Coalescent Theory Research Articles

Mechanism of grain boundary angle on solidification cracking in directed energy deposition Hastelloy X superalloys

Solidification cracking occurs only when the grain boundary (GB) angle (θ) exceeds a critical value. This value, known as the critical cracked GB angle (θ*), can be predicted from the grain coalescence theory based on GB-angle-dependent GB energy. However, the calculated value (θc*) is always less than the measured value in experiments (θe*), which is also confirmed in our directed energy deposition Hastelloy X superalloys. In addition to GB energy, there are evidences showing that GB angle can affect cracking by changing dendrite spacings. We show by experiments and phase field simulations that, same as GB energy, the dendrite spacings at GBs increase with GB angle, but its effect on solidification cracking sensitivity (SCS) is opposite to GB energy. Depending on their relative contributions, three ranges can be identified. In the first range of θ<θc*, both dendrite spacings and GB energy have negligible effects on dendrite coalescence, compared to the case inside a grain. In the second range of θc*<θ<θe*, dendrite spacings counteract the effect of high GB energy on SCS. It is exactly this effect that induces the gap in θ* between theory and experiments. In the third range of θ>θe*, GB energy plays a dominant role and leads to severe solidification cracking. After including the effect of dendrite spacings on SCS, we predict θ*=15° in directed energy deposition Hastelloy X superalloys, close to the experimental value of 18°. These new findings provide new insights for suppressing cracking by controlling the dendrite spacings near GBs.

Whole genome phylogenomics helps to resolve the phylogenetic position of the Zygothrica genus group (Diptera, Drosophilidae) and the causes of previous incongruences

Incomplete Lineage Sorting (ILS) and introgression are among the two main factors causing incongruence between gene and species trees. Advances in phylogenomic studies have allowed us to overcome most of these issues, providing reliable phylogenetic hypotheses while revealing the underlying evolutionary scenario. Across the last century, many incongruent phylogenetic reconstructions were recovered for Drosophilidae, employing a limited sampling of genetic markers or species. In these studies, the monophyly and the phylogenetic positioning of the Zygothrica genus group stood out as one of the most controversial questions. Thus, here, we addressed these issues using a phylogenomic approach, while accessing the influence of ILS and introgressions on the diversification of these species and addressing the spatio-temporal scenario associated with their evolution. For this task, the genomes of nine specimens from six Neotropical species belonging to the Zygothrica genus group were sequenced and evaluated in a phylogenetic framework encompassing other 39 species of Drosophilidae. Nucleotide and amino acid sequences recovered for a set of 2,534 single-copy genes by BUSCO were employed to reconstruct maximum likelihood (ML) concatenated and multi-species coalescent (MSC) trees. Likelihood mapping, quartet sampling, and reticulation tests were employed to infer the level and causes of incongruence. Lastly, a penalized-likelihood molecular clock strategy with fossil calibrations was performed to infer divergence times. Taken together, our results recovered the subdivision of Drosophila into six different lineages, one of which clusters species of the Zygothrica genus group (except for H. duncani). The divergence of this lineage was dated to Oligocene ∼ 31 Mya and seems to have occurred in the same timeframe as other key diversification within Drosophila. According to the concatenated and MSC strategies, this lineage is sister to the clade joining Drosophila (Siphlodora) with the Hawaiian Drosophila and Scaptomyza. Likelihood mapping, quartet sampling, reticulation reconstructions as well as introgression tests revealed that this lineage was the target of several hybridization events involving the ancestors of different Drosophila lineages. Thus, our results generally show introgression as a major source of previous incongruence. Nevertheless, the similar diversification times recovered for several of the Neotropical Drosophila lineages also support the scenario of multiple and simultaneous diversifications taking place at the base of Drosophilidae phylogeny, at least in the Neotropics.

Ancient Introgression in Mouse Lemurs (Microcebus: Cheirogaleidae) Explains 20 Years of Phylogenetic Uncertainty

Mouse lemurs (genus Microcebus) are a clade of approximately 26 named species of small, nocturnal primates endemic to Madagascar. The genus radiated one to ten million years ago and is morphologically cryptic, with most species having been named within the past 20 years largely based on phylogenetic analysis of short fragments of mitochondrial data. More recent work has been focused on revisiting species designations with autosomal nuclear data using more sophisticated statistical approaches. The order of speciation events in Microcebus remains contentious, particularly with regard to the placement of the M. ravelobensis clade. We investigated support for previous phylogenetic hypotheses based on available whole-genome assemblies from six species and an outgroup. We recovered over 4,000 one-to-one orthologs from these assemblies and used concatenation and coalescent species tree methods to evaluate if differences between previous studies were due to methodological differences or to limitations from too few loci. Observed gene tree discordance was high with patterns inconsistent with incomplete lineage sorting alone. Therefore, we estimated phylogenetic networks to investigate ancient introgression events that may explain observed gene tree distributions and previous phylogenetic conflicts. A network model, invoking some role for introgressive hybridization in the early evolution of Microcebus, better characterizes phylogenetic relationships than does any binary species tree. Our results provide insights into the biogeographic history of a threatened and diverse group of primates while also highlighting an important role for phylogenetic network methods in resolving cases of phylogenetic uncertainty.

The coalescent in finite populations with arbitrary, fixed structure

The coalescent is a stochastic process representing ancestral lineages in a population undergoing neutral genetic drift. Originally defined for a well-mixed population, the coalescent has been adapted in various ways to accommodate spatial, age, and class structure, along with other features of real-world populations. To further extend the range of population structures to which coalescent theory applies, we formulate a coalescent process for a broad class of neutral drift models with arbitrary – but fixed – spatial, age, sex, and class structure, haploid or diploid genetics, and any fixed mating pattern. Here, the coalescent is represented as a random sequence of mappings C=Ctt=0∞ from a finite set G to itself. The set G represents the “sites” (in individuals, in particular locations and/or classes) at which these alleles can live. The state of the coalescent, Ct:G→G, maps each site g∈G to the site containing g’s ancestor, t time-steps into the past. Using this representation, we define and analyze coalescence time, coalescence branch length, mutations prior to coalescence, and stationary probabilities of identity-by-descent and identity-by-state. For low mutation, we provide a recipe for computing identity-by-descent and identity-by-state probabilities via the coalescent. Applying our results to a diploid population with arbitrary sex ratio r, we find that measures of genetic dissimilarity, among any set of sites, are scaled by 4r(1−r) relative to the even sex ratio case.

Bringing light into deep-sea biodiversity: a systematic revision and molecular phylogeny of the genus Scaphander Montfort, 1810 (Gastropoda: Cephalaspidea), with a focus on the Indo-Pacific

Abstract Scaphander is a genus of mostly deep-sea, soft-bottom gastropods distributed nearly worldwide. Its taxonomic history is complex, with 32 species currently accepted, most based on shells only. In this work, we revise the diversity and systematics of Scaphander, with a focus on the Indo-Pacific region, using a detailed morphological study and molecular phylogenetics. Conchological and anatomical characters, such as digestive and male reproductive systems were compared, and original descriptions and type material were investigated. Additionally, molecular species delimitation methods were used, such as Assemble Species by Automatic Partitioning (ASAP) based on the gene cytochrome c oxidase subunit I, and the multispecies coalescent method Species Tree And Classification Estimation, Yarely (STACEY) based on a dataset of five gene markers. Thirty-three Scaphander species were recognized worldwide, 10 still based only on shells. Five species are here described as new to science, namely Scaphander amygdalus sp. nov., Scaphander cornus sp. nov., Scaphander obnubilus sp. nov., Scaphander semicallus sp. nov. and Scaphander solomonensis sp. nov. The most diverse region is the Western Pacific (17 species), followed by the Atlantic (12 species) and the Indian Ocean (7 species).

Evolution of chromosomal inversions across an avian radiation.

