A STUDY USING DEMOGRAPHIC DATA OF GENETIC DRIFT AND NATURAL SELECTION IN AN ISOLATED MEDITERRANEAN COMMUNITY: BAYÁRCAL (LA ALPUJARRA, SOUTH-EAST SPAIN)

2011 ◽  
Vol 43 (4) ◽  
pp. 401-411
Author(s):  
F. LUNA ◽  
A. R. TARELHO ◽  
A. M. CAMARGO ◽  
V. ALONSO
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Genetic Drift ◽  
Demographic Transition ◽  
Demographic Data ◽  
Human Populations ◽  
Native Population ◽  
Evolutionary Mechanisms ◽  
Developing Communities ◽  
Mediterranean Community

SummaryNatural selection and genetic drift are two evolutionary mechanisms that can be analysed in human populations using their fertility and mortality patterns, and their reproductive size and isolation, respectively. This paper analyses the models of natural selection and genetic drift in Bayárcal, south-east Spain, and compares them with the observed models in the rest of the Alpujarran region. Demographic data were obtained from a sample of 77 families (48.45% of the population, with 547 inhabitants). The genetic drift and natural selection action was evaluated with the Coefficient of Breeding Isolation (CBI of Lasker and Kaplan) and Crow's index, respectively. The CBI (23.23/12.61) suggests that genetic drift is near to acting, and Crow's index (I=0.58) is slightly higher than that observed in the rest of La Alpujarra. Although the reproductive isolation of Bayárcal is not effective enough for genetic drift to act, it is near when marital migrants inside the Bayárcal valley are considered as a native population. The natural selection pattern is not different from that of the rest of La Alpujarra, but it tends towards the model of developing communities, where the demographic transition has not yet begun.

scholarly journals The genetic structure of admixed populations.

Genetics ◽  
1991 ◽  
Vol 127 (2) ◽  
pp. 417-428 ◽  
Author(s):  
J C Long
Keyword(s):  
Natural Selection ◽  
Genetic Structure ◽  
Genetic Drift ◽  
Hybrid Population ◽  
Fixation Index ◽  
Human Populations ◽  
Random Errors ◽  
Chi Square ◽  
Testing Procedures ◽  
Chi Square Test

Abstract A method for simultaneously estimating the admixture proportions of a hybrid population and Wright's fixation index, FST, for that hybrid is presented. It is shown that the variance of admixture estimates can be partitioned into two components: (1) due to sample size, and (2) due to evolutionary variance (i.e., genetic drift). A chi-square test used to detect heterogeneity of admixture estimates from different alleles, or loci, can now be corrected for both sources of random errors. Hence, its value for the detection of natural selection from heterogeneous admixture estimates is improved. The estimation and testing procedures described above are independent of the dynamics of the admixture process. However, when the admixture dynamics can be specified, FST can be predicted from genetic principles. Two admixture models are considered here, gene flow and intermixture. These models are of value because they lead to very different predictions regarding the accumulation of genes from the parental populations and the accumulation of variance due to genetic drift. When there is not evidence for natural selection, and it is appropriate to apply these models to data, the variance effective size (Ne) of the hybrid population can be estimated. Applications are made to three human populations: two of these are Afro-American populations and one is a Yanomamö Indian village. Natural selection could not be detected using the chi-square test in any of these populations. However, estimates of effective population sizes do lead to a richer description of the genetic structure of these populations.

Modeling Evolution in the Classroom: An Interactive LEGO Simulation

2017 ◽  
Vol 79 (2) ◽  
pp. 128-134 ◽  
Author(s):  
Abby Hongsermeier ◽  
Nealy F. Grandgenett ◽  
Dawn M. Simon
Keyword(s):  
High School ◽  
High School Students ◽  
Natural Selection ◽  
Genetic Drift ◽  
Evolutionary Theory ◽  
Introductory Biology ◽  
Comprehensive Understanding ◽  
School Students ◽  
Evolutionary Mechanisms ◽  
Biology Students

Evolutionary theory is critical for a comprehensive understanding of biology, yet students often fail to grasp its underlying principles. This results partially from ineffective teaching; however, the use of interactive activities could alleviate this problem. In this guided investigation of evolutionary mechanisms, students use LEGO bricks to simulate how mutation, migration, genetic drift, and natural selection can affect the evolution of a population. This exercise was undertaken and assessed with college introductory biology students, but is also appropriate for advanced high school students.

