edodes strains. Among the four geographic populations, the Central China population displayed a lower genetic diversity. Multiple analyses resolved two unambiguous genetic groups that corresponded to two regions from which the samples were collected—one was a high-altitude region (region 1) and the other was a low-altitude region (region 2). Results from analysis of molecular variance suggested that the majority of genetic variation was contained within populations (74.8 %). Although there was a strong genetic differentiation between populations (F _ST ?=?0.252), the variability of ITS sequences from representative strains of the two regions (<3 %) could not support the existence of cryptic species. Pairwise F _ST values and Nei’s genetic distances showed that there were relatively lower genetic differentiations and genetic distances between populations from the same region. Geographic distribution could play a vital role in the formation of the observed population structure. Mycelium growth rate and precocity of L. edodes strains displayed significant differences between the two regions. Strains from region 2 grew faster and fructified earlier, which could be a result of adaptation to local environmental factors. To the best of our knowledge, this was the first study on the genetic structure and differentiation between populations, as well as the relationship between genetic structure and phenotypic traits in L. edodes.     

Assessment of spatial–temporal variation in natural populations of <Emphasis Type="Italic">Brassica incana</Emphasis> in south Italy: implications for conservation

Brassica incana is a secondary-gene pool wild relative of Brassica oleracea. Twenty-two B. incana populations are recorded in Italy, where the species has recently been pointed out as in priority need of conservation. While data on the spatial and temporal variation of B. incana Italian populations are completely lacking, this information is useful in conservation planning for this species. Three populations from the Sorrento peninsula and from the islands of Ischia and Capri, collected in 1984 and 2012, were characterised for 12 morpho-phenological and 21 genetic traits to assess their spatial–temporal variation. The populations were quite different for morpho-phenological and genetic traits. Spatial differentiation was high and easily explained by the isolation. Temporal differentiation between the Sorrento and Ischia populations was high and explained by a reduction in the population census across time, while it was not significant between the two Capri accessions as such pointing to a major effect of genetic drift. Numerical dimension is extremely relevant in evaluating conservation priorities since it has a major impact on population dynamics over time. The Sorrento and Ischia populations are under threat and urgently need conservation actions, suggesting an alarming scenario for the survival of other crop wild relative populations which are similar in census. Our data also show that, in an allogamous and self-incompatible species like B. incana, populations of 100–200 individuals maintain high allelic diversity. According to obtained results, natural populations of species with similar reproductive system and census can be considered at low risk of genetic erosion.     

Demographic history and population genetic structure of <Emphasis Type="Italic">Hagenia abyssinica</Emphasis> (Rosaceae), a tropical tree endemic to the Ethiopian highlands and eastern African mountains

The distribution of genetic diversity among natural populations is significantly shaped by geographical and environmental heterogeneity. The key objectives of this study were to outline the population genetic structure and to investigate the effects of historical and current factors in shaping the population structure of an endemic tropical tree, Hagenia abyssinica. We used 11 polymorphic microsatellites to estimate genetic variability and evaluate gene flow among natural populations of H. abyssinica. Further, we employed ecological niche modeling approaches, to analyze the demographic history and map potential distributions of H. abyssinica during the Last Glacial Maximum and the present. Significant levels of genetic diversity (H _O = 0.477, H _E = 0.439) were observed among the sampled locations. High coefficient of genetic differentiation (F _ST = 0.32) and considerable genetic variation within the sampled locations (68.01%) were detected. Our results indicated the existence of three genetic groups with limited gene exchange and revealed positive correlations (r = 0.425, P < 0.05) between genetic diversity and geo-graphic distance. The ecological niche modeling (ENM) results support the existence of three distribution zones during the Last Glacial Maximum (LGM), with high probability of occurrence (0.8–1.0), and indicated slight distribution disturbances during and after the LGM. The fundamental patterns of genetic diversity and population structuring of H. abyssinica result from a combination of both environmental and geographical factors, including long-term isolation by distance and characteristic life history of this species. Our ENM results identified three zones that could have served as glacial refugia for this species and lay a foundation for further studies, outlining demographic histories and population structures of Afromontane species.     

