Analysis Of Gene Flow Research Articles

A consequential one-night stand: Episodic historical hybridization leads to mitochondrial takeover in sympatric desert ant-eating spiders

Disentangling the genomic intricacies underlying speciation and the causes of discordance between sources of evidence can offer remarkable insights into evolutionary dynamics. The ant-eating spider Zodarion nitidum, found across the Middle East and Egypt, displays yellowish and blackish morphs that co-occur sympatrically. These morphs additionally differ in behavioral and physiological features and show complete pre-mating reproductive isolation. In contrast, they possess similar sexual features and lack distinct differences in their mitochondrial DNA. We analyzed both Z. nitidum morphs and outgroups using genome-wide and additional mitochondrial DNA data. The genomic evidence indicated that Yellow and Black are reciprocally independent lineages without signs of recent admixture. Interestingly, the sister group of Yellow is not Black but Z. luctuosum, a morphologically distinct species. Genomic gene flow analyses pinpointed an asymmetric nuclear introgression event, with Yellow contributing nearly 5 % of its genome to Black roughly 320,000 years ago, intriguingly aligning with the independently estimated origin of the mitochondrial DNA of Black. We conclude that the blackish and yellowish morphs of Z. nitidum are long-diverged distinct species, and that the ancient and modest genomic introgression event registered resulted in a complete mitochondrial takeover of Black by Yellow. This investigation underscores the profound long-term effects that even modest hybridization events can have on the genome of organisms. It also exemplifies the utility of phylogenetic networks for estimating historical events and how integrating independent lines of evidence can increase the reliability of such estimations.

Geographic patterns and ecological adaptations of Manila clam (Ruditapes philippinarum) along the Chinese coast: Insights from migration dynamics and gene flow

The Manila Clam (Ruditapes Philippinarum) is one of the most economically significant marine bivalves along the China coast. In recent years, due to the escalating scale of aquaculture, the artificial activities of "cross-regional introduction" have to some extent exerted an influence on the genetic diversity and structure of clam larvae, leading to an ongoing occurrence of genetically mixed clam larvae populations and ambiguous genetic foundation of germplasm resources in China. Therefore, there is an imperative need to gain profound insights into the lineage, genetic structure, and assess the adaptability potential of clams originating from both northern and southern regions. We use Specific Locus Amplified Framents technology to simplify genome sequencing of wild clams along the coast of China. Through genetic diversity, genetic structure, gene flow, and selection elimination analysis, the results show that clams can be divided into distinct north-south lineages, with Wafangdian in Liaoning (RPLW), Zhangzi Island in Liaoning (RPLZ), and Laizhou in Shandong (RPSL) comprise the northern lineage, while Lianjiang in Fujian (RPFL) constitutes the southern lineage. The artificial relocation of clams in China has resulted in a blended population structure among local clams. The genetic functional differences between clams from the north and south are primarily manifest in energy metabolism, and the adaptive evolution of clams is mainly associated with temperature. This integrative research not only furnishes valuable insights into the genetic structure of clam populations, thereby contributing to the advancement of natural conservation and genetic breeding efforts for clams but also establishes the groundwork for a comprehensive exploration of clam adaptive evolution.

Genome resequencing reveals genetic status of Macrobrachium rosenbergii populations in China