scholarly journals Epidemiology of Hereditary Diseases in the Karachay-Cherkess Republic

2020 ◽  
Vol 21 (1) ◽  
pp. 325 ◽  
Author(s):  
Rena A. Zinchenko ◽  
Amin Kh. Makaov ◽  
Andrey V. Marakhonov ◽  
Varvara A. Galkina ◽  
Vitaly V. Kadyshev ◽  
...  
Keyword(s):  
Ethnic Groups ◽  
Genetic Drift ◽  
Genetic Heterogeneity ◽  
Current Knowledge ◽  
Population Analysis ◽  
Demographic Data ◽  
Hereditary Diseases ◽  
Dna Polymorphisms ◽  
Human Populations ◽  
Total Prevalence

Prevalence and allelic heterogeneity of hereditary diseases (HDs) could vary significantly in different human populations. Current knowledge of HDs distribution in populations is generally limited to either European data or analyses of isolated populations which were performed several decades ago. Thus, an acknowledgement of the HDs prevalence in different modern open populations is important. The study presents the results of a genetic epidemiological study of hereditary diseases (HDs) in the population of the Karachay-Cherkess Republic (KChR). Clinical screening of a population of 410,367 people for the identification of HDs was conducted. The population surveyed is represented by five major ethnic groups—Karachays, Russians, Circassians, Abazins, Nogais. The study of the populations was carried out in accordance with the proprietary protocol of genetic epidemiological examination designed to identify >3500 HDs easily diagnosed during clinical examination by qualified specialists specializing in the HDs. The protocol consists of the population genetic and medical genetic sections and is intended for comprehensive population analysis based on the data on different genetic systems, including the genes of HDs, DNA polymorphisms, demographic data collected during hospital-based survey. 8950 families (with 10,125 patients) with presumably the HDs were initially identified as a result of the survey and data collection through various sources of registration (from 1156 medical workers from 163 medical institutions). A diagnosis of hereditary pathology was established in 1849 patients (from 1295 families). Two hundred and thirty nosological forms were revealed (in 1857 patients from 1295 families). The total prevalence of HDs was 1:221. Differences between populations and ethnic groups were identified: 1:350 in Russians, 1:195 in Karachays, 1:199 in Circassians, 1:218 in Abazins, 1:135 in Nogais. Frequent diseases were determined, the presence of marked genetic heterogeneity was identified during the confirmatory DNA diagnosis. To explain the reasons for the differentiation of populations by load of HD, a correlation analysis was carried out between the FST (random inbreeding) in populations and HDs load values. This analysis showed genetic drift is probably one of the leading factors determining the differentiation of KChR populations by HDs load. For the first time, the size of the load and spectrum of HDs in the populations of the KChR are determined. We have demonstrated genetic drift to be one of the main factors of the population dynamics in studied population. A significant genetic heterogeneity of HDs, both allelic and locus, was revealed in KChR.

Exploring Genetic Drift & Natural Selection through a Simulation Activity

1998 ◽  
Vol 60 (9) ◽  
pp. 681-683 ◽  
Author(s):  
Timothy J. Maret ◽  
Steven W. Rissing
Keyword(s):  
Natural Selection ◽  
Genetic Drift

The Causal Structure of Natural Selection

2021 ◽  
Author(s):  
Charles H. Pence
Keyword(s):  
Natural Selection ◽  
Case Studies ◽  
Genetic Drift ◽  
Evolutionary Theory ◽  
Causal Structure ◽  
Philosophy Of Biology ◽  
Philosophy Of Physics ◽  
Potential Value ◽  
Multi Level ◽  
Evolutionary Explanations

Recent arguments concerning the nature of causation in evolutionary theory, now often known as the debate between the 'causalist' and 'statisticalist' positions, have involved answers to a variety of independent questions – definitions of key evolutionary concepts like natural selection, fitness, and genetic drift; causation in multi-level systems; or the nature of evolutionary explanations, among others. This Element offers a way to disentangle one set of these questions surrounding the causal structure of natural selection. Doing so allows us to clearly reconstruct the approach that some of these major competing interpretations of evolutionary theory have to this causal structure, highlighting particular features of philosophical interest within each. Further, those features concern problems not exclusive to the philosophy of biology. Connections between them and, in two case studies, contemporary metaphysics and philosophy of physics demonstrate the potential value of broader collaboration in the understanding of evolution.

