Genetic diversity and the genetic structure of natural populations of Chamaecyparis obtusa: implications for management and conservation

We investigated 25 natural populations of Chamaecyparis obtusa using 51 cleaved amplified polymorphic sequence (CAPS) markers, which were developed using information on sequence-tagged sites (STS) in Cryptomeria japonica. Most CAPS markers have codominant expression patterns, and are suitable for population studies because of their robustness and convenience. We estimated various genetic diversity parameters, including average heterozygosity (H(e)) and allelic richness and found that the more peripheral populations tended to have lower genetic diversity than central populations, in agreement with a previous theoretical study. The overall genetic differentiation between populations was low, but statistically significant (G(ST)=0.039), and similar to the level reported in a previous allozyme study. We attempted to detect non-neutral loci associated with local adaptation to clarify the relationship between the fixation index (F(ST)) and H(e) values for each locus and found seven candidates non-neutral loci. Phylogenetic tree analysis of the populations and Bayesian clustering analysis revealed a pattern of gradually increasing isolation of populations with increasing geographical distance. Three populations had a high degree of linkage disequilibrium, which we attribute to severe bottlenecks due to human disturbance or competition with other species during their migration from refugia after the most recent glaciation. We concluded that the small populations in western Japan and in Kanto district are more important, from a conservation perspective, than the populations in central Japan, due to their genetic divergence, relatively small sizes and restricted areas.     

Relationships between plant diversity,vegetation cover,and site conditions: implications for grassland conservation in the Greater Caucasus

Overgrazing, land use abandonment and increasing recreational activities have altered the vegetation of high-montane and subalpine grassland of the Caucasus. The failure of previous restoration efforts with unsuitable and exotic plant species indicates the need for information on the present vegetation and in which way it might change. Within the Greater Caucasus, we have described and quantified the mountain grassland which develops under characteristic overgrazed and eroded site conditions. Further, we have proposed potential native plant species for revegetation to restore and conserve valuable mountain grassland habitats. We used non-metric dimensional scaling ordination and cluster comparison of functional plant groups to describe a gradient of grassland vegetation cover. For our study region, we identified four major vegetation types with increasing occurrence of ruderal pasture weeds and tall herb vegetation on abandoned hay meadows within the subalpine zone. Within high-montane grassland a decline of plant diversity can be observed on sites of reduced vegetation cover. Due to a low potential of the grassland ecosystem to balance further vegetation cover damage, the long-term loss of diverse habitats can be expected. We conclude with management recommendations to prevent erosion and habitat loss of precious mountain grasslands.     

Relationships between taxonomic and functional components of diversity: implications for conservation of tropical freshwater fishes

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Patterns of ancestry and genetic diversity in reintroduced populations of the slimy sculpin: implications for conservation

Reintroductions are a common approach for preserving intraspecific biodiversity in fragmented landscapes. However, they may exacerbate the reduction in genetic diversity initially caused by population fragmentation because the effective population size of reintroduced populations is often smaller and reintroduced populations also tend to be more geographically isolated than native populations. Mixing genetically divergent sources for reintroduction purposes is a practice intended to increase genetic diversity. We documented the outcome of reintroductions from three mixed sources on the ancestral composition and genetic variation of a North American fish, the slimy sculpin (Cottus cognatus). We used microsatellite markers to evaluate allelic richness and heterozygosity in the reintroduced populations relative to computer simulated expectations. Sculpins in reintroduced populations exhibited higher levels of heterozygosity and allelic richness than any single source, but only slightly higher than the single most genetically diverse source population. Simulations intended to mimic an ideal scenario for maximizing genetic variation in the reintroduced populations also predicted increases, but they were only moderately greater than the most variable source population. We found that a single source contributed more than the other two sources at most reintroduction sites. We urge caution when choosing whether to mix source populations in reintroduction programs. Genetic characteristics of candidate source populations should be evaluated prior to reintroduction if feasible. When combined with knowledge of the degree of genetic distinction among sources, simulations may allow the genetic diversity benefits of mixing populations to be weighed against the risks of outbreeding depression in reintroduced and nearby populations.     

Estimating the genetic diversity and spatial structure of Bulgarian Castanea sativa populations by SSRs: implications for conservation

Sweet chestnut (Castanea sativa Mill.) is a multipurpose species of great ecological and economic importance in southwest Bulgaria. Bulgarian chestnut forests are severely degraded, however, due to the intensive exploitation and bad management that have occurred over the last 2000 years. Given the urgent need to define conservation strategies to preserve the biodiversity of Bulgarian chestnut, we estimated its genetic variability. A set of eight microsatellite primers were used to analyze the genetic diversity and structure of six C. sativa populations distributed throughout the range of species in Bulgaria. Results showed a generally high level of genetic diversity but little divergence among populations. A significant, positive, within-population inbreeding coefficient (Fis) was observed in four populations. A STRUCTURE analysis revealed three genetic clusters. Using a landscape approach, significant genetic barriers among populations were found by integrating genetics with geographical distance. We hypothesize that one population is a relict from a glacial refugium; the structure of the remaining populations is probably the result of a combination of natural events and human impacts. For the purposes of conservation planning, we have identified populations that are particularly rich in diversity and private alleles that are good candidates for preservation.     

Genetic diversity in fragmented populations of the critically endangered spider orchid Caladenia huegelii: implications for conservation

The Orchidaceae is characterised by a diverse range of life histories, reproductive strategies and geographic distribution, reflected in a variety of patterns in the population genetic structure of different species. In this study, the genetic diversity and structure was assessed within and among remnant populations of the critically endangered sexually deceptive orchid, Caladenia huegelii. This species has experienced severe recent habitat loss in a landscape marked by ancient patterns of population fragmentation within the Southwest Australian Floristic Region, a global biodiversity hotspot. Using seven polymorphic microsatellite loci, high levels of within-population diversity (mean alleles/locus = 6.73; mean H _E = 0.690), weak genetic structuring among 13 remnant populations (F _ST = 0.047) and a consistent deficit of heterozygotes from Hardy–Weinberg expectation were found across all populations (mean F _IS = 0.22). Positive inbreeding coefficients are most likely due to Wahlund effects and/or inbreeding effects from highly correlated paternity and typically low fruit set. Indirect estimates of gene flow (Nm = 5.09 using F _ST; Nm = 3.12 using the private alleles method) among populations reflects a historical capacity for gene flow through long distance pollen dispersal by sexually deceived wasp pollinators and/or long range dispersal of dust-like orchid seed. However, current levels of gene flow may be impacted by habitat destruction, fragmentation and reduced population size. A genetically divergent population was identified, which should be a high priority for conservation managers. Very weak genetic differentiation indicates that the movement and mixing of seeds from different populations for reintroduction programs should result in minimal negative genetic effects.     

Translocation of wild populations: conservation implications for the genetic diversity of the black-lipped pearl oyster Pinctada margaritifera

Translocation has been widely studied as a tool for conservation management to restore or enhance degraded populations. On the contrary, few studies have been conducted on translocation for commercial purposes. In this study, we evaluate the genetic consequences of translocation of wild individuals of Pinctada margaritifera on farmed and adjacent wild populations. We tested the hypotheses that translocations would induce high genetic heterogeneity in farmed populations and this heterogeneity would then leak into the adjacent wild populations. In fact, farmed samples exhibit high levels of heterogeneity and low pairwise relatedness compared to wild populations, highlighting the pooling of genetically divergent populations into farms. We also demonstrate that this heterogeneity is transmitted to adjacent wild populations as a result of interbreeding. Adjacent wild populations tend to have higher genetic diversity values and greater pairwise relatedness coefficient with farmed populations than wild populations. Overall, pearl culture in French Polynesia promotes the mixing of unrelated individuals in farmed locations and reduces genetic divergence among geographically distant populations as well as among farmed and wild populations of a same lagoon. We also studied for the first time a farmed population originating from spat collected in a lagoon where release of hatchery-produced larvae occurred 10 years ago and we were able to identify four distinct genetic groups. These groups contribute highly to reproduction and caused considerable genetic drift in the lagoon, suggesting that hatchery-produced larvae are neither sustainable method for pearl culture nor for conserving the diversity of P. margaritifera in French Polynesia.     

Effects of chemical contaminants on genetic diversity in natural populations: implications for biomonitoring and ecotoxicology

The conservation of genetic diversity has emerged as one of the central issues in conservation biology. Although researchers in the areas of evolutionary biology, population management, and conservation biology routinely investigate genetic variability in natural populations, only a handful of studies have addressed the effects of chemical contamination on population genetics. Chemical contamination can cause population reduction by the effects of somatic and heritable mutations, as well as non-genetic modes of toxicity. Stochastic processes in small populations, increased mutation load, and the phenomenon of mutational meltdown are compounding factors that cause reduced fitness and accelerate the process of population extirpation. Although the original damage caused by chemical contaminants is at the molecular level, there are emergent effects at the level of populations, such as the loss of genetic diversity, that are not predictable based solely on knowledge of the mechanism of toxicity of the chemical contaminants. Therefore, the study of evolutionary toxicology, which encompasses the population-genetic effects of environmental contaminants, should be an important focus of ecotoxicology. This paper reviews the issues surrounding the genetic effects of pollution, summarizes the technical approaches that can be used to address these issues, and provides examples of studies that have addressed some of them.     

Neotropical bats in the canopy: diversity,community structure,and implications for conservation

We compare results of parallel ground and canopy netting of bats (Microchiroptera) in three adjacent forest sites near Belém, Brazil, to document possible differences in vertical distribution of species. We caught 1871 individuals representing 49 species of three families (Emballonuridae, Phyllostomidae, Vespertilionidae). Capture effort, totaling 1955.5 mistnet hours in several cycles over a two-year period, was similar for ground and canopy nets. The canopy rigs yielded more species (n = 41) than the ground nets (n = 35), but both samples were characterized by rank abundance curves with similar shape and with a dominance of frugivores (Phyllostomidae). Nearly half (n = 24) of the species were captured in numbers too small (n < 6) to allow firm classification, but differences in capture frequencies of some of the better-sampled species in high and low nets reveal vertical stratification. Species-specific differences in diet, foraging strategies, roost sites, and sampling bias contribute to this pattern. As a result of the differential use of space among bats, alterations of forest structure are likely to result in changes in structure and function of local bat communities, but our limited knowledge of natural history and ecology of many species limits definition of changes. We see a critical need for further research into the extent to which habitat complexity influences species richness and abundance of bats. This information is especially important in view of the need to develop and apply conservation-oriented programs to maintain biodiversity. A review of recent improvements in techniques for inventorying bats shows that a combination of methods, including mistnetting and acoustic monitoring, is mandatory for such studies.     

Low neutral and immunogenetic diversity in northern fringe populations of the green toad Bufotes viridis: implications for conservation

Genetic variation is often lower at high latitudes, which may compromise the adaptability and hence survival of organisms. Here we show that genetic variability is negatively correlated with northern latitude in European green toads (Bufotes viridis). The result holds true for both putatively neutral microsatellite variation and supposedly adaptive MHC Class IIB variation. In particular, our findings have bearing on the conservation status of this species in Sweden, on the northern limit of its distribution where local populations are small and fragmented. These genetically impoverished populations are closely related to other populations found around the Baltic Sea basin. The low neutral and adaptive variation in these fringe populations compared to population at central ranges confirms a pattern shared across all other amphibians so far studied. In Sweden, the situation of green toads is of concern as the remaining populations may not have the evolutionary potential to cope with present and future environmental challenges.

     

Low genetic diversity and significant structuring in the endangered Mentha cervina populations and its implications for conservation

Eighteen populations of the endangered aromatic and medicinal plant Mentha cervina (Lamiaceae) were sampled across its natural range, in the western half of the Iberian Peninsula, and inter-simple sequence repeats (ISSRs) markers were used to assess genetic diversity and population structure. M. cervina populations exhibited a relatively low genetic diversity (percentage of polymorphic loci PPB = 14.2–58.3%, Nei's genetic diversity H_e = 0.135–0.205, Shannon's information index I = 0.08 − 0.33). However, the genetic diversity at species level was relatively high (PPB = 98.3%; H_e = 0.325; I = 0.23). The results of the analysis of molecular variance indicated very structured populations, with 50% of the variance within populations, 44% among populations and 6% between regions defined by hydrographic basins, in line with the gene differentiation coefficient (G_ST = 0.532). A Mantel test did not find significant correlation between genetic and geographic distance matrices (r = 0.064), indicating that isolation by distance is not shaping the present genetic structure. The levels and patterns of genetic diversity in M. cervina populations were assumed to result largely from a combination of evolutionary history and its unique biological traits, such as breeding system, low capacity of dispersion, small effective size and habitat fragmentation. The high genetic differentiation among populations indicates the necessity of conserving the maximum possible number of populations. The results also provide information to select sites for ex situ conservation. Optimal harvesting strategies, cultivation and tissue culture should also be developed as soon as possible to guarantee sustainable use of the species under study.     

Relationships of the Galapagos flora

Joseph Dalton Hooker's pioneer 1847 paper on Galapagos plants and their relationships is a classic in the field of phytogeography. It was the first study of its kind to be published, comparing the islands' flora with island and continental floras elsewhere, hypothesizing on the dispersal mechanisms of the plants, and pointing out anomalies in the inter-island distributions of the native species. These are still three of the primary concerns of contemporary phytogeographers, and the present paper contrasts Hooker's findings with those of today. Despite the accumulation of a large amount of data since his time, many of Hooker's conclusions regarding Galapagos phytogeography remain valid.     