The giant freshwater prawn (Macrobrachium rosenbergii) has been widely cultured in China since 1990s. In this study, 189 individuals were sampled from 10 distinct populations, including original populations introduced from abroad and domesticated strains in China, namely Florida (FD), "Nantaihu No.2" (NT), Vietnam (YN), Sri Lanka (SK), Bangladesh (ML), Thailand (TG), Taiwan (TW), "Shufeng No.1" (SF), Zhengda (ZD) and New Myanmar (NMD). The genetic diversity and population structure of these populations were analyzed based on a dataset of 300,828 genome-wide SNP loci. The population structure analysis showed that the 10 populations shared 4 ancestors, and the domestic populations (i.e., SF, ZD, TW and NT) shared a common ancestor. The phylogenetic analysis showed that the 10 populations were grouped into 4 branches, with all the domestic populations clustering together. Estimation of fixation index (Fst) values revealed relatively lower Fst values among the domestic populations, in contrast to the more significant differences observed between domestic and foreign-origin populations. Gene flow analysis revealed three significant events of genetic exchange among the 10 populations: (1) from YN to the common ancestor of FD, TG and the domestic populations, (2) from NMD to the common ancestor of TG and FD, and (3) from the common ancestor of NMD, YN, ML and SK to ZD population. In addition, selective sweep analysis, utilizing Fst and nucleotide diversity (Pi) estimations, was conducted on representative populations (i.e., ML and SF), and 7 positively selected genes were identified, including Prospero Homeobox 1 (Prox1), Forkhead Box L1 (Foxl1), Tousled Like Kinase 2 (TLK2), G Protein Subunit Alpha 14 (Gna14), Uronyl 2-sulfotransferase (Ust), MAX Network Transcriptional Repressor (Mnt) and Importin-9 (Ipo9). These findings contribute to elucidating the breeding potential of the introduced populations and provide insights into the genetic status of the domestic breeding strains of M. rosenbergii in China.

Mitochondrial phylogeography of grassland caterpillars (Lepidoptera: Lymantriinae: Gynaephora) endemic to the Qinghai-Tibetan plateau.

Grassland caterpillars (Lepidoptera: Lymantriinae: Gynaephora) are the most damaging pests to alpine meadows in the Qinghai-Tibetan Plateau (QTP). Here, we conducted extensive sampling from 39 geographic populations covering almost the entire distribution of the eight QTP Gynaephora (Hübner) species to investigate phylogeographic patterns and speciation based on two mitochondrial genes (COI and ND5). A total of 40 haplotypes were detected in the 39 populations, with >70% of all haplotypes not shared between populations. The monophyletic QTP Gynaephora migrated from non-QTP regions during the Pliocene, corresponding to the uplift of the QTP, suggesting a mode of transport into the QTP. Among the eight QTP Gynaephora species described by morphological characteristics, two species (G. alpherakii and G. menyuanensis) were recovered as monophyletic groups (Clades B and C), while the remaining six formed two monophyletic clades: Clade A (G. qinghaiensis, G. jiuzhiensis, and G. qumalaiensis) and Clade D (G. aureata, G. ruoergensis, and G. minora). These results suggested that the number of the QTP Gynaephora species may be overestimated and further studies based on both morphological and nuclear gene data are needed. Genetic differentiation and speciation of the QTP Gynaephora were likely driven by the QTP uplifts and associated climate fluctuations during the Pleistocene, indicated by divergence time estimation, suggesting that isolation and subsequent divergence was the dominant mode of speciation. The Sanjiangyuan region (i.e., Clade A, characterized by high genetic diversity) may have been a glacial refugium of the QTP Gynaephora, as supported by analyses of gene flow and biogeography. High levels of genetic diversity were found in QTP Gynaephora, without population expansion, which may explain the high-altitude adaptation and outbreaks of grassland caterpillars in alpine meadows of the QTP. This study provides the largest phylogeographic analysis of QTP Gynaephora and improves our understanding of the diversity and speciation of QTP insects.

Genetic diversity, population structure, and phylogenetic relationships of a widespread East Asia herb, Cryptotaenia japonica Hassk. (Apiaceae) based on genomic SNP data generated by dd-RAD sequencing.

Single-nucleotide polymorphisms (SNPs) represent the most prevalent form of genomic polymorphism and are extensively used in population genetics research. Using dd-RAD sequencing, a high-throughput sequencing method, we investigated the genome-level diversity, population structure, and phylogenetic relationships among three morphological forms of the widely distributed taxon Cryptotaenia japonica Hassk., which is native to East Asia. Our study aimed to assess the species status of C. japonica according to its genetic structure and genetic diversity patterns among 66 naturally distributed populations, comprising 26C. japonica f. japonica, 36C. japonica f. dissecta (Y. Yabe) Hara and 4C. japonica f. pinnatisecta S. L. Liou accessions. Based on genomic SNP data generated by dd-RAD sequencing, we conducted genetic diversity, principal component, neighbor-joining (NJ) phylogenetic, admixture clustering, and population differentiation analyses. The findings revealed the following: (1) 5,39,946 unlinked, high-quality SNPs, with mean π, H O, H E and F IS values of 0.062, 0.066, 0.043 and -0.014, respectively, were generated; (2) population divergence was unaffected by isolation through distance; (3) six main distinct regions corresponding to geographic locations and exhibiting various levels of genetic diversity were identified; (4) pairwise F ST analysis showed significant (P < 0.05) population differentiation in 0%-14% of populations among the six regions after sequential Bonferroni correction; and (5) three migration events (historical gene flow) indicated east‒west directionality. Moreover, contemporary gene flow analysis using Jost's D, Nei's G ST, and Nm values highlighted the middle latitude area of East Asia as a significant contributor to genetic structuring in C. japonica. Overall, our study elucidates the relatively low genetic differentiation and population structure of C. japonica across East Asia, further enhancing our understanding of plant lineage diversification in the Sino-Japanese Floristic Region.

Climatic fluctuations, geographic features, and evolutionary forces: Shaping high genomic diversity and local adaptation in Muntiacus reevesi

AbstractAimGenetic diversity is crucial for species adaptability. Understanding the mechanisms behind its formation and maintenance is essential for effective conservation. Recent studies have demonstrated that despite experiencing severe population bottlenecks, Muntiacus reevesi retains high genetic diversity and continues its northward migration, indicative of ongoing adaptive evolution. However, our comprehension of this phenomenon remains incomplete. The objective of this study is to explore the mechanisms underlying the formation of high genetic diversity and the genomic characteristics associated with local adaptation, using M. reevesi as a case study.LocationSouthern China.MethodsWe analysed resequencing data from 62 genomes and identified 29,124,081 high‐quality single‐nucleotide polymorphisms (SNPs). We used population genetics, demographic history, population differentiation, gene flow analysis software, and genotype‐environment association (GEA) models to assess the factors that have contributed to high genetic diversity and environmental adaptability in the historical climate and geographical context.ResultsThe study identified that during Pleistocene climatic fluctuations, M. reevesi diverged into eastern (DB and WJW populations) and western lineages (WL, BA, and QL populations), all displayed high genetic diversity. Historically, M. reevesi maintained large effective populations, but contemporary human‐induced threats have led to a significant decline. Population differentiation models suggest distinct expansion pathways for eastern and western lineages, resulting in population admixture, with mountain corridors facilitating gene flow and maintaining high genetic diversity. Additionally, environmental‐genotype analysis revealed local adaptation in the QL‐BA population, highlighting candidate adaptive genes (ME3 and PRKG1) potentially linked to cold adaptation and foraging behaviour.ConclusionThis study enhances our understanding of the mechanisms behind the high genetic diversity and environmental adaptability of M. reevesi, offering insights into how bottleneck populations maintain diversity, crucial for biogeographic research and conservation strategies for similar species.

Genome-wide data reveal bi-direction and asymmetrical hybridization origin of a fern species Microlepia matthewii.

Natural hybridization is common and plays a crucial role in driving biodiversity in nature. Despite its significance, the understanding of hybridization in ferns remains inadequate. Therefore, it is imperative to study fern hybridization to gain a more comprehensive understanding of fern biodiversity. Our study delves into the role of hybridization in shaping fern species, employing Microlepia matthewii as a case study to investigate its origins of hybridization. We performed double digest Genotyping-by-sequencing (dd-GBS) on M. matthewii and its potential parent species, identifying nuclear and chloroplast SNPs. Initially, nuclear SNPs were employed to construct the three cluster analysis: phylogenetic tree, principal component analysis, and population structure analysis. Subsequently, to confirm whether the observed genetic mixture pattern resulted from hybridization, we utilized two methods: ABBA-BABA statistical values in the D-suite program and gene frequency covariance in the Treemix software to detect gene flow. Finally, we employed chloroplast SNPs to construct a phylogenetic tree, tracing the maternal origin. The analysis of the nuclear SNP cluster revealed that M. matthewii possesses a genetic composition that is a combination of M. hancei and M. calvescens. Furthermore, the analysis provided strong evidence of significant gene flow signatures from the parental species to the hybrid, as indicated by the two gene flow analyses. The samples of M. matthewii cluster separately with M. hancei or M. calvescens on the chloroplast systematic tree. However, the parentage ratio significantly differs from 1:1, suggesting that M. matthewii is a bidirectional and asymmetrical hybrid offspring of M. hancei and M. calvescens.

