Conservation genetics of a rare Gerbil species: a comparison of the population genetic structures and demographic histories of the locally rare Pygmy Gerbil and the common Anderson's Gerbil

Background  

One of the major challenges in evolutionary biology is identifying rare species and devising management plans to protect them while also sustaining their genetic diversity. However, in attempting a broad understanding of rarity, single-species studies provide limited insights because they do not reveal whether the factors that affect rare species differ from those that affect more common species. To illustrate this important concept and to arrive at a better understanding of the form of rarity characterizing the rare Gerbillus henleyi, we explored its population genetic structure alongside that of the locally common Gerbillus andersoni allenbyi. We trapped gerbils in several locations in Israel's western and inner Negev sand dunes. We then extracted DNA from ear samples, and amplified two mitochondrial sequences: the control region (CR) and the cytochrome oxidase 2 gene (CO2).     

Within-host competitive exclusion among species of the anther smut pathogen

Background  

Host individuals represent an arena in which pathogens compete for resources and transmission opportunities, with major implications for the evolution of virulence and the structure of populations. Studies to date have focused on competitive interactions within pathogen species, and the level of antagonism tends to increase with the genetic distance between competitors. Anther-smut fungi, in the genus Microbotryum, have emerged as a tractable model for within-host competition. Here, using two pathogen species that are frequently found in sympatry, we investigated whether the antagonism seen among genotypes of the same species cascades up to influence competition among pathogen species.     

The impact of phages on interspecific competition in experimental populations of bacteria

Background  

Phages are thought to play a crucial role in the maintenance of diversity in natural bacterial communities. Theory suggests that phages impose density dependent regulation on bacterial populations, preventing competitive dominants from excluding less competitive species. To test this, we constructed experimental communities containing two bacterial species (Pseudomonas fluorescens and Pseudomonas aeruginosa) and their phage parasites. Communities were propagated at two environmental temperatures that reversed the outcome of competition in the absence of phage.     

Impacts of feral horses on a desert environment

Background  

Free-ranging horses (Equus caballus) in North America are considered to be feral animals since they are descendents of non-native domestic horses introduced to the continent. We conducted a study in a southern California desert to understand how feral horse movements and horse feces impacted this arid ecosystem. We evaluated five parameters susceptible to horse trampling: soil strength, vegetation cover, percent of nonnative vegetation, plant species diversity, and macroinvertebrate abundance. We also tested whether or not plant cover and species diversity were affected by the presence of horse feces.     

Determination of the genetic structure of remnant Morus boninensis Koidz. trees to establish a conservation program on the Bonin Islands, Japan

Background  

Morus boninensis, is an endemic plant of the Bonin (Ogasawara) Islands of Japan and is categorized as "critically endangered" in the Japanese red data book. However, little information is available about its ecological, evolutionary and genetic status, despite the urgent need for guidelines for the conservation of the species. Therefore, we adopted Moritz's MU concept, based on the species' current genetic structure, to define management units and to select mother tree candidates for seed orchards.     

Genetic variation in the invasive avian parasite, <Emphasis Type="Italic">Philornis downsi</Emphasis> (Diptera,Muscidae) on the Galápagos archipelago

Background  

Understanding the dispersal and genetic structure of invasive insects across islands is important for designing management plans that are appropriate at spatial and temporal scales. For invasive parasites, population dynamics are largely determined by the distribution and density of their host species. The introduced parasitic fly, Philornis downsi, parasitises nestlings of endemic birds on all major islands of the Galápagos archipelago. The fly's high mortality and fitness impacts are of conservation concern for vulnerable and declining species of Darwin's finches. Using microsatellite data in Bayesian clustering and landscape genetic analyses, we examine gene flow and dispersal in P. downsi between three islands and across habitats (highlands, lowlands) and examine for the presence of population bottlenecks. We also examine variation at the mitochondrial gene CO1 across islands to establish if cryptic species were present.     

The odor of origin: kinship and geographical distance are reflected in the marking pheromone of male beewolves (<Emphasis Type="Italic">Philanthus triangulum</Emphasis> F., Hymenoptera,Crabronidae)

Background  

Pheromones play an important role for mate finding and courtship in many insects. In species where males are the signaling sex, females are expected to choose among potential mates with regard to the emitter's quality and/or genetic compatibility. One important aspect is the balance between negative and positive effects of in- vs. outbreeding. In the present study, we aimed to assess the potential of the territory marking pheromone of European beewolves as an indicator for genetic compatibility in the context of female choice.     

Selenium hyperaccumulation offers protection from cell disruptor herbivores

Background  

Hyperaccumulation, the rare capacity of certain plant species to accumulate toxic trace elements to levels several orders of magnitude higher than other species growing on the same site, is thought to be an elemental defense mechanism against herbivores and pathogens. Previous research has shown that selenium (Se) hyperaccumulation protects plants from a variety of herbivores and pathogens. Selenium hyperaccumulating plants sequester Se in discrete locations in the leaf periphery, making them potentially more susceptible to some herbivore feeding modes than others. In this study we investigate the protective function of Se in the Se hyperaccumulators Stanleya pinnata and Astragalus bisulcatus against two cell disrupting herbivores, the western flower thrips (Frankliniella occidentalis) and the two-spotted spider mite (Tetranychus urticae).     

