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publicMay 2020View details →

Data from: The socially parasitic ant Polyergus mexicanus has host-associated genetic population structure and related neighboring nests

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publicFeb 2023View details →

Data for: Dissecting the genetic architecture of leaf morphology traits in mungbean (Vigna radiata (L.) Wizcek) using genome‐wide association study

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publicOct 2023View details →

Data from: Identifying genetic variation associated with environmental variation and drought-tolerance phenotypes in ponderosa pine

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publicNov 2022View details →

Data from: Sugar pine association genetics and performance in a post-fire restoration planting

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opencc-zeroMay 2020View details →

Data from: Disease swamps molecular signatures of genetic-environmental associations to abiotic factors in Tasmanian devil (Sarcophilus harrisii) populations

Landscape genomics studies focus on identifying candidate genes under selection via spatial variation in abiotic environmental variables, but rarely by biotic factors such as disease. The Tasmanian devil (Sarcophilus harrisii) is found only on the environmentally heterogeneous island of Tasmania and is threatened with extinction by a nearly 100% fatal, transmissible cancer, devil facial tumor disease (DFTD). Devils persist in regions of long-term infection despite epidemiological model predictions of species' extinction, suggesting possible adaptation to DFTD. Here, we test the extent to which spatial variation and genetic diversity are associated with the abiotic environment and/or DFTD. We employ genetic-environment association analyses using a RAD-capture panel including 6,886 SNPs from 3,286 individuals sampled pre- and post-disease arrival. Pre-disease, we find significant correlations of allele frequencies with environmental variables, including 365 unique loci linked to 71 genes, suggesting local adaptation to abiotic environment. The majority of candidate loci detected pre-DFTD were not detected post disease arrival. Several post-DFTD candidate loci were associated with disease prevalence and were in linkage disequilibrium with genes involved in tumor suppression and immune response. Loss of apparent signal of abiotic local adaptation post-disease suggests swamping by the strong selection resulting from the rapid onset of DFTD.

opencc-zeroSep 2020View details →

Symbiotic efficiency and genetic characterization of bacteria associated with cowpea genotypes grown in semiarid tropics of Kenya

Cowpea (Vigna unguiculata (L.) Walp) is an important multipurpose legume crop grown in arid semiarid areas of sub-Saharan Africa. The crop associates with a wide diversity of high ecological value rhizobia bacteria, improving biological soil fertility and crop production. Here, we evaluated the symbiotic efficiency (SE) and genetic diversity of native rhizobia isolated from root nodules of cowpea genotypes cultivated in semiarid areas of Kenya. Rhizobia trapping and SE experiments were done in the greenhouse while genetic diversity was evaluated based on 16S rRNA gene sequencing. Ninety four bacterial nodule isolates were purified from root nodules and placed into 20 groups based on morphological characteristics. SE of the native isolates varied (p<0.0001) significantly. Remarkably, two isolates, M2 and M3 recorded higher SE of 82.49 % and 72.76 % respectively compared to the commercial strain Bradyrhizobia sp. USDA 3456 (67.68 %). The isolates closely resembled bacteria belonging to the genus Rhizobium and non-rhizobial endophytes Enterobacter, Strenotrophomonas, Pseudomonas, and Paraburkholderia. For the first time, we report the presence of an efficient native nodule isolate Paraburkholderia phenoliruptrix BR3459a in Kenya. Our results form an important step towards the development of efficient microbial inocula which are pertinent for sustainable food production in African agriecosystems.

opencc-zeroOct 2020View details →

Data from: A nested association mapping panel in Arabidopsis thaliana for mapping and characterizing genetic architecture

Linkage and association mapping populations are crucial public resources that facilitate the characterization of trait genetic architecture in natural and agricultural systems. We define a large nested association mapping panel (NAM) from 14 publicly available recombinant inbred populations (RILs) of Arabidopsis thaliana, which share a common recurrent parent (Col-0). Using a genotype-by-sequencing approach (GBS), we identified single nucleotide polymorphisms (SNPs; range 563-1525 per population) and subsequently built updated linkage maps in each of the 14 RIL sets. Simulations in individual RIL populations indicate that our GBS markers have improved power to detect small effect QTL and enhanced resolution of QTL support intervals in comparison to original linkage maps. Using these robust linkage maps, we imputed a common set of publicly available parental SNPs into each RIL linkage map, generating overlapping markers across all populations. Though ultimately depending on allele frequencies at causal loci, simulations of the NAM panel suggest that surveying between 4 to 7 of the 14 RIL populations provides high resolution of the genetic architecture of complex traits, relative to a single mapping population.