Genome resequencing reveals population divergence and local adaptation of blacklegged ticks in the United States.

Tick vectors and tick-borne disease are increasingly impacting human populations globally. An important challenge is to understand tick movement patterns, as this information can be used to improve management and predictive modelling of tick population dynamics. Evolutionary analysis of genetic divergence, gene flow and local adaptation provides insight on movement patterns at large spatiotemporal scales. We develop low coverage, whole genome resequencing data for 92 blacklegged ticks, Ixodes scapularis, representing range-wide variation across the United States. Through analysis of population genomic data, we find that tick populations are structured geographically, with gradual isolation by distance separating three population clusters in the northern United States, southeastern United States and a unique cluster represented by a sample from Tennessee. Populations in the northern United States underwent population contractions during the last glacial period and diverged from southern populations at least 50 thousand years ago. Genome scans of selection provide strong evidence of local adaptation at genes responding to host defences, blood-feeding and environmental variation. In addition, we explore the potential of low coverage genome sequencing of whole-tick samples for documenting the diversity of microbial pathogens and recover important tick-borne pathogens such as Borrelia burgdorferi. The combination of isolation by distance and local adaptation in blacklegged ticks demonstrates that gene flow, including recent expansion, is limited to geographical scales of a few hundred kilometres.

Genetic diversity and population structure of grapevine Roditis leaf discoloration‐associated virus in Turkey vineyards

AbstractGrapevine Roditis leaf discoloration‐associated virus (GRLDaV) is a type of virus that infects grapevines. This research aimed to determine the prevalence of GRLDaV in Turkey vineyards and investigate the genetic diversity and population structure of the selected viral isolates from Turkey compared to isolates from other countries. In this study, 800 shoot samples from Turkey vineyards were collected in late spring and autumn from different regions. The samples were analysed by RT‐PCR targeting the partial RNaseH‐like gene region of the virus genome. The overall prevalence of GRLDaV was 8.1% among the samples. Phylogenetic analysis of the GRLDaV genome showed that the GRLDaV isolates were clustered into two major lineages. The nucleotide diversity (π) value of Group I, including only Mediterranean isolates, was lower than Group II, suggesting little variation among isolates. Even though π values were low among the geographical regions in Turkey, the region with the highest nucleotide diversity was the Aegean population, followed by the Eastern and Mediterranean populations. Comparison between nonsynonymous and synonymous substitutions showed that negative selection acts on synonymous amino acids. Along with neutrality tests and gene flow analyses, it was emphasized that genetic drift played an important role in shaping the GRLDaV populations. This study provides important information on the prevalence and genetic diversity of GRLDaV in Turkey vineyards. The findings will help to develop better strategies to manage and control this virus, which can cause significant economic losses in grape industries.

Transcriptome sequencing data provides a solid base to understand the phylogenetic relationships, biogeography and reticulated evolution of the genus Zamia L. (Cycadales: Zamiaceae).

Cycad is a key lineage to understand the early evolution of seed plants and their response to past environmental changes. However, tracing the evolutionary trajectory of cycad species is challenging when the robust relationships at inter- or infrageneric level are not well resolved. Here, using 2,901 single-copy nuclear genes, we explored the species relationships and gene flow within the second largest genus of cycads, i.e., Zamia, based on phylotranscriptomic analyses of 90% extant Zamia species. Based on a well-resolved phylogenetic framework, we performed gene flow analyses, molecular dating, and biogeographical reconstruction to examine the spatiotemporal evolution of Zamia. We also performed ancestral state reconstruction (ASR) of a total of 62 traits of the genus to comprehensively investigate its morphological evolution. Zamia is comprised of seven major clades corresponding to seven distinct distribution areas in the Americas, with at least three reticulation nodes revealed in this genus. Extant lineages of Zamia initially diversified around 18.4-32.6 (29.14) million years ago (MA) in the Mega-Mexico, and then expanded eastward into the Caribbean and southward into Central and South America. ASR revealed homoplasy in most of the morphological characters. This study revealed congruent phylogenetic relationships from comparative methods/datasets, with some conflicts being the result of incomplete lineage sorting and ancient/recent hybridization events. The strong association between the clades and the biogeographic areas suggested that ancient dispersal events shaped the modern distribution pattern, and regional climatic factors may have resulted in the following in-situ diversification. Climate cooling starting during the mid Miocene is associated with the global expansion of Zamia to the tropical South America that have dramatically driven lineage diversification in the New World flora, as well as the extinction of cycad species in the nowadays cooler regions of both hemispheres as indicated by the fossil records.