Chromosomal inversions are structural mutations that can play a prominent role in adaptation and speciation. Inversions segregating across species boundaries (trans-species inversions) are often taken as evidence for ancient balancing selection or adaptive introgression but can also be due to incomplete lineage sorting (ILS). Using whole-genome resequencing data from 18 populations of 11 recognized munia species in the genus Lonchura (N = 176 individuals), we identify four large para- and pericentric inversions ranging in size from 4 to 20 Mb. All four inversions co-segregate across multiple species and predate the numerous speciation events associated with the rapid radiation of this clade across the prehistoric Sahul (Australia, New Guinea) and Bismarck Archipelago. Using coalescent theory, we infer that trans-specificity is improbable for neutrally segregating variation despite substantial ILS characterizing this young radiation. Instead, maintenance of all three autosomal inversions (chr1, chr5, chr6) is best explained by selection acting along eco-geographic clines not observed for the collinear parts of the genome. In addition, the large sex chromosome inversion largely aligns with species boundaries and shows signatures of repeated positive selection for both alleles. This study provides evidence for trans-species inversion polymorphisms involved in both adaptation and speciation. It further highlights the importance of informing selection inference using a null model of neutral evolution derived from the collinear part of the genome.

Abstract SY02-03: Stochastic modeling of clonal evolution in carcinogenesis

Abstract In order to develop strategies that can detect cancer earlier, we need to better understand the dynamics of cancer evolution during the human lifetime. Starting from gestation, this includes measuring both the timing of early somatic mutations that lead to clonal mosaicism as well as the growth rates of mutated clones that carry higher potential for malignant transformation. Continuous observation of this evolving clonal composition across a lifetime is not feasible, therefore mathematical models are needed to integrate data from longitudinal and cross-sectional samples and infer these dynamics. Stochastic models of clonal evolution offer such a framework and provide a means for predicting individual clone trajectories into the future. Furthermore, if measurements of evolution are to be utilized clinically for early detection and patient risk stratification, faster methods to apply these models to data are required. To this end, we derived methods using coalescent theory for single-cell DNA sequencing data that enable instantaneous estimation of the growth rate of a clone along with its confidence intervals. Our tool is available in an open source R package, cloneRate, and provides the first method for constructing valid confidence intervals of growth rates analytically without having to rely on Bayesian inference techniques and complex simulations. When applying our methods to recent datasets derived from normal and neoplastic human blood cells, we quantified increased fitness effects of multi-hit driver mutations and found that higher initial clone growth rates led to decreased time to cancer diagnosis in patients. We can also use these models to estimate other important biological parameters that are difficult to measure in vivo such as bounds for total number of hematopoietic stem cells and expansion rates in early development. Ultimately, the ability to easily and quickly parameterize clonal dynamics in individual patients will benefit future early detection efforts and screening strategies for many cancer types. Citation Format: Kit Curtius. Stochastic modeling of clonal evolution in carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr SY02-03.

Reconstruct recent multi-population migration history by using identical-by-descent sharing

Identical-by-descent (IBD) is a fundamental genomic characteristic in population genetics and has been widely used for population history reconstruction. However, limited by the nature of IBD, which could only capture the relationship between two individuals/haplotypes, existing IBD-based history inference is constrained to two populations. In this study, we propose a framework by leveraging IBD sharing in multi-population and develop a method, MatrixIBD, to reconstruct recent multi-population migration history. Specifically, we employ the structured coalescent theory to precisely model the genealogical process and then estimate the IBD sharing across multiple populations. Within our model, we establish a theoretical connection between migration history and IBD sharing. Our method is rigorously evaluated through simulations, revealing its remarkable accuracy and robustness. Furthermore, we apply MatrixIBD to Central and South Asia in the Human Genome Diversity Project and successfully reconstruct the recent migration history of three closely related populations in South Asia. By taking into account the IBD sharing across multiple populations simultaneously, MatrixIBD enables us to attain clearer and more comprehensive insights into the history of regions characterized by complex migration dynamics, providing a holistic perspective on intricate patterns embedded within the recent population migration history.