Differential invasion success in aquatic invasive species: the role of within- and among-population genetic diversity

Despite a well-developed theoretical basis for the role of genetic diversity in the colonization process, contemporary investigations of genetic diversity in biological invasions have downplayed its importance. Observed reductions in genetic diversity have been argued to have a limited effect on the success of establishment and impact based on empirical studies; however, those studies rarely include assessment of failed or comparatively less-successful biological invasions. We address this gap by comparing genetic diversity at microsatellite loci for taxonomically and geographically paired aquatic invasive species. Our four species pairs contain one highly successful and one less-successful invasive species (Gobies: Neogobius melanostomus, Proterorhinus semilunaris; waterfleas: Bythotrephes longimanus, Cercopagis pengoi; oysters: Crassostrea gigas, Crassostrea virginica; tunicates: Bortylloides violaceous, Botryllus schlosseri). We genotyped 2717 individuals across all species from multiple locations in multiple years and explicitly test whether genetic diversity is lower for less-successful biological invaders within each species pair. We demonstrate that, for gobies and tunicates, reduced allelic diversity is associated with lower success of invasion. We also found that less-successful invasive species tend to have greater divergence among populations. This suggests that intraspecific hybridization may be acting to convert among-population variation to within-population variation for highly successful invasive species and buffering any loss of diversity. While our findings highlight the species-specific nature of the effects of genetic diversity on invasion success, they do support the use of genetic diversity information in the management of current species invasions and in the risk assessment of potential future invaders.     

Variation in the <Emphasis Type="Italic">COI</Emphasis> gene of the freshwater pearl mussel <Emphasis Type="Italic">Margaritifera margaritifera</Emphasis> from River Vuokkijoki

The freshwater pearl mussel Margaritifera margaritifera L. is one of the most endangered freshwater mussels in the world. Effective conservation of threatened species requires not only ecological, but also genetic information from the target species and populations. Since low genetic diversity can reduce the ability of a species to adapt to environmental changes, maintaining genetic diversity has been identified as one of the key elements in successful conservation programs. We examined genetic variation of the freshwater pearl mussel from the River Vuokkijoki, Karelia, Russia. We sequenced a fragment of the cytochrome c oxidase subunit I gene (COI) from 22 individuals and compared the data to 32 previously published COI sequences available in GenBank. We identified 10 different COI haplotypes in the sequenced samples, three of which had not been previously reported. Our results show that the River Vuokkijoki has high genetic diversity and suggest that the colonization of this northern freshwater pearl mussel population might have occurred from multiple and even distant refugia. Therefore, the freshwater pearl mussel population of the River Vuokkijoki is valuable for the conservation of the whole species.     

Population and Conservation Genetics in an Endangered Lemur, <Emphasis Type="Italic">Indri indri</Emphasis>, Across Three Forest Reserves in Madagascar

Population decline and fragmentation often lead to reduced genetic diversity and population differentiation. Habitat destruction throughout Madagascar has caused population decline and extinction of many endemic species. Lemur populations, including those of the largest extant lemur, Indri indri, have been fragmented into remaining forest patches. We assessed the level of genetic diversity in indri populations in three protected reserves by genotyping a total of 43 individuals at 17 microsatellite loci. Genetic diversity in terms of heterozygosity was high in all three reserves, with no differences between reserves. Population structure and F _ST analyses revealed Analamazaotra Forest Station and the Torotorofotsy Conservation Area, which are separated by ca. 18 km to be genetically differentiated from each other with some admixture. Betampona Strict Nature Reserve, which is separated from the other reserves by ca. 130 km, exhibited clear population genetic differentiation, with no signs of admixture with the other reserves. Our genetic diversity estimates are similar to those for other Indridae in similar habitats and may reflect past rather than current population processes, given that populations have declined recently. Our results suggest that Betampona may be genetically isolated and that it is important to maintain gene flow between remaining populations to prevent loss of genetic diversity for the future conservation of Indri indri.     

