Application effectiveness of "Youxin-1" in genetic diversity and structure analysis of local chickens.

China's local chicken breeds are rich in resources, and have formed different germplasm characteristics in the process of long-term selection and evolution. Scientific assessment of population genetic diversity and identification of inter-breed genetic structure are of great value to the protection and innovative utilization of local chicken breed resource. In order to evaluate the application effectiveness of 23K SNP chip "Youxin-1" in the analysis of genetic diversity and genetic structure of local chickens, we used RADseq to identify genomic genetic variation of 21 local chicken breeds and developed 23K chip "Youxin-1". The genetic statistics of each variety were calculated based on two sets of SNP data, and correlation, fitting and phylogenetic analysis were carried out to evaluate the application effectiveness of the chip. The results showed that the observed heterozygosity (Ho), polymorphism information content (PIC), inbred coefficient (FROH) and genetic differentiation coefficient (Fst) calculated based on the two SNP data sets were basically consistent in the 21 local chicken breeds. The genetic diversity of Langya chicken (LA), Piao chicken (PJ) and Wenchang chicken (WC) was relatively rich. The genetic diversity of Bian chickens (BJ), Langshan chickens (LS), Gushi chickens (GS), Dongxiang blue-eggshell chickens (DX) and Beijing fatty chickens (BY) was relatively poor, and the correlation coefficients of Ho, PIC, FROH and average Fst in the two groups were 0.794, 0.901, 0.926 and 0.984, respectively, all reaching extremely significant levels (P<0.01) with a high degree of fit (P<0.001) and R2 were 0.644, 0.827, 0.916 and 0.927. For the two sets of SNP data, the evolutionary tree constructed by neighbor-joining (NJ) method and maximum likelihood (ML) method was reasonable, and the 21 local chicken breeds were generally divided into six categories, which was consistent with the formation history and geographical distribution of the varieties. The 23K chip also realized reasonable clustering of the five new varieties without individual deviation. There are some differences in the estimation of genetic statistics using SNP with different densities, and data standardization is needed. 23K chip has good efficacy in the analysis of genetic diversity and structure of local chickens.

Analysis of genetic diversity among three Triplophysa tenuis populations by RAD-seq.

To investigate the genetic diversity of Triplophysa tenuis in the Shule River Basin of Gansu province, three populations were sequenced via RAD-seq technology. Twenty-nine microsatellite (SSR) markers with polymorphisms were finally screened to access the genetic diversity among the populations, of which 15 had high polymorphisms. The quantity of the alleles detected in the three populations of T. tenuis varied from 2 to 24. The locus with the most alleles was SSRC1, which had 24 alleles. Among the 29 SSRs, the range of effective allele number, observed heterozygosity, expected heterozygosity, and polymorphic information content were 1.246-16.615, 0.222-1, 0.198-0.940, and 0.178-0.937, respectively. Most of the identified loci were in the Hardy-Weinberg equilibrium. Analysis of the population structure revealed that the Yumen and Changma populations shared the same origin, while the Qiaowan population was different from them. The developed SSR markers discovered in this study will contribute to the conservation research on T. tenuis and the conservation of the fishery resources of the Shule River, providing scientific guidance for the development and utilization of T. tenuis resources and environmental protection.

Towards the conservation of the crucian carp in Europe: Prolific hybridization but no evidence for introgression between native and non-native taxa.

Hybridization plays a pivotal role in evolution, influencing local adaptation and speciation. However, it can also reduce biodiversity, which is especially damaging when native and non-native species meet. Hybridization can threaten native species via competition (with vigorous hybrids), reproductive resource wastage and gene introgression. The latter, in particular, could result in increased fitness in invasive species, decreased fitness of natives and compromise reintroduction or recovery conservation practices. In this study, we use a combination of RAD sequencing and microsatellites for a range-wide sample set of 1366 fish to evaluate the potential for hybridization and introgression between native crucian carp (Carassius carassius) and three non-native taxa (Carassius auratus auratus, Carassius auratus gibelio and Cyprinus carpio) in European water bodies. We found hybridization between native and non-native taxa in 82% of populations with non-natives present, highlighting the potential for substantial ecological impacts from hybrids on crucian carp populations. However, despite such high rates of hybridization, we could find no evidence of introgression between these taxa. The presence of triploid backcrosses in at least two populations suggests that the lack of introgression among these taxa is likely due to meiotic dysfunction in hybrids, leading to the production of polyploid offspring which are unable to reproduce sexually. This result is promising for crucian reintroduction programs, as it implies limited risk to the genetic integrity of source populations. Future research should investigate the reproductive potential of triploid hybrids and the ecological pressures hybrids impose on C. carassius.