Pleistocene climate oscillations have shaped the expansion and contraction speciation model of the globose Eriosyce sect. Neoporteria cacti in Central Chile.

Pleistocene climatic oscillations, characterized by arid (interglacial) and pluvial (glacial) phases, have profoundly impacted the floras of Mediterranean climates. Our study investigates the hypothesis that these climatic extremes have promoted phases of range expansion and contraction in the Eriosyce sect. Neoporteria, resulting in pronounced genetic structuring and restricted gene flow. Utilizing nuclear microsatellite markers, we genotyped 251 individuals across 18 populations, encompassing all 14 species and one subspecies within the Eriosyce sect. Neoporteria. Additionally, Species Distribution Models (SDMs) were employed to reconstruct past (Last Interglacial, Last Glacial Maximum, Mid-Holocene) and current potential distribution patterns, aiming to delineate the climatic influences on species' range dynamics. The gene flow analysis disclosed disparate levels of genetic interchange among species, with marked restrictions observed between entities that are geographically or ecologically separated. Notably, E. subgibbosa from Hualpen emerged as genetically distinct, warranting its exclusion for clearer genetic clustering into north, central, and south clusters. The SDMs corroborated these findings, showing marked range expansions during warmer periods and contractions during colder times, indicating significant shifts in distribution patterns in response to climatic changes. Our findings emphasize the critical role of Pleistocene climatic fluctuations in driving the dynamic patterns of range expansions and contractions that have led to geographic isolation and speciation within the Eriosyce sect. Neoporteria. Even in the face of ongoing gene flow, these climate-driven processes have played a pivotal role in sculpting the species' genetic architecture and diversity. This study elucidates the complex interplay between climatic variability and evolutionary dynamics among Mediterranean cacti in central Chile, highlighting the necessity of considering historical climatic millenial oscillations in conservation and evolutionary biology studies.

Seasonal migration directs and facilitates gene flow in the Broad-tailed and Lucifer Sheartail Hummingbirds

Gene flow, the movement of genes between populations, profoundly influences genetic and phenotypic homogeneity among populations. This study investigates gene flow patterns in two migratory hummingbird species, Selasphorus platycercus and Calothorax lucifer, shedding light on the intricate interplay between migration, resource availability, and genetic diversity. Using previously published information on microsatellites, we examine the genetic makeup and the movement of genes within populations. Selasphorus platycercus displays distinct genetic groups which can be associated with its migratory behaviour. Gene flow analysis suggests a higher level of connectivity among populations sharing winter ranges. In contrast, Calothorax lucifer populations exhibit genetic divergence despite overlapping winter ranges, possibly due to environmental niche adaptation and limited reproductive opportunities for dispersing individuals. While geographical distance does not explain genetic differentiation in these species, environmental niche similarities appear to facilitate gene flow. This study underscores the significance of migratory routes, resource availability, and niche adaptation in shaping gene flow dynamics in hummingbirds. Understanding these dynamics is crucial for the conservation and management of these unique avian populations.