On multi-type Cannings models and multi-type exchangeable coalescents

A multi-type neutral Cannings population model with migration and fixed subpopulation sizes is analyzed. Under appropriate conditions, as all subpopulation sizes tend to infinity, the ancestral process, properly time-scaled, converges to a multi-type coalescent sharing the exchangeability and consistency property. The proof gains from coalescent theory for single-type Cannings models and from decompositions of transition probabilities into parts concerning reproduction and migration respectively. The following section deals with a different but closely related multi-type Cannings model with mutation and fixed total population size but stochastically varying subpopulation sizes. The latter model is analyzed forward and backward in time with an emphasis on its behavior as the total population size tends to infinity. Forward in time, multi-type limiting branching processes arise for large population size. Its backward structure and related open problems are briefly discussed.

Coalescence and sampling distributions for Feller diffusions

Consider the diffusion process defined by the forward equation ut(t,x)=12{xu(t,x)}xx−α{xu(t,x)}x for t,x≥0 and −∞<α<∞, with an initial condition u(0,x)=δ(x−x0). This equation was introduced and solved by Feller to model the growth of a population of independently reproducing individuals. We explore important coalescent processes related to Feller’s solution. For any α and x0>0 we calculate the distribution of the random variable An(s;t), defined as the finite number of ancestors at a time s in the past of a sample of size n taken from the infinite population of a Feller diffusion at a time t since since its initiation. In a subcritical diffusion we find the distribution of population and sample coalescent trees from time t back, conditional on non-extinction as t→∞. In a supercritical diffusion we construct a coalescent tree which has a single founder and derive the distribution of coalescent times.

Relativistic Phase Space Diffusion of Compact Object Binaries in Stellar Clusters and Hierarchical Triples

The LIGO/Virgo detections of compact object mergers have posed a challenge for theories of binary evolution and coalescence. One promising avenue for producing mergers dynamically is through secular eccentricity oscillations driven by an external perturber, be it a tertiary companion (as in the Lidov–Kozai, LK, mechanism) or the tidal field of the stellar cluster in which the binary orbits. The simplest theoretical models of these oscillations use a “doubly averaged” (DA) approximation, averaging both over the binary’s internal Keplerian orbit and its “outer” barycentric orbit relative to the perturber. However, DA theories do not account for fluctuations of the perturbing torque on the outer orbital timescale, which are known to increase a binary’s eccentricity beyond the maximum DA value, potentially accelerating mergers. Here we reconsider the impact of these short-timescale fluctuations in the test-particle quadrupolar limit for binaries perturbed by arbitrary spherical cluster potentials (including LK as a special case), in particular including 1pN general relativistic (GR) apsidal precession of the internal orbit. Focusing on the behavior of the binary orbital elements around peak eccentricity, we discover a new effect, relativistic phase space diffusion (RPSD), in which a binary can jump to a completely new dynamical trajectory on an outer orbital timescale, violating the approximate conservation of DA integrals of motion. RPSD arises from an interplay between secular behavior at extremely high eccentricity, short-timescale fluctuations, and rapid GR precession, and can change the subsequent secular evolution dramatically. This effect occurs even in hierarchical triples, but has not been uncovered until now.

Divergence of the freshwater sleeper, Neodontobutishainanensis (Chen, 1985) (Teleostei, Odontobutidae), in the Pearl River basin and on Hainan Island of southern China.

Study of divergence of freshwater fish populations between island and adjacent mainland areas can shed light on the phylogeographical relationships of these regions. Neodontobutishainanensis is a freshwater fish species restricted to Hainan Island and in Guangdong and Guangxi provinces in the southern mainland China. We examine the phylogenetic relationship and population structure of N.hainanensis based on 3,176 nuclear loci using a gene-capture method. STRUCTURE analysis and principal coordinate analyses (PCA) indicate that populations from Guangdong, Guangxi and Hainan are each distinct, except that some individuals of the Guangdong population share minor genetic components with individuals of the Guangxi population. In the concatenated gene tree, the Hainan population is grouped with the Guangdong population, but the coalescent tree groups the Hainan population as the sister to the Guangxi population. Finally, coalescent simulations confirmed the divergence pattern supported by the coalescent tree and revealed a one-way introgression from the Guangxi population to the Guangdong population, which can explain the discordant results supported by the concatenated and coalescent phylogenetic analyses. Due to recent decline of N.hainanensis populations and the genetic patterns in this species, as revealed in this study, the populations in the three areas should be treated as separate conservation units.

Resolving the phylogeny of Thladiantha (Cucurbitaceae) with three different target capture pipelines

BackgroundDespite recent advances, reliable tools to simultaneously handle different types of sequencing data (e.g., target capture, genome skimming) for phylogenomics are still scarce. Here, we evaluate the performance of the recently developed pipeline Captus in comparison with the well-known target capture pipelines HybPiper and SECAPR. As test data, we analyzed newly generated sequences for the genus Thladiantha (Cucurbitaceae) for which no well-resolved phylogeny estimate has been available so far, as well as simulated reads derived from the genome of Arabidopsis thaliana.ResultsOur pipeline comparisons are based on (1) the time needed for data assembly and locus extraction, (2) locus recovery per sample, (3) the number of informative sites in nucleotide alignments, and (4) the topology of the nuclear and plastid phylogenies. Additionally, the simulated reads derived from the genome of Arabidopsis thaliana were used to evaluate the accuracy and completeness of the recovered loci. In terms of computation time, locus recovery per sample, and informative sites, Captus outperforms HybPiper and SECAPR. The resulting topologies of Captus and SECAPR are identical for coalescent trees but differ when trees are inferred from concatenated alignments. The HybPiper phylogeny is similar to Captus in both methods. The nuclear genes recover a deep split of Thladiantha in two clades, but this is not supported by the plastid data.ConclusionsCaptus is the best choice among the three pipelines in terms of computation time and locus recovery. Even though there is no significant topological difference between the Thladiantha species trees produced by the three pipelines, Captus yields a higher number of gene trees in agreement with the topology of the species tree (i.e., fewer genes in conflict with the species tree topology).

Tree-based QTL mapping with expected local genetic relatedness matrices

Understanding the genetic basis of complex phenotypes is a central pursuit of genetics. Genome-wide association studies (GWASs) are a powerful way to find genetic loci associated with phenotypes. GWASs are widely and successfully used, but they face challenges related to the fact that variants are tested for association with a phenotype independently, whereas in reality variants at different sites are correlated because of their shared evolutionary history. One way to model this shared history is through the ancestral recombination graph (ARG), which encodes a series of local coalescent trees. Recent computational and methodological breakthroughs have made it feasible to estimate approximate ARGs from large-scale samples. Here, we explore the potential of an ARG-based approach to quantitative-trait locus (QTL) mapping, echoing existing variance-components approaches. We propose a framework that relies on the conditional expectation of a local genetic relatedness matrix (local eGRM) given the ARG. Simulations show that our method is especially beneficial for finding QTLs in the presence of allelic heterogeneity. By framing QTL mapping in terms of the estimated ARG, we can also facilitate the detection of QTLs in understudied populations. We use local eGRM to analyze two chromosomes containing known body size loci in a sample of Native Hawaiians. Our investigations can provide intuition about the benefits of using estimated ARGs in population- and statistical-genetic methods in general.

Simulation‐based decision‐making and implementation of tools in hybrid crop breeding pipelines

