Genetic Differentiation Research Articles

Unveiling Genetic Diversity Among Bacterial Isolates Using SCoT Markers.

This study aimed to unveil the genetic diversity among 47 bacterial isolates from various species using start codon targeted (SCoT) markers. Six SCoT primers yielded 219 reproducible bands, with 89.04% exhibiting polymorphism. The amplification process generated 28 to 50 fragments per primer, with an average of 36.50. Genetic diversity was quantified using polymorphic information content (PIC) values ranging from 0.11 to 0.14, with SCoT32 showing the highest PIC (0.14) and SCoT23 the lowest (0.11). The resolving power (RP) index, used to assess primer discriminatory power, varied significantly, with SCoT23 demonstrating the highest RP (6.00) and SCoT29 the lowest (4.51). Comparative analysis with conventional markers like M13 and (GTG)5 revealed that certain SCoT primers exhibited superior PIC values, which indicates enhanced utility for interspecies differentiation. The high discrimination level achieved by SCoT primers underscores their effectiveness in genetic differentiation and biodiversity assessment within bacterial populations. This research highlights SCoT markers as powerful tools for microbial genetic studies, which offers valuable insights into bacterial diversity and provides a robust methodological framework for future investigations aimed at elucidating genetic variation and improving species identification. The application of SCoT markers represents a significant advancement in molecular techniques for bacterial characterization and phylogenetic analysis, demonstrating their potential to enhance our understanding of microbial genetics and evolution.

Recent advances in adaptation genomics in fumarole fields, an overlooked extreme environment.

Extreme environments and plants thriving in them, known as extremophytes, offer promising platforms for studying the diverse adaptive mechanisms that have evolved in plants. However, research on adaptation to extreme environments is still limited to those environments where model species or their relative can survive. Fumarole fields, an extreme environment often overlooked, are characterized by multi-hazardous abiotic stressors, including atmospheric contamination (high concentration of H2S, SO2, and CO2), high soil temperature (~60℃), and strong soil acidification (pH=2-3). These conditions make fumarole fields a rich source for studying stress tolerance mechanisms in plants. In this review, we highlight the recent ecological, physiological, and genomic advances involved in fumarole field adaptation, and discuss the forward avenues. The studies outlined in this paper demonstrate that the extreme levels of abiotic stressors found in fumarole fields make them unparalleled field laboratories for studying the unknown stress tolerance mechanisms, warranting further genomic assessments. Some studies succeeded in identifying genes associated with fumarole field adaptation and shedding light on evolutionary implications; however, they have also encountered challenges such as limited genome resources and high genetic differentiation from related species and/or neighboring populations. To overcome such difficulties, we propose integrating ecophysiological and genomic approaches, drawing from the recent studies in other extreme environments. We expect that further studies in the fumarole fields will contribute to broadening our general knowledge of the limits of life.

What in Earth? Analyses of Canadian soil populations of Aspergillus fumigatus

Aspergillus fumigatus is a globally distributed mold and a major cause of opportunistic infections in humans. Because most infections are from environmental exposure, it’s critical to understand environmental populations of A. fumigatus. Soil is a major ecological niche for A. fumigatus. Here we analyzed 748 soil isolates from 21 locations in six provinces and one territory in Canada. All isolates were genotyped using nine microsatellite markers. Due to small sample size and/or close proximities for some local samples, these isolates were grouped into 16 local geographic and ecological populations. Our results indicated high allelic and genotypic diversities within most local and provincial populations. Interestingly, low but statistically significant genetic differentiations were found among geographic populations within Canada, with relatively similar proportions of strains and genotypes belonging to two large genetic clusters. In Hamilton, Ontario and Vancouver, BC, where two and three ecological populations were analyzed respectively, we found limited genetic difference among them. Most local and provincial populations showed evidence of both clonality and recombination, with no population showing random recombination. Of the 748 soil isolates analyzed here, two were resistant to triazole antifungals. We discuss the implications of our results to the evolution and epidemiology of A. fumigatus.