Analysis of the Genetic Diversity and Mating System of the Endangered Plant Keteleeria davidiana var. calcarea

Keteleeria davidiana var. calcarea is an endangered plant endemic to China. It is mainly distributed in the karst areas of the Guangxi and Guizhou Provinces. It is characterized by small populations and intermittent distribution. This study aimed to explore the genetic diversity and mating system of wild populations of Keteleeria davidiana var. calcarea in fragmented habitats. To achieve this, we genotyped 46 maternal trees and 214 progenies from four fragmented populations of Keteleeria davidiana var. calcarea using nine pairs of microsatellite primers. The genetic diversity of Keteleeria davidiana var. calcarea (Ho = 0.68, He = 0.63) was lower than that of the species overall but higher than that of other Keteleeria plants. The incidence of unbiased expected heterozygosity (uHe) and allelic richness (Ar) was higher in the maternal generation than in the progeny. This suggests that the genetic diversity of the progeny was lower than that of the maternal generation. Keteleeria davidiana var. calcarea is divided into four populations, but there is significant genetic exchange between the populations according to STRUCTURE and gene flow analyses. The multilocus mating system analysis (MLTR) results indicate that the multilocus outcrossing rate (tm) was 0.902, the single-locus outcrossing rate (ts) was 0.606, the bimaternal inbreeding coefficient (tm-ts) was 0.295, and the coefficient of inbreeding depression(δ) was 0.904. These results suggest a certain degree of selfing and inbreeding in Keteleeria davidiana var. calcarea. To prevent problems associated with inbreeding and conserve the genetic diversity of Keteleeria davidiana var. calcarea, we recommend establishing seed gardens, using artificial pollination, and employing asexual propagation techniques for conservation intervention.

Taxonomy of Naumann’s and dusky, red-throated and black-throated thrush complexes (Aves: Turdidae) using morphological and molecular characteristics

Abstract Species are the basic units in evolution and biodiversity and thus a reasonable species classification is essential to assess and protect biodiversity. The classifications of the Naumann’s and dusky thrush complexes and the red-throated and black-throated thrush complexes are not well defined in Turdidae (Aves, Passeriformes). Herein, we use qualitative and quantitative morphological characters and molecular data to review the taxonomy of these thrush complexes. These four thrushes can be distinguished with qualitative features of feather color and striping. These birds cannot be divided by quantitative features, which only work on two groups of thrush complexes. Phylogenetic analysis based on mitochondrial genes indicate that all haplotypes might be divided into two monophyletic clades corresponding to two groups of thrush complexes. According to coalescence-based species delimitation and the gen-morph species concept, these two groups of thrush complexes should be separated as two distinctive species (T. naumanni and T. ruficollis) and including two subspecies per species. This species classification is also supported by gene flow analysis. There is a significant mixing between these two thrush species in the neighbor-joining (NJ) tree and the cluster analysis using a few microsatellite loci. This leads to a pattern of nuclear-mitochondrial discordance between the two birds that can be explained by several potential mechanisms. This study provides the first comprehensive classification of the two thrush complexes on a population level using morphological and molecular characteristics, which will be useful in expanding our understanding of species division among thrush complexes.

Barriers and corridors: Assessment of gene flow and movement among red panda populations in eastern Himalayas

Landscape features can impede dispersal, gene flow, and population demography, resulting in the formation of several meta-populations within a continuous landscape. Understanding a species' ability to overcome these barriers is critical for predicting genetic connectivity and population persistence, and implementing effective conservation strategies. In the present study, we conducted a fine-scale spatial genetic analysis to understand the contemporary gene flow within red panda populations in the Eastern Himalayas. Employing geometric aspects of reserve design, we delineated the critical core habitats for red pandas, which comprise 14.5 % of the landscape (12,189.75 Km2), with only a mere 443 Km2 falling within the protected areas. We identified corridors among the core habitats, which may be vital for the species' long-term genetic viability. Furthermore, we identified substantial landscape barriers, including Sela Pass in the western region, Siang river in the central region, and the Dibang river, Lohit river, along with Dihang, Dipher, and Kumjawng passes in the eastern region, which hinder gene flow. We suggest managing red panda populations through the creation of Community Conservation Reserves in the identified core habitats, following landscape-level management planning based on the core principles of geometric reserve design. This includes a specific emphasis on identified core habitats of red panda (CH-RP 5 and CH-RP 8) to facilitate corridors and implement meta-population dynamics. We propose the development of a comprehensive, long-term conservation and management plan for red pandas in the transboundary landscape, covering China, Nepal, and Bhutan.