AbstractNew technologies have been developed over the last few years aiming to support breeding pipeline optimization for long‐term genetic gains. However, the implementation of these new tools and their impact on any breeding program's budget are not well studied. Here, we compare multiple breeding pipeline strategies accounting for genomic selection and high‐throughput phenotyping (HTP) by means of hybrid gain and cost‐effectiveness. We simulated a hybrid crop breeding program through coalescent theory. We compared two strategies for parental updates and four breeding pipelines: conventional breeding pipeline; conventional breeding pipeline with HTP; conventional breeding pipeline with genomic selection; conventional breeding pipeline with genomic selection and HTP. All analyses were implemented under three different levels of genotype‐by‐environment interaction (G×E) and two trait heritabilities (0.3 and 0.7). Overall, the results show that scenarios with early parental selection perform better than the others. In addition, the implementation of HTP delivered the highest hybrid gain in the long‐term, whereas the implementation of genomic selection seems to be more cost‐effective. We suggest, considering breeding programs with complex trait inheritance and accounting for higher levels of G×E, investing in breeding pipelines accounting for genomic selection as a strategy to create and maintain long‐term hybrid gain. Moreover, considering an unconstrained budget, the investment in both, genomic selection and HTP, represents the best strategy. Hence, these results provide strategies that may aid breeders in optimizing self‐pollination breeding programs.

Unravelling phylogenetic relationships of the tribe Cereeae using target enrichment sequencing.

Cactaceae are succulent plants, quasi-endemic to the American continent, and one of the most endangered plant groups in the world. Molecular phylogenies have been key to unravelling phylogenetic relationships among major cactus groups, previously hampered by high levels of morphological convergence. Phylogenetic studies using plastid markers have not provided adequate resolution for determining generic relationships within cactus groups. This is the case for the tribe Cereeae s.l., a highly diverse group from tropical America. Here we aimed to reconstruct a well-resolved phylogenetic tree of tribe Cereeae and update the circumscription of suprageneric and generic groups in this tribe. We integrated sequence data from public gene and genomic databases with new target sequences (generated using the customized Cactaceae591 probe set) across representatives of this tribe, with a denser taxon sampling of the subtribe Cereinae. We inferred concatenated and coalescent phylogenetic trees and compared the performance of both approaches. Six well-supported suprageneric clades were identified using different datasets. However, only genomic datasets, especially the Cactaceae591, were able to resolve the contentious relationships within the subtribe Cereinae. We propose a new taxonomic classification within Cereeae based on well-resolved clades, including new subtribes (Aylosterinae subtr. nov., Uebelmanniinae subtr. nov. and Gymnocalyciinae subtr. nov.) and revised subtribes (Trichocereinae, Rebutiinae and Cereinae). We emphasize the importance of using genomic datasets allied with coalescent inference to investigate evolutionary patterns within the tribe Cereeae.

Active Surface Flows Accelerate the Coarsening of Lipid Membrane Domains.

Phase separation of multicomponent lipid membranes is characterized by the nucleation and coarsening of circular membrane domains that grow slowly in time as ∼t^{1/3}, following classical theories of coalescence and Ostwald ripening. In this Letter, we study the coarsening kinetics of phase-separating lipid membranes subjected to nonequilibrium forces and flows transmitted by motor-driven gliding actin filaments. We experimentally observe that the activity-induced surface flows trigger rapid coarsening of noncircular membrane domains that grow as ∼t^{2/3}, a 2x acceleration in the growth exponent compared to passive coalescence and Ostwald ripening. We analyze these results by developing analytical theories based on the Smoluchowski coagulation model and the phase field model to predict the domain growth in the presence of active flows. Our Letter demonstrates that active matter forces may be used to control the growth and morphology of membrane domains driven out of equilibrium.

CloneRate: fast estimation of single-cell clonal dynamics using coalescent theory.