Molecular characterization and genetic variability of Toxocara vitulorum from naturally infected buffalo calves for the first time in Bangladesh.

Toxocara vitulorum is one of the deadliest parasite of buffalo calves in Bangladesh. This study was conducted to explore genetic variability within and among the T. vitulorum populations in buffalo calves of Bangladesh. Genomic DNA was extracted, ITS2, COX1 and NAD1 gene were amplified and sequenced. Distinct 29 ITS2, 21 unique NAD1 and 24 COX1 genotypes were detected among the T. vitulorum of different geographic regions. These three gene genotypes similarities ranged from 97 to 99%, when these were compared to best hit scoring T. vitulorum sequences retrieved from GenBank. A total of 12 and 6 unique haplotypes were detected for COX1 and NAD1 gene sequences. The average nucleotide and haplotype diversity for COX1 and NAD1 were 0.0931 & 0.89493 and 0.00658 & 0.77895 respectively and the recorded values were more dispersed than previously published values. The pairwise Nst values ranged from −0.050 to 0.602 and Fst from −0.050 to 0.600 between all the T. vitulorum genotypes indicated huge genetic differentiation which were reportedly higher than other published reports Fst values. This is the first report of T. vitulorum on the basis of COX1 gene in Bangladesh. The study findings will be helpful for further extensive epidemiological studies regarding anthelmintic resistance, control and prevention of T. vitulorum infection in buffalo calves.

South! Phylogeography of the Antarctic fairy shrimp Branchinecta gaini and its closest Patagonian congener Branchinecta granulosa reveals a long-term association of freshwater fauna with the southern continent

AbstractBranchinecta gaini Daday, 1910 is the southernmost extant Anostracan species occurring in various localities across Maritime Antarctica. Since this region was almost completely glaciated during the Last Glacial Maximum, the identification of potential glacial refugia and the colonization sequence of freshwater habitats within Maritime Antarctica remains primary biogeographic objective for understanding the evolution of the Antarctic environment. To evaluate the history of B. gaini in Maritime Antarctica, we performed phylogeographic analyses of B. gaini and its closest Patagonian congener Branchinecta granulosa Daday, 1902. We sampled 47 populations from all three Antarctic bioregions where B. gaini occurs – South Orkney Islands, North-west and North-east Antarctic Peninsula. B. granulosa was represented by 8 populations from Patagonia. Molecular analyses of two mitochondrial (16S, COI) and one nuclear (ITS2) marker showed low overall mitochondrial variability and the ambiguous nature of ITS2 variability. The species assessment revealed insufficient genetic differentiation between B. gaini and B. granulosa to consider them two separate species. Therefore, the widely accepted idea that there is a species of Branchinecta endemic to Antarctica and sub-Antarctic islands should be omitted, and B. gaini should be synonymized with B. granulosa. Molecular clock analysis of COI for two substitution rates dated the separation of B. gaini from B. granulosa to the Pleistocene (170 – 502 ka BP and 17 – 50 ka BP, respectively). Therefore, Antarctic populations of B. gaini separated from Patagonian B. granulosa before or during the Last Glacial Maximum, indicating an older association with the southern continent than previously anticipated. The geographic distribution of haplotypes further suggests that B. gaini most likely survived at least the last glacial period in an as-yet unknown refugium in Antarctica.