scholarly journals Dynamics of natural selection in two generations (on the example of the population of the Kirovograd region)

2021 ◽  
Vol 29 ◽  
pp. 152-156
Author(s):  
K. K. Kovleva ◽  
N.A. Kozak
Keyword(s):  
Natural Selection ◽  
First Generation ◽  
Second Generation ◽  
Selection Index ◽  
Genetic Load ◽  
Modern Medicine ◽  
Reproductive Age ◽  
Human Populations ◽  
Medical Histories ◽  
Total Selection

Aim. In connection with the success of modern medicine, the pressure of natural selection in various civilized human populations is weakening, which leads to the accumulation of a genetic load. The purpose of this work was to trace the change in the intensity of natural selection among population of the Kirovograd region in two successive generations. Methods. The collection of material was carried out in 2020 and 2021. Anonymous questionnaires were conducted and medical histories of women of post-reproductive age of the Kirovograd region were studied. The first generation included 40 women born in 1937–1959; the second generation consists of 273 women born in 1960–1981. Results. The total selection index was 0.27 in the first generation, and 0.37 in the second generation. The percentage of women who have not had pregnancies increased from the first generation to the second from 2.5 to 3.7, respectively. Conclusions. The index of total selection in the Kirovograd region population for one generation increased by almost one and a half times (from 0.27 to 0.37), as well as the index of differential fertility (from 0.25 to 0.35). Keywords: reproductive characteristics, Kirovograd population, Crow's index, selection, generations.

scholarly journals The collapse of genetic incompatibilities in a hybridizing population

2021 ◽  
Author(s):  
Tianzhu Xiong ◽  
James L MALLET
Keyword(s):  
Gene Regulation ◽  
Reproductive Isolation ◽  
Genetic Drift ◽  
Recombination Rate ◽  
Time Scale ◽  
Genetic Incompatibility ◽  
Genetic Process ◽  
Underlying Mechanisms ◽  
The Stability

Genetic incompatibility has long been considered to be a hallmark of speciation due to its role in reproductive isolation. Previous analyses of the stability of epistatic incompatibility show that it is subject to collapse upon hybridization. In the present work, we derive explicitly the distribution of the lifespan of two-locus incompatibilities, and show that genetic drift, along with recombination, is critical in determining the time scale of collapse. The first class of incompatibilities, where derived alleles separated in parental populations act antagonistically in hybrids, survive longer in smaller populations when incompatible alleles are (co)dominant and tightly linked, but collapse more quickly when they are recessive. The second class of incompatibilities, where fitness is reduced by disrupting co-evolved elements in gene regulation systems, collapse on a time scale proportional to the exponential of effective recombination rate. Overall, our result suggests that the effects of genetic drift and recombination on incompatibility's lifespan depend strongly on the underlying mechanisms of incompatibilities. As the time scale of collapse is usually shorter than the time scale of establishing a new incompatibility, the observed level of genetic incompatibilities in a particular hybridizing population may be shaped more by the collapse than by their initial accumulation. Therefore, a joint theory of accumulation-erosion of incompatibilities is in need to fully understand the genetic process under speciation with hybridization.

scholarly journals Evolution of gene regulatory networks by means of selection and random genetic drift

2018 ◽  
Author(s):  
Antonios Kioukis ◽  
Pavlos Pavlidis
Keyword(s):  
Natural Selection ◽  
Positive Selection ◽  
Genetic Drift ◽  
Regulatory Networks ◽  
Fitness Landscape ◽  
Random Genetic Drift ◽  
Maturation Period ◽  
Evolutionary Forces ◽  
Gene Regulatory

The evolution of a population by means of genetic drift and natural selection operating on a gene regulatory network (GRN) of an individual has not been scrutinized in depth. Thus, the relative importance of various evolutionary forces and processes on shaping genetic variability in GRNs is understudied. Furthