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opencc-zeroApr 2024View details →

Data from: Genetic analysis of red deer (Cervus elaphus) administrative management units in a human-dominated landscape - patterns of genetic diversity, population structure and gene flow

Red deer (Cervus elaphus) throughout central Europe are impacted by different anthropogenic activities including habitat fragmentation, selective hunting, and translocations. This has substantial influences on genetic diversity and the long-term conservation of local populations of this species. Here we use genetic samples from 480 red deer individuals to assess the genetic diversity and differentiation of the 12 administrative management units located in Schleswig Holstein, the northernmost federal state in Germany. We applied multiple analytical approaches and show that the history of local populations (i.e., translocations, culling of individuals outside of designated red deer zones, and anthropogenic infrastructures) has led to comparably low levels of genetic diversity. The mean expected heterozygosity was below 0.6 and we observed on average 4.2 alleles across 12 microsatellite loci. Effective population sizes below the recommended level of 50 were estimated for multiple local populations. Our estimates of genetic structure and gene flow show that red deer in northern Germany are best described as a complex network of asymmetrically connected subpopulations, with high genetic exchange among some local populations and reduced connectivity of others. Genetic diversity was also correlated with population densities of neighboring management units. Based on these findings, we suggest that connectivity among existing management units needs to be considered in the practical management of the species, which means that some administrative management units should be managed together, while the effective isolation of other units needs to be mitigated.

opencc-zeroOct 2023View details →

First insights into population structure and genetic diversity versus host specificity in trypanorhynch tapeworms using multiplexed shotgun genotyping

Theory predicts relaxed host specificity and high host vagility should contribute to reduced genetic structure in parasites while strict host specificity and low host vagility should increase genetic structure. Though these predictions are intuitive, they have never been explicitly tested in a population genomic framework. Trypanorhynch tapeworms, which parasitize sharks and rays (elasmobranchs) as definitive hosts, are the only order of elasmobranch tapeworms that exhibit considerable variability in their definitive host specificity. This allows for unique combinations of host use and geographic range, making trypanorhynchs ideal candidates for studying how these traits influence population-level structure and genetic diversity. Multiplexed shotgun genotyping (MSG) datasets were generated to characterize component population structure and infrapopulation diversity for a representative of each trypanorhynch suborder: the ray-hosted Rhinoptericola megacantha (Trypanobatoida) and the shark-hosted Callitetrarhynchus gracilis (Trypanoselachoida). Adults of R. megacantha are more host-specific and less broadly distributed than adults of C. gracilis, allowing correlation between these factors and genetic structure. Replicate tapeworm specimens were sequenced from the same host individual, from multiple conspecific hosts within and across geographic regions, and from multiple definitive host species. For R. megacantha, population structure coincided with geography rather than host species. For C. gracilis, limited population structure was found, suggesting a potential link between degree of host specificity and structure. Conspecific trypanorhynchs from the same host individual were found to be as, or more, genetically divergent from one another as from conspecifics from different host individuals. For both species, high levels of homozygosity and positive FIS values were documented.

opencc-by-4.0Jan 2022View details →

FIG. 1 in Demographic and spatial structure at the stage of expansion in the populations of some alien land snails in Belgorod city (Central Russian Upland)

FIG. 1. Map of study sites. РИС. 1. Карта раЗмеЩения исследуемых участков.

opencc-zeroFeb 2022View details →

Genetic structure in the nonbreeding range of rufa Red Knots suggests distinct Arctic breeding populations

An understanding of the migratory connectivity between breeding and nonbreeding areas is fundamental to the management of long-distance migrants under pressure from habitat change along their flyways. Here we describe evidence for genetic structure within the nonbreeding range of the endangered Arctic-Canadian rufa subspecies of Red Knots (Calidris canutus). Using blood and tissue samples from the major nonbreeding regions in Argentina (Tierra del Fuego and Río Negro), northern Brazil (Maranhão), and southeastern USA (Florida), we estimated genetic structure in 514 amplified fragment length polymorphism (AFLP) loci, applying cluster assignment analyses in DAPC, assignPOP, and STRUCTURE. Using a priori location information, individuals could be correctly re-assigned to their nonbreeding regions, which validated that the assignment accuracy of the data was sufficient. Without using a priori location information, we detected 3–5 genotype clusters, and posterior assignment probabilities of samples to these genotype clusters varied among the three regions. Lastly a chi-square test confirmed that allele frequencies varied significantly among nonbreeding regions, rejecting the hypothesis that samples were drawn from a single gene pool. Our findings hint at undescribed structure within the Red Knot rufa breeding range in the Canadian Arctic and indicate that each rufa nonbreeding area in this study hosts a different subsample of these breeding populations. The observation that nonbreeding sites of rufa Red Knots contain different genetic pools argues for separate conservation management of these sites.

