Negligence in the Atlantic forest,northern Brazil: a case study of an endangered orchid

Currently, many Brazilian orchids are threatened with extinction resulting from habitat loss and intense harvesting pressure stemming from their value as ornamental plants. Therefore, the genetic diversity in remaining populations is fundamental to the survival of these species in natural environments. In order to inform conservation strategies, this study evaluated the genetic diversity and structure of Cattleya granulosa populations. The sample consisted of 151 individuals from 12 populations in the Atlantic Forest, northeastern Brazil, evaluated using 91 ISSR markers. Genetic variability was assessed through molecular variance, diversity indexes, clusters of genotypes through Bayesian analysis, and tests for genetic bottlenecks. From all polymorphic loci, genetic diversity (H_E) varied between 0.210 and 0.321 and the Shannon index ranged from 0.323 and 0.472. Significant genetic differentiation between populations (Φ_ST = 0.391; P < 0.0001) resulted in the division of the populations into five groups based on the log-likelihood Bayesian analysis. We found significant positive correlation between geographical and genetic distances between populations (r = 0.794; P = 0.017), indicating isolation by distance. Patterns of allelic diversity within populations suggest the occurrence of bottlenecks in most C. granulosa populations (n = 8). Therefore, in order to maintain the genetic diversity of the species, the conservation of spatially distant groups is necessary.     

Genetic Variation in Three Endangered Species of Encholirium (Bromeliaceae) from Cadeia do Espinhaço, Brazil, Setected using RAPD Markers

Encholirium is a Brazilian genus of Bromeliaceae that occurs exclusively in rocky landscapes. This work aimed to generate basic information for the conservation of three Encholirium species that are endemic to the rocky mountains of Cadeia do Espinhaço, employing population genetic analyses. E. pedicellatum and E. biflorum have only one very small population each, both occurring in unprotected, private land sites, being critically endangered. E. subsecundum is more widespread, and some of its populations dwell in protected areas. Five Random Amplified Polymorphic DNA (RAPD) primers generated approximately 60 polymorphic bands for each species. This technique demonstrated the presence of a single RAPD profile for every individual sampled (except for one clone found in E. biflorum). High levels of genetic variability were not expected, due to the clonal habit of the plants and small size of the populations. Populations of E. biflorum and E. pedicellatum presented, respectively, 16.06% (Φ _st  = 0.16, p<0.001) and 8.44% (Φ _st  = 0.08, p<0.001) of the total genetic diversity attributable to genetic differences among groups within the populations. In E. subsecundum, 14.52% (Φ _st  = 0.15, p<0.001) of the total genetic diversity was found among populations. Estimates of the Shannon’s Diversity Index provided similar results. These results are valuable for the development of conservation strategies.     

Genetic diversity and genetic structure in wild populations of Mexican oregano (Lippia graveolens H.B.K.) and its relationship with the chemical composition of the essential oil

Mexican oregano is an aromatic plant traditionally harvested from wild populations by rural communities; however, there is little information about population genetics aspects of this species. Moreover, considering that the variation in essential oil production of aromatic plants has been attributed to several environmental as well as genetic factors, in this study we estimated the genetic diversity and genetic structure from 14 wild populations of L. graveolens located in four different bioclimatic regions in southeastern Mexico using AFLP markers. The overall genetic diversity of L. graveolens described as the percentage of polymorphic loci (PPL = 60.9 %) and Nei’s gene diversity (H _j  = 0.17) was moderate, but not associated with the bioclimatic conditions. Genetic variation was analyzed at chemotype and population levels. Regarding chemotypes, thymol had the highest genetic diversity (PPL = 82.8 % and H _j  = 0.22). PCoA revealed that chemotypes exhibit a certain level of genetic differentiation. Maximum parsimony dendrogram showed a grouping of individuals with a predominant chemotype. Bayesian analyses revealed a low, but significant differentiation among chemotypes (θ _ΙΙ = 0.008). Regarding populations, gene diversity showed significant differences (F _13,1204 = 22.8, P < 0.001); populations dominated by individuals from the thymol chemotype showed the highest gene diversity (H _j  = 0.31–0.25), while populations with exclusively sesquiterpene chemotype showed the lowest value (H _j  = 0.058). Cluster and Bayesian analyses (θ _ΙΙ = 0.027) revealed a low level of genetic differentiation among populations. Correlation analysis showed a significant association between the distance matrices based on the genetic markers (AFLP) and chemical compounds of essential oil (r = 0.06, P < 0.001). Our results suggest an important genetic influence on the observed chemical profiles. Nevertheless, other biotic and abiotic environmental pressures also play an important role in determining the chemotype and structure found in this aromatic species.     

