Population Genomics Research Articles

Population genomics and transcriptomics of Plasmodium falciparum in Cambodia and Vietnam uncover key components of the artemisinin resistance genetic background

The emergence of Plasmodium falciparum parasites resistant to artemisinins compromises the efficacy of Artemisinin Combination Therapies (ACTs), the global first-line malaria treatment. Artemisinin resistance is a complex genetic trait in which nonsynonymous SNPs in PfK13 cooperate with other genetic variations. Here, we present population genomic/transcriptomic analyses of P. falciparum collected from patients with uncomplicated malaria in Cambodia and Vietnam between 2018 and 2020. Besides the PfK13 SNPs, several polymorphisms, including nonsynonymous SNPs (N1131I and N821K) in PfRad5 and an intronic SNP in PfWD11 (WD40 repeat-containing protein on chromosome 11), appear to be associated with artemisinin resistance, possibly as new markers. There is also a defined set of genes whose steady-state levels of mRNA and/or splice variants or antisense transcripts correlate with artemisinin resistance at the base level. In vivo transcriptional responses to artemisinins indicate the resistant parasite’s capacity to decelerate its intraerythrocytic developmental cycle (IDC), which can contribute to the resistant phenotype. During this response, PfRAD5 and PfWD11 upregulate their respective alternatively/aberrantly spliced isoforms, suggesting their contribution to the protective response to artemisinins. PfRAD5 and PfWD11 appear under selective pressure in the Greater Mekong Sub-region over the last decade, suggesting their role in the genetic background of the artemisinin resistance.

Population genomics of eastern oysters, Crassostrea virginica, in a well-mixed estuarine system: advancement and implications for restoration strategies

Eastern oysters, Crassostrea virginica, are historically a keystone species in many of the estuaries in which they reside, providing critical ecosystem services. Because oyster populations have been on the decline for the past century, restoration initiatives currently are underway in many estuarine systems, including Great Bay Estuary (GBE), New Hampshire. Results of prior studies of eastern oyster population genomics cannot be applied directly to GBE, as it is a well-mixed estuarine system that is relatively contained, and the sources of recruits are split among cultivated and native. This study aimed to identify the population genomic structure of eastern oysters in GBE to facilitate determination of effective population size and estimation of genetic differentiation among subpopulations. Results showed moderate genomic differentiation among native, cultivated, and restoration C. virginica subpopulations in the Bay. A small number of breeders (Ne=163–276) was found in all subpopulations except the Lamprey River site (Ne=995). This research provides a contemporary snapshot of eastern oyster subpopulation structure at the genomic level in GBE that will facilitate restoration and enhanced management.

Integrating genetic and morphological data to assess species delimitation of two Japanese large abalones: Haliotis discus discus and H. madaka

Abstract Two large abalone species prevalent in the Japanese archipelago, Haliotis discus discus and H. madaka, are considered to have different morphological characteristics, and previous population genomics analyses have suggested that they have distinct genomic features. However, integrated analyses comparing the genetic and morphological data from these species are lacking; thus, it remains unclear whether these two species are distinct biological species. In this study, we performed integrated genetic and morphological analyses on individuals of the two species captured in Tokushima Prefecture, Japan. Genetic analysis based on 118 species-diagnostic single-nucleotide polymorphism (SNP) loci showed that H. discus discus and H. madaka were clearly assigned to distinct genetic clusters corresponding to the two species, with the exception of one H. madaka individual showing evidence of genomic introgression from H. discus discus. Multiple statistical analyses based on quantitative characteristics of shell shape and foot muscle color suggested that this H. madaka individual with genomic introgression from H. discus discus had H. discus discus-like quantitative characteristics consistently. In summary, this study suggests that H. discus discus and H. madaka are distinct biological species reproductively isolated in natural environments, but genomic introgression possibly blurs the species boundary between H. discus discus and H. madaka.

Endangered Pinto/Northern Abalone (Haliotis kamtschatkana) are Panmictic Across Their 3700 km Range Along the Pacific Coast of North America.

Connectivity is integral to the dynamics of metapopulations through dispersal and gene flow, and understanding these processes is essential for guiding conservation efforts. Abalone, broadcast-spawning marine snails associated with shallow rocky habitats, have experienced widespread declines, and all seven North American species are threatened. We investigated the connectivity and population genomics of pinto/northern abalone (Haliotis kamtschatkana), the widest-ranging of abalone species. We employed reduced representation sequencing (RADseq) to generate single nucleotide polymorphism (SNP) data, assessing population connectivity and potential adaptive variation at 12 locations across the full range from Alaska to Mexico. Despite depleted populations, our analysis of over 6000 SNPs across nearly 300 individuals revealed that pinto abalone maintains a high genetic diversity with no evidence of a genetic bottleneck. Neutral population structure and isolation by distance were extremely weak, indicating panmixia across the species' range (global F ST = 0.0021). Phylogenetic analysis, principal components analysis, and unsupervised clustering methods all supported a single genetic population. However, slight population differentiation was noted in the Salish Sea and Inside Passage regions, with evidence for higher barriers to dispersal relative to outer coastal areas. This north-central region may also represent the species' ancestral range based on relatively low population-specific F ST values; the northern and southern extremes of the range likely represent range expansions. Outlier analysis did not identify consensus loci implicated in adaptive variation, suggesting limited adaptive differentiation. Our study sheds light on the evolutionary history and contemporary gene flow of this threatened species, providing key insights for conservation strategies, particularly in sourcing broodstock for ongoing restoration efforts.

Sustained Fishing Threatens Globally Protected Species: Insights from Digital Catch and Genomic Data

Small-scale fisheries capture a wide marine biodiversity including highly vulnerable and endangered species. Despite global conservation efforts, at regional scale, strategies to conserve threatened species are often constrained by poor biological information and a paucity of fisheries data to understand the level of threat posed to their populations. In Myanmar, devil and manta rays (mobulids) are caught for meat consumption and export of gill plates. The impact of this exploitation is not fully understood as mobulid rays, especially in this region, have been poorly studied, catch levels are under-reported and the fishery is unregulated. An accurate knowledge of the species composition and catch levels is an important first step to inform potential management and protection strategies for these species. This study is the first to combine digital catch recording alongside genomic tools to analyze mobulid rays caught in the Tanintharyi Region of south Myanmar. Our catch data analyses indicate a sustained catch and decrease in total landings of mobulids from 2016 to 2018 in Tanintharyi. We identified five species of mobulid rays, including the first record of M. tarapacana for Myanmar. Our analyses of population genomics provided evidence of structured populations of M. thurstoni and partial admixture in M. mobular. Our findings are highly valuable 1) contributing to fill the knowledge gap for these threaten species in the region, and 2) as the first documentation of sustained fishing pressure these rays are exposed to, and the species under potential fishing threat in the Tanintharyi Region, a high priority biodiversity hotspot.

Beyond Asexual: Genomics-Driven Progress in Unveiling Sexual Reproduction in Cereal Rust Fungi.

Recent advances in genomics technologies have revolutionized our understanding of cereal rust fungi, providing unprecedented insights into the complexities of their sexual life cycle. Genomic approaches, including long-read sequencing, genome assembly, and haplotype phasing technologies, have revealed critical insights into mating systems, genetic diversity, virulence evolution, and host adaptation. Population genomics studies have uncovered diverse reproductive strategies across different cereal rust species and geographic regions, highlighting the interplay between sexual recombination and asexual reproduction. Transcriptomics have begun to unravel the gene expression networks driving sexual reproduction, while complementary omics approaches such as proteomics, and metabolomics offer potential insights into the underlying molecular processes. Despite this progress, many aspects of rust sexual reproduction remain elusive. Integrating multiple omics approaches with advanced cell biology techniques can help address these knowledge gaps, particularly in understanding sexual reproduction and its role in pathogen evolution. This comprehensive approach will be crucial for developing more targeted and resilient crop protection strategies, ultimately contributing to global food security.

Haplotype-Based Approach Represents Locus Specificity in the Genomic Diversification Process in Humans (Homo sapiens)

Background/Objectives: Recent progress in evolutionary genomics on human (Homo sapiens) populations has revealed complex demographic events and genomic changes. These include population expansion with complicated migration, substantial population structure, and ancient introgression from other hominins, as well as human characteristics selections. Nevertheless, the genomic regions in which such evolutionary events took place have remained unclear. Methods: Here, we focused on eight loci containing the haplotypes that were previously presented as atypical for the mutation pattern in sequence and/or geographic distribution pattern with the model of recent African origin, which constitute two major clusters: African only, and global. This was the consensus model before information regarding introgression from Neanderthal (Homo neanderthalensis) was available. We compared diversity in identical datasets of the modern human population genome, with the 1000 Genomes project among them. Results/Conclusions: This study identified representative genomic regions that show traces of various demographic events and genomic changes that modern humans have undergone by categorizing the relationships in sequence similarity and in worldwide geographic distribution among haplotypes.

Population genomics of a thermophilic cyanobacterium revealed divergence at subspecies level and possible adaptation genes

BackgroundCyanobacteria are diverse phototrophic microbes with ecological importance and potential for biotechnology applications. One species of thermophilic cyanobacteria, Thermosynechococcus taiwanensis, has been studied for biomass pyrolysis, estrogen degradation, and the production of bioethanol, monosaccharide, and phycocyanin. To better understand the diversity and evolution of this species, we sampled across different regions in Taiwan for strain isolation and genomic analysis.ResultsA total of 27 novel strains were isolated from nine of the 12 hot springs sampled and subjected to whole genome sequencing. Including strains studied previously, our genomic analyses encompassed 32 strains from 11 hot springs. Genome sizes among these strains ranged from 2.64 to 2.70 Mb, with an average of 2.66 Mb. Annotation revealed between 2465 and 2576 protein-coding genes per genome, averaging 2537 genes. Core-genome phylogeny, gene flow estimates, and overall gene content divergence consistently supported the within-species divergence into two major populations. While isolation by distance partially explained the within-population divergence, the factors driving divergence between populations remain unclear. Nevertheless, this species likely has a closed pan-genome comprising approximately 3030 genes, with our sampling providing sufficient coverage of its genomic diversity. To investigate the divergence and potential adaptations, we identified genomic regions with significantly lower nucleotide diversity, indicating loci that may have undergone selective sweeps within each population. We identified 149 and 289 genes within these regions in populations A and B, respectively. Only 16 genes were common to both populations, suggesting that selective sweeps primarily targeted different genes in the two populations. Key genes related to functions such as photosynthesis, motility, and ion transport were highlighted.ConclusionsThis work provides a population genomics perspective on a hot spring cyanobacterial species in Taiwan. Beyond advancing our understanding of microbial genomics and evolution, the strains collected and genome sequences generated in this work provide valuable materials for future development and utilization of biological resources.

Genetic advancements and future directions in ruminant livestock breeding: from reference genomes to multiomics innovations.

Ruminant livestock provide a rich source of products, such as meat, milk, and wool, and play a critical role in global food security and nutrition. Over the past few decades, genomic studies of ruminant livestock have provided valuable insights into their domestication and the genetic basis of economically important traits, facilitating the breeding of elite varieties. In this review, we summarize the main advancements for domestic ruminants in reference genome assemblies, population genomics, and the identification of functional genes or variants for phenotypic traits. These traits include meat and carcass quality, reproduction, milk production, feed efficiency, wool and cashmere yield, horn development, tail type, coat color, environmental adaptation, and disease resistance. Functional genomic research is entering a new era with the advancements of graphical pangenomics and telomere-to-telomere (T2T) gap-free genome assembly. These advancements promise to improve our understanding of domestication and the molecular mechanisms underlying economically important traits in ruminant livestock. Finally, we provide new perspectives and future directions for genomic research on ruminant genomes. We suggest how ever-increasing multiomics datasets will facilitate future studies and molecular breeding in livestock, including the potential to uncover novel genetic mechanisms underlying phenotypic traits, to enable more accurate genomic prediction models, and to accelerate genetic improvement programs.

