Isolation by environment and its consequences for range shifts with global change: Landscape genomics of the invasive plant common tansy.

Invasive species are a growing global economic and ecological problem. However, it is not well understood how environmental factors mediate invasive range expansion. In this study, we investigated the recent and rapid range expansion of common tansy across environmental gradients in Minnesota, USA. We densely sampled individuals across the expanding range and performed reduced representation sequencing to generate a dataset of 3071 polymorphic loci for 176 individuals. We used non-spatial and spatially explicit analyses to determine the relative influences of geographic distance and environmental variation on patterns of genomic variation. We found no evidence for isolation by distance but strong evidence for isolation by environment, indicating that environmental factors may have modulated patterns of range expansion. Land use classification and soils were particularly important variables related to population structure although they operated on different spatial scales; land use classification was related to broad-scale patterns and soils were related to fine-scale patterns. All analyses indicated a distinctive genetic cluster in the most recently invaded portion of the range. Individuals from the far northwestern range margin were separated from the remainder of the range by reduced migration, which was associated with environmental resistance. This portion of the range was invaded primarily in the last 15 years. Ecological niche models also indicated that this cluster was associated with the expansion of the niche. While invasion is often assumed to be primarily influenced by dispersal limitation, our results suggest that ongoing invasion and range shifts with climate change may be strongly affected by environmental heterogeneity.

Genetic diversity, spatial connectivity, and population structure of Asian silurid catfish Wallago attu (Bloch and Schneider, 1801) in the Ganga River System: insights from mitochondrial DNA analysis.

BACKGROUND: The Ganga River System (GRS) is a biodiversity hotspot, its ecological richness is shaped by a complex geological history. In this study, we examined the genetic diversity, spatial connectivity, and population structure of the Asian Silurid catfish, Wallago attu, across seven tributaries of the GRS. METHODS AND RESULTS: We employed three mitochondrial DNA (mtDNA) regions: cytochrome c oxidase subunit I (COXI), cytochrome b (Cyt b), and control region (CR). Our comprehensive dataset encompassed 2420 bp of mtDNA, derived from 176 W. attu individuals across 19 sampling sites within the seven rivers of GRS. Our findings revealed high gene diversity (Hd:0.99) within W. attu populations. Analysis of Molecular Variance (AMOVA) highlighted that maximum genetic variations were attributed within the populations, and the observed genetic differentiation among the seven populations of W. attu ranged from low to moderate. Network analysis uncovered the presence of three distinct genetic clades, showing no specific association with seven studied rivers. Bayesian skyline plots provided insights into the demographic history of W. attu, suggesting a recent population expansion estimated to have occurred approximately 0.04 million years ago (mya) during the Pleistocene epoch. CONCLUSIONS: These results significantly enhance our understanding of the genetic diversity and spatial connectivity of W. attu, serving as a vital foundation for developing informed conservation strategies and the sustainable management of this economically valuable resource within the Ganga River System.

Study on the origin of the Baise horse based on whole-genome resequencing.

The Baise horse, an indigenous horse breed mainly distributed in the Baise region of Guangxi province in southwest China, has a long history as draft animal. However, there is a lack of research regarding the origin and ancestral composition of the Baise horse. In this study, whole-genome resequencing data from 236 horses of seven Chinese indigenous horse breeds, five foreign horse breeds, and four Przewalski's horses were used to investigate the relationships between the Baise horse and other horse breeds. The results showed that foreign horse breeds had no significant impact on the formation of the Baise horse. The two southwestern horse populations, the Debao pony and the Jinjiang horse, exhibit the closest genetic affinity with the Baise horse. This is consistent with their adjacent geographical distribution. Analysis of the migration route revealed a gene flow from the Chakouyi horse into the Baise horse. In summary, our results confirm that the formation of the Baise horse did not involve participation from foreign breeds. Geographical distance emerges as a crucial factor in determining the genetic relationships with the Baise horse. Gene flows of indigenous horse breeds along ancient routes of trade activities had played a role in the formation of the Baise horse.

Unraveling genomic diversity and positive selection signatures of Qaidam cattle through whole-genome re-sequencing.

Qaidam cattle are a typical Chinese native breed inhabiting northwest China. They bear the characteristics of high cold and roughage tolerance, low-oxygen adaptability and good meat quality. To analyze the genetic diversity of Qaidam cattle, 60 samples were sequenced using whole-genome resequencing technology, along with 192 published sets of whole-genome sequencing data of Indian indicine cattle, Chinese indicine cattle, North Chinese cattle breeds, East Asian taurine cattle, Eurasian taurine cattle and European taurine cattle as controls. It was found that Qaidam cattle have rich genetic diversity in Bos taurus, but the degree of inbreeding is also high, which needs further protection. The phylogenetic analysis, principal component analysis and ancestral component analysis showed that Qaidam cattle mainly originated from East Asian taurine cattle. Qaidam cattle had a closer genetic relationship with the North Chinese cattle breeds and the least differentiation from Mongolian cattle. Annotating the selection signals obtained by composite likelihood ratio, nucleotide diversity analysis, integrated haplotype score, genetic differentiation index, genetic diversity ratio and cross-population extended haplotype homozygosity methods, several genes associated with immunity, reproduction, meat, milk, growth and adaptation showed strong selection signals. In general, this study provides genetic evidence for understanding the germplasm characteristics of Qaidam cattle. At the same time, it lays a foundation for the scientific and reasonable protection and utilization of genetic resources of Chinese local cattle breeds, which has great theoretical and practical significance.

Whole genome resequencing-based analysis of plateau adaptation in Meiren yak (Bos grunniens).

The Meiren yak is an important genetic resource in Gansu Province, China. In this study, we aimed to explore the evolutionary history and population structure of the genetic resource of Meiren yak and to mine the characteristic genes of Meiren yak. We analysed a total of 93 yaks of eight yak breeds based on whole genome resequencing combined with population genomics and used θπ ratio and Fst method to screen the selected sites in the genome region. The results proved that Meiren yak can be used as a potential genetic resource in Gansu Province. The genes in Meiren yak with positive selection in selection signal analysis were subjected to the Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses, which indicated that the genes were related to the adaptability to high altitude and hypoxic environment. By analysing the genetic variation of Meiren yak at the genome-wide level, this study provided a theoretical basis for genetic improvement of Meiren yak and for the development of high-quality yak resources.

Genetic diversity and population structure of modern wheat (Triticum aestivum L.) cultivars in Henan Province of China based on SNP markers.

BACKGROUND: Henan is the province with the greatest wheat production in China. Although more than 100 cultivars are used for production, many cultivars are still insufficient in quality, disease resistance, adaptability and yield potential. To overcome these limitations, it is necessary to constantly breed new cultivars to maintain the continuous and stable growth of wheat yield and quality. To improve breeding efficiency, it is important to evaluate the genetic diversity and population genetic structure of its cultivars. However, there are no such reports from Henan Province. Therefore, in this study, single nucleotide polymorphism (SNP) markers were used to study the population genetic structure and genetic diversity of 243 wheat cultivars included in a comparative test of wheat varieties in Henan Province, aiming to provide a reference for the utilization of backbone parents and the selection of hybrid combinations in the genetic improvement of wheat cultivars. RESULTS: In this study, 243 wheat cultivars from Henan Province of China were genotyped by the Affymetrix Axiom Wheat660K SNP chip, and 21 characteristics were investigated. The cultivars were divided into ten subgroups; each subgroup had distinct characteristics and unique utilization value. Furthermore, based on principal component analysis, Zhoumai cultivars were the main hybrid parents, followed by Aikang 58, high-quality cultivars, and Shandong cultivars. Genetic diversity analysis showed that 61.3% of SNPs had a high degree of genetic differentiation, whereas 33.4% showed a moderate degree. The nucleotide diversity of subgenome B was relatively high, with an average π value of 3.91E-5; the nucleotide diversity of subgenome D was the lowest, with an average π value of 2.44E-5. CONCLUSION: The parents used in wheat cross-breeding in Henan Province are similar, with a relatively homogeneous genetic background and low genetic diversity. These results will not only contribute to the objective evaluation and utilization of the tested cultivars but also provide insights into the current conditions and existing challenges of wheat cultivar breeding in Henan Province, thereby facilitating the scientific formulation of breeding objectives and strategies to improve breeding efficiency.