While evolutionary approaches to medicine show promise, measuring evolution itself is difficult due to experimental constraints and the dynamic nature of body systems. In cancer evolution, continuous observation of clonal architecture is impossible, and longitudinal samples from multiple timepoints are rare. Increasingly available DNA sequencing datasets at single-cell resolution enable the reconstruction of past evolution using mutational history, allowing for a better understanding of dynamics prior to detectable disease. There is an unmet need for an accurate, fast, and easy-to-use method to quantify clone growth dynamics from these datasets. We derived methods based on coalescent theory for estimating the net growth rate of clones using either reconstructed phylogenies or the number of shared mutations. We applied and validated our analytical methods for estimating the net growth rate of clones, eliminating the need for complex simulations used in previous methods. When applied to hematopoietic data, we show that our estimates may have broad applications to improve mechanistic understanding and prognostic ability. Compared to clones with a single or unknown driver mutation, clones with multiple drivers have significantly increased growth rates (median 0.94 versus 0.25 per year; P = 1.6×10-6). Further, stratifying patients with a myeloproliferative neoplasm (MPN) by the growth rate of their fittest clone shows that higher growth rates are associated with shorter time to MPN diagnosis (median 13.9 versus 26.4 months; P = 0.0026). We developed a publicly available R package, cloneRate, to implement our methods (Package website: https://bdj34.github.io/cloneRate/). Source code: https://github.com/bdj34/cloneRate/.

The Qatari population's genetic structure and gene flow as revealed by the Y chromosome.

The Y-chromosome has been widely used in forensic genetic applications and human population genetic studies due to its uniparental origins. A large database on the Qatari population was created for comparison with other databases from the Arabian Peninsula, the Middle East, and Africa. We provide a study of 23 Y-STR loci included in PowerPlex Y23 (Promega, USA) that were genotyped to produce haplotypes in 379 unrelated males from Qatar, a country at the crossroads of migration patterns. Overall, the most polymorphic locus provided by the Promega kit was DYS458, with a genetic diversity value of 0.85 and a haplotype diversity of 0.998924. Athey's Haplogroup Predictor tool was used to predict haplogroups from Y-STR haplotypes in the Qatari population. In a median-joining network, the haplogroup J1 predominance (49%) in Qatar generated a star-like expansion cluster. The graph of population Q-matrix was developed using Y-STR data from 38 Middle Eastern and 97 African populations (11,305 individuals), and it demonstrated a stronger sub-grouping of countries within each ethnic group and showed the effect of Arabs on the indigenous Berbers of North Africa. The estimated migration rate between the Qatari and other Arabian populations was inferred using Bayesian coalescence theory in the Migrate-n program. According to the Gene Flow study, the main migration route was from Yemen to Kuwait through Qatar. Our research, using the PowerPlex Y23 database, shows the importance of gene diversity, as well as regional and social structuring, in determining the utility of demographic and forensic databases.

Phylogenomic analysis provides diagnostic tools for the identification of Anastrepha fraterculus (Diptera: Tephritidae) species complex.

Insect pests cause tremendous impact to agriculture worldwide. Species identification is crucial for implementing appropriate measures of pest control but can be challenging in closely related species. True fruit flies of the genus Anastrepha Schiner (Diptera: Tephritidae) include some of the most serious agricultural pests in the Americas, with the Anastrepha fraterculus (Wiedemann) complex being one of the most important due to its extreme polyphagy and wide distribution across most of the New World tropics and subtropics. The eight morphotypes described for this complex as well as other closely related species are classified in the fraterculus species group, whose evolutionary relationships are unresolved due to incomplete lineage sorting and introgression. We performed multifaceted phylogenomic approaches using thousands of genes to unravel the evolutionary relationships within the A. fraterculus complex to provide a baseline for molecular diagnosis of these pests. We used a methodology that accommodates variable sources of data (transcriptome, genome, and whole-genome shotgun sequencing) and developed a tool to align and filter orthologs, generating reliable datasets for phylogenetic studies. We inferred 3031 gene trees that displayed high levels of discordance. Nevertheless, the topologies of the inferred coalescent species trees were consistent across methods and datasets, except for one lineage in the A. fraterculus complex. Furthermore, network analysis indicated introgression across lineages in the fraterculus group. We present a robust phylogeny of the group that provides insights into the intricate patterns of evolution of the A. fraterculus complex supporting the hypothesis that this complex is an assemblage of closely related cryptic lineages that have evolved under interspecific gene flow. Despite this complex evolutionary scenario, our subsampling analysis revealed that a set of as few as 80 loci has a similar phylogenetic resolution as the genome-scale dataset, offering a foundation to develop more efficient diagnostic tools in this species group.