Genomic and bioacoustic variation in a midwife toad hybrid zone: A role for reinforcement?

Hybrid zones, i.e., geographic areas where diverging lineages meet, hybridize and eventually mix their genomes, offer opportunities to understand the mechanisms behind reproductive isolation and speciation. Hybrid zones are particularly well suited to study reinforcement, i.e., the process by which selection against hybridization increases reproductive barriers, which, in anuran amphibians, is typically expressed by increased divergence in advertisement calls-the main cue to assortative mating-in parapatric ranges. Using mitochondrial barcoding (16S sequences), population genomics (thousands of SNPs) and bioacoustic analyses (four call parameters), we examine the hybrid zone between two incipient species of midwife toads (Alytes obstetricans and A. almogavarii) in southern France, with the purposes of locating their transition, measuring genetic introgression, and documenting potential signatures of reinforcement. We map range boundaries in the Eastern Pyrenees and the southwestern foothills of the Massif Central, namely along the Ariège valley and the Montagne Noire area. Similarly to another transition between these species in Spain, we found the hybrid zone to be narrow, involving geographically restricted gene flow (~20 km wide allele frequency clines) and barrier loci (i.e., loci resisting introgression), both suggestive of partial post-zygotic isolation (hybrid incompatibilities). The calls of the species overlap less inside than outside the hybrid zone, due to a reduction of their standing variation rather than a shift towards distinctive variants. While neutral causes cannot be excluded, this pattern follows the general expectations of reinforcement, yet without reproductive character displacement. Our study highlights the potential of amphibian hybrid zones to assess the genetic and behavioral drivers of reproductive isolation in statu nascendi and under various evolutionary contexts.

Overview of the Saccharomyces cerevisiae population structure through the lens of 3,034 genomes.

With the rise of high-throughput sequencing technologies, a holistic view of genetic variation within populations-through population genomics studies-appears feasible, although it remains an ongoing effort. Genetic variation arises from a diverse range of evolutionary forces, with mutation and recombination being key drivers in shaping genomes. Studying genetic variation within a population represents a crucial first step in understanding the relationship between genotype and phenotype and the evolutionary history of species. In this context, the budding yeast Saccharomyces cerevisiae has been at the forefront of population genomic studies. In addition, it has a complex history that involves adaptation to a wide range of wild and human-related ecological niches. Although to date more than 3,000 diverse isolates have been sequenced, there is currently a lack of a resource bringing together sequencing data and associated metadata for all sequenced isolates. To perform a comprehensive analysis of the population structure of S. cerevisiae, we collected genome sequencing data from 3,034 natural isolates and processed the data uniformly. We determined ploidy levels, identified single nucleotide polymorphisms (SNPs), small insertion-deletions (InDels), copy number variations (CNVs), and aneuploidies across the population, creating a publicly accessible resource for the yeast research community. Interestingly, we showed that this population captures ∼93% of the species diversity. Using neighbor-joining and Bayesian methods, we redefined the populations, revealing clustering patterns primarily based on ecological origin. This work represents a valuable resource for the community and efforts have been made to make it evolvable and integrable to future yeast population studies.

The Genomic Signature and Transcriptional Response of Metal Tolerance in Brown Trout Inhabiting Metal-Polluted Rivers.