opencc-zeroFeb 2022View details →

Population structure, patterns of natal dispersal, and demographic history in a declining aerial insectivore, the purple martin Progne subis

Genetic variation is a fundamental component of biodiversity, and studying population structure, gene flow, and demographic history can help guide conservation strategies for many species. Like other aerial insectivores, the purple martin (Progne subis) is in decline, and yet their genetic background remains largely unknown. To address this knowledge gap, we assessed population structure in the nominate eastern subspecies (P. s. subis) with relation to natal dispersal and examined historical genetic patterns in all three subspecies (P. s. subis, P. s. arboricola, P. s. hesperia) across their North American breeding range by estimating effective population sizes over time. We used next-generation sequencing strategies for genomic analyses, integrating whole-genome resequencing data with continent-wide band encounter records to examine natal dispersal. We documented population structure across P. s. subis, with the highest differentiation between the northern (Alberta) and more southern colonies and following patterns of isolation-by-distance. Consistent with spatial patterns of genetic differentiation, we also found greater longitudinal than latitudinal natal dispersal distances, signifying potential latitudinal constraints on gene flow. Earlier contractions in effective population sizes in the western P. s. arboricola and P. s. hesperia compared to the eastern P. s. subis subspecies suggest these subspecies originated from two different glacial refugia. Together, these findings support latitudinal distinction in P. s. subis, and elucidate the origin of subspecies differentiation, highlighting the importance to conserve populations across the range to maximize genetic diversity and adaptive potential in the purple martin.

opencc-by-4.0Mar 2022View details →

Salt flat microbial diversity and population structure along a salinity gradient

In this study, we examined the abundance of microbial communities in coastal sabkha and sabkha-shore regions in Abu Dhabi, UAE using 16s rDNA, and performed whole-genome metagenome analysis to elucidate the genetic heterogeneity of microbial species. Based on the 16s rDNA based prokaryotic microbial profile, we identified unusual coastal sabkha-specific microbial communities, consistent with the whole genome metagenome analysis. Out of 225 assembled microbial metagenomes, we analyzed 82 of the most abundant assembled genomes at the order and class taxonomic levels. We observed diversity was higher for some microbial populations on the inner regions of the sabkha as well as outside it, although the overall population diversity was higher within the sabkha. Our results show genetic structure over local spatial scales, different level of homologous recombination for different species as well as gene-specific selective sweeps. These results pave the way to understanding the ecological roles, salt stress tolerance mechanisms, and potential applications of sabkha microbial genes.

opencc-zeroApr 2022View details →

IIb-RAD-seq coupled with random forest classification indicates regional population structuring and sex-specific differentiation in salmon lice (Lepeophtheirus salmonis)

The aquaculture industry has been dealing with salmon lice problems forming serious threats to salmonid farming. Several treatment approaches have been used to control the parasite. Treatment effectiveness must be optimized, and the systematic genetic differences between sub-populations must be studied to monitor louse species and enhance targeted control measures. We have used IIb-RAD sequencing in tandem with a random forest classification algorithm to detect the regional genetic structure of the Norwegian salmon lice and identify important markers for sex differentiation of this species. We identified 19428 single nucleotide polymorphisms (SNPs) from 95 individuals of salmon lice. These SNPs, however, were not able to distinguish differential structure of lice populations. Using the random forest algorithm, we selected 91 SNPs important for geographical classification and 14 SNPs important for sex classification. The geographically important SNP data substantially improved the genetic understanding of the population structure and classified regional demographic clusters along the Norwegian coast. We also uncovered SNP markers that could help determine the sex of the salmon louse. A large portion of the SNPs identified to be under directional selection were also ranked highly important by random forest. According to our findings, there is a regional population structure of salmon lice associated with the geographical location along the Norwegian coastline.