opencc-zeroOct 2021View details →

Effects of maternal genotypic identity and genetic diversity of the red mangrove Rhizophora mangle on associated soil bacterial communities: a field-based experiment

Loss of plant biodiversity can result in reduced abundance and diversity of associated species with implications for ecosystem functioning. In ecosystems low in plant species diversity, such as Neotropical mangrove forests, it is thought that genetic diversity within the dominant plant species could play an important role in shaping associated communities. Here, we used a manipulative field experiment to study the effects of maternal genotypic identity and genetic diversity of the red mangrove Rhizophora mangle on the composition and richness of associated soil bacterial communities. Using terminal restriction fragment length polymorphism (T-RFLP) community fingerprinting, we found that bacterial community composition differed among R. mangle maternal genotypes but not with genetic diversity. Bacterial taxa richness, total soil nitrogen, and total soil carbon were not significantly affected by maternal genotypic identity or genetic diversity of R. mangle. Our findings show that genotype selection in reforestation projects could influence soil bacterial community composition. Further research is needed to determine what impact these bacterial community differences might have on ecosystem processes, such as carbon and nitrogen cycling.

opencc-zeroDec 2020View details →

Genetic mechanisms associated with floral initiation and the repressive effect of fruit on flowering in apple (Malus x domestica Borkh)

Many apple cultivars are subject to biennial fluctuations in flowering and fruiting. It is believed that this phenomenon is caused by a repressive effect of developing fruit on the initiation of flowers in the apex of proximal bourse shoots. However, the genetic pathways of floral initiation are incompletely described in apple, and the biological nature of floral repession by fruit is currently unknown. In this study, we characterize the transcriptional landscape of bourse shoot apices in the biennial cultivar, 'Honeycrisp', during the period of floral initiation, in trees bearing a high fruit load and in trees without fruit. Trees with high fruit load produced almost exclusively vegetative growth in the subsequent year, whereas the trees without fruit produced flowers on the majority of the potential flowering nodes. Using RNA-based sequence data, we documented gene expression at high resolution, identifying >11,000 transcripts that had not been previously annotated, and characterized expression profiles associated with vegetative growth and flowering. We also conducted a census of genes related to known flowering genes, organized the phylogenetic and syntenic relationships of these genes, and compared expression among homologs. Several genes closely related to AP1, FT, FUL, LFY, and SPLS were more strongly expressed in apices from non-bearing, floral-determined trees, consistent with their presumed floral-promotive roles. In contast, a homolog of TFL1 exhibited strong and persistent up-regulation only in apices from bearing, vegetative-determined trees, suggesting a roles in floral repression. Additionally, we identified four GIBBERELLIC ACID (GA) 2 OXIDASE genes that were expressed to relatively high levels in apices from bearing trees. These results define the flowering-related transcriptional landscape in apple, and strongly support previous studies implicating both gibberellins and TFL1 as key components in repression of flowering by fruit.

opencc-zeroDec 2020View details →

Plasmodium falciparum genomic surveillance reveals spatial and temporal trends, association of genetic and physical distance, and household clustering

Molecular epidemiology using genomic data can help identify relationships between malaria parasite population structure, malaria transmission intensity, and ultimately help generate actionable data to assess the effectiveness of malaria control strategies. Genomic data, coupled with geographic information systems data, can further identify clusters or hotspots of malaria transmission, parasite genetic and spatial connectivity, and parasite movement by human or mosquito mobility over time and space. In this study, we performed longitudinal genomic surveillance in a cohort of 70 participants over four years from different neighborhoods and households in Thiès, Senegal—a region of exceptionally low malaria transmission (entomological inoculation rate (EIR) less than 1). Genetic identity (identity by state) was established using a 24 single nucleotide polymorphism molecular barcode and a multivariable linear regression model was used to establish genetic and spatial relationships. Our results show clustering of genetically similar parasites within households and a decline in genetic similarity of parasites with increasing distance. One household showed extremely high diversity and warrants further investigation as to the source of these diverse genetic types. This study illustrates the utility of genomic data with traditional epidemiological approaches for surveillance and detection of trends and patterns in malaria transmission not only by neighborhood but also by household. This approach can be implemented regionally and countrywide to strengthen and support malaria control and elimination efforts.

Data from: Host-targeted RAD-Seq reveals genetic changes in the coral Oculina patagonica associated with range expansion along the Spanish Mediterranean coast

Many organisms are expanding their ranges in response to changing environmental conditions. Understanding the patterns of genetic diversity and adaptation along an expansion front is crucial to assessing a species' long-term success. While next-generation sequencing techniques can reveal these changes in fine detail, ascribing them to a particular species can be difficult for organisms that live in close association with symbionts. Using a novel modified restriction-site associated DNA sequencing (RAD-Seq) protocol to target coral DNA, we collected 595 coral-specific single nucleotide polymorphisms (SNPs) from 189 colonies of the invasive coral Oculina patagonica from the Spanish Mediterranean coast, including established core populations and two expansion fronts. Surprisingly, populations from the recent northern expansion are genetically distinct from the westward expansion and core populations, and also harbor greater genetic diversity. We found that temperature may have driven adaptation along the northern expansion, as genome scans for selection found three candidate loci associated with temperature in the north but none in the west. We found no genomic signature of selection associated with artificial substrate, which has been proposed for explaining the rapid spread of O. patagonica. This suggests that this coral is simply an opportunistic colonizer of free space made available by coastal habitat modifications. Our results suggest that unique genetic variation, possibly due to limited dispersal across the Ibiza Channel, an influx of individuals from different depths, and/or adaptation to cooler temperatures along the northern expansion front may have facilitated the northward range expansion of O. patagonica in the western Mediterranean.

opencc-zeroDec 2011View details →

Data from: Phenotypic and genetic divergence among harbour porpoise populations associated with habitat regions in the North Sea and adjacent seas.

Determining the mechanisms that generate population structure is essential to the understanding of speciation and the evolution of biodiversity. Here, we investigate a geographic range that transects two habitat gradients, the North Sea to North Atlantic transition, and the temperate to sub-polar regions. We studied the harbour porpoise (Phocoena phocoena), a small odontocete inhabiting both sub-polar and temperate waters. To assess differentiation among putative populations we measured morphological variation at cranial traits (N=462 individuals) and variation at eight microsatellite loci for 338 of the same individuals from Norwegian, British and Danish waters. Significant morphological differentiation reflected the size of the buccal cavity. Porpoises forage in relatively shallow waters preying mainly on benthic species in British and Danish waters, and on mesopelagic and pelagic fish off the coast of Norway. We suggest that the observed differentiation may be explained by resource specialization and either adaptation or developmental responses to different local habitats.

Data from: Fine-scale temperature associated genetic structure between inshore and offshore populations of sea scallop (Placopecten magellanicus)

In the northwest Atlantic Ocean, sea scallop (Placopecten magellanicus) have been characterized by a latitudinal genetic cline with a breakpoint between northern and southern genetic clusters occurring at ~45°N along eastern Nova Scotia, Canada. Using 96 diagnostic single nucleotide polymorphisms (SNPs) capable of discriminating between northern and southern clusters, we examined fine-scale genetic structure of scallops among 27 sample locations, spanning the largest geographic range evaluated in this species to date (~37-51°N). Here, we confirmed previous observations of northern and southern groups, but we show that the boundary between northern and southern clusters is not a discrete latitudinal break. Instead, at latitudes near the previously described boundary, we found unexpected patterns of fine-scale genetic structure occurring between inshore and offshore sites. Scallops from offshore sites, including St. Pierre Bank and the eastern Scotian Shelf, clustered with southern stocks, whereas inshore sites at similar latitudes clustered with northern stocks. Our analyses revealed significant genetic divergence across small spatial scales (i.e., 129 to 221 km distances), and that spatial structure over large and fine scales was strongly associated with temperature during seasonal periods of thermal minima. Clear temperature differences between inshore and offshore locations may explain the fine-scale structuring observed, such as why southern lineages of scallop occur at higher latitudes in deeper, warmer offshore waters. Our study supports growing evidence that fine-scale population structure in marine species is common, often environmentally associated, and that consideration of environmental and genomic data can significantly enhance the identification of marine diversity and management units.

opencc-zeroDec 2018View details →

Data from: Fur seal microbiota are shaped by the social and physical environment, show mother-offspring similarities and are associated with host genetic quality

Despite an increasing appreciation of the importance of host-microbe interactions in ecological and evolutionary processes, the factors shaping microbial communities in wild populations remain poorly understood. We therefore exploited a natural experiment provided by two adjacent Antarctic fur seal (Arctocephalus gazella) colonies of high and low social density and combined 16S rRNA metabarcoding with microsatellite profiling of mother-offspring pairs to investigate environmental and genetic influences on skin microbial communities. Seal-associated bacterial communities differed profoundly between the two colonies, despite the host populations themselves being genetically undifferentiated. Consistent with the hypothesis that social stress depresses bacterial diversity, we found that microbial alpha diversity was significantly lower in the high-density colony. Seals from one of the colonies that contained a stream also carried a subset of freshwater-associated bacteria, indicative of an influence of the physical environment. Furthermore, mothers and their offspring shared similar microbial communities, in support of the notion that microbes may facilitate mother-offspring recognition. Finally, a significant negative association was found between bacterial diversity and heterozygosity, a measure of host genetic quality. Our study thus uncovers a complex interplay between environmental and host genetic effects, while also providing empirical support for the leash model of host control, which posits that bacterial communities are driven not only by bottom-up species interactions, but also by top-down host regulation. Taken together, our findings have broad implications for understanding host-microbe interactions as well as prokaryotic diversity in general.

opencc-zeroDec 2014View details →

Data from: Intermediate habitat associations by hybrids may facilitate genetic introgression in a songbird

Hybridization or the interbreeding of genetically discrete populations or species can occur where ranges of genetically distinct units overlap. Golden-winged warblers Vermivora chrysoptera, a species that has been in steady decline for decades, highlight the potential population-level consequences of hybridization. A major factor implicated in their decline is hybridization with their sister species, the blue-winged warbler Vermivora cyanoptera, which has likely been exacerbated by historic and current land-use practices. We examined habitat associations of golden-winged and blue-winged warblers, phenotypic hybrids, and cryptic hybrids (i.e. mismatch between plumage phenotype and genotype as identified by mitochondrial DNA) in an area of relatively recent range overlap and hybridization in northern New York, USA. To explore the robustness of these results, we then compared the patterns from New York with habitat associations from the central Pennsylvanian Appalachian Mountains where blue-winged warblers either do not occur or are in very low abundance, yet cryptic golden-winged warbler hybrids are present. From 2008 to 2011, we captured 122 birds in New York and 28 in Pennsylvania and collected blood samples, which we used to determine maternal ancestry. For each bird captured, we measured territory-level (50-m radius circles) habitat, and later used remote-sensing data to quantify habitat on the territories and in surrounding areas (100-, 250-, and 500-m radius circles). In New York, golden-winged warblers occupied structurally heterogeneous territories surrounded by homogeneously structured, contiguous deciduous forest, far from urban areas. Blue-winged warblers showed opposite associations, and hybrids' habitat associations were typically intermediate. In Pennsylvania, the habitat associations of golden-winged warblers and their cryptic hybrids were remarkably similar to those in New York. These findings suggest that patterns of habitat occupancy by hybrids may promote contact with golden-winged warblers and thus likely facilitate genetic introgression, even in areas where the parental species are not sympatric.

Data from: Experimental evolution across different thermal regimes yields genetic divergence in recombination fraction but no divergence in temperature-associated plastic recombination

Phenotypic plasticity is pervasive in nature. One mechanism underlying the evolution and maintenance of such plasticity is environmental heterogeneity. Indeed, theory indicates that both spatial and temporal variation in the environment should favor the evolution of phenotypic plasticity under a variety of conditions. The frequency of recombination in the model system Drosophila melanogaster has long been known to exhibit phenotypic plasticity in response to temperature. Here were use a panel of replicated experimental evolution populations of D. melanogaster to test whether variable environments favor enhanced plasticity in recombination rate in response to temperature. In contrast to expectation, we find no evidence for enhanced plasticity in recombination in the variable environment lines. Our data confirm a role of temperature in mediating recombination fraction in D. melanogaster, and indicate that recombination is genetically and plastically depressed under lower temperatures. Our data further suggest that the genetic architectures underlying plastic recombination and population-level variation in recombination rate are likely to be distinct.

Data from: Genetic diversity of melon aphids Aphis gossypii associated with landscape features