Industrial pollution is a major driver of ecosystem degradation, but it can also act as a driver of contemporary evolution. As a result of intense mining activity during the Industrial Revolution, several rivers across the southwest of England are polluted with high concentrations of metals. Despite the documented negative impacts of ongoing metal pollution, brown trout (Salmo trutta L.) survive and thrive in many of these metal-impacted rivers. We used population genomics, transcriptomics, and metal burdens to investigate the genomic and transcriptomic signatures of potential metal tolerance. RADseq analysis of six populations (originating from three metal-impacted and three control rivers) revealed strong genetic substructuring between impacted and control populations. We identified selection signatures at 122 loci, including genes related to metal homeostasis and oxidative stress. Trout sampled from metal-impacted rivers exhibited significantly higher tissue concentrations of cadmium, copper, nickel and zinc, which remained elevated after 11 days in metal-free water. After depuration, we used RNAseq to quantify gene expression differences between metal-impacted and control trout, identifying 2042 differentially expressed genes (DEGs) in the gill, and 311 DEGs in the liver. Transcriptomic signatures in the gill were enriched for genes involved in ion transport processes, metal homeostasis, oxidative stress, hypoxia, and response to xenobiotics. Our findings reveal shared genomic and transcriptomic pathways involved in detoxification, oxidative stress responses and ion regulation. Overall, our results demonstrate the diverse effects of metal pollution in shaping both neutral and adaptive genetic variation, whilst also highlighting the potential role of constitutive gene expression in promoting metal tolerance.

Transposable element accumulation drives genome size increase in Hylesia metabus (Lepidoptera: Saturniidae), an urticating moth species from South America

Abstract We present the first nuclear genome assembly and a complete mitogenome for Hylesia metabus (Arthropoda; Insecta; Lepidoptera; Saturniidae). The assembled nuclear genome sequence is 1,271 Mb long, which is among the 10 largest lepidopteran genome assemblies published to date. It is scaffolded in 31 pseudo chromosomes, has a BUSCO score of 99.5%, and has a highly conserved synteny compared to phylogenetically close species. Repetitive elements make up 67% of the nuclear genome and are mainly located in intergenic regions, among which LINEs were predominant, with CR1-Zenon being the most abundant. Phylogenetic and comparative analyses of H. metabus assembly and 17 additional Saturniidae and Sphingidae assemblies suggested that an accumulation of repetitive elements likely led to the increased size of H. metabus’ genome. Gene annotation using Helixer identified 26,122 transcripts. The Z scaffold was identified using both a synteny analysis and variations of coverage for two resequenced male and female H. metabus. The H. metabus nuclear genome and mitogenome assemblies can be found and browsed on the BIPAA website and constitute useful resources for future population and comparative genomics studies.

Haplotype-resolved genome and population genomics of the threatened garden dormouse in Europe.

Genomic resources are important for evaluating genetic diversity and supporting conservation efforts. The garden dormouse (Eliomys quercinus) is a small rodent that has experienced one of the most severe modern population declines in Europe. We present a high-quality haplotype-resolved reference genome for the garden dormouse, and combine comprehensive short and long-read transcriptomics data sets with homology-based methods to generate a highly complete gene annotation. Demographic history analysis of the genome reveal a sharp population decline since the last interglacial, indicating an association between colder climates and population declines before anthropogenic influence. Using our genome and genetic data from 100 individuals, largely sampled in a citizen-science project across the contemporary range, we conduct the first population genomic analysis for this species. We find clear evidence for population structure across the species' core Central European range. Notably, our data show that the Alpine population, characterized by strong differentiation and reduced genetic diversity, is reproductively isolated from other regions and likely represents a differentiated evolutionary significant unit (ESU). The predominantly declining Eastern European populations also show signs of recent isolation, a pattern consistent with a range expansion from Western to Eastern Europe during the Holocene, leaving relict populations now facing local extinction. Overall, our findings suggest that garden dormouse conservation may be enhanced in Europe through the designation of ESUs.

The evolution of dbSNP: 25 years of impact in genomic research.