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 26 C. japonica f. japonica, 36 C. japonica f. dissecta (Y. Yabe) Hara and 4 C. 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.

Phylogenetic insights into the Salicaceae: The evolution of willows and beyond.

The Salicaceae includes approximately 54 genera and over 1,400 species with a cosmopolitan distribution. Members of the family are well-known for their diverse secondary plant metabolites, and they play crucial roles in tropical and temperate forest ecosystems. Phylogenetic reconstruction of the Salicaceae has been historically challenging due to the limitations of molecular markers and the extensive history of hybridization and polyploidy within the family. Our study employs whole-genome sequencing of 74 species to generate an extensive phylogeny of the Salicaceae. We generated two RAD-Seq enriched whole-genome sequence datasets and extracted two additional gene sets corresponding to the universal Angiosperms353 and Salicaceae-specific targeted-capture arrays. We reconstructed maximum likelihood-based molecular phylogenies using supermatrix and coalescent-based supertree approaches. Our fossil-calibrated phylogeny estimates that the Salicaceae originated around 128 million years ago and unravels the complex taxonomic relationships within the family. Our findings confirm the non-monophyly of the subgenus Salix s.l. and further support the merging of subgenera Chamaetia and Vetrix, both of which exhibit intricate patterns within and among different sections. Overall, our study not only enhances our understanding of the evolution of the Salicaceae, but also provides valuable insights into the complex relationships within the family.

Two new species of Paraphlomis (Lamiales, Lamiaceae) from limestone karsts in Guangdong Province, China.

Paraphlomisqingyuanensis and P.baiwanensis (Lamiaceae), two new species from the limestone area in Guangdong Province, China, are described. Morphologically, both species belong to P.ser.Subcoriaceae C.Y. Wu & H.W. Li. A close relationship between the two new and P.subcoriacea was revealed by molecular phylogenetic analyses based on ETS and ITS. Further morphological and population genetic evidence indicated that they are distinct species in Paraphlomis. According to the IUCN Red List Categories and Criteria, P.qingyuanensis and P.baiwanensis were assessed as Endangered (EN) and Deficient (DD), respectively.

Unveiling a potential threat to forest ecosystems: molecular diagnosis of Alliaria petiolata, a newly introduced alien plant in Korea.

Identifying stages of a species invasion in a new habitat (i.e., colonization, establishment, and landscape spread) and their primary determinants in biological invasion warrants attention, as it provides vital insights for preventing non-native species from becoming pervasive invaders. However, delineating invasion stages and their associated factors can pose significant challenges due to the ambiguous distinctions between these stages. Alliaria petiolata, one of the most noxious weeds in woodland habitats, has recently been introduced to Korea and observed in a few distant locations. Although the plant's spread has been relatively slow thus far, rapid spread is highly likely in the future, given the high invasive potential reported elsewhere. We indirectly diagnose the current status of A. petiolata invasion in Korea through the assessment of genetic diversity and phylogenetic inferences using genome-wide molecular markers and cytological data. We analyzed 86 individual samples collected from two native and six introduced populations, employing 1,172 SNPs. Our analysis estimated within- and among-population genetic diversity and included two clustering analyses. Furthermore, we investigated potential gene flow and reticulation events among the sampled populations. Our data unraveled that Korean garlic mustard exhibits a hexaploid ploidy level with two distinct chromosome numbers, 2n = 36 and 42. The extent of genetic diversity measured in Korean populations was comparable to that of native populations. Using genome-wide SNP data, we identified three distinct clusters with minor gene flow, while failing to detect indications of reticulation among Korean populations. Based on the multifaceted analyses, our study provides valuable insights into the colonization process and stressed the importance of closely monitoring A. petiolata populations in Korea.