Transcriptome data analysis provides insights into the conservation of Michelia lacei, a plant species with extremely small populations distributed in Yunnan province, China.

Michelia lacei W.W.Smith (Magnoliaceae), was classified as a Plant Species with Extremely Small Populations (PSESP) by the Yunnan Provincial Government in both action plans of 2012 and 2021. This evergreen tree is known for its high ornamental and scientific value, but it faces significant threats due to its extremely small population size and narrow geographical distribution. The study aims to understand the genetic structure, diversity, and demographic history of this species to inform its conservation strategies. The analysis of transcriptome data from 64 individuals across seven populations of M. lacei identified three distinct genetic clusters and generated 104,616 single-nucleotide polymorphisms (SNPs). The KM ex-situ population, originating from Longling County, exhibited unique genetic features, suggesting limited gene flow. The genetic diversity was substantial, with significant differences between populations, particularly between the KM lineage and the OTHER lineage. Demographic history inferred from the data indicated population experienced three significant population declines during glaciations, followed by periods of recovery. We estimated the effective population size (Ne) of the KM and OTHER lineages 1,000 years ago were 85,851 and 416,622, respectively. Gene flow analysis suggested past gene flow between populations, but the KM ex-situ population showed no recent gene flow. A total of 805 outlier SNPs, associated with four environmental factors, suggest potential local adaptation and showcase the species' adaptive potential. Particularly, the BZ displayed 515 adaptive loci, highlighting its strong potential for adaptation within this group. The comprehensive genomic analysis of M. lacei provides valuable insights into its genetic background and highlights the urgent need for conservation efforts. The study underscores the importance of ex-situ conservation methods, such as seed collection and vegetative propagation, to safeguard genetic diversity and promote population restoration. The preservation of populations like MC and BZ is crucial for maintaining the species' genetic diversity. In-situ conservation measures, including the establishment of in-situ conservation sites and community engagement, are essential to enhance protection awareness and ensure the long-term survival of this threatened plant species.

Population structure and microscale morphological differentiation in a freshwater snail from the Chilean Altiplano

BackgroundThe diversity and population genetic structure of many species have been shaped by historical and contemporary climatic changes. For the species of the South American Altiplano, the historical climatic changes are mainly related to the wet events of great magnitude and regional influence that occurred during the Pleistocene climatic oscillations (PCOs). In contrast, contemporary climate changes are associated with events of lesser magnitude and local influence related to intensifications of the South American Summer Monsoon (SASM). Although multiple studies have analyzed the effect of PCOs on the genetic patterns of highland aquatic species, little is known about the impact of contemporary climate changes in recent evolutionary history. Therefore, in this study, we investigated the change in population structure and connectivity using nuclear and mitochondrial markers throughout the distribution range of Heleobia ascotanensis, a freshwater Cochliopidae endemic to the Ascotán Saltpan. In addition, using geometric morphometric analyses, we evaluated the concomitance of genetic divergence and morphological differentiation.ResultsThe mitochondrial sequence analysis results revealed the presence of highly divergent co-distributed and geographically nested haplotypes. This pattern reflects an extension in the distribution of groups that previously would have differentiated allopatrically. These changes in distribution would have covered the entire saltpan and would be associated with the large-scale wet events of the PCOs. On the other hand, the microsatellite results defined five spatially isolated populations, separated primarily by geographic barriers. Contemporary gene flow analyses suggest that post-PCO, climatic events that would have connected all populations did not occur. The morphometric analyses results indicate that there is significant morphological differentiation in the populations that are more isolated and that present the greatest genetic divergence.ConclusionsThe contemporary population structure and morphological variation of H. ascotanensis mainly reflect the post-PCO climatic influence. Although both markers exhibit high genetic structuring, the microsatellite and morphology results show the preponderant influence of fragmentation in recent evolutionary history. The contemporary genetic pattern shows that in species that have limited dispersal capabilities, genetic discontinuities can appear rapidly, erasing signs of historical connectivity.

Temporal analysis of genetic diversity and gene flow in the threatened catfish Pseudoplatystoma magdaleniatum from a dammed neotropical river.