Genetic diversity and structure related to expansion history and habitat isolation: stone marten populating rural–urban habitats

Background

Population genetic diversity and structure are determined by past and current evolutionary processes, among which spatially limited dispersal, genetic drift, and shifts in species distribution boundaries have major effects. In most wildlife species, environmental modifications by humans often lead to contraction of species’ ranges and/or limit their dispersal by acting as environmental barriers. However, in species well adapted to anthropogenic habitat or open landscapes, human induced environmental changes may facilitate dispersal and range expansions. In this study, we analysed whether isolation by distance and deforestation, among other environmental features, promotes or restricts dispersal and expansion in stone marten (Martes foina) populations.

Results

We genotyped 298 martens from eight sites at twenty-two microsatellite loci to characterize the genetic variability, population structure and demographic history of stone martens in Poland. At the landscape scale, limited genetic differentiation between sites in a mosaic of urban, rural and forest habitats was mostly influenced by isolation by distance. Statistical clustering and multivariate analyses showed weak genetic structuring with two to four clusters and a high rate of gene flow between them. Stronger genetic differentiation was detected for one stone marten population (NE1) located inside a large forest complex. Genetic differentiation between this site and all others was 20% higher than between other sites separated by similar distances. The genetic uniqueness index of NE1 was also twofold higher than in other sites. Past demographic history analyses showed recent expansion of this species in north-eastern Poland. A decrease in genetic diversity from south to north, and MIGRAINE analyses indicated the direction of expansion of stone marten.

Conclusions

Our results showed that two processes, changes in species distribution boundaries and limited dispersal associated with landscape barriers, affect genetic diversity and structure in stone marten. Analysis of local barriers that reduced dispersal and large scale analyses of genetic structure and demographic history highlight the importance of isolation by distance and forest cover for the past colonization of central Europe by stone marten. This confirmed the hypothesis that human-landscape changes (deforestation) accelerated stone marten expansion, to which climate warming probably has also been contributing over the last few decades.

     

Genetic structure of Leptopilina boulardi populations from different climatic zones of Iran

Background  

The genetic structure of populations can be influenced by geographic isolation (including physical distance) and ecology. We examined these effects in Leptopilina boulardi, a parasitoid of Drosophila of African origin and widely distributed over temperate and (sub) tropical climates.     

Wildtype epidermal growth factor receptor (Egfr) is not required for daily locomotor or masking behavior in mice

Background  

Recent studies have implicated the epidermal growth factor receptor (EGFR) within the subparaventricular zone as being a major mediator of locomotor and masking behaviors in mice. The results were based on small cohorts of mice homozygous for the hypomorphic Egfr ^wa2 allele on a mixed, genetically uncontrolled background, and on intraventricular infusion of exogenous EGFR ligands. Subsequenlty, a larger study using the same genetically mixed background failed to replicate the original findings. Since both previous approaches were susceptible to experimental artifacts related to an uncontrolled genetic background, we analyzed the locomotor behaviors in Egfr ^wa2 mutant mice on genetically defined, congenic backgrounds.     

Wildlife translocation: the conservation implications of pathogen exposure and genetic heterozygosity

Background  

A key challenge for conservation biologists is to determine the most appropriate demographic and genetic management strategies for wildlife populations threatened by disease. We explored this topic by examining whether genetic background and previous pathogen exposure influenced survival of translocated animals when captive-bred and free-ranging bighorn sheep (Ovis canadensis) were used to re-establish a population that had been extirpated in the San Andres Mountains in New Mexico, USA.     

Tracking the global dispersal of a cosmopolitan insect pest, the peach potato aphid

Background  

Global commerce and human transportation are responsible for the range expansion of various insect pests such as the plant sucking aphids. High resolution DNA markers provide the opportunity to examine the genetic structure of aphid populations, identify aphid genotypes and infer their evolutionary history and routes of expansion which is of value in developing management strategies. One of the most widespread aphid species is the peach-potato aphid Myzus persicae, which is considered as a serious pest on various crops in many parts of the world. The present study examined the genetic variation of this aphid at a world scale and then related this to distribution patterns. In particular, 197 aphid parthenogenetic lineages from around the world were analysed with six microsatellite loci.     

Feeding ecology of elasmobranch fishes in coastal waters of the Colombian Eastern Tropical Pacific

Background  

Stomach contents of 131 specimens of five elasmobranch species (Mustelus lunulatus, Dasyatis longa, Rhinobatos leucorhynchus, Raja velezi and Zapteryx xyster) caught in the central fishing zone in the Pacific Ocean of Colombia were counted and weighed to describe feeding habits and dietary overlaps.     