Genetic Diversity Losses in Mantis Shrimp Oratosquilla oratoria Offspring Created for Supportive Releases Using an Ecological Breeding in Earthen Pond Method

ABSTRACTArtificial breeding of mantis shrimp Oratosquilla oratoria, using the ecological breeding in earthen pond (EBEP) method, has been carrying out from 2019, and the produced larvae have always been used for supportive breeding programs in Bohai Bay. To assess the degree of fidelity of enhancement programs used an EBEP method to native genetic pools, genetic diversity at 10 microsatellite loci was analyzed in three hatchery offspring populations, their wild parent stocks, and their wild contemporaneous offspring. Significant decrease in the almost genetic diversity parameters and highly significant differences in shannon's information index (decreasing by 22.54%–40.97%) and allelic richness (33.80%–46.87%) were observed between in hatchery populations. This further created relatively more genetic differentiation between the hatchery and wild population, as the pairwise Fst values and genetic distances showed. The mean pairwise relatedness coefficients showed higher values within hatchery populations and lower values within wild populations. Hatchery populations contained the fewest full‐sib families and offspring were extremely distributed in 10–11 full‐sib groups in each hatchery population. The relatively small number of actual spawning females and large variance in parental contribution to the next generation possibly causes allele reduction in the hatchery population, which in turn leads to a decrease in allelic diversity and an increase in genetic similarities among individuals. Promoting synchrony of ovarian development in females, providing good conditions for incubation and larvae culture and balancing the contributions of parents will be important in future breeding propagation.

Snow leopard phylogeography and population structure supports two global populations with single refugial origin

AbstractSnow leopards (Panthera uncia) inhabit the mountainous regions of High Asia, which experienced serial glacial contraction and expansion during climatic cycles of the Pleistocene. The corresponding impacts of glacial vicariance may have alternately promoted or constrained genetic differentiation to shape the distribution of genetic lineages and population structure. We studied snow leopard phylogeography across High Asia by examining range-wide historical and contemporary genetic structure with mitochondrial DNA and microsatellite markers. We genotyped 182 individuals from across snow leopard range and sequenced portions of the mitogenome in a spatially stratified subset of 80 individuals to infer historical biogeographic and contemporary patterns of genetic diversity. We observed a lack of phylogeographic structure, and analyses suggested a single refugial origin for all sampled populations. Molecular data provided tentative evidence of a hypothesized glacial refugia in the Tian Shan-Pamir-Hindu Kush-Karakoram mountain ranges, and detected mixed signatures of population expansion. Concordant assessments of microsatellite data indicated two global genetic populations, though we detected geographic differences between historical and contemporary population structure and connectivity inferred from mitochondrial and microsatellite data, respectively. Using the largest sample size and geographic coverage to date, we demonstrate novel information on the phylogeographic history of snow leopards, and corroborate existing interpretations of snow leopard connectivity and genetic structure. We recommend that conservation efforts incorporate genetic data to define and protect meaningful conservation units and their underlying genetic diversity, and to maintain the snow leopard’s adaptive potential and continued resilience to environmental changes.

Genetická charakterizace tisu červeného (Taxus baccata L.) v širší oblasti Podyjí/Thayatal a na Svitavsku s vazbou na ochranářský management

The aim of the work is to determine the genetic diversity, genetic differentiation and genetic structure of subpopulations of the specially protected common yew in the area of South Moravian Podyjí (Czech Republic), Thayatal (Austria) and in the Svitavy region (Czech Republic) using DNA analyses (nSSR-nuclear Simple Sequence Repeats). The subjects of the analyses were yews of 1) natural occurrences in the territory of the Podyjí National Park (NP), 2) cultural origin in the Podyjí NP, 3) natural occurrences in the Thayatal NP (Austria), 4) natural occurrences outside the Podyjí NP, and 5) cultural origin in the Podyjí region outside the NP. For the comparison and better interpretation of results there also were analysed geographically more distant subpopulations, 6) natural occurrences in the Hřebečský ridge (NW Moravia), 7) cultural yew occurrences in the Svitavy region (NE Bohemia & NW Moravia), 8) natural occurrences in the Jílovské yews (N Bohemia), and 9) natural occurrences in the Moravian Karst (S Moravia). We observed higher level of genetic diversity (Ho = 0.54; He = 0.77), the FST with ENA correction ranged from 0.007 to 0.123. According to a STRUCTURE analysis, high genetic similarity was observed between samples from the Podyjí NP and Hřebečský ridge. The impact of the analysis results on the conservation management of tested populations was outlined.