The striped catfish Pseudoplatystoma magdaleniatum is a large-sized migratory species from the north Andes region, endemic to Magdalena basin and one of the major fishery resources. Despite the estimated reduction of over 80% of the fisheries production of this species throughout the basin in recent decades, its population in the lower Magdalena-Cauca basin showed healthy genetics after molecular analyses. However, the current conservation status of this species and several habitat disturbances demand the re-evaluation of its population genetics to infer evolutionary risks and assess potential changes. This work analyzed a total of 164 samples from the Cauca River collected downstream the Ituango Dam between 2019-2021 using species-specific microsatellite markers to compare the genetic diversity and structure in samples collected between 2010-2014 from the lower Magdalena-Cauca basin, previously analyzed. Our results showed a relatively stable panmictic population over time (4 to 10 years), with high genetic diversity and evidence of recent bottleneck. Promoting habitat connectivity to conserve gene flow, characterizing diversity and genetic structure over the entire basin, and integrating the results with future monitoring are important aspects for the management planning for P. magdaleniatum in the Magdalena-Cauca basin.

Molecular tracking of Acidovorax citrulli: Unveiling pathogen dynamics and blotch disease outbreaks through specific markers

Acidovorax citrulli (Ac), a gram-negative bacterium, is the causal agent of bacterial fruit blotch (BFB), which poses a significant threat to cucurbit crop production worldwide. Understanding the genetic diversity of Ac is crucial for identifying sources of resistance and implementing effective disease management strategies. In this study, we conducted the first genetic characterization of Ac strains collected in Turkey using Inter-Simple Sequence Repeat (ISSR) markers. These markers were selected based on repetitive domains mapped on the complete reference genome sequence of Acidovorax citrulli strain NWB SC196. The identity of the Turkish strains was confirmed through molecular (PCR) and serological (Immunofluorescence test and ELISA) methods, while the selected ISSRs, which exhibited similarity to flanked regions in the pathogen's whole genome sequence, were employed to assess the genetic diversity among Ac strains. We compared the profiles of Turkish strains with those of a collection of Ac strains from various countries, including the US, to explore a possible common origin. Specifically, we considered the dissemination of these strains through rootstocks used for grafted seedling production (Cucurbita maxima ? Cucurbita moschata). The results demonstrated a shared genetic profile, suggesting a potential link between Ac strains collected in Turkey and foreign strains. The Mauve analysis, utilizing whole genome sequences of various Ac strains available in the NCBI database, displayed similar clustering patterns to those obtained using our selected molecular markers, confirming the discriminatory efficiency of our method. Based on the high discriminatory power of the selected markers, our proposed method offers a rapid and straightforward approach for genetic analysis of intraspecific variation and monitoring Ac gene flow across countries. The characterized strains and markers presented in this study serve as valuable resources and reference materials for further genetic investigations and tracking contamination sources associated with Ac.

Complete Chloroplast Genome Sequence of Dahlia imperialis (Asteraceae): Comparative Analysis and Phylogenetic Relationships

The genus Dahlia has approximately 40 species; however, the complete chloroplast genome has been reported only for one species. Due to this lack of information on the chloroplast genomes, the phylogenetic relationships within the Dahlia genus remain unclear. Therefore, the present study sequenced the complete chloroplast genome of D. imperialis for the first time. This genome was 152,084 bp long with a typical quadripartite structure and a GC content of 38.45%. A total of 134 genes were annotated in the genome, including 86 protein-coding genes, 38 transfer RNA genes, 8 ribosomal RNA genes, and 2 pseudogenes. The detailed analysis identified UUA as the most frequently used codon and found 62 intergenic repeat sequences and 157 SSR loci in the D. imperialis genome. Phylogenetic analysis based on 49 chloroplast genomes showed that Dahlia was a monophyletic group, with D. imperialis positioned at the base of this clade. Network evolution and gene flow analysis unveiled extensive hybridization events within the Heliantheae alliance, especially in Dahlia. Thus, the comprehensive analysis of the complete chloroplast genome of D. imperialis enriches the information on the genetic resources of the Dahlia species, provides valuable information for reconstructing their phylogeny, and reveals the evolutionary dynamics of the Dahlia chloroplast genome.