Four Pristionchus species associated with two mass-occurring Parafontaria laminata populations.
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ABSTRACT:
SUBMITTER: Kanzaki N
PROVIDER: S-EPMC8015285 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Differences in ploidy levels among different fern species have a vast influence on their mating system, their colonization ability and on the gene flow among populations. Differences in the colonization abilities of species with different ploidy levels are well known: tetraploids, in contrast to diploids, are able to undergo intra-gametophytic selfing. Because fertilization is a post-dispersal process in ferns, selfing results in better colonization abilities in tetraploids because of single spore colonization. Considerably less is known about the gene flow among populations of different ploidy levels. The present study examines two rare fern species that differ in ploidy. While it has already been confirmed that tetraploid species are better at colonizing, the present study focuses on the gene flow among existing populations. We analyzed the genetic structure of a set of populations in a 10×10 km study region using isoenzymes. Genetic variation in tetraploid species is distributed mainly among populations; the genetic distance between populations is correlated with the geographical distance, and larger populations host more genetic diversity than smaller populations. In the diploid species, most variability is partitioned within populations; the genetic distance is not related to geographic distance, and the genetic diversity of populations is not related to the population size. This suggests that in tetraploid species, which undergo selfing, gene flow is limited. In contrast, in the diploid species, which experience outcrossing, gene flow is extensive and the whole system behaves as one large population. Our results suggest that in ferns, the ability to colonize new habitats and the gene flow among existing populations are affected by the mating system.
| S-EPMC3447768 | biostudies-literature
Project description:Two new species of Pristionchus, P. lucani n. sp. and P. bulgaricus n. sp., are described from France and Bulgaria, respectively. Additionally, new morphological and morphometric data are provided for two previously described species from Europe, P. brevicauda (Kotlán, 1928) Paramonov, 1952 and P. clavus (von Linstow, 1901) Sudhaus and Fürst von Lieven, 2003. A phylogeny including these four species was inferred from a dataset including 26 ribosomal protein-coding genes, sequences of which are original for P. bulgaricus n. sp. and P. clavus. Relationships support a radiation of all sequenced European Pristionchus species from a single, gonochoristic common ancestor, and current knowledge of species ranges supports "western" and "eastern" clades. Similar diagnostic morphologies reflect the close relationships among the new and recharacterized species, especially P. bulgaricus n. sp., P. brevicauda, and P. clavus, although mating tests as well as genetic and phylogenetic separation support their identities as unique species. Our results show that Pristionchus species in Europe are more diverse than typological characters suggest, and thus biological and molecular profiling will be essential for future delimitation of Pristionchus species from the region.
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Project description:The genus Pristionchus (Kreis, 1932) consists of more than 30 soil nematode species that are often found in association with scarab beetles. Three major radiations have resulted in the "maupasi species group" in America, the "pacificus species group" in Asia, and the "lheritieri species group," which contains species from Europe and Asia. Phylogenetic analysis indicates that a group of three species, including the gonochorists P. elegans and P. bucculentus and the hermaphrodite P. fissidentatus, is basal to the above-mentioned radiations. Two novel species are described here: Pristionchus paulseni sp. n. from Taiwan and P. yamagatae sp. n. from Japan by means of morphology, morphometrics and genome-wide transcriptome sequence analysis. Previous phylotranscriptomic analysis of the complete Pristionchus genus recognized P. paulseni sp. n. as the sister species of P. fissidentatus, and thus its importance for macro-evolutionary studies. Specifically, the gonochorist P. paulseni sp. n. and the hermaphrodite P. fissidentatus form a species pair that is the sister group to all other described Pristionchus species. P. paulseni sp. n. has two distinct mouth forms, supporting the notion that the mouth dimorphism is ancestral in the genus Pristionchus.The genus Pristionchus (Kreis, 1932) consists of more than 30 soil nematode species that are often found in association with scarab beetles. Three major radiations have resulted in the “maupasi species group” in America, the “pacificus species group” in Asia, and the “lheritieri species group,” which contains species from Europe and Asia. Phylogenetic analysis indicates that a group of three species, including the gonochorists P. elegans and P. bucculentus and the hermaphrodite P. fissidentatus, is basal to the above-mentioned radiations. Two novel species are described here: Pristionchus paulseni sp. n. from Taiwan and P. yamagatae sp. n. from Japan by means of morphology, morphometrics and genome-wide transcriptome sequence analysis. Previous phylotranscriptomic analysis of the complete Pristionchus genus recognized P. paulseni sp. n. as the sister species of P. fissidentatus, and thus its importance for macro-evolutionary studies. Specifically, the gonochorist P. paulseni sp. n. and the hermaphrodite P. fissidentatus form a species pair that is the sister group to all other described Pristionchus species. P. paulseni sp. n. has two distinct mouth forms, supporting the notion that the mouth dimorphism is ancestral in the genus Pristionchus.
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Project description:BackgroundFat mass and lean mass are two biggest components of body mass. Both fat mass and lean mass are under strong genetic determinants and are correlated.MethodsWe performed a bivariate genome-wide association meta-analysis of (lean adjusted) leg fat mass and (fat adjusted) leg lean mass in 12,517 subjects from 6 samples, and followed by in silico replication in large-scale UK biobank cohort sample (N?=?370 097).ResultsWe identified four loci that were significant at the genome-wide significance (GWS, ??=?5.0?×?10-8) level at the discovery meta-analysis, and successfully replicated in the replication sample: 2q36.3 (rs1024137, pdiscovery?=?3.32?×?10-8, preplication?=?4.07?×?10-13), 5q13.1 (rs4976033, pdiscovery?=?1.93?×?10-9, preplication?=?6.35?×?10-7), 12q24.31 (rs4765528, pdiscovery?=?7.19?×?10-12, preplication?=?1.88?×?10-11) and 18q21.32 (rs371326986, pdiscovery?=?9.04?×?10-9, preplication?=?2.35?×?10-95). The above four pleiotropic loci may play a pleiotropic role for fat mass and lean mass development.ConclusionsOur findings further enhance the understanding of the genetic association between fat mass and lean mass and provide a new theoretical basis for their understanding.
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Project description:Symbiotic relationships between microbes and plants are common and well studied in terrestrial ecosystems, but little is known about such relationships in aquatic environments. We compared the phylogenetic diversities of leaf- and root-attached bacteria from four species of aquatic angiosperms using denaturing gradient gel electrophoresis (DGGE) and DNA sequencing of PCR-amplified 16S rRNA genes. Plants were collected from three beds in Chesapeake Bay at sites characterized as freshwater (Vallisneria americana), brackish (Potomogeton perfoliatus and Stuckenia pectinata), and marine (Zostera marina). DGGE analyses showed that bacterial communities were very similar for replicate samples of leaves from canopy-forming plants S. pectinata and P. perfoliatus and less similar for replicate samples of leaves from meadow-forming plants Z. marina and V. americana and of roots of all species. In contrast, bacterial communities differed greatly among plant species and between leaves and roots. DNA sequencing identified 154 bacterial phylotypes, most of which were restricted to single plant species. However, 12 phylotypes were found on more than one plant species, and several of these phylotypes were abundant in clone libraries and represented the darkest bands in DGGE banding patterns. Root-attached phylotypes included relatives of sulfur-oxidizing Gammaproteobacteria and sulfate-reducing Deltaproteobacteria. Leaf-attached phylotypes included relatives of polymer-degrading Bacteroidetes and phototrophic Alphaproteobacteria. Also, leaves and roots of three plant species hosted relatives of methylotrophic Betaproteobacteria belonging to the family Methylophilaceae. These results suggest that aquatic angiosperms host specialized communities of bacteria on their surfaces, including several broadly distributed and potentially mutualistic bacterial populations.