Genetic diversity, population genetic structure and gene flow in the rare and endangered wild plant Cypripedium macranthos revealed by genotyping-by-sequencing.

BACKGROUND: Genetic diversity, genetic structure, and gene flow in plant populations and their influencing factors are important in conservation biology. Cypripedium macranthos is one of the few wild orchids with high ornamental value in northern China. However, over the past decade, excessive collection, trading, tourism development, habitat fragmentation, deceptive pollination, and seed germination difficulties have all caused a sharp decline in the number of C. macranthos individuals and its population. In order to propose a scientific and effective conservation strategy, the genetic diversity, genetic structure and gene flow of the current CM population are urgent scientific issues to be clarified. RESULTS: Here, 99 individuals of C. macranthos from north and northeast China were analyzed to evaluate the genetic diversity, gene flow among populations, and genetic structure by genotyping-by-sequencing. More than 68.44 Gb high-quality clean reads and 41,154 SNPs were obtained. Our data based on bioinformatics methods revealed that C. macranthos has lower genetic diversity, high levels of historical gene flow, and moderate-to-high genetic differentiation between populations. The gene migration model revealed that the direction of gene flow was mainly from northeast populations to north populations in China. The results of genetic structure analysis showed that 11 C. macranthos populations can be considered as two groups, and further divided into four subgroups. Moreover, the Mantel test detected no significant "Isolation by Distance" between populations. CONCLUSIONS: Our study demonstrates that the present genetic diversity and genetic structure of C. macranthos populations were mainly caused by biological characteristics, human interference, habitat fragmentation, and restricted gene flow. Finally, constructive measures, which can provide a basis for the proposal of conservation strategies, have been suggested.

Testing for adaptive changes linked to range expansion following a single introduction of the fall webworm.

Adaptive evolution following colonization can affect the impact of invasive species. The fall webworm (FWW) invaded China 40 years ago through a single introduction event involving a severe bottleneck and subsequently diverged into two genetic groups. The well-recorded invasion history of FWW, coupled with a clear pattern of genetic divergence, provides an opportunity to investigate whether there is any sign of adaptive evolution following the invasion. Based on genome-wide SNPs, we identified genetically separated western and eastern groups of FWW and correlated spatial variation in SNPs with geographical and climatic factors. Geographical factors explained a similar proportion of the genetic variation across all populations compared with climatic factors. However, when the two population groups were analysed separately, environmental factors explained more variation than geographical factors. SNP outliers in populations of the western group had relatively stronger response to precipitation than temperature-related variables. Functional annotation of SNP outliers identified genes associated with insect cuticle protein potentially related to desiccation adaptation in the western group and genes associated with lipase biosynthesis potentially related to temperature adaptation in the eastern group. Our study suggests that invasive species may maintain the evolutionary potential to adapt to heterogeneous environments despite a single invasion event. The molecular data suggest that quantitative trait comparisons across environments would be worthwhile.

Global population genetic structure and lineage differentiation of the stable fly, Stomoxys calcitrans.

The bloodsucking fly, Stomoxys calcitrans (Diptera: Muscidae), is a cosmopolitan pest that transmits potential pathogens mechanically. We conduct phylogeographic analyses of S. calcitrans to resolve its global population genetic structure for establishing baseline of molecular studies. Results from mitochondrial gene suggested that the major divergence of S. calcitrans predominantly occurred 0.32-0.47 million years ago (Mya) and the subsequent diversifications took place during 0.13-0.27 Mya. The Ethiopian region was deduced as the most likely origin of S. calcitrans and the Nearctic lineages were considered to have originated from Oriental or Palaearctic regions. Our results further revealed that each biogeographic region of S. calcitrans likely maintains its genetic specialty, and yet, those non-monophyletic relationships were possibly caused by ancestral retention, dispersal with mammals, long-distance migration, and the international livestock industries. Moreover, the three highly diverged Ethiopian lineages may be putative cryptic species that require clarification of their veterinary importance. Unravelling the genetic structure of stable fly and preventing gene flow among biogeographic regions through anthropogenic activities are thus pivotal in livestock industry administration, particularly genetic exchange among differentiated lineages that might lead to the consequence of ecological trait alterations.

Chromosome-level genome assembly and population genomic analyses provide insights into adaptive evolution of the red turpentine beetle, Dendroctonus valens.

BACKGROUND: Biological invasions are responsible for substantial environmental and economic losses. The red turpentine beetle (RTB), Dendroctonus valens LeConte, is an important invasive bark beetle from North America that has caused substantial tree mortality in China. The lack of a high-quality reference genome seriously limits deciphering the extent to which genetic adaptions resulted in a secondary pest becoming so destructive in its invaded area. RESULTS: Here, we present a 322.41 Mb chromosome-scale reference genome of RTB, of which 98% of assembled sequences are anchored onto fourteen linkage groups including the X chromosome with a N50 size of 24.36 Mb, which is significantly greater than other Coleoptera species. Repetitive sequences make up 45.22% of the genome, which is higher than four other Coleoptera species, i.e., Mountain pine beetle Dendroctonus ponderosae, red flour beetle Tribolium castaneum, blister beetle Hycleus cichorii, and Colorado potato beetle Leptinotarsa decemlineata. We identify rapidly expanded gene families and positively selected genes in RTB, which may be responsible for its rapid environmental adaptation. Population genetic structure of RTB was revealed by genome resequencing of geographic populations in native and invaded regions, suggesting substantial divergence of the North American population and illustrates the possible invasion and spread route in China. Selective sweep analysis highlighted the enhanced ability of Chinese populations in environmental adaptation. CONCLUSIONS: Overall, our high-quality reference genome represents an important resource for genomics study of invasive bark beetles, which will facilitate the functional study and decipher mechanism underlying invasion success of RTB by integrating the Pinus tabuliformis genome.

Genome-wide SNPs reveal the fine-scale population structure of Laodelphax striatellus in China using double-digest restriction site-associated DNA sequencing.

The small brown planthopper (SBPH), Laodelphax striatellus (Fallén) is one of the most destructive rice pests and has caused serious economic losses in China. To clarify the genetic differentiation and population genetic structure of this insect pest, we investigated the genomic polymorphisms, genetic differentiation, and phylogeography of 31 SBPH populations from 28 sampling sites from three climatic zones of China using double-digest restriction site-associated DNA sequencing (ddRADseq). In total, 2,813,221,369 high-quality paired-end reads from 306 individuals and 1925 single nucleotide polymorphisms (SNPs) were obtained. Low levels of genetic diversity and significant genetic differentiation were observed among the SBPH populations, and three genetic clusters were detected in China. Neutrality tests and bottleneck analysis provided strong evidence for recent rapid expansion with a severe bottleneck in most populations. Our work provides new insights into the genetics of the SBPH and will contribute to the development of effective management strategies for this pest.

Chromosome-Level Genome Assembly and Population Genomic Analyses Reveal Geographic Variation and Population Genetic Structure of Prunus tenella.

