Study Of Population Evolution Research Articles

Genetic Diversity and Population Structure of Leptosphaeria biglobosa from the Winter Oilseed Rape Region in China.

Phoma stem canker (blackleg), caused by the fungi Leptosphaeria maculans (anamorph Phoma lingam) and L. biglobosa, is one of the most devastating diseases in oilseed rape (Brassica napus L.) production worldwide. However, the population structure and genetic variation of L. biglobosa populations in China have rarely been investigated. Here, a collection of 214 fungal strains of blackleg from China (including Shaanxi, Jiangxi, Hubei, Jiangsu, Chongqing, Sichuan, Guangxi, Guizhou, Hunan, and Henan) and Europe (France and Ukraine) was identified as L. biglobosa. Three simple sequence repeat (SSR) markers were developed to characterize their population structure. The results showed that the Nei's average gene diversity ranged from 0.6771 for the population from Jiangsu to 0.3009 for the population from Hunan. In addition, most of the genetic variability (96%) occurred within groups and there were only relatively small amounts among groups (4.0%) (FST = 0.043, p = 0.042 < 0.05). Pairwise population differentiation (FST) suggested that significant genetic differentiation was observed between different L. biglobosa populations. Bayesian and unweighted average method analysis revealed that these L. biglobosa strains were clustered into three branches, and three European strains were similar to those from eastern China. The pathogenicity assay showed that those in Group III were significantly more virulent than those in Group I (t = 2.69, p = 0.016). The study also showed that Group III was dominant in Chinese L. biglobosa populations, which provides new insights for the further study of population evolution and the management of this pathogen.

Synthetic catalog of black holes in the Milky Way

Aims. We present an open-access database that includes a synthetic catalog of black holes (BHs) in the Milky Way, divided by the components disk, bulge, and halo. Methods. To calculate the evolution of single and binary stars, we used the updated population synthesis code StarTrack. We applied a new model of the star formation history and chemical evolution of Galactic disk, bulge, and halo that was synthesized from observational and theoretical data. This model can be easily employed for other studies of population evolution. Results. We find that at the current Milky Way (disk+bulge+halo) contains about 1.2 × 108 single BHs with an average mass of about 14 M⊙, and 9.3 × 106 BHs in binary systems with an average mass of 19 M⊙. We present basic statistical properties of the BH population in three Galactic components such as the distributions of BH masses, velocities, or the numbers of BH binary systems in different evolutionary configurations. Conclusions. The metallicity of a stellar population has a significant effect on the final BH mass through the stellar winds. The most massive single BH in our simulation of 113 M⊙ originates from a merger of a BH and a helium star in a low-metallicity stellar environment in the Galactic halo. We constrain that only ∼0.006% of the total Galactic halo mass (including dark matter) can be hidden in the form of stellar origin BHs. These BHs cannot be detected by current observational surveys. We calculated the merger rates for current Galactic double compact objects (DCOs) for two considered common-envelope models: ∼3–81 Myr−1 for BH-BH, ∼1–9 Myr−1 for BH-neutron star (NS), and ∼14–59 Myr−1 for NS-NS systems. We show the evolution of the merger rates of DCOs since the formation of the Milky Way until the current moment with the new star formation model of the Galaxy.

From Fixation Probabilities to d-player Games: An Inverse Problem in Evolutionary Dynamics.

The probability that the frequency of a particular trait will eventually become unity, the so-called fixation probability, is a central issue in the study of population evolution. Its computation, once we are given a stochastic finite population model without mutations and a (possibly frequency dependent) fitness function, is straightforward and it can be done in several ways. Nevertheless, despite the fact that the fixation probability is an important macroscopic property of the population, its precise knowledge does not give any clear information about the interaction patterns among individuals in the population. Here we address the inverse problem: from a given fixation pattern and population size, we want to infer what is the game being played by the population. This is done by first exploiting the framework developed in Chalub and Souza (J Math Biol 75:1735-1774, 2017), which yields a fitness function that realises this fixation pattern in the Wright-Fisher model. This fitness function always exists, but it is not necessarily unique. Subsequently, we show that any such fitness function can be approximated, with arbitrary precision, using d-player game theory, provided d is large enough. The pay-off matrix that emerges naturally from the approximating game will provide useful information about the individual interaction structure that is not itself apparent in the fixation pattern. We present extensive numerical support for our conclusions.