Genetic variation of <Emphasis Type="Italic">Spartina alterniflora</Emphasis> intentionally introduced to China

Spread of smooth cordgrass (Spartina alterniflora) in China is an exceptional example of unanticipated outcomes arising from intentional introductions. It has been proposed that in China, management strategies used to establish S. alterniflora inadvertently promoted evolutionary outcomes that have contributed to other Spartina invasions. In this study, we assessed whether S. alterniflora in China exhibits genetic signatures of mechanisms known to promote invasion success, including large founding populations, evolved self-fertility, ‘superior source ecotypes’, and post-introduction admixture. This involved comparing microsatellite genotype and chloroplast haplotype variation among Chinese populations to other invasive S. alterniflora populations as well as native range populations, inclusive of samples from all reported source areas. We found distinct signatures of source population contributions to Chinese populations, as well as evidence of post-introduction admixture, and no evidence of limitations from a genetic bottleneck. Measures of inbreeding were well below what has been found in other non-native populations that have evolved self-fertility. Differences in genetic diversity among sites were similar to latitudinal patterns in the native range, but could be attributable to introduction history. Comparisons to other invasive populations indicate that a combination of common and idiosyncratic processes have contributed to the success of S. alterniflora in China and elsewhere, with intentional introductions promoting mechanisms that accelerate rates of spread and widespread invasion.     

Geography,geology and ecology influence population genetic diversity and structure in the endangered endemic Azorean <Emphasis Type="Italic">Ammi</Emphasis> (Apiaceae)

Three Azorean endemic Ammi species were initially described: Ammi trifoliatum (Wats.) Trel., Ammi seubertianum (Wats.) Trel. and Ammi huntii (Wats.) Trel. Many taxonomic changes have been conducted, and one to three species have been considered. Two species are currently accepted: A. trifoliatum, which occurs in almost every island, and A. seubertianum, with a narrower distribution. In this research, the population genetic diversity and structure of the Azorean Ammi species were assessed using eight specifically designed SSR markers. A wide sampling of A. seubertianum and A. trifoliatum was conducted in seven Azorean islands, and four A. huntii herbarium samples were also included to further contribute to the taxonomy of this genus in Azores. Flores populations showed the highest genetic diversity, while North of Topo, in São Jorge, showed the lowest. None of the populations analysed displayed signs of putative inbreeding. The population genetic structure analyses conducted partially provided support for the two currently accepted species, but other possible cryptic taxa may also be present. The complex clustering obtained seems to result from a combined action of geography, geology and ecology, and although island-specific genetic patterns were found, environmental conditions connected to different altitudes and the existence of micro-niches may also play an important role. A thorough morphological revision and ecophysiological studies should be conducted to clarify the number of endemic taxonomic entities present in the Azores archipelago.     

Genetic diversity and population structure of common walnut (<Emphasis Type="Italic">Juglans regia</Emphasis>) in China based on EST-SSRs and the nuclear gene phenylalanine ammonia-lyase (<Emphasis Type="Italic">PAL</Emphasis>)

Common walnut (Juglans regia L.) is an economically important temperate tree species valued for both its nut and wood. We investigated the genetic diversity and population structure of J. regia germplasm from 13 locations in China using 10 markers derived from expressed sequences (EST-SSR) and sequence polymorphisms within the phenylalanine ammonia-lyase (PAL) gene. Analysis of the population genetic structure based on EST-SSRs showed distinct populations in northern versus southern China that were not reflected in the spatial distribution of PAL haplotypes. High levels of population differentiation were probably the result of reproductive isolation and in southern China, hybridization with Juglans sigillata. The results indicate the possible presence of distinct evolutionary lineages of J. regia in the Qinling and Daba Mountains of China and in Yunnan province that may require ecological management if they are to be retained as in situ resources.     