Prunus tenella is a rare and precious relict plant in China. It is an important genetic resource for almond improvement and an indispensable material in ecological protection and landscaping. However, the research into molecular breeding and genetic evolution has been severely restricted due to the lack of genome information. In this investigation, we created a chromosome-level genomic pattern of P. tenella, 231 Mb in length with a contig N50 of 18.1 Mb by Hi-C techniques and high-accuracy PacBio HiFi sequencing. The present assembly predicted 32,088 protein-coding genes, and an examination of the genome assembly indicated that 94.7% among all assembled transcripts were alignable to the genome assembly; most (97.24%) were functionally annotated. By phylogenomic genome comparison, we found that P. tenella is an ancient group that diverged approximately 13.4 million years ago (mya) from 13 additional closely related species and about 6.5 Mya from the cultivated almond. Collinearity analysis revealed that P. tenella is highly syntenic and has high sequence conservation with almond and peach. However, this species also exhibits many presence/absence variants. Moreover, a large inversion at the 7588 kb position of chromosome 5 was observed, which may have a significant association with phenotypic traits. Lastly, population genetic structure analysis in eight different populations indicated a high genetic differentiation among the natural distribution of P. tenella. This high-quality genome assembly provides critical clues and comprehensive information for the systematic evolution, genetic characteristics, and functional gene research of P. tenella. Moreover, it provides a valuable genomic resource for in-depth study in protection, developing, and utilizing P. tenella germplasm resources.

[Exploration of transcriptome SSR markers and its application in genetic diversity assessment of Asarum sieboldii].

To explore the genetic diversity of Asarum sieboldii this study developed SSR markers based on transcriptome sequencing results and five populations of A.sieboldii from different regions were used as samples for genetic diversity assessment using software such as GenALEx 6.5, NTSYS 2.1, and Structure 2.3.4. The results showed that 16 SSR markers with high polymorphism and good repeatability were selected from the A.sieboldii transcriptome. Primers designed based on the flanking sequences of these markers successfully amplified 56 polymorphic fragments from 150 individual samples of the five A.sieboldii populations. On average, each primer amplified 3.5 polymorphic fragments, ranging from 2 to 8. The mean values of expected heterozygosity(H_e), Shannon's diversity index(I), Nei's gene diversity index(H), and the polymorphic information content(PIC) were 0.172, 0.281, 0.429, and 0.382, respectively. The mean population differentiation coefficient(F_(ST)) was 0.588, consistent with the analysis of molecular variance(AMOVA) results, which indicated greater genetic variation among A.sieboldii populations(69%) than that within populations(31%). The percentage of polymorphic loci(PPL) ranged from highest to lowest as SNJ>LN>SY>SZ>TB. Principal coordinate analysis(PCoA) and UPGMA clustering analysis further revealed genetic clustering of A.sieboldii individuals based on their geographical distribution, consistent with the results of the structure clustering analysis. In summary, the SSR markers developed from the transcriptome effectively assessed the genetic differentiation and population structure of natural A.sieboldii populations, revealing a relatively low genetic diversity in A.sieboldii, with genetic variation primarily observed at the population level and a correlation between population differentiation and geographic distance.

Whole-genome resequencing confirms reproductive isolation between sympatric demes of brown trout (Salmo trutta) detected with allozymes.

The sympatric existence of genetically distinguishable populations of the same species remains a puzzle in ecology. Coexisting salmonid fish populations are known from over 100 freshwater lakes. Most studies of sympatric populations have used limited numbers of genetic markers making it unclear if genetic divergence involves certain parts of the genome. We returned to the first reported case of salmonid sympatry, initially detected through contrasting homozygosity at a single allozyme locus (coding for lactate dehydrogenase A) in brown trout in the small Lakes Bunnersjöarna, Sweden. First, we verified the existence of the two coexisting demes using a 96-SNP fluidigm array. We then applied whole-genome resequencing of pooled DNA to explore genome-wide diversity within and between these demes; nucleotide diversity was higher in deme I than in deme II. Strong genetic divergence is observed with genome-wide FST  ≈ 0.2. Compared with data from populations of similar small lakes, this divergence is of similar magnitude as that between reproductively isolated populations. Individual whole-genome resequencing of two individuals per deme suggests higher inbreeding in deme II versus deme I, indicating different degree of isolation. We located two gene-copies for LDH-A and found divergence between demes in a regulatory section of one of these genes. However, we did not find a perfect fit between the sequence data and previous allozyme results, and this will require further research. Our data demonstrates genome-wide divergence governed mostly by genetic drift but also by diversifying selection in coexisting populations. This type of hidden biodiversity needs consideration in conservation management.

Finding the adaptive needles in a population-structured haystack: A case study in a New Zealand mollusc.

Genetic adaptation to future environmental conditions is crucial to help species persist as the climate changes. Genome scans are powerful tools to understand adaptive landscapes, enabling us to correlate genetic diversity with environmental gradients while disentangling neutral from adaptive variation. However, low gene flow can lead to both local adaptation and highly structured populations, and is a major confounding factor for genome scans, resulting in an inflated number of candidate loci. Here, we compared candidate locus detection in a marine mollusc (Onithochiton neglectus), taking advantage of a natural geographical contrast in the levels of genetic structure between its populations. O. neglectus is endemic to New Zealand and distributed throughout an environmental gradient from the subtropical north to the subantarctic south. Due to a brooding developmental mode, populations tend to be locally isolated. However, adult hitchhiking on rafting kelp increases connectivity among southern populations. We applied two genome scans for outliers (Bayescan and PCAdapt) and two genotype-environment association (GEA) tests (BayeScEnv and RDA). To limit issues with false positives, we combined results using the geometric mean of q-values and performed association tests with random environmental variables. This novel approach is a compromise between stringent and relaxed approaches widely used before, and allowed us to classify candidate loci as low confidence or high confidence. Genome scans for outliers detected a large number of significant outliers in strong and moderately structured populations. No high-confidence GEA loci were detected in the context of strong population structure. However, 86 high-confidence loci were associated predominantly with latitudinally varying abiotic factors in the less structured southern populations. This suggests that the degree of connectivity driven by kelp rafting over the southern scale may be insufficient to counteract local adaptation in this species. Our study supports the expectation that genome scans may be prone to errors in highly structured populations. Nonetheless, it also empirically demonstrates that careful statistical controls enable the identification of candidate loci that invite more detailed investigations. Ultimately, genome scans are valuable tools to help guide further research aiming to determine the potential of non-model species to adapt to future environments.

Population genetics of Sambar (Rusa unicolor) from the Western Himalayas: preliminary findings.

BACKGROUND: The sambar (Rusa unicolor) is one of the largest deer distributed across diverse habitats of India and threatened due to habitat loss, changes in the land-use patterns, illegal poaching, and anthropogenic disturbances. Here, we report the first population genetics account of sambar deer from the Western Himalayas. METHODS AND RESULTS: We observed relatively compromised genetic diversity (π = 0.0008 ± 0.0006 at mtDNA and Ho = 0.499 ± 0.056 at nDNA). We identified 60 unique individuals using a select panel of seven loci (PID sib cum 1.60E-03). Bayesian skyline plot showed a stable demographic history since the past 8 kyr with a decline in recent years. The population lacked genetic structuring, likely due to the contiguous distribution and large dispersal patterns of sambar. CONCLUSION: The preliminary findings are valuable in exploring the utility of genetic diversity in monitoring the sambar population, estimating density following capture-recapture analysis, and aid to the conservation planning of sambar in large landscapes.

Population Genetic Characteristics and Mating Type Frequency of Venturia effusa from Pecan in South America.

Scab, caused by the plant-pathogenic fungus Venturia effusa, is a major disease of pecan in South America, resulting in loss of quantity and quality of nut yield. Characteristics of the populations of V. effusa in South America are unknown. We used microsatellites to describe the genetic diversity and population structure of V. effusa in South America, and determined the mating type status of the pathogen. The four hierarchically sampled orchard populations from Argentina (AR), Brazil (BRC and BRS), and Uruguay (UR) had moderate to high genotypic and gene diversity. There was evidence of population differentiation (Fst = 0.196) but the correlation between geographic distance and genetic distance was not statistically significant. Genetic differentiation was minimal between the UR, BRC, and BRS populations, and these populations were more clearly differentiated from the AR population. The MAT1-1 and MAT1-2 mating types occurred in all four orchards and their frequencies did not deviate from the 1:1 ratio expected under random mating; however, multilocus linkage equilibrium was rejected in three of the four populations. The population genetics of South American populations of V. effusa has many similarities to the population genetics of V. effusa previously described in the United States. Characterizing the populations genetics and reproductive systems of V. effusa are important to establish the evolutionary potential of the pathogen and, thus, its adaptability-and can provide a basis for informed approaches to utilizing available host resistance and determining phytosanitary needs.

Population genetic structure of diphyllobothriid tapeworms (Cestoda: Diphyllobothriidea) parasitising fish in the Baikal Rift Zone.

Tapeworms of the genus Dibothriocephalus are widely distributed throughout the world, and some are agents of human diphyllobothriasis, one of the most important fish-borne zoonoses caused by a cestode parasite. Until now, the population genetic structure of diphyllobothriid tapeworms in the Baikal Rift Zone (BRZ) has remained unexplored. The major aim of this study was to analyse the population genetic structure of D. dendriticus and D. ditremus parasitising fish in the BRZ based on internal transcribed spacer 1 (ITS1) and mitochondrial gene cytochrome oxidase subunit I (cox1) sequences. We found that both species had complex population genetic structures. Each species formed 2 clades (D. dendriticus: Clade 1 & 2; D. ditremus Clade A & B) that differed in genetic diversity. D. dendriticus haplotypes in Clade 1 formed a star-like sub-network with a main haplotype, whereas the haplotypes in Clade 2 formed a diffuse network. We assumed that the complex population genetic structure of D. dendriticus was a consequence of populations evolving under different palaeoecological conditions during the Last Glacial Maximum. In contrast to D. dendriticus, both clades in the D. ditremus samples formed a diffuse network. Our findings revealed hypothetical pathways in the formation of the population genetic structure of diphyllobothriids in the BRZ. On one hand, isolation by distance played an important role; on the other hand, lake recolonisation from refugia and a genetic bottleneck after the end of the Last Glacial Maximum had a possible influence.

Analysis of the population genetic structure using microsatellite markers in goat populations in Taiwan.

Due to the poor growth rate of the Taiwan black (TB) goat in Taiwan, many exotic breeds were brought into breeding schemes to improve TB goat. However, the excessive cross-breeding of alien species with TB goat has decreased its population numbers, genetic variation and biodiversity. Therefore, TB goat population considered an endemic species in Taiwan that needed to be conservation. The objective of the present study was to analyze the genetic structure and TB goat using genetic markers for genetic improvement and to sustain germplasm conservation and utilization. 15 microsatellite markers, divided into three sets, were used to analyze 690 goats sampled from 10 goat populations. The average number of alleles (Na) and effective alleles (Ne) was 11.87 ± 3.93 and 5.093 ± 1.768, respectively. The average expected heterozygosity (HE) and observed heterozygosity (HO) was 0.780 ± 0.084 and 0.602 ± 0.116, respectively. The average polymorphic information content (PIC) was 0.747 ± 0.103; FIS was 0.058 ± 0.075. All 15 microsatellite markers were highly polymorphic. The genetic distances between individuals were estimated to construct a phylogenetic tree. In present study, the 690 goat samples were divided into 8 clusters. The results indicated that these 15 microsatellite markers successfully clustered goat populations in Taiwan and could assist in the preservation of TB goats.

Population genetic structure of Neoschongastia gallinarum in South China based on mitochondrial DNA markers.

The genetic diversity and differentiation of four geographic populations of Neoschongastia gallinarum were evaluated using concatenated mitochondrial gene sequences (pCOI, pCOII, and pND5). Based on the results, the N. gallinarum populations had high genetic diversity and strong ecological adaptability. Genetic differentiation among paired populations calculated using concatenated mitochondrial gene sequences revealed that geographic isolation resulted in genetic differentiation among the populations of N. gallinarum, and gene flow between populations associated with human trade activities. Systematic development and molecular variance based on haplotypes revealed that genetic variation existed in different haplotypes; however, no clear rule related to geographic region was found. Further, genetic variation was mainly derived from individuals within the population. A neutral test based on concatenated mitochondrial gene sequences and nucleotide pair differences revealed that N. gallinarum did not experience an obvious population expansion in recent historical periods. Accordingly, the population size was relatively stable.