Updated mtDNA study of Guinea-Bissau immigrant population living in Lisbon

Guinea-Bissau is a country on the west coast of African Continent.Before the arrival of Europeans and until the XVII century, the territory was part of the Gabu kingdom, Mali Empire.In the past decades the number of immigrants in Portugal has grown and Guinean immigrant community is one of the largest immigrant communities. Most of those immigrants are based in Lisbon metropolitan region.Over the last decades, mtDNA has become an important genetic marker in human and population evolution studies, as well as in forensic and clinical case studies. Maternal inheritance, high copy number, lack of recombination and high mutation rateare characteristics that makes this genetic marker useful instudies of human origin and evolution.The non-coding mtDNAregion presents high genetic variability and the haplotypes obtained through the study of this region fall into haplogroups with specific polymorphisms shared by all individuals with a common ancestor.We studied 80 blood samples from Guinean immigrants living in Lisbon. mtDNA control region was amplified and sequenced between positions 16024 and 576, using two sets of primers - L15971/H016 and L16555/H639 -.The study of the control region revealed high genetic diversity within Guinean immigrants, with a high frequency of unique haplotypes. Most of the obtained mitochondrial DNAsequences belong to African haplogroups.As the result of the integration of African immigrants in Lisbon population we will have, in a near feature, individuals borned in Portugal with Portuguese nationality exhibiting mtDNA haplotypes typical of regions of the African Continent.

Development of polymorphic microsatellite markers of Obolodiplosis robiniae (Haldeman) (Diptera: Cecidomyiidae), a North American pest invading Asia.

Microsatellite markers were developed for epidemiological studies on the black locust gall midge Obolodiplosis robiniae (Haldeman) (Diptera: Cecidomyiidae), a native North America pest introduced to Europe and Asia. Polymorphism at each locus was tested on 68 individuals from six populations reared from infected host leaves of Robinia pseudoacacia L. collected in China. Fourteen loci were found to be polymorphic, with the number of alleles ranging from 3 to 10. The observed heterozygosity varied evenly from 0.2667 to 0.6540. For populations, the observed heterozygosity ranged from 0.1429 to 1.000. The allele frequency of the predominant allele varied from 0.250 to 0.500. All loci with negative FST values indicated heterozygote excess in each locus with six populations. Of 14 loci, four were observed to have FST values up to 0.05, which indicated negligible genetic differentiation within the population. Significant deviations (P < 0.05) from the expected Hardy–Weinberg equilibrium, as evaluated using the Markov chain algorithm for each locus and for all six populations, were observed, and genotypic linkage disequilibrium was clearly detected. These markers represent a useful tool to design strategies for integrated pest management and in the study of population evolution in this important introduced pest.

Influence of variations in threshold of bad mutations on age structure of the population

Computer study of population evolution in a modified Penna model is presented, where different thresholds T for bad mutation may be assigned to individuals. The model indicates a possible source of such fluctuations of T due to embryo period of life before birth. Changes in age characteristics of the population, survival rate and mutation distributions at equilibrium are discussed. Results of computer simulation are compared with the standard Penna model with no fluctuation in T. We obtained larger equilibrium population for the same environmental capacity. However, the survival rate is smaller and the age of the oldest individuals also decreases. This is also reflected in age distribution of the population, similar at older populations and with higher decrease rate among younger ones. Also, the mutation accumulation is similar for older ages, yet younger individuals may absorb more mutations as a result of the presence of some items with threshold value above the average T. We conclude that fluctuations in threshold T may alter population characteristics, also in terms of measurable statistics in population such as age distribution or the survival rate.