Higher immunocompetence is associated with higher genetic diversity in feral honey bee colonies (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

Honey bees are the most important managed pollinators as they provide key ecosystem services for crop production worldwide. Recent losses of honey bee colonies in North America and Europe have demonstrated a need to develop strategies to improve their health and conserve their populations. Previously, we showed that feral honey bees—colonies that live in the wild without human assistance—exhibit higher levels of immunocompetence than managed colonies in North Carolina (USA). In a first attempt to investigate the underlying mechanisms of this difference in immune response, here we characterize the genetic composition of feral and managed honey bees using microsatellite markers. Our results reveal significant but small genetic differentiation between feral and managed honey bee colonies (?_CT = 0.047, P?=?0.03) indicating admixture between these two groups. Higher genetic diversity was correlated with higher immune response in feral (P _MANOVA = 0.011) but not managed bees, despite the fact that the latter group showed significantly higher average genetic diversity (P _ANCOVA < 0.001). These findings suggest that genetic diversity is positively associated with immunocompetence in feral honey bee colonies, and that the benefits of genetic diversity are obscured in managed bees, perhaps as a result of artificial selection. We hypothesize that high genetic variability provides the raw material upon which natural selection acts and generates adaptive genotypes in unmanaged populations. Feral populations could be useful sources of genetic variation to use in breeding programs that aim to improve honey bee health.     

Genetic structure and phylogeography of Pyrus pashia L. (Rosaceae) in Yunnan Province, China, revealed by chloroplast DNA analyses

In this study, we investigated two chloroplast intergenic spacers (accD-psaI and trnL-trnF) for a total of 266 individuals over 22 populations of Pyrus pashia to detect the genetic diversity, genetic, and phylogeographic structure and provide needed information for the development of conservation strategies. Thirteen haplotypes (H1–H13) were recognized. A high level of total diversity was detected (H _T?=?0.746). Analysis of molecular variance indicated that the genetic variation mainly existed within populations, representing 59.61 % of the total variation. Genetic differentiation among populations was high (F _st?=?0.404). A Mantel test did not show a correlation between the genetic and geographic distances (r?=?0.139, P?=?0.09, 1,000 permutations), implying that geographic distance was not critical to gene flow among populations. A significantly higher N _st than G _st (N _st?=?0.420, G _st?=?0.402, P?<?0.05) reflected the phylogeographic structure in P. pashia. While nested clade analyses of clade 2-2 showed that restricted gene flow existed among populations, clades 1-2 and 2-1, and the total cladogram exhibited contiguous range expansion events in P. pashia. Both sum of square deviations and the raggedness index failed to reject the sudden demographic expansion model. The overall population expansion of P. pashia was estimated to occur between 621,000 and 209,000 years ago.     

Genetic Diversity and Geographic Differentiation of the Giant Tiger Shrimp (Penaeus monodon) in Thailand Analyzed by Mitochondrial COI Sequences

Genetic diversity and geographic differentiation of the giant tiger shrimp, Penaeus monodon, in Thai waters (Satun, Trang, Phangnga, and Ranong in the Andaman Sea and Chumphon and Trat in the Gulf of Thailand) were examined by COI polymorphism (N = 128). We observed 28 COI mitotypes across all investigated individuals. The sequence divergence between pairs of mitotypes was 0.00–20.76%. A neighbor-joining tree clearly indicated lineage separation of Thai P. monodon and large nucleotide divergence between interlineage mitotypes but limited divergence between intralineage mitotypes. High genetic diversity was found (mean sequence divergence = 6.604%, haplotype diversity = 0.716–0.927, π = 2.936–8.532%). F-statistics (F _ST) and an analysis of molecular variance (AMOVA) indicated that the gene pool of Thai P. monodon was not homogeneous but genetically differentiated intraspecifically (P < 0.05). Six samples of P. monodon could be allocated into three different genetic populations: Trat (A), Chumphon (B), and the Andaman samples Satun, Trang, Phangnga, and Ranong (C). Contradictory results regarding patterns of geographic differentiation previously reported by various molecular approaches were clarified by this study.     

Genetic diversity and structure of Lilium pumilum DC. in southeast of Qinghai–Tibet plateau

Lilium pumilum DC. is a valuable species not only for its showy flowers but also for its edible and medicinal values. As one of the distribution areas of L. pumilum, Qinghai–Tibet plateau has unique environmental features which have high impact on the evolution of the species. No population genetic studies have been done for L. pumilum so far. To provide the first reference data for evolutionary study and understanding the influence of eco-geographic factors on the distribution of genetic variation in L. pumilum, interspecific simple sequence repeat markers were used to investigate genetic diversity and population structure of 28 populations sampled from southeast of Qinghai–Tibet plateau. Fifteen selected primers generated a total of 147 polymorphic bands. The genetic diversity was low within populations (average He = 0.173), but higher at the species level (He = 0.392). A clear population structure and high level of genetic differentiation (F _ST = 0.518) were detected by unweighted pair group method for arithmetic averages, principle coordinate analysis and Bayesian clustering. All clustering approaches supported a division of the 28 populations into 4 major groups for which analysis of molecular variance confirmed a significant variation among groups (34.3 %). These population genetic parameters suggest limited gene flow among populations and evidence for isolation by distance (r = 0.272, P < 0.0001) was found in this study. Altitude, AMT and AMP explained 9.5, 11.5 and 14.0 % of the total variance among populations indicating that eco-geographic factors have a significant effect. Considering the low within-population genetic diversity, high differentiation among populations and the increasing anthropogenic pressure on the species, in situ conservation measures were recommended to preserve L. pumilum in Qinghai–Tibet plateau.     

Population structure and conservation implications for the loggerhead sea turtle of the Cape Verde Islands

The Cape Verde Islands harbour the second largest nesting aggregation of the globally endangered loggerhead sea turtle in the Atlantic. To characterize the unknown genetic structure, connectivity, and demographic history of this population, we sequenced a segment of the mitochondrial (mt) DNA control region (380 bp, n = 186) and genotyped 12 microsatellite loci (n = 128) in females nesting at three islands of Cape Verde. No genetic differentiation in either haplotype or allele frequencies was found among the islands (mtDNA F _ST = 0.001, P > 0.02; nDNA F _ST = 0.001, P > 0.126). However, population pairwise comparisons of the mtDNA data revealed significant differences between Cape Verde and all previously sequenced Atlantic and Mediterranean rookeries (F _ST = 0.745; P < 0.000). Results of a mixed stock analysis of mtDNA data from 10 published oceanic feeding grounds showed that feeding grounds of the Madeira, Azores, and the Canary Islands, in the Atlantic Ocean, and Gimnesies, Pitiüses, and Andalusia, in the Mediterranean sea, are feeding grounds used by turtles born in Cape Verde, but that about 43% (±19%) of Cape Verde juveniles disperse to unknown areas. In a subset of samples (n = 145) we evaluated the utility of a longer segment (~760 bp) amplified by recently designed mtDNA control region primers for assessing the genetic structure of Atlantic loggerhead turtles. The analysis of the longer fragment revealed more variants overall than in the shorter segments. The genetic data presented here are likely to improve assignment and population genetic analyses, with significant conservation and research applications.     

High level of genetic variation within clonal orchid Goodyera repens

Type of reproduction has an important effect on the maintenance of particular populations and species persistence in time and space. This trait significantly influences the ecological and genetic structure of populations, and in consequence the evolution of species. The primary objectives of this study were: to estimate genetic diversity within and among populations of clonal species Goodyera repens from different populations in northeastern Poland, and to amount factors shaping the genetic structure of this orchid. Based on 451 rosettes of G. repens from 11 localities in northeastern Poland, we conducted a genetic population analysis using allozymes. We included information on population size, flowering, fruit set and seed dispersal to elucidate their influences on genetic diversity of this species. Populations differed according to demographic properties. The majority of seeds (86.4–94.8 %) were found at a distance of 0.2 m. We observed a high level of genetic (P _PL = 50 %, A = 1.68, H _O = 0.210, H _E = 0.204) and genotypic diversity (G = 163, G/N _S = 0.66, G _U = 30.2 %), and low but statistically significant genetic differentiation among populations (F _ST = 0.060; P < 0.001). We suggest that the genetic diversity of G. repens is mainly an effect of the abundance of pine and spruce forest communities suitable for this species in NE Poland and the high level of sexual reproduction.     