Understanding Species Boundaries that Arise from Complex Histories: Gene Flow Across the Speciation Continuum in the Spotted Whiptail Lizards.

Gene flow between diverging lineages challenges the resolution of species boundaries and the understanding of evolutionary history in recent radiations. Here, we integrate phylogenetic and coalescent tools to resolve reticulate patterns of diversification and use a perspective focused on evolutionary mechanisms to distinguish interspecific and intraspecific taxonomic variation. We use this approach to resolve the systematics for one of the most intensively studied but difficult to understand groups of reptiles: the spotted whiptail lizards of the genus Aspidoscelis (A. gularis complex). Whiptails contain the largest number of unisexual species known within any vertebrate group and the spotted whiptail complex has played a key role in the generation of this diversity through hybrid speciation. Understanding lineage boundaries and the evolutionary history of divergence and reticulation within this group is therefore key to understanding the generation of unisexual diversity in whiptails. Despite this importance, long-standing confusion about their systematics has impeded understanding of which gonochoristic species have contributed to the formation of unisexual lineages. Using reduced representation genomic data, we resolve patterns of divergence and gene flow within the spotted whiptails and clarify patterns of hybrid speciation. We find evidence that biogeographically structured ecological and environmental variation has been important in morphological and genetic diversification, as well as the maintenance of species boundaries in this system. Our study elucidates how gene flow among lineages and the continuous nature of speciation can bias the practice of species delimitation and lead taxonomists operating under different frameworks to different conclusions (here we propose that a two species arrangement best reflects our current understanding). In doing so, this study provides conceptual and methodological insights into approaches to resolving diversification patterns and species boundaries in rapid radiations with complex histories, as well as long-standing taxonomic challenges in the field of systematic biology.

Neutral markers reveal complex population structure across the range of a widespread songbird.

Understanding how both contemporary and historical physical barriers influence gene flow is key to reconstructing evolutionary histories and can allow us to predict species' resilience to changing environmental conditions. During the last glacial maximum (LGM), many high latitude North American bird species were forced into glacial refugia, including mountain bluebirds (Silia currucoides). Within their current breeding range, mountain bluebirds still experience a wide variety of environmental conditions and barriers that may disrupt gene flow and isolate populations. Using single nucleotide polymorphisms (SNPs) obtained through restriction site-associated DNA sequencing, we detected at least four genetically distinct mountain bluebird populations. Based on this structure, we determined that isolation-by-distance, the northern Rocky Mountains, and discontinuous habitat are responsible for the low connectivity and the overall history of each population going back to the last glacial maximum. Finally, we identified five candidate genes under balancing selection and three loci under diversifying selection. This study provides the first look at connectivity and gene flow across the range of these high-altitude and high latitude songbirds.

Deciphering Pteronia's evolution in the Cape Floristic Region: A comprehensive study disputes polyploid deficiency and affirms diploid radiation.

The Greater Cape Floristic Region (GCFR) is renowned for its exceptional biodiversity, accommodating over 11 000 plant species, notable degree of endemism, and substantial diversification within limited plant lineages, a phenomenon ascribed to historical radiation events. While both abiotic and biotic factors contribute to this diversification, comprehensive genomic alterations, recognized as pivotal in the diversification of angiosperms, are perceived as uncommon. This investigation focuses on the genus Pteronia, a prominent representative of the Asteraceae family in the GCFR. Employing NGS-based HybSeq and RADSeq methodologies, flow cytometry, karyology, and ecological modeling, we scrutinize the intricacies of its polyploid evolution. Phylogenetic reconstructions using 951 low-copy nuclear genes confirm Pteronia as a well-supported, distinct clade within the tribe Astereae. The ingroup displays a structure indicative of rapid radiation likely antedating polyploid establishment, with the two main groups demarcated by their presence or absence in the fynbos biome. Genome size analysis encompasses 1293 individuals across 347 populations, elucidating significant variation ranging from 6.1 to 34.2 pg (2C-value). Pteronia demonstrates substantially large genome sizes within Astereae and phanerophytes. Polyploidy is identified in 31% of the studied species, with four discerned ploidy levels (2x, 4x, 6x, 8x). Cytotypes exhibit marked distinctions in environmental traits, influencing their distribution across biomes and augmenting their niche differentiation. These revelations challenge the presumed scarcity of polyploidy in the Cape flora, underscoring the imperative need for detailed population studies. The intricate evolutionary history of Pteronia, characterized by recent polyploidy and genome size variation, contributes substantially to the comprehension of diversification patterns within the GCFR biodiversity hotspot.

Intergeneric hybrid origin of the invasive tetraploid Cirsium vulgare.

The invasive tetraploid Cirsium vulgare hybridizes with both Cirsium and Lophiolepis. Its conflicted position in molecular phylogenies, and its peculiar combination of morphological, anatomical, and genomic features that are alternatively shared with representatives of Cirsium or Lophiolepis, strongly suggest its intergeneric hybrid origin. Genetic relationships of C. vulgare (8 samples) with genus Lophiolepis (11 species) and other representatives of genus Cirsium (12 species) were evaluated using restriction site-associated DNA sequencing (RADseq) and examined using analytical and imaging approaches, such as NeighborNet, Heatmap, and STRUCTURE, to identify nuclear genomes admixture. Estimation of the intensity of spontaneous hybridization within and between Cirsium and Lophiolepis was based on herbarium revisions and published data for all reported hybrids pertinent to taxa currently included in Cirsium or Lophiolepis. The genome of any examined Cirsium species is more similar to C. vulgare than to any Lophiolepis species, and vice versa. The nuclear genome of the tetraploid C. vulgare is composed of two equivalent parts, each attributable either to Lophiolepis or to Cirsium; the organellar RADseq data clustered C. vulgare with the genus Cirsium. Spontaneous hybridization between Cirsium and Lophiolepis is significantly less intensive than within these genera. Our analyses provide compelling evidence that the invasive species C. vulgare has an allotetraploid intergeneric origin, with the maternal parent from Cirsium and the paternal from Lophiolepis. For the purpose of delimiting monophyletic genera, we propose keeping Lophiolepis separate from Cirsium and segregating C. vulgare into the hybridogenous genus Ascalea.

A Diverging Species within the Stewartia gemmata (Theaceae) Complex Revealed by RAD-Seq Data.

Informed species delimitation is crucial in diverse biological fields; however, it can be problematic for species complexes. Showing a peripatric distribution pattern, Stewartia gemmata and S. acutisepala (the S. gemmata complex) provide us with an opportunity to study species boundaries among taxa undergoing nascent speciation. Here, we generated genomic data from representative individuals across the natural distribution ranges of the S. gemmata complex using restriction site-associated DNA sequencing (RAD-seq). Based on the DNA sequence of assembled loci containing 41,436 single-nucleotide polymorphisms (SNPs) and invariant sites, the phylogenetic analysis suggested strong monophyly of both the S. gemmata complex and S. acutisepala, and the latter was nested within the former. Among S. gemmata individuals, the one sampled from Mt. Tianmu (Zhejiang) showed the closest evolutionary affinity with S. acutisepala (which is endemic to southern Zhejiang). Estimated from 2996 high-quality SNPs, the genetic divergence between S. gemmata and S. acutisepala was relatively low (an Fst of 0.073 on a per-site basis). Nevertheless, we observed a proportion of genomic regions showing relatively high genetic differentiation on a windowed basis. Up to 1037 genomic bins showed an Fst value greater than 0.25, accounting for 8.31% of the total. After SNPs subject to linkage disequilibrium were pruned, the principal component analysis (PCA) showed that S. acutisepala diverged from S. gemmata along the first and the second PCs to some extent. By applying phylogenomic analysis, the present study determines that S. acutisepala is a variety of S. gemmata and is diverging from S. gemmata, providing empirical insights into the nascent speciation within a species complex.