Rivers and spatial distance are drivers of genetic diversity in the south American dwarf caiman (Paleosuchus palpebrosus)

AbstractThe distribution of species and the way that lineages are structured are the result of intrinsic historical processes of the species and their relationships with landscape features. Paleosuchus palpebrosus is one of the smallest crocodilians in the world and has a wide geographic distribution in South America, occurring in different habitats. Here, we analyzed mitochondrial cytochrome b sequences of 227 individuals, investigated how elements of landscape heterogeneity impact genetic differentiation, and evaluated the evolutionary and phylogeographic history of the species. Thus, we hypothesized that landscape structures, such as aridity and slope, should act as resistance surfaces to population connectivity, while rivers could mediate the dispersion of the species as a conductor of the gene flow. The analyses recovered three main lineages of P. palpebrosus. While most of the observed genetic variation was explained by geographic resistance distance, river connectivity had a smaller contribution for the observed variation. We also found a recent history with limited genetic divergence throughout the wide distribution of the species. Our findings highlight the main drivers for the evolutionary history of the species and how landscape features can shape the diversification, especially if we consider rivers as a facilitator of gene flow.

Lost in space and time: robust demography and enhanced resilience buffer adverse environmental effects in a highly isolated and sedentary pre-pleistocene landscape vertebrate

BackgroundFew animal populations have been studied under the framework of the OCBIL theory, which addresses the ecology and evolution of biodiversity on old climatically buffered infertile landscapes. Available genetic data challenge the low connectivity and high genetic differentiation predicted for isolated tepui-summit vertebrate communities, suggesting potential dispersal among summits. However, the OCBIL theory posits reduced dispersibility, enhanced resilience to habitat fragmentation and inbreeding due to small populations. We tested these hypotheses by conducting the first analytic evaluation of the spatial ecology and population biology of a tepui-summit vertebrate at multiple spatial scales.ResultsWe used harmonic radar tracking (100 individuals/448 points of contact) and capture-mark-recapture data (596 individuals captured/52 recaptured) to reveal the temporal niche, microhabitat use, population size, and dispersal abilities of the tepui-summit endemic toad Oreophrynella quelchii on Roraima-tepui. Abundance was determined using a closed population model incorporating sources of variation in capture probability. We tested the relative influence of biotic and abiotic variables on distances moved through model selection. Our data indicate that the population size of O. quelchii is remarkably large (ca. 12 million individuals), with strong seasonal demographic fluctuations. Ecology and observed limited spatial movements challenge the likelihood of active dispersal among tepui tops in this species. Our results are counter to those predicted by the available genetic data but support two hypotheses of the OCBIL theory: reduced dispersibility and enhanced resilience. However, they do not support the expectation of a small refugial population size.ConclusionWe postulate that the insular, hostile tepui-summit environment tends to produce robust demographic populations, likely to buffer stochastic adverse environmental effects, rather than diversity, as observed in much younger post-Pleistocene Neotropical landscapes. Our results draw attention to the value of faunal studies using an OCBIL framework to better understand the ecology and evolution of this unique biota worldwide.

Genetic Diversity and Population Structure of Endangered Orchid Cypripedium flavum in Fragmented Habitat Using Fluorescent AFLP Markers