Genetic diversity of the endangered Chinese endemic herb Saruma henryi Oliv. (Aristolochiaceae) and its implications for conservation

Saruma henryi Oliv., the only representative of the monotypic genus Saruma Oliv. (Aristolochiaceae), is an endangered perennial herb endemic to China. It is a phylogenetically, ecologically, and medicinally important species. In the present study, inter-simple sequence repeat (ISSR) markers were employed to investigate the genetic diversity and differentiation of 14 populations. A total of 16 selected primers yielded 175 bright and discernible bands, with an average of 10.94 per primer. POPGENE analysis showed that the genetic diversity was quite low at the population level (h = 0.0447–0.1243; I = 0.0642–0.1853; PPB = 10.29–36.57%), but pretty high at the species level (h = 0.2603; I = 0.3857; PPB = 73.71%). The hierarchical analysis of molecular variance (AMOVA) revealed a high level of genetic differentiation among populations (67.18% of total variance components, P < 0.001), in line with the gene differentiation coefficient (G _ST = 0.6903) and the limited among-population gene flow (N _m = 0.2243). Both Principal Coordinates Analysis (PCoA) and UPGMA cluster analysis supported the grouping of all 14 populations into three geographic groups, among which there occurred a moderate level of genetic differentiation (33.18% of total variance components, P < 0.001) as shown by AMOVA analysis. In addition, Mantel test revealed a significant correlation between genetic and geographic distances among populations (r = 0.7792, P = 0.001), indicating the role of geographic isolation in shaping its present population genetic structure. The present levels and patterns of genetic diversity of S. henryi were assumed to result largely from its breeding system, geographic isolation, clonal growth, its unique biological traits and evolutionary history. The high genetic differentiation among populations implies that the conservation efforts should aim to preserve all the extant populations of this endangered herb.     

Genetic differences between wild and hatchery populations of Korean spotted sea bass (Lateolabrax maculatus) inferred from microsatellite markers

The spotted sea bass, Lateolabrax maculatus, is popular in recreational fishing and aquaculture in Korea. Its natural population has declined during the past two decades; thus, beginning in the early 2000s stock-enhancement programs were introduced throughout western and southern coastal areas. In this study, genetic similarities and differences between wild and hatchery populations were assessed using multiplex assays with 12 highly polymorphic microsatellite loci; 96 alleles were identified. Although many unique alleles were lost in the hatchery samples, no significant reductions were found in heterozygosity or allelic diversity in the hatchery compared to the wild population. High genetic diversity (He = 0.724–0.761 and Ho = 0.723–0.743), low inbreeding coefficient (F _IS = 0.003–0.024) and Hardy–Weinberg equilibrium were observed in both wild and hatchery populations. However, the genetic heterogeneity between the populations was significant. Therefore, genetic drift likely promoted inter-population differentiation, and rapid loss of genetic diversity remains possible. Regarding conservation, genetic variation should be monitored and inbreeding controlled in a commercial breeding program.     

Genetic and morphological variability in the Raddia brasiliensis complex (Poaceae: Bambusoideae)

Raddia brasiliensis forms a species complex with the recently segregated R. megaphylla, R. lancifolia, R. soderstromii and R. stolonifera, occurring in the Atlantic rainforest, Brazil. Allozymic markers were used in 272 individuals of 14 populations of this group to investigate its genetic variability, correlating this with morphological variability, and testing the proposed taxonomy based on multivariate morphometrics. Genetic variability was low in almost all populations (P = 22.2–66.7, A = 1.3–2.0, H _e=0.04–0.17). R. brasiliensis showed a very high endogamy (F _IS = 0.329). Values for genetic and morphological structuring were very high to high (F _ST = 0.43, A _MRPP = 0.22; F _ST = 0.19, A _MRPP = 0.10 and F _ST = 0.18, A _MRPP = 0.39), respectively, for R. brasiliensis, R. soderstromii and R. megaphylla. The lowest genetic identity between populations was also found in R. brasiliensis, and the highest morphological differentiation was found between populations of R. megaphylla. Allozymic and morphological data were congruent and complementary, and confirm that we are dealing with five distinct species as previously circumscribed.     