Fast and non-invasive PCR sexing of primates: apes, Old World monkeys, New World monkeys and Strepsirrhines

Background  

One of the key tools for determining the social structure of wild and endangered primates is the ability to sex DNA from small amounts of non-invasive samples that are likely to include highly degraded DNA. Traditional markers for molecular sex determination of primates are developed on the basis of the human sequence and are often non-functional in distantly related primate species. Hence, it is highly desirable to develop markers that simultaneously detect Y- and X-chromosome specific sequences and also work across many species.     

Patterns of genetic structuring in the coral Pocillopora damicornis on reefs in East Africa

Background  

Studies of population genetic structures provide an indication of direction and magnitude of larval transport and hence are an important component in the assessment of the ability of reefs to recover from severe disturbance. This paper reports data on population genetic structures in the coral Pocillopora damicornis from 26 reefs in Kenya and Tanzania.     

Current models broadly neglect specific needs of biodiversity conservation in protected areas under climate change

Background  

Protected areas are the most common and important instrument for the conservation of biological diversity and are called for under the United Nations' Convention on Biological Diversity. Growing human population densities, intensified land-use, invasive species and increasing habitat fragmentation threaten ecosystems worldwide and protected areas are often the only refuge for endangered species. Climate change is posing an additional threat that may also impact ecosystems currently under protection. Therefore, it is of crucial importance to include the potential impact of climate change when designing future nature conservation strategies and implementing protected area management. This approach would go beyond reactive crisis management and, by necessity, would include anticipatory risk assessments. One avenue for doing so is being provided by simulation models that take advantage of the increase in computing capacity and performance that has occurred over the last two decades.     

The world's richest tadpole communities show functional redundancy and low functional diversity: ecological data on Madagascar's stream-dwelling amphibian larvae

Background  

Functional diversity illustrates the range of ecological functions in a community. It allows revealing the appearance of functional redundancy in communities and processes of community assembly. Functional redundancy illustrates the overlap in ecological functions of community members which may be an indicator of community resilience. We evaluated patterns of species richness, functional diversity and functional redundancy on tadpole communities in rainforest streams in Madagascar. This habitat harbours the world's most species-rich stream tadpole communities which are due to their occurrence in primary habitat of particular interest for functional diversity studies.     

An in planta, Agrobacterium-mediated transient gene expression method for inducing gene silencing in rice (Oryza sativa L.) leaves

Background

Although the genetic structure of rice germplasm has been characterized worldwide, few studies investigated germplasm from Thailand, the world’s largest exporter of rice. Thailand and the International Rice Research Institute (IRRI) have diverse collections of rice germplasm, which could be used to develop breeding lines with desirable traits. This study aimed to investigate the level of genetic diversity and structures of Thai and selected IRRI germplasm. Understanding the genetic structure and relationships among these germplasm will be useful for parent selection used in rice breeding programs.

Results

From the 98 InDel markers tested for single copy and polymorphism, 19 markers were used to evaluate 43 Thai and 57 IRRI germplasm, including improved cultivars, breeding lines, landraces, and 5 other Oryza species. The Thai accessions were selected from all rice ecologies such as irrigated, deep water, upland, and rainfed lowland ecosystems. The IRRI accessions were groups of germplasm having agronomic desirable traits, including temperature-sensitive genetic male sterility (TGMS), new plant type, early flowering, and biotic and abiotic stress resistances. Most of the InDel markers were genes with diverse functions. These markers produced the total of 127 alleles for all loci, with a mean of 6.68 alleles per locus, and a mean Polymorphic Information Content (PIC) of 0.440. Genetic diversity of Thai rice were 0.3665, 0.4479 and 0.3972 for improved cultivars, breeding lines, and landraces, respectively, while genetic diversity of IRRI improved and breeding lines were 0.3272 and 0.2970, respectively. Cluster, structure, and differentiation analyses showed six distinct groups: japonica, TGMS, deep-water, IRRI germplasm, Thai landraces and breeding lines, and other Oryza species.

Conclusions

Thai and IRRI germplasm were significantly different. Thus, they can be used to broaden the genetic base and trait improvements. Cluster, structure, and differentiation analyses showed concordant results having six distinct groups, in agreement with their development, and ecologies.     

Effects of intraspecific competition on the life cycle of the stonefly, <Emphasis Type="Italic">Nemurella pictetii</Emphasis> (Plecoptera: Nemouridae)

Background  

Considerable variation of life cycle duration in given insect species has been frequently recorded. Splitting of populations into cohorts with different life cycle lengths may occur, sometimes even between siblings from the same batch. Larval populations of the stonefly Nemurella pictetii in central Europe regularly split into a very fast developing and a normal univoltine cohort, leading to partial multivoltinism. The causes for such variation remain unknown but presumably act on the larval stage in which most of the life cycle is spent. We therefore studied possible effects of intraspecific competition on growth and development of larvae in the laboratory.