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Project description:Human malaria parasite species were originally acquired from other primate hosts and subsequently became endemic, then spread throughout large parts of the world. A major zoonosis is now occurring with Plasmodium knowlesi from macaques in Southeast Asia, with a recent acceleration in numbers of reported cases particularly in Malaysia. To investigate the parasite population genetics, we developed sensitive and species-specific microsatellite genotyping protocols and applied these to analysis of samples from 10 sites covering a range of >1,600 km within which most cases have occurred. Genotypic analyses of 599 P. knowlesi infections (552 in humans and 47 in wild macaques) at 10 highly polymorphic loci provide radical new insights on the emergence. Parasites from sympatric long-tailed macaques (Macaca fascicularis) and pig-tailed macaques (M. nemestrina) were very highly differentiated (FST = 0.22, and K-means clustering confirmed two host-associated subpopulations). Approximately two thirds of human P. knowlesi infections were of the long-tailed macaque type (Cluster 1), and one third were of the pig-tailed-macaque type (Cluster 2), with relative proportions varying across the different sites. Among the samples from humans, there was significant indication of genetic isolation by geographical distance overall and within Cluster 1 alone. Across the different sites, the level of multi-locus linkage disequilibrium correlated with the degree of local admixture of the two different clusters. The widespread occurrence of both types of P. knowlesi in humans enhances the potential for parasite adaptation in this zoonotic system.
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Project description:Seed germination is a critical stage in the life cycle of most plants and is defined by specific tolerance thresholds beyond which rates and success of germination rapidly decline. Previous studies have demonstrated that widespread plant species commonly germinate over a broad range of temperatures and water stress levels, whereas range-restricted species often exhibit a narrower germination window in terms of temperature and moisture. We investigated the relationships of the key germination traits of maximum germination (G max) and time to 50% germination (t 50) in response to temperature (5-35°C) and water stress (-1.5-0 MPa) in four co-occurring Western Australian native Eucalyptus species with widely varying biogeography. Eucalyptus caesia subsp. caesia and E. ornata exhibit a highly localized distribution and a narrow geographical range, being restricted either to granite outcrops or the upper slopes and tops of lateritic rises, respectively. These two species were compared with the two widespread and dominant congenerics E. salmonophloia and E. salubris. There was a distinctive hump-shaped response of t 50 to temperature and an exponential response to water stress, characteristic of rate- and threshold-limited processes, but no consistent pattern in the response of G max. The four species were significantly different in their thermal performance of t 50, with E. caesia and E. ornata displaying narrower thermal tolerance ranges than the two widespread species. In terms of mean final germination percentage, the two range-restricted endemic taxa exhibited higher lability in their response to thermal stress and drought stress compared to the two broadly distributed congenerics. These findings indicate a link between distributional extent, temperature and water stress tolerance and may have implications for identifying ecological filters of rarity and endemism.
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| PRJNA295078 | ENA
Project description:BackgroundHybridization and introgression are vital sources of novel genetic variation driving diversification during reticulated evolution. Quercus is an important model clade, having extraordinary diverse and abundant members in the Northern hemisphere, that are used to studying the introgression of species boundaries and adaptive processes. China is the second-largest distribution center of Quercus, but there are limited studies on introgressive hybridization.ResultsHere, we screened 17 co-dominant nuclear microsatellite markers to investigate the hybridization and introgression of four oaks (Quercus acutissima, Quercus variabilis, Quercus fabri, and Quercus serrata) in 10 populations. We identified 361 alleles in the four-oak species across 17 loci, and all loci were characterized by high genetic variability (HE = 0.844-0.944) and moderate differentiation (FST = 0.037-0.156) levels. A population differentiation analysis revealed the following: allopatric homologous (FST = 0.064) < sympatric heterogeneous (FST = 0.071) < allopatric heterogeneous (FST = 0.084). A Bayesian admixture analysis determined four types of hybrids (Q. acutissima × Q. variabilis, Q. fabri × Q. serrata, Q. acutissima × Q. fabri, and Q. acutissima × Q. variabilis × Q. fabri) and their asymmetric introgression. Our results revealed that interspecific hybridization is commonly observed within the section Quercus, with members having tendency to hybridize.ConclusionsOur study determined the basic hybridization and introgression states among the studied four oak species and extended our understanding of the evolutionary role of hybridization. The results provide useful theoretical data for formulating conservation strategies.
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Project description:Four new Epicephala species that feed on the seeds of Glochidionsphaerogynum (Phyllanthaceae) from Yinggeling Mountain Nature Reserves in Hainan Province of China are described: Epicephaladomina sp. n., Epicephalaimpolliniferens sp. n., Epicephalaangustisaccula sp. n. and Epicephalacamurella sp. n. The latter two species are also associated with Glochidionwrightii. Photographs of adults and genital structures are provided.
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