Genetic diversity is crucial for determining the evolutionary potential of a species and is essential for developing optimal conservation strategies. The impact of habitat fragmentation on the genetic diversity of food-deceptive orchids seems to be unpredictable because of their specialized seed and pollen dispersal mechanisms. The habitat of deceptive Cypripedium flavum was severely fragmented during the past half century. This study investigated the genetic diversity and structure of seven fragmented Cypripedium flavum populations in Shangrila County using AFLP markers. A total of 376 alleles were identified, with a range of 70 to 81 alleles per locus. The species exhibited considerable genetic diversity, as evidenced by an average Nei’s gene diversity (H) of 0.339 and a Shannon’s information index (I) of 0.505, with all loci being polymorphic. Based on Molecular Variance (AMOVA), 8.75% of the genetic differentiation was found among populations, while the remaining 91.25% of genetic variation occurred within populations. Population structure analysis revealed that the C. flavum germplasm can be categorized into five distinct groups, among which there was significant gene flow. Despite habitat fragmentation, C. flavum still retained a high level of genetic diversity, and the substantial gene flow (5.0826) is a key factor in maintaining the genetic diversity. These findings offer valuable insights for the conservation and potential use of C. flavum genetic resources.

Comparative Mitogenomics Analysis Revealed Evolutionary Divergence among Purpureocillium Species and Gene Arrangement and Intron Dynamics of Ophiocordycipitaceae.

The species of Purpureocillium are cosmopolitan and multitrophic fungi that can infect a wide range of invertebrate hosts. This study reports the mitogenome of P. atypicola, a specialized spider pathogenic fungus. The 112,465 bp mitogenome encoded genes typically found in fungal mitogenomes, and a total of 52 introns inserted into seven genes. A comparison with three other Purpureocillium species revealed significant differences in length and intron number, primarily due to intron variation; however, there was no dynamic variation in the introns of the cox1 gene within the same species of the Purpureocillium genus. Different mitochondrial protein-coding genes showed variable degrees of genetic differentiation among these species, but they were all under purifying selection. Additionally, frequent intron loss or gain events were detected to have occurred during the evolution of the Ophiocordycipitaceae mitogenomes, yet the gene arrangement remains conserved. A phylogenetic analysis of the combined mitochondrial gene set gave identical and well-supported tree topologies. The estimated age of the crown of Ophiocordycipitaceae and Purpureocillium were around the Early Cretaceous period (127 Mya) and Late Cretaceous period (83 Mya), respectively. The results of this study advance our understanding of the genomics, evolution, and taxonomy of this important fungal group.

Ancestry and genetic differentiation of red foxes (Vulpes vulpes) on the Isle of Wight

Ancestry and genetic differentiation of red foxes (Vulpes vulpes) on the Isle of Wight

Mitochondrial data unravels the human-mediated introduction of Mediodactylus kotschyi (Squamata: Gekkonidae) to the Central Balkan Peninsula

Abstract Kotschy’s gecko, Mediodactylus kotschyi, is native to the Eastern part of the Mediterranean Basin and a successful colonizer, with an extensive distribution across the Balkans and outside its native range. In Serbia, it was presumed native in Prizren (Kosovo and Metohija province) and introduced across the remaining territory. To explore the origin of Serbian Kotschy’s gecko, we collected specimens from most of the Serbian populations where the species was recorded and assessed their phylogenetic relationships based on three mtDNA markers (COI, cytb, 16S rRNA) under Maximum Likelihood (ML) and Bayesian Inference (BI) approaches. First, our results support that the specimens found in Serbia belong to M. kotschyi. Second, all populations except Prizren belong to the subspecies M. kotschyi skopjensis. Furthermore, the Italian populations are sister to the specimens from Prizren, suggesting a Balkan origin for these populations, which settled in Apulia likely through ancient human-mediated dispersion. The small genetic differentiation found suggests that Kotschy’s gecko rapidly colonized the Central Balkans, originating from Northern Greece and North Macedonia. The results also suggest a story of multiple, complex (most likely) human-mediated introductions. However, further studies should be conducted to properly elucidate the colonization pathways, and to truly disentangle the potential fast natural range expansion from an anthropogenic dispersion of this gecko species.

Germplasm Resources Evaluation of Cultured Largemouth Bass (Micropterus salmoides) in China Based on Whole Genome Resequencing.