Which contributes more to the relict flora distribution pattern in East Asia, geographical processes or climate change? New evidence from the phylogeography of Rehderodendron kwangtungense.

BACKGROUND: Relict species are important for enhancing the understanding of modern biogeographic distribution patterns. Although both geological and climatic changes since the Cenozoic have affected the relict flora in East Asia, the contributions of geographical processes remain unclear. In this study, we employed restriction-site associated DNA sequencing (RAD-seq) and shallow genome sequencing data, in conjunction with ecological niche modeling (ENM), to investigate the spatial genetic patterns and population differentiation history of the relict species Rehderodendron kwangtungense Chun. RESULTS: A total of 138 individuals from 16 populations were collected, largely covering the natural distribution of R. kwangtungense. The genetic diversity within the R. kwangtungense populations was extremely low (HO = 0.048 ± 0.019; HE = 0.033 ± 0.011). Mantel tests revealed isolation-by-distance pattern (R2 = 0.38, P < 0.001), and AMOVA analysis showed that the genetic variation of R. kwangtungense occurs mainly between populations (86.88%, K = 7). Between 23 and 21 Ma, R. kwangtungense underwent a period of rapid differentiation that coincided with the rise of the Himalayas and the establishment of the East Asian monsoon. According to ENM and population demographic history, the suitable area and effective population size of R. kwangtungense decreased sharply during the glacial period and expanded after the last glacial maximum (LGM). CONCLUSION: Our study shows that the distribution pattern of southern China mountain relict flora may have developed during the panplain stage between the middle Oligocene and the early Miocene. Then, the flora later fragmented under the force of orogenesis, including intermittent uplift during the Cenozoic Himalayan orogeny and the formation of abundant rainfall associated with the East Asian monsoon. The findings emphasized the predominant role of geographical processes in shaping relict plant distribution patterns.

Readsynth: short-read simulation for consideration of composition-biases in reduced metagenome sequencing approaches.

BACKGROUND: The application of reduced metagenomic sequencing approaches holds promise as a middle ground between targeted amplicon sequencing and whole metagenome sequencing approaches but has not been widely adopted as a technique. A major barrier to adoption is the lack of read simulation software built to handle characteristic features of these novel approaches. Reduced metagenomic sequencing (RMS) produces unique patterns of fragmentation per genome that are sensitive to restriction enzyme choice, and the non-uniform size selection of these fragments may introduce novel challenges to taxonomic assignment as well as relative abundance estimates. RESULTS: Through the development and application of simulation software, readsynth, we compare simulated metagenomic sequencing libraries with existing RMS data to assess the influence of multiple library preparation and sequencing steps on downstream analytical results. Based on read depth per position, readsynth achieved 0.79 Pearson's correlation and 0.94 Spearman's correlation to these benchmarks. Application of a novel estimation approach, fixed length taxonomic ratios, improved quantification accuracy of simulated human gut microbial communities when compared to estimates of mean or median coverage. CONCLUSIONS: We investigate the possible strengths and weaknesses of applying the RMS technique to profiling microbial communities via simulations with readsynth. The choice of restriction enzymes and size selection steps in library prep are non-trivial decisions that bias downstream profiling and quantification. The simulations investigated in this study illustrate the possible limits of preparing metagenomic libraries with a reduced representation sequencing approach, but also allow for the development of strategies for producing and handling the sequence data produced by this promising application.

Different reference genomes determine different results: Comparing SNP calling in RAD-seq of Engelhardia roxburghiana using different reference genomes.