Allozyme diversity levels in two congeneric Dioon spp. (Zamiaceae, Cycadales) with contrasting rarities

Allozyme diversity and population genetic structure studies were conducted in populations of two Mexican cycad species occurring in adjacent and closely related biogeographic regions. We evaluated if rarity traits in Dioon caputoi, a micro-endemic species, and Dioon merolae, a regional endemic with a wider distribution, influence levels of genetic diversity in different ways. We also explored if genetic structure differs in these species, considering that they have similar population histories. Our results indicate that D. caputoi harbors lower levels of genetic diversity and allelic richness (H _E = 0.358, P = 76.9, A _r = 1.86) than D. merolae (H _E = 0.446, P = 92.3, A _r = 2). However, genetic structure does not differ between the two species despite their contrasting geographic distributions (F _ST = 0.06 vs. 0.07; D. caputoi and D. merolae, respectively). The comparison of population genetic structure information with historical and geographical aspects of the populations suggests that the rarity of D. caputoi might be due to relatively recent local ecological factors.     

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.     

Genetic variation and population differentiation of the endochitinase gene family in Pinus monticola

In the present study, we characterized nucleotide variations of the Pinus monticola class IV endochitinase (PmCh4) family. Using primers targeting at conserved amino acid motifs of plant class IV endochitinases, genomic DNA was amplified. Sequence data analysis identified five novel genes in the PmCh4 family with one pseudogene. Single nucleotide polymorphisms of the PmCh4 family were surveyed in seven open-pollinated seed lots representing diverse geographical distribution. Variable levels of average pairwise nucleotide diversity (π = 0.00422–0.02079) and relatively high levels of haplotype diversity (H _d = 0.85–0.96) were revealed at PmCh4 loci. Based on nucleotide variation, P. monticola populations were clustered into two main groups by phylogenetic analysis based on Nei’s genetic distance. The Mantel test revealed no correlation between geographical and genetic distances (r = ?0.11, P = 0.59). A further SNP genetic diversity study on more P. monticola populations throughout Western North America may help the design of sampling regimes for tree breeding, genetic conservation and assisted migration under climate change.     

Genetic structure of the Korean black scraper Thamnaconus modestus inferred from microsatellite marker analysis

The Korean black scraper, Thamnaconus modestus, is one of the most economically important maricultural fish species in Korea. However, the annual catch of this fish has been continuously declining over the past several decades. In this study, the genetic diversity and relationships among four wild populations and two hatchery stocks of Korean black scraper were assessed based on 16 microsatellite (MS) markers. A total of 319 different alleles were detected over all loci with an average of 19.94 alleles per locus. The hatchery stocks [mean number of alleles (N _A) = 12, allelic richness (A _R) = 12, expected heterozygosity (He) = 0.834] showed a slight reduction (P > 0.05) in genetic variability in comparison with wild populations (mean N _A = 13.86, A _R = 12.35, He = 0.844), suggesting a sufficient level of genetic variation in the hatchery populations. Similarly low levels of inbreeding and significant Hardy–Weinberg equilibrium deviations were detected in both wild and hatchery populations. The genetic subdivision among all six populations was low but significant (overall F _ST = 0.008, P < 0.01). Pairwise F _ST, a phylogenetic tree, and multidimensional scaling analysis suggested the existence of three geographically structured populations based on different sea basin origins, although the isolation-by-distance model was rejected. This result was corroborated by an analysis of molecular variance. This genetic differentiation may result from the co-effects of various factors, such as historical dispersal, local environment and ocean currents. These three geographical groups can be considered as independent management units. Our results show that MS markers may be suitable not only for the genetic monitoring of hatchery stocks but also for revealing the population structure of Korean black scraper populations. These results will provide critical information for breeding programs, the management of cultured stocks and the conservation of this species.     

Molecular Phylogeography and Evolutionary History of the Estuarine Copepod, Acartia Tonsa, on the Northwest Atlantic Coast