opencc-by-4.0Nov 2021View details →

Fig. 1 in Effect Of Farming And Rainfall On The Species Diversity, Population Density And Community Structure Of Birds Breeding In The Kalahari Woodland, Ne Namibia

Fig. 1. The location of the transect (indicated with red arrow).

opencc-by-4.0Nov 2021View details →

Fig. 2 in Effect Of Farming And Rainfall On The Species Diversity, Population Density And Community Structure Of Birds Breeding In The Kalahari Woodland, Ne Namibia

Fig. 2. Monthly rainfall in Katima Mulilo in 2014 and 2015.

opencc-by-4.0Nov 2021View details →

Fig. 4 in Effect Of Farming And Rainfall On The Species Diversity, Population Density And Community Structure Of Birds Breeding In The Kalahari Woodland, Ne Namibia

Fig. 4. Percentage of main nesting guilds in 2014 and 2015.

opencc-by-4.0Apr 2022View details →

Gene flow between wild trees and cultivated varieties shapes the genetic structure of sweet chestnut (Castanea sativa Mill.) populations

The sweet chestnut orchards (Castanea sativa Mill.) are traditionally planted in the northern Adriatic region. This study investigates their population structure, as well as the genetic background of three toponymous clonal varieties. Six genomic simple sequence repeat (gSSR) and nine EST-derived SSR (EST-SSR) loci were utilized in this study. We have identified five closely related clones, which represent a singular, polyclonal marron variety, found in all three cultivation areas, acompanied by many hybrids, resulting from the breeding between cultivated and wild chestnuts.

opencc-by-4.0Mar 2019View details →

Fig. 3 in Population Densities And Community Structure Of Birds Breeding In A Suburban Wooded Grassland In The Highveld Of Lesotho

Fig. 3. Comparison of main feeding (A) and nesting (B) guilds in avian community in 1998 and 2001.

opencc-zeroApr 2022View details →

Lack of spatial and temporal genetic structure of Japanese eel (Anguilla japonica) populations

Japanese eel (Anguilla japonica) is an important food source in East Asia whose population has dramatically declined since the 1970s. Despite past analysis with DNA sequencing, microsatellite and isozyme methods, management decisions remain hampered by contradictory findings. For example, it remains unresolved whether Japanese eels are a single panmictic population or whether they harbor significant substructure. Accurate assessment of population genetic substructure, both spatial and temporal, is essential for determining the relevant number of distinct management units appropriate for this species. In the present study, we assayed genetic variation genome-wide using Restriction Site Associated DNA Sequencing (RAD-seq) technology to analyze the population genetic structure of Japanese eels. For analysis of temporal isolation, five "cohort" samples were collected yearly from 2005 to 2009 in the Yangtze River Estuary. For analysis of spatial structure, five "arrival wave" samples were collected in China in 2009, and two arrival wave samples were collected in Japan in 2001. In each cohort of each arrival wave, five individuals were collected for a total of 55 eels sampled. In total, 214,210 loci were identified from these individuals, 106,652 of which satisfied quality checks and were retained for further analysis. There was relatively little population differentiation between arrival waves and cohorts collected either at different locations during the same year (Fst = 0.077) or at the same location collected over subsequent years (Fst = 0.082), and locations displayed no consistent isolation-by-distance.

opencc-zeroMay 2022View details →

Small giants: Tributaries rescue spatially structured populations from extirpation in a highly fragmented stream