Historical range contraction,and not taxonomy,explains the contemporary genetic structure of the Australian tree <Emphasis Type="Italic">Acacia dealbata</Emphasis> Link

Irrespective of its causes, strong population genetic structure indicates a lack of gene flow. Understanding the processes that underlie such structure, and the spatial patterns it causes, is valuable for conservation efforts such as restoration. On the other hand, when a species is invasive outside its native range, such information can aid management in the non-native range. Here we explored the genetic characteristics of the Australian tree Acacia dealbata in its native range. Two subspecies of A. dealbata have previously been described based on morphology and environmental requirements, but recent phylogeographic data raised questions regarding the validity of this taxonomic subdivision. The species has been widely planted within and outside its native Australian range and is also a highly successful invasive species in many parts of the world. We employed microsatellite markers to investigate the population genetic diversity and structure among 42 A. dealbata populations from across the species’ native range. We also tested whether environmental variables purportedly relevant for the putative separation of subspecies are linked with population genetic differentiation. We found no relationship between population genetic structure of A. dealbata in Australia and these environmental features. Rather, we identified two geographically distinct genetic clusters that corresponded with populations in the northeastern part of mainland Australia, and the southern mainland and Tasmanian range of the species. Our results do not support the taxonomic subdivision of the species into two distinct subspecies based on environmental features. We therefore assume that the observed morphological differences between the putative subspecies are plastic phenotypic responses. This study provides population genetic information that will be useful for the conservation of the species within Australia as well as to better understand the invasion dynamics of A. dealbata.     

Genetic diversity of a hitchhiker and prized food source in the Anthropocene: the Asian green mussel <Emphasis Type="Italic">Perna viridis</Emphasis> (Mollusca,Mytilidae)

Insight into a species’ native and introduced range is essential in understanding the invasion process. Genetic diversity, propagule pressure and environmental conditions all have been recognised as playing a determinant role in invasion success. Here, we aimed to investigate the genetic diversity and population genetic structure (using the COI mtDNA gene region and 22 nDNA microsatellite markers) of the Asian green mussel Perna viridis within its potential native range in Asia and at introduced locations in the USA and the Caribbean. We also analyse genetic data from vessel intercepts and an incursion. By doing so, we aimed to identify genetic signatures that could allow to track vessel samples to their source and provide further insight into potential high-risk invasive populations or areas. Three top hierarchical clusters were identified using the individual-based Bayesian clustering method in STRUCTURE, corresponding to populations in three world regions: (1) USA and Caribbean, (2) India and (3) Southeast Asia. Within Southeast Asia, additional analysis indicate a shallow genetic differentiation of three subgroups consisting of (3a) Thailand, (3b) Taiwan and Hong-Kong, and (3c) a cluster of Singapore–Indonesia samples. Overall, the population structure found in this study suggests that the markers used could be useful in identifying source populations, particularly between the three mains world regions. Most surprisingly however, this study shows that the genetic diversity of samples collected from vessel intercepts and incursions did not differ significantly from established populations in Southeast Asia. In this region, in addition to the high vessel connectivity and number of P. viridis transported, all sampled populations are likely to pose a comparable risk in terms of genetic diversity. The present work represents the most comprehensive population genetic study of P. viridis, and the first to address the potential genetic introduction risk posed by populations of this species. The information and genetic markers in this study constitute a valuable addition to the tools already used to infer on potential high-risk source populations of P. viridis. They should therefore prove useful for biosecurity surveillance and management actions directed at this species.     

Population genetic diversity and geographical differentiation of MHC class II DAB genes in the vulnerable Chinese egret (<Emphasis Type="Italic">Egretta eulophotes</Emphasis>)

Major histocompatibility complex (MHC) genes are excellent markers for the study of adaptive genetic variation occurring over different geographical scales. The Chinese egret (Egretta eulophotes) is a vulnerable ardeid species with an estimated global population of 2600–3400 individuals. In this study, we sampled 172 individuals of this egret (approximately 6 % of the global population) from five natural populations that span the entire distribution range of this species in China. We examined their population genetic diversity and geographical differentiation at three MHC class II DAB genes by identifying eight exon 2 alleles at Egeu-DAB1, eight at Egeu-DAB2 and four at Egeu-DAB3. Allelic distributions at each of these three Egeu-DAB loci varied substantially within the five populations, while levels of genetic diversity varied slightly among the populations. Analysis of molecular variance showed low but significant genetic differentiation among five populations at all three Egeu-DAB loci (haplotype-based ?_ST: 0.029, 0.020 and 0.042; and distance-based ?_ST: 0.036, 0.027 and 0.043, respectively; all P < 0.01). The Mantel test suggested that this significant population genetic differentiation was likely due to an isolation-by-distance pattern of MHC evolution. However, the phylogenetic analyses and the Bayesian clustering analysis based on the three Egeu-DAB loci indicated that there was little geographical structuring of the genetic differentiation among five populations. These results provide fundamental population information for the conservation genetics of the vulnerable Chinese egret.     