The Single Nucleotide Polymorphism Database (dbSNP), established in 1998 by the National Center for Biotechnology Information (NCBI), has been a critical resource in genomics for cataloging small genetic variations. Originally focused on single nucleotide polymorphisms (SNPs), dbSNP has since expanded to include a variety of genetic variants, playing a key role in genome-wide association studies (GWAS), population genetics, pharmacogenomics, and cancer research. Over 25 years, dbSNP has grown to include more than 4.4 billion submitted SNPs and 1.1 billion unique reference SNPs, providing essential data for identifying disease-related genetic variants and studying human diversity. Integrating large-scale projects like 1000 Genomes, gnomAD, TOPMed, and ALFA has expanded dbSNP's catalog of human genetic variation, increasing its usefulness for research and clinical applications. Keeping up with advancements such as next-generation sequencing and cloud-based infrastructure, dbSNP remains a cornerstone of genetic research supporting continued discoveries in precision medicine and population genomics. DATABASE URL: https://www.ncbi.nlm.nih.gov/snp.

Thematic Layers of Genomic Susceptibility for Conservation Monitoring.

Population genomics has great potential to inform applied conservation management and associated policy. However, the bioinformatic analyses and interpretation of population genomic datasets can be daunting and difficult to convey to nonspecialists, including on-the-ground conservationists that work with many state, federal and international agencies. We think that individual population genomic metrics of interest can be interpolated and ultimately distilled into thematic GIS layers that represent spatiotemporal genomic potential (or conversely, susceptibility) in conservation monitoring. As examples relevant to ongoing conservation efforts, we use introgressive hybridisation and individual heterozygosity to illustrate a conceptual approach for mapping population genomic susceptibility. The general framework of thematic layers could be extended to integrate key genomic metrics (e.g., runs of homozygosity and genomic load) that are relevant to many conservation efforts.

Genetic diversity insights from population genomics and machine learning tools for Nordic Arctic charr (Salvelinus alpinus) populations

Arctic charr (Salvelinus alpinus) is a salmonid species of high ecological and commercial value in the Holarctic region. Nevertheless, more information is needed about its underlying genetic diversity and population structure in the Nordics, especially regarding farmed populations. High-throughput sequencing was applied in three Arctic charr populations of anadromous or landlocked origin from Finland, Norway and Sweden. More specifically, the animals from the Swedish and Norwegian populations originated from a major egg supplier and producer, respectively. Furthermore, in the case of the Finnish population, the sampled animals originated from the only active conservation program for Arctic charr in the country with a potential interest in farming. Using double-digest restriction site-associated DNA sequencing (ddRAD-seq) on more than 500 fish, over 2000 single nucleotide polymorphisms (SNPs), both in the form of individual SNPs and as read haplotypes, were used to study the genetic diversity and structure of those populations. Genetic diversity metrics were similar between the Norwegian and the Swedish populations. However, substantially lower (40–50 %) genetic diversity was found in the Finnish population. Moreover, considerable genetic differentiation was implied between the studied populations as the mean fixation index (FST) was above 0.1 in all pairwise comparisons. All populations were easily discernible through either principal component analysis (PCA) or discriminant analysis of principal components (DAPC). In addition, unsupervised machine learning models such as K-means, Gaussian and Bayesian Gaussian mixtures were assessed for their ability to detect genetic clusters. A preceding dimensionality reduction step by PCA resulted in all three models, suggesting that the most probable number of clusters was three. Overall, our study affirmed the utility of the developed ddRAD-seq genotyping method and unveiled the genetic structure of the studied populations, both of which could contribute to their more efficient management by captive breeding.

Population genomics informs the management of harvested snappers across north-western Australia

Failure to consider population structure when managing harvested fishes increases the risk of stock depletion, yet empirical estimates of population structure are often lacking for important fishery species. In this study, we characterise genetic variation in single nucleotide polymorphisms (SNPs) to assess population structure for three harvested species of tropical snappers across the broad (up to 300 km wide) and extensive (~ 4000 km) continental shelf of north-western Australia. Comparisons across ~ 300 individuals per species, showed remarkably similar patterns of genetic structure among Lutjanus sebae (red emperor), L. malabaricus (saddletail snapper) and Pristipomoides multidens (goldband snapper) despite subtle differences in biological and ecological traits. Low levels of genetic subdivision were reflected in an isolation by distance relationship where genetic connectivity increased with geographic proximity. This indicates extensive but not unlimited dispersal across the north-western Australian shelf. Our findings provide evidence of connectivity between current management areas, violating the assumption of multiple independent stocks. Spatial stock assessment models may be more suitable for the management of these species however demographic connectivity rates cannot be accurately estimated from the conventional population genetic approaches applied in this study. We recommend that managers aim to maintain adequate spawning biomass across current management areas, and assess stocks at finer scales, where practical.

Urbanization affects population connectivity, reproductive success and phenotypic traits in the Mediterranean cliff species Brassica incana (Brassicaceae)

Biotic and abiotic changes induced by urbanization can highly affect the ecology and evolution of plant species. Indeed, urban development can have a major impact on plant population genomics, reproductive success and phenotypic traits hence influencing the adaptive strategies and the ecological functions of plant species within ecosystems. Through a holistic study of the impact of urbanization on the genetic and ecological dynamics of a Mediterranean plant species, we shed light on the mechanisms driving plant responses to urban environments. By focusing on 15 populations of the Mediterranean cliff species Brassica incana distributed along an urbanization gradient, we first analyzed the potential drivers of among-population genomic differentiation using a landscape genomics approach. Then, we provided a comprehensive understanding of the complex interplay among ecological factors (climate, herbivore damage, pollinator community), reproductive (relative fruit set and seed-ovule ratio) and phenotypic (glucosinolate content, flower number) traits involved in the response of B. incana populations to urban pressures using complementary Structural Equation Modeling (SEM) and correlative approaches. Our results show that urbanization reduces among-population connectivity by influencing the genomic differentiation among populations. Also, according to SEM analysis, urbanization showed direct and indirect (mediated by mean annual temperature) effects on both pollinator community and herbivory levels, and direct and indirect (mediated by honeybees and long-tongued bees) effects on plant reproductive success. Additionally, urban populations showed higher contents of a glucosinolate compound (glucobrassicin). Taken together, our findings suggest that urbanization can shape genomic differentiation, reproductive success and phenotypic variation. We showed that the impact of urbanization is rather complex and is likely mediated by the interplay between direct and indirect effects of abiotic and biotic conditions on B. incana. Overall, we documented how urban development can shape eco-evolutionary dynamics of a cliff species located in a densely inhabited Mediterranean area.

Comparative population genomics analysis for chicken body sizes using genome-wide SNPs.

This study aims to investigate the selection history, genome regions, and candidate genes associated with different chicken body sizes, thereby providing insights into the genetic basis of complex economic traits such as chicken body size and growth. In this study, a total of 217 individuals from eight breeds were selected. According to body size, they were divided into two groups: large chickens and bantam chickens, with four breeds in each group. Firstly, we investigate population structure by principal component analysis (PCA), phylogenetic tree, and ancestry component analysis. Next, we recognize runs of homozygosity (ROH) islands through calculating ROH. Finally, we carry out selection signatures analysis utilizing population differentiation index and nucleic acid diversity. The population structure analysis show that large and bantam chickens are clearly separated. Large chickens are clustered together, the bantam chickens are relatively dispersed. The results of ROH island analysis show that 48 and 56 ROH islands were identified in large and bantam chickens respectively. Among the interesting ROH islands, a total of eight candidate genes were identified. In selection signatures analysis, a total of 322 selected genes were annotated in large chickens, such as POU1F1, BMP10, enrichment in 16 GO terms. In bantam chickens, a total of 447 selected genes were annotated, such as IGF1, GRB10, enrichment in 20 GO terms and 2 KEGG pathways. The haplotype analysis results show that GRB10 has differences in chickens of different body sizes. By population structure, ROH islands, and selection signatures analysis, we have identified multiple genes associated with chicken body size, growth, and development (such as BMP10, IGF1, GRB10, etc). This provides a theoretical reference for the subsequent development of molecular markers for chicken body size and the analysis of the genetic mechanism of chicken body size.