Background: Largemouth bass (Micropterus salmoides), a valuable freshwater fish species, has experienced significant genetic decline in China due to prolonged domestic breeding and limited introduction of new genetic material. It is necessary to have a comprehensive understanding of the genetic status of largemouth bass populations in China. Method: In this study, we conducted population genetic analyses on nine cultured largemouth bass populations using whole genome resequencing. Results: A total of 3.23 Tb of clean bases were generated, with average Q20 and Q30 values of 98.17% and 94.25%, respectively, and 2,140,534 high-quality SNPs were obtained. Relatively high genetic diversity was observed across all populations. Combined with linkage disequilibrium (LD) patterns, the Wanlu (WL) population possessed the highest genetic diversity, and the Longyou (LY) population possessed the lowest genetic diversity. Additionally, population structure analyses, including pairwise F-statistics, phylogenetic trees, PCA, and admixture analysis, revealed significant genetic differentiation, particularly between the WL, LY, and other 7 populations, while also indicating the occurrence of a common admixture event. Finally, TreeMix inferred migration events from the WL to the Chuanlu (CL) population and from the Taiwan breeding population (TWL) to the Guanglu (GL) population. Conclusions: These findings provide a critical foundation for developing conservation and breeding strategies for largemouth bass in China.

GWAS for root yield and its contributing traits in Withania somnifera (L.) dunal: First report

Ashwagandha [Withania somnifera (L.) Dunal] is a significant medicinal plant, with limited information on its genetic variability. This study evaluateed genetic diversity among 96 ashwagandha genotypes with the aim of developing strategies to improve root yield and secondary metabolites. A joint ANOVA indicated significant variability within the evaluated panel. Key traits, such as root girth, fresh root yield and dry root yield showed positive and significant correlations at both tested years. Molecular markers (SRAP, ISSR, and SSR) were used to assess genetic diversity. Amplified PCR products ranged from 210 bp (SRAP-22) to 1350 bp (SRAP-19), with PIC value ranged from 0.332 (SSR 20) to 0.494 (ISD 11), indicated moderate informativeness of markers. Genetic diversity analysis using Dice's coefficient formed six clusters, identifying two genotypes (86 and 87) as highly diverse. Population structure analysis revealed five clusters with an Fst range of 0.21–0.36, indicating allele flow among genotypes. The highest genetic differentiation was observed between clusters G2 and G4 (Fst = 0.1253). On the basis of structure analysis, genotypes in cluster G5 exhibited similar genetic make-up. A genome-wide association study (GWAS) identified a 490 bp locus of the SRAP 49 marker as highly effective and informatice. This locus was broadly associated with fresh root yield (FW) and dry root yield (DW) across individual and pooled environments. The positive correlation between these traits suggests simultaneous improvement is feasible. This study highlights the importance of genetic diversity for enhancing root yield and provides valuable insights for the genetic improvement of ashwagandha.

Genome-wide diversity, linkage disequilibrium, and admixture in the main Colombian Creole pig breeds

Colombian Creole pigs have adapted to tropical conditions for over 500 years. They have been modified by natural and artificial selection in different regions. At present, the diversity and current introgression status are unknown. The objective was to estimate the genomic diversity, linkage disequilibrium, population structure, and admixture of four Colombian pig breeds and their relationship with other breeds worldwide. Three Colombian pig breeds (SPE-San Pedreño, 11 samples; ZUN-Zungo, 11 samples; CM-Casco de Mula, ten samples) from the conservation nucleus and one biotype not recognized as a breed (CCH-Criollo Chocoano, seven samples) were genotyped using the Illumina GGP-Porcine80K chip. Open-access data from seven international breeds were also included. Colombian Creole pigs showed moderate genetic differentiation (FST 0.14) globally, but several groups of animals separated, suggesting local clustering due to geographical isolation or different founding effects. Colombian Creole pigs showed breed imprinting and specific grouping in all analyses except for CCH, which, like the Ecuadorian Creole, was a cluster of admixtures. The Colombian Creole pigs revealed a significant relationship with the Iberian pig and some other breeds to varying degrees. However, good maintenance of the conservation nucleus was evidenced. Potential adaptive genes, mainly related to immunological functions, were found, according to FST and pcadapt analyses. This study provides a foundation and scientific data for policy decisions on zoogenetic resources.