Microsatellite markers revealed moderate genetic diversity and population differentiation of moso bamboo (<Emphasis Type="Italic">Phyllostachys edulis</Emphasis>)—a primarily asexual reproduction species in China

As an ecologically and economically important endemic bamboo species, moso (Phyllostachys edulis) has been widely distributed in Southern China. In the paper, 20 fluorescently labeled microsatellite markers were used to evaluate the genetic structure of Ph. edulis including 34 representative populations (803 individuals) covering the geographic range in China. Moderate genetic diversity (H?= 0.376) and differentiation (Gst?= 0.162) were detected at the species level, with the majority of genetic diversity occurring within populations (84.55%). Bayesian model-based structure analysis and sNMF/ANLS-AS method revealed the presence of two and three clusters. When K?=?2, majority of populations (except SX) were clustered together (C1). It implied that SX, known as an introduced and isolated founder population, significantly differed from other populations for distinct environmental selection and allele mutation with the proof of scarce outcrossing and relatively high frequency of private allele. While K?=?3, two subgroups (C1a of 18 populations and C1b of 14 populations) were detected within C1. The C1b displayed as a belt-shape region with an east-west direction. It coincided with the extremely high artificial selection in C1b (lower genetic diversity than that of C1a) due to the intensive plantation in the last four decades. Our results implied that the population protection and germplasm collection of moso bamboo should be not only from representative populations in Zhejiang, Jiangxi, Fujian, and other places with intensive cultivation in the east of China, but from populations with high level of gene and genotypic diversity in the west (e.g., HN5, GD1, GZ2, YN1, and SX).     

Lost but not forgotten: MHC genotypes predict overwinter survival despite depauperate MHC diversity in a declining frog

The amphibian disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has contributed to the decline of Chiricahua leopard frogs (Rana chiricahuensis), a federally threatened species native to the Southwestern United States. We characterized immunogenetic variability in R. chiricahuensis by sequencing an expressed Major Histocompatibility Complex (MHC) class IIβ gene across 13 natural populations in Arizona, USA, as well as 283 individuals that were captive reared from two egg masses. We recovered a total of five class IIβ MHC alleles compared to 84 alleles previously characterized in eight natural populations of the Arizona congener R. yavapaiensis, demonstrating reduced MHC diversity in R. chiricahuensis. One allele was fixed in five populations but none of the R. chiricahuensis alleles were closely related to R. yavapaiensis allele Q, which is significantly associated with chytridiomycosis resistance in laboratory trials. Nine of 13 R. chiricahuensis population localities were Bd positive, and bearing allele RachDRB*04 was the best genetic predictor of an individual being infected with Bd. A total of three class IIβ alleles were recovered from captive reared individuals, which were released to two natural population localities followed by recapture surveys to assess MHC-based survival over winter, the time when chytridiomycosis outbreaks are most severe. At one site, all released animals were fixed for a single allele and MHC-based survival could not be assessed. At the second site, fewer than half of the released but all of the recaptured individuals were homozygous for RachDRB*05, indicating that MHC genotype is important in determining Bd survival under natural field conditions. We conclude that the limited MHC variation in R. chiricahuensis is likely the consequence rather than the cause of natural selection favoring alleles that promote survival in the face of Bd. Our study highlights that preserving even low levels of functional genetic variation may be essential for population persistence, and that local disease adaptation may present as a reduction in genetic diversity. These finding also suggest that for populations that have declined due to a specific infectious pathogen, MHC-based genetically-informed reintroduction approaches may enhance species recovery efforts.