Mammal diversity and taxonomy in Italy: implications for conservation

The paper attempts to describe Italian mammal diversity in an evolutionary context. With 122 species according latest researches, Italy holds the richest mammal assemblage among European countries. Specific taxa are often represented by clearly distinctive lineages and several of them appear restricted to the Italian peninsula. Poor knowledge of taxonomy and uncritical application of IUCN threat categories at the national level could produce a flawed set of conservation priorities, independently from the rigorous application of the proposed guidelines for national Red List assessments. Furthermore, classical conservation assessments and protective legislation only consider traditionally named taxa, often privileging insular taxa of artificial origin but neglecting most of the results of genetic and molecular studies on intraspecific variation. The aim of the present work is to outline the need to incorporate phylogenetic and biogeographic data in the assessment of conservation priorities among mammals in Italy, in order to maximise the national contribution to biodiversity conservation in Europe. To this end, distribution, threat status, intraspecific and supraspecific taxonomy of the native mammal fauna should be analysed in a global context. Phylogeographic patterns emerging from previous studies indicate the general inadequacy of continental European populations serving as sources for re-stocking or re-introductions operations in Italy and the other European peninsulas. Thus the importance of integrating international guidelines on reintroductions with a clear understanding of national biogeographical peculiarities is highlighted.     

Classification, diversity, and distribution of Chilean Asteraceae: implications for biogeography and conservation

This paper provides a synopsis of the Chilean Asteraceae genera according to the most recent classification. Asteraceae is the richest family within the native Chilean flora, with a total of 121 genera and c . 863 species, currently classified in 18 tribes. The genera are distributed along the whole latitudinal gradient in Chile, with a centre of richness at 33°–34° S. Almost one-third of the genera show small to medium-small ranges of distribution, while two-thirds have medium-large to large latitudinal ranges of distribution. Of the 115 mainland genera, 46% have their main distribution in the central Mediterranean zone between 27°–37° S. Also of the mainland genera, 53% occupy both coastal and Andean environments, while 33% can be considered as strictly Andean and 20% as strictly coastal genera. The biogeographical analysis of relationships allows the distinction of several floristic elements and generalized tracks: the most marked floristic element is the Neotropical, followed by the antitropical and the endemic element. The biogeographical analysis provides important insights into the origin and evolution of the Chilean Asteraceae flora. The presence of many localized and endemic taxa has direct conservation implications.     

Genetic diversity and structure in fragmented populations of the endangered species Ranunculus cabrerensis (Ranunculaceae): implications for conservation

Ranunculus cabrerensis is an endemic and endangered species of the Northwestern Iberian Peninsula. The molecular markers AFLP and ISSR were used to investigate the genetic diversity and population structure of four populations across its known distribution. Fifteen selective primer combinations of AFLP and seventeen ISSR primer combinations produced a total of 2830 and 103 unambiguously repeatable fragments respectively, of which 97.57 and 81.38% were polymorphic for both markers. The genetic diversity of R. cabrerensis at species level was high (H _E = 0.294 by ISSR and H _E = 0.191 by AFLP) and differentiation between sampled locations was also relatively high (G _ST = 0.316 and 0.158 by ISSR and AFLP analysis respectively) compared to other studies of endangered and rare species using the same techniques. The analysis of molecular variance (AMOVA) indicated that the main genetic variation was within sampled locations (73% by AFLP; 52% by ISSR), even though the variation among locations was also significant. Principal Coordinates, NeighborNet and Bayesian analyses revealed a weak but significant relationship between the genetic structures of different populations in R. cabrerensis, with gene flow acting as a homogenizing force that prevents stronger differentiation of populations. Finally, suggestions for conservation strategies to preserve the genetic resources of this species are outlined.     

Forage use and niche partitioning by non-native bumblebees in New Zealand: implications for the conservation of their populations of origin

Bumblebees were introduced into New Zealand from the UK approximately 120 years ago and four species became established. Two of these, Bombus terrestris and B. hortorum, are common in Europe whilst two, B. ruderatus and B. subterraneus, have experienced declines, and the latter is now extinct in the UK. The presence of these species in New Zealand presents an opportunity to study their ecology in a contrasting environment. Forage visits made by bumblebees in New Zealand were recorded across a season. Ninety-six percent of visits were to six non-native forage plants (Cirsium vulgare, Echium vulgare, Hypericum perforatum, Lotus corniculatus, Lupinus polyphyllus and Trifolium pratense). All but L. polyphyllus are European plant species, and three are noxious weeds in New Zealand. Several of these plants have decreased in abundance in the UK, providing a potential explanation for the declines of B. ruderatus and B. subterraneus in Britain. In contrast to studies conducted elsewhere, B. ruderatus, B. terrestris and B. hortorum did not differ in diet breadth and overlap in forage use was high, probably due to the reduced diversity of bumblebee forage plants present in New Zealand. Diel partitioning of forage use between the species was observed, with foraging activity of B. hortorum greatest in the morning and evening, B. ruderatus greatest in the middle of the day and B. terrestris intermediate between the two. These patterns correspond to the climatic preferences of each species as evidenced by their geographic ranges. Implications for bumblebee conservation in the UK are discussed.