Coastal estuaries are useful model systems to study the ecological and evolutionary responses of organisms to highly variable, discontinuous habitats. For this study, the molecular population genetic diversity of the planktonic calanoid copepod Acartia tonsa (Dana, 1849) was described based on DNA sequence variation for a 183 base-pair region of the mitochondrial 16S rRNA gene. Samples of A. tonsa were collected from four estuaries on the Atlantic coast of the USA during 1993 and 1994, one estuary on the Gulf of Mexico coast in 1994, and one site on the Pacific coast of the USA in 1994. Dispersal of A. tonsa was shown to be restricted, with significant population genetic structuring between different estuaries. For all but the closely-adjacent MA and RI samples, frequencies of haplotypes and/or length polymorphisms within one haplotype (caused by insertion/deletion mutations) revealed highly significant genetic differentiation and geographic isolation. Mt16S haplotypes of A. tonsa from Atlantic and Gulf of Mexico estuaries were assorted among four deeply-diverged clades. Haplotypes within each clade differed by <2%, while differences among clades of 10% to 14% approached those between described Acartia species (e.g., 19% to 28% among A. clausi, A. hudsonica, and A. longiremis). Atlantic and Pacific coast samples identified as A. tonsa had no haplotypes in common and genetic differences between haplotypes ranged from 18% to 29%; phylogenetic analysis supported the separation of Pacific coast A. tonsa as a distinct species. We hypothesize that the observed patterns of molecular genetic diversity and structure of A. tonsa resulted from responses to historical climatic variation, including episodic range compression and displacement, and alteration of NW Atlantic coastal and estuarine environments.     

Genetic population structure and low genetic diversity in the over-exploited sea cucumber <Emphasis Type="Italic">Holothuria edulis</Emphasis> Lesson, 1830 (Echinodermata: Holothuroidea) in Okinawa Island

Understanding genetic connectivity is fundamental for ecosystem-based management of marine resources. Here we investigate the metapopulation structure of the edible sea cucumber Holothuria edulis Lesson, 1830 across Okinawa Island, Japan. This species is of economic and ecological importance and is distributed from the Red Sea to Hawai‘i. We examined sequence variation in fragments of mitochondrial cytochrome oxidase subunit I (COI) and 16S ribosomal RNA (16S), and nuclear histone (H3) at six locations across Okinawa Island. We found higher haplotype diversity for mtDNA (COI: Hd = 0.69 and 16S: Hd = 0.67) and higher heterozygosity of nDNA (H3: H _E = 0.39) in populations from the west coast of Okinawa compared to individuals from populations on the east coast (COI: Hd = 0.40; 16S: Hd = 0.21; H3: H _E = 0.14). Overall population structure was significant (AMOVA results for COI: Φ _ST = 0.49, P < 0.0001; 16S: Φ _ST = 0.34, P < 0.0001; H3: Φ _ST = 0.12, P < 0.0001). One population in the east, Uruma, showed elevated pairwise Φ _ST values in comparisons with all other sites and a marked reduction of genetic diversity (COI: Hd = 0.25 and 16S: Hd = 0.24), possibly as a consequence of a shift to a more dominant asexual reproduction mode. Recent reports have indicated that coastal development in this area influences many marine organisms, and ecosystem degradation in this location could cause the observed decrease of genetic diversity and isolation of H. edulis in Uruma. Our study should provide valuable data to help with the urgently needed management of sea cucumber populations in Okinawa, and indicates particular attention needs to be paid to vulnerable locations.     

Cryptic genetic subdivision in the San Benito evening primrose (Camissonia benitensis)

When rare plants are distributed across a range of habitats, ecotypic differentiation may arise requiring customized conservation measures. The rate of local adaptation may be accelerated in complex landscapes with numerous physical barriers to gene flow. In such cases, examining the distribution of genetic diversity is essential in determining conservation management units. We investigated the distribution of genetic diversity in the federally threatened Camissonia benitensis (Onagraceae), which grows in two distinct serpentine habitats across several watersheds in San Benito, Fresno, and Monterey Cos., CA, USA. We compared genetic diversity with that of its two widespread relatives, C. contorta and C. strigulosa, and examined the potential for hybridization with the latter species. Genotyping results using seven heterospecific microsatellite markers indicate that differentiation between habitat types was weak (F _ST = 0.0433) and in an AMOVA analysis, there was no significant partitioning of molecular variation between habitats. Watersheds accounted for 11.6 % of the molecular variation (pairwise F _ST = 0.1823–0.4275). Three cryptic genetic clusters were identified by InStruct and STRUCTURE that do not correlate with habitat or watershed. C. benitensis exhibits 5–11× higher inbreeding levels and 0.54× lower genetic diversity in comparison to its close relatives. We found no evidence of hybridization between C. benitensis and C. strigulosa. To maximize conservation of the limited amount of genetic diversity in C. benitensis, we recommend mixing seed representing the three cryptic genetic clusters across the species’ geographic range when establishing new populations.