Habitat fragmentation is a pervasive threat to biodiversity. Linearly arranged habitats such as stream networks are particularly vulnerable to fragmentation. As the landscape becomes increasingly human-dominated, conservation values of fragmented habitat patches cannot be overlooked. It is critical to understand the demographic mechanisms of population persistence or extirpation in fragmented patches. We studied the dynamics of spatially structured populations of two Japanese landlocked salmonids persisting for > 30 years in a headwater stream network that is highly fragmented due to low-head dams in the mainstem. We parameterised and analysed spatial matrix population models using 9-year mark-recapture data. Tributaries supported higher survival rates in some life stages, and movement was asymmetrical from the tributaries to the mainstem. Accordingly, population growth rates were higher in the tributary patches than the mainstem in both species despite the tributaries occupying only 12 or 18% of the study stream network by surface area. The tributaries harboured more physically and hydraulically complex instream habitats (i.e., higher wood density and flow refugia), indicating that habitat patch quality was more important than habitat patch size in determining the dynamics of these spatially structured populations. Tributary locations in the stream network were important in the trajectory of these populations. The upstream-dwelling charr persisted in the highly fragmented mainstem patch (i.e., six impassable infrastructures in a < 500 m patch) due to immigration of fish from upstream including the tributary. However, the downstream-dwelling salmon have been gradually extirpated from the uppermost section of the fragmented mainstem patch because they could not maintain a positive population growth rate after the loss of emigrants was accounted for and immigration was prevented due to fragmentation. Synthesis and applications: We conclude that small tributaries have rescued the spatially structured populations from extirpation (charr) or at least slowed down extirpation (salmon). Legal protection of headwaters as aquatic habitats is weak globally. Our results suggest that stream management plans underestimating the demographic value of small tributaries will likely fail to conserve populations of headwater inhabitants and therefore endanger aquatic biodiversity. We discuss conservation implications of this study related to habitat connectivity and fisheries management.

opencc-zeroMay 2022View details →

Population structure and genetic variance among local populations of an non-native earthworm species in Minnesota, USA

A variety of human activities have been identified as driving factors for the release and spread of invasive earthworm species in North America. Population genetic markers can help to identify locally relevant anthropogenic vectors and provide insights into the processes of population dispersal and establishment. We sampled the invasive European earthworm species Lumbricus terrestris at nine sites and several bait shops within the metropolitan area of Minneapolis-St. Paul in Minnesota, USA. We used microsatellite markers to infer genetic diversity and population structure, and 16S rDNA to address multiple introduction events, including bait dumping, which is a common source of L. terrestris introductions into the wild. Our results indicate multiple introductions but not from current bait dumping. Overall, genetic structure was low and earthworms >5000 m apart were genetically differentiated, except for one sampling location, indicating jump-dispersal followed by population establishment. Further, earthworms at one location north of Minneapolis established from one or few founder individuals, suggesting that earthworm invasions are ongoing. We therefore encourage further monitoring of earthworm populations using molecular markers, in order to disentangle the different human-related vectors contributing to the spread of earthworms and their establishment, which is essential to develop adequate management strategies.

Assessing population structure and genetic diversity in U.S. Suffolk sheep to define a framework for genomic selection

Long-term sustainability of breeds depends on having sufficient genetic diversity for adaptability to change, whether driven by climatic conditions or by priorities in breeding programs. Genetic diversity in Suffolk sheep in the U.S. was evaluated in four ways: 1) using genetic relationships from pedigree data [(n=64,310 animals recorded in the U.S. National Sheep Improvement Program (NSIP)]; 2) using molecular data (n=304 Suffolk genotyped with the OvineHD BeadChip); 3) comparing Australian (n=109) and Irish (n=55) Suffolk sheep to those in the U.S. using molecular data; and 4) assessing genetic relationships (connectedness) among active Suffolk flocks (n=18) in NSIP. By characterizing genetic diversity, a goal was to define the structure of a reference population for use for genomic selection strategies in this breed. Pedigree-based mean inbreeding level for the most recent year of available data was 5.5%. Ten animals defined 22.8% of the current gene pool. The effective population size (Ne) ranged from 27.5 to 244.2 based on pedigree and was 79.5 based on molecular data. Expected (HE) and observed (HO) heterozygosity were 0.317 and 0.306, respectively. Model-based population structure included 7 subpopulations. From Principal Component Analysis, countries separated into distinct populations. Within the U.S. population, flocks formed genetically disconnected clusters. A decline in genetic diversity over time was observed from both pedigree and genomic-based derived measures with evidence of population substructure as measured by FST. Using these measures of genetic diversity, a framework for establishing a genomic reference population in U.S. Suffolk sheep engaged in NSIP was proposed.

A genetically isolated dingo population in western Victoria, Australia, reveals greater structuring of the Australian dingo

The Australian dingo is a relatively recent anthropogenic addition to the Australian fauna, which spread rapidly across the continent and has since widely interbred with modern dogs. Genetic studies of dingoes have given rise to speculation about their entry to the continent and subsequent biogeographic effects, but few studies of their contemporary population structure have been conducted. Here we investigated the dingo ancestry and population structure of free-living dogs in western Victoria and contrasted it with a wider southern Australian sample. We wished to determine whether their geographic isolation was mirrored in genetic isolation. To address this question, we analysed genetic data using Bayesian clustering and discriminant analysis of principal components, and summarised genetic diversity at the population and individual levels. Upon finding low genetic diversity in western Victoria, we tested for a recent genetic bottleneck. The broader southern Australia sample (n=1,138) comprised mostly hybrid animals, with ~30% dingoes. All western Victorian individuals (n= 59) appeared to be hybrids with high dingo ancestry. The population showed no evidence of admixture with other populations and no recent bottleneck. Based upon our characterisation of this unusual mainland population, we sound caution for future studies assuming homogeneity of dingoes across the continent.

Stable dingo population structure and purity over 11 years of lethal management

Interactions between predators and humans are a key driver of human-wildlife conflicts and can underpin the management of predator populations. Management of the impacts of dingoes (Canis familiaris) on livestock and native species is a prime example of a persistent and contentious predator management issue with potential impacts on the integrity of dingo populations. To manage the potential impacts of dingoes and their control, it is imperative to understand the effects of control approaches on their populations in the short and long term. Hybridisation of dingoes with domestic dogs (C. familiaris) threatens the genetic integrity of pure dingoes. It has been hypothesised that lethal control of dingoes can facilitate hybridisation by disrupting pack social structures leading to increased dingo-domestic dog interactions. Here we use dingo genetic samples from three distinct sampling periods: 2009, 2014, and 2020, within the Murchison Regional Vermin Cell (MRVC) area in Western Australia (WA). At the time of the study, the MRVC was a large, partially-fenced area in which dingo control has been performed for many decades. We assess dingo purity, population clustering, gene flow, and individual relatedness in the context of ongoing control. We identified three genetically distinct populations in the study area, consistent with previous genetic studies of WA, but did not find any evidence of change in dingo purity or population characteristics, however barrier fencing may be influencing recent gene flow. Policy implications: The metapopulation of dingoes in the southern rangelands of WA appears to be stable over the 11 years assessed here and there is no evidence that lethal control to reduce losses to livestock production and for conservation of native wildlife is putting dingo purity at risk. Fencing appears to be an effective management tool as there is some evidence it is separating dingo populations in areas where the fences are well maintained.

Population structure and demographic analyses of Acanthocybium solandri from the Indo-Pacific and Atlantic oceans

This repository contains scripts, data and results for a populaton genomics study of genetic structure and demography of wahoo, Acanthocybium solandri, published in Journal of Biogeography: Haro-Bilbao et al. (2021) Global connections with some genomic differentiation occur between Indo-Pacific and Atlantic Ocean wahoo, a large circumtropical pelagic fish. In this work, we generated population allele frequencies for wahoo sampled at 11 locations around the globe using a pooled ezRAD approach. Using thousands of genome-wide SNPs, we demonstrated a significant (but subtle) genetic divide between wahoo from the Indo-Pacific and those from the Atlantic. This genetic differentiation likely occurs against a background of high gene glow throughout the evolutionary history of wahoo, as we inferred from demographic analysis of select population pairs within and between oceanic regions. Analyses contained in this repository are for: (1) Filtering pooled ezRAD allele counts (assembled with dDocent and imputed using poolne_estim); (2) Estimation of genetic differentiation among globally sampled wahoo populations; (3) Estimation of site frequency spectra from joint allele frequencies among select population pairs; (4) Inference of demographic parameters (using δaδi); and (5) Generations of demographic simulation summary statistics. Most of the analyses are performed in R and can be run directly from within the repository directory, this includes: allele filtering, estimation of genetic differentiation, estimaiton of site frequency spectra, and generation of demographic summary statistics. Demographic inference using δaδi requires setup of a Unix environment: input data files and execution scripts are provided, but their implementation needs to be customised.