Genetic characterisation of Annona crassiflora as basis for conservation and breeding

Abstract Annona crassiflora is a fruit-bearing tree species native to the Cerrado that has ecological and economic potential, mainly due to the production of attractive and useful fruits for a number of species, including humans. To provide a basis for its conservation and breeding, the objective was to assess the diversity and genetic structure of natural populations of the species using inter-simple sequence repeat (ISSR) molecular markers. Eight populations were analysed in the state of Minas Gerais, Brazil, with 24 individuals randomly sampled in each population, reaching a total of 192 trees. Ten ISSR primers were used, resulting in high genetic diversity for the combined data (H* = 0.35 and I* = 0.52). However, a wide range of representative values was observed in the individual assessment of populations, with JAN, GM and MC standing out for their low genetic diversity, resulting in H* of 0.19, 0.23 and 0.24 and I* of 0.28, 0.34 and 0.35, respectively. An analysis of molecular variance showed greater variation within populations, indicating gene flow (Nm), but genetic differentiation between populations was moderate. Bayesian analysis, although resulting in four genetic groups, revealed the presence of a majority group for the GM and JAN populations. We propose measures to maintain these populations, such as raising awareness of local extractivism and planting genetically divergent seedlings. Furthermore, we recommend including of all populations in conservation and breeding programmes, aiming to cover the maximum genetic variation for the species.

Comparative Population Genomic Diversity and Differentiation in Trapdoor Spiders and Relatives (Araneae, Mygalomorphae).

Although patterns of population genomic variation are well-studied in animals, there remains room for studies that focus on non-model taxa with unique biologies. Here we characterise and attempt to explain such patterns in mygalomorph spiders, which are generally sedentary, often occur as spatially clustered demes and show remarkable longevity. Genome-wide single nucleotide polymorphism (SNP) data were collected for 500 individuals across a phylogenetically representative sample of taxa. We inferred genetic populations within focal taxa using a phylogenetically informed clustering approach, and characterised patterns of diversity and differentiation within- and among these genetic populations, respectively. Using phylogenetic comparative methods we asked whether geographical range sizes and ecomorphological variables (behavioural niche and body size) significantly explain patterns of diversity and differentiation. Specifically, we predicted higher genetic diversity in genetic populations with larger geographical ranges, and in small-bodied taxa. We also predicted greater genetic differentiation in small-bodied taxa, and in burrowing taxa. We recovered several significant predictors of genetic diversity, but not genetic differentiation. However, we found generally high differentiation across genetic populations for all focal taxa, and a consistent signal for isolation-by-distance irrespective of behavioural niche or body size. We hypothesise that high population genetic structuring, likely reflecting combined dispersal limitation and microhabitat specificity, is a shared trait for all mygalomorphs. Few studies have found ubiquitous genetic structuring for an entire ancient and species-rich animal clade.

Revealing the Genetic Differentiation of Rattus norvegicus (Berkenhout 1769) Populations by Analyzing Two Mitochondrial Markers

Rattus norvegicus (Brown rat) has a great importance for public health and economy because it lives in close association with human populations. However, molecular systematic studies on global populations of R. norvegicus are very few. In this study, sequences obtained from Europe, Asia, Africa, and America regions were analyzed using mitochondrial Cytochrome-b and Cytochrome oxidase-I gene regions and genetic differentiation levels between these populations were revealed. Accordingly, samples belonging to the studied populations did not split in Bayesian Inference trees and Median-joining networks; these samples also formed common haplotypes, and mean genetic distance and fixation index values were generally low. The results of the study showed that gene flow between these populations may be continuing due to the transportation activity by humans.