Advances in next-generation sequencing (NGS) have significantly reduced the cost and improved the efficiency of obtaining single nucleotide polymorphism (SNP) markers, particularly through restriction site-associated DNA sequencing (RAD-seq). Meanwhile, the progression in whole genome sequencing has led to the utilization of an increasing number of reference genomes in SNP calling processes. This study utilized RAD-seq data from 242 individuals of Engelhardia roxburghiana, a tropical tree of the walnut family (Juglandaceae), with SNP calling conducted using the STACKS pipeline. We aimed to compare both reference-based approaches, namely, employing a closely related species as the reference genome versus the species itself as the reference genome, to evaluate their respective merits and limitations. Our findings indicate a substantial discrepancy in the number of obtained SNPs between using a closely related species as opposed to the species itself as reference genomes, the former yielded approximately an order of magnitude fewer SNPs compared to the latter. While the missing rate of individuals and sites of the final SNPs obtained in the two scenarios showed no significant difference. The results showed that using the reference genome of the species itself tends to be prioritized in RAD-seq studies. However, if this is unavailable, considering closely related genomes is feasible due to their wide applicability and low missing rate as alternatives. This study contributes to enrich the understanding of the impact of SNP acquisition when utilizing different reference genomes.

Phylogenomic analyses re-examine the evolution of reinforcement and hypothesized hybrid speciation in Phlox wildflowers.

The tree of life is riddled with reticulate evolutionary histories, and some clades, such as the eastern standing Phlox, appear to be hotspots of hybridization. In this group, there are two cases of reinforcement and nine hypothesized hybrid species. Given their historical importance in our understanding of plant speciation, the relationships between these taxa and the role of hybridization in their diversification require genomic validation. Using phylogenomic analyses, we resolve the evolutionary relationships of the eastern standing Phlox and evaluate hypotheses about whether and how hybridization and gene flow played a role in their diversification. Our results provide novel resolution of the phylogenetic relationships in this group, including paraphyly across some taxa. We identify gene flow during one case of reinforcement and find genomic support for a hybrid lineage underlying one of the five hypothesized homoploid hybrid speciation events. Additionally, we estimate the ancestries of four allotetraploid hybrid species. Our results are consistent with hybridization contributing to diverse evolutionary outcomes within this group; although, not as extensively as previously hypothesized. This study demonstrates the importance of phylogenomics in evaluating hypothesized evolutionary histories of non-model systems and adds to the growing support of interspecific genetic exchange in the generation of biodiversity.

Parallel patterns of genetic diversity and structure in circumboreal species of the Sphagnum capillifolium complex.

PREMISE: Shared geographical patterns of population genetic variation among related species is a powerful means to identify the historical events that drive diversification. The Sphagnum capillifolium complex is a group of closely related peat mosses within the Sphagnum subgenus Acutifolia and contains several circumboreal species whose ranges encompass both glaciated and unglaciated regions across the northern hemisphere. In this paper, we (1) inferred the phylogeny of subg. Acutifolia and (2) investigated patterns of population structure and genetic diversity among five circumboreal species within the S. capillifolium complex. METHODS: We generated RAD sequencing data from most species of the subg. Acutifolia and samples from across the distribution ranges of circumboreal species within the S. capillifolium complex. RESULTS: We resolved at least 14 phylogenetic clusters within the S. capillifolium complex. Five circumboreal species show some common patterns: One population system comprises plants in eastern North America and Europe, and another comprises plants in the Pacific Northwest or around the Beringian and Arctic regions. Alaska appears to be a hotspot for genetic admixture, genetic diversity, and sometimes endemic subclades. CONCLUSIONS: Our results support the hypothesis that populations of five circumboreal species within the S. capillifolium complex survived in multiple refugia during the last glacial maximum. Long-distance dispersal out of refugia, population bottlenecks, and possible adaptations to conditions unique to each refugium could have contributed to current geographic patterns. These results indicate the important role of historical events in shaping the complex population structure of plants with broad distribution ranges.

Ongoing introgression of a secondary sexual plumage trait in a stable avian hybrid zone.

Hybrid zones are dynamic systems where natural selection, sexual selection, and other evolutionary forces can act on reshuffled combinations of distinct genomes. The movement of hybrid zones, individual traits, or both are of particular interest for understanding the interplay between selective processes. In a hybrid zone involving two lek-breeding birds, secondary sexual plumage traits of Manacus vitellinus, including bright yellow collar and olive belly color, have introgressed ~50 km asymmetrically across the genomic center of the zone into populations more genetically similar to Manacus candei. Males with yellow collars are preferred by females and are more aggressive than parental M. candei, suggesting that sexual selection was responsible for the introgression of male traits. We assessed the spatial and temporal dynamics of this hybrid zone using historical (1989-1994) and contemporary (2017-2020) transect samples to survey both morphological and genetic variation. Genome-wide single nucleotide polymorphism data and several male phenotypic traits show that the genomic center of the zone has remained spatially stable, whereas the olive belly color of male M. vitellinus has continued to introgress over this time period. Our data suggest that sexual selection can continue to shape phenotypes dynamically, independent of a stable genomic transition between species.

Polyploidy and hybridization in the Mediterranean: unravelling the evolutionary history of Centaurium (Gentianaceae).

BACKGROUND AND AIMS: Polyploidy is considered one of the main mechanisms of plant evolution and speciation. In the Mediterranean Basin, polyploidy has contributed to making this region a biodiversity hotspot, along with its geological and climatic history and other ecological and biogeographical factors. The Mediterranean genus Centaurium (Gentianaceae) comprises ~25 species, of which 60 % are polyploids, including tetraploids and hexaploids. To date, the evolutionary history of centauries has been studied using Sanger sequencing phylogenies, which have been insufficient to fully understand the phylogenetic relationships in this lineage. The goal of this study is to gain a better understanding of the evolutionary history of Centaurium by exploring the mechanisms that have driven its diversification, specifically hybridization and polyploidy. We aim to identify the parentage of hybrid species, at the species or clade level, as well as assessing whether morphological traits are associated with particular ploidy levels. METHODS: We sequenced RADseq markers from 42 samples of 28 Centaurium taxa, and performed phylogenomic analyses using maximum likelihood, summary coalescent SVDquartets and Neighbor-Net approaches. To identify hybrid taxa, we used PhyloNetworks and the fastSTRUCTURE algorithm. To infer the putative parental species of the allopolyploids, we employed genomic analyses (SNIPloid). The association between different traits and particular ploidy levels was explored with non-metric multidimensional scaling. KEY RESULTS: Our phylogenetic analyses confirmed the long-suspected occurrence of recurrent hybridization. The allopolyploid origin of the tetraploid C. serpentinicola and the hexaploids C. mairei, C. malzacianum and C. centaurioides was also confirmed, unlike that of C. discolor. We inferred additional signatures of hybridization events within the genus and identified morphological traits differentially distributed in different ploidy levels. CONCLUSIONS: This study highlights the important role that hybridization has played in the evolution of a Mediterranean genus such as Centaurium, leading to a polyploid complex, which facilitated its diversification and may exemplify that of other Mediterranean groups.

A comprehensive framework for the delimitation of species within the Bemisia tabaci cryptic complex, a global pest-species group.

Identifying cryptic species poses a substantial challenge to both biologists and naturalists due to morphological similarities. Bemisia tabaci is a cryptic species complex containing more than 44 putative species; several of which are currently among the world's most destructive crop pests. Interpreting and delimiting the evolution of this species complex has proved problematic. To develop a comprehensive framework for species delimitation and identification, we evaluated the performance of distinct data sources both individually and in combination among numerous samples of the B. tabaci species complex acquired worldwide. Distinct datasets include full mitogenomes, single-copy nuclear genes, restriction site-associated DNA sequencing, geographic range, host speciation, and reproductive compatibility datasets. Phylogenetically, our well-supported topologies generated from three dense molecular markers highlighted the evolutionary divergence of species of the B. tabaci complex and suggested that the nuclear markers serve as a more accurate representation of B. tabaci species diversity. Reproductive compatibility datasets facilitated the identification of at least 17 different cryptic species within our samples. Native geographic range information provides a complementary assessment of species recognition, while the host range datasets provide low rate of delimiting resolution. We further summarized different data performances in species classification when compared with reproductive compatibility, indicating that combination of mtCOI divergence, nuclear markers, geographic range provide a complementary assessment of species recognition. Finally, we represent a model for understanding and untangling the cryptic species complexes based on the evidence from this study and previously published articles.