Despite increasing evidence that landscape features strongly influence the abundance and dispersal of insect populations, landscape composition has seldom been explicitly linked to genetic structure. We conducted a genetic study of the melon aphid, Aphis gossypii, in two counties of Beijing, China during spring migration using samples from watermelon. We performed aphid genetic analysis using restriction-site-associated DNA-sequencing (2b-RAD) and investigated the relationship between land cover and the genetic diversity. The percentage area of land cover (cropland, vegetable, orchard, grassland, woodland) was quantified in each particular scale (ranging from 0.5 km to 3 km) and was used as a predictor variable in our generalized linear models. We found a moderate level of genetic differentiation among 9 sampled populations. Geographic distance and genetic distance were not significantly associated, indicating that geographic location was not a barrier to migration. These 9 populations could be clustered depending on their level of genetic diversity (high and low). The genetic diversity (Shannon's information index) was positively correlated with grassland at the spatial scales of 1 and 2 km and negatively with orchard and vegetable at 0.5 and 1 km. Genetic diversity was best predicted by the grassland + orchard + vegetable model at a spatial scale of 1 km. Based on the method of relative weights, orchard land had the greatest relative importance, followed by grassland and vegetable land, in that order. This study contributes to our understanding of the genetic variation of aphids in agricultural landscapes.

opencc-zeroDec 2011View details →

Data from: Genetic mapping identifies a major locus spanning P450 clusters associated with pyrethroid resistance in kdr-free Anopheles arabiensis from Chad

Prevention of malaria transmission throughout much of Africa is dependent on bednets that are impregnated with pyrethroid insecticides. Anopheles arabiensis is the major malaria vector in Chad and efforts to control this vector are threatened by the emergence of pyrethroid resistance. WHO bioassays revealed that An. arabiensis from Ndjamena is resistant to pyrethroids and dichlorodiphenyltrichloroethane (DDT) but fully susceptible to carbamates and organophosphates. No 1014F or 1014S kdr alleles were detected in this population. To determine the mechanisms that are responsible for resistance, genetic crosses were established between the Ndja strain and an insecticide susceptible population from Mozambique. Resistance was inherited as an autosomal trait and quantitative trait locus (QTL) mapping identified a single major locus on chromosome 2R, which explained 24.4% of the variance in resistance. This QTL is enriched in P450 genes including 25 cytochrome P450s in total. One of these, Cyp6p4 is 22-fold upregulated in the Ndja strain compared with the susceptible. Piperonyl butoxide (PBO) synergist and biochemical assays further support a role for P450s in conferring pyrethroid resistance in this population.

opencc-zeroDec 2015View details →

Data from: Effects of host genetics and environment on egg-associated microbiotas in brown trout (Salmo trutta)

Recent studies found fish egg-specific bacterial communities that changed over the course of embryogenesis, suggesting an interaction between the developing host and its microbiota. Indeed, single-strain infections demonstrated that the virulence of opportunistic bacteria is influenced by environmental factors and host immune genes. However, the interplay between a fish embryo host and its microbiota has not been studied yet at the community level. To test whether host genetics affects the assemblage of egg-associated bacteria, adult brown trout (Salmo trutta) were sampled from a natural population. Their gametes were used for full-factorial in vitro fertilizations to separate sire from dam effects. In total, 2520 embryos were singly raised under experimental conditions that differently support microbial growth. High-throughput 16S rRNA amplicon sequencing was applied to characterize bacterial communities on milt and fertilized eggs across treatments. Dam and sire identity influenced embryo mortality, time until hatching and composition of egg-associated microbiotas, but no link between bacterial communities on milt and on fertilized eggs could be found. Elevated resources increased embryo mortality and modified bacterial communities with a shift in their putative functional potential. Resource availability did not significantly affect any parental effects on embryo performance. Sire identity affected bacterial diversity that turned out to be a significant predictor of hatching time: embryos associated with high bacterial diversity hatched later. We conclude that both host genetics and the availability of resources define diversity and composition of egg-associated bacterial communities that then affect the life history of their hosts.

Data from: Genome-wide exon-capture approach identifies genetic variants of Norway spruce genes associated with susceptibility to Heterobasidion parviporum infection

Root and butt rot caused by members of the Heterobasidion annosum species complex is the most economically important disease of conifer trees in boreal forests. Wood decay in the infected trees dramatically decreases their value and causes considerable losses to forest owners. Trees vary in their susceptibility to Heterobasidion infection, but the genetic determinants underlying the variation in the susceptibility are not well-understood. We performed the identification of Norway spruce genes associated with the resistance to Heterobasidion parviporum infection using genome-wide exon-capture approach. Sixty-four clonal Norway spruce lines were phenotyped, and their responses to H. parviporum inoculation were determined by lesion length measurements. Afterwards, the spruce lines were genotyped by targeted resequencing and identification of genetic variants (SNPs). Genome-wide association analysis identified 10 SNPs located within 8 genes as significantly associated with the larger necrotic lesions in response to H. parviporum inoculation. The genetic variants identified in our analysis are potential marker candidates for future screening programs aiming at the differentiation of disease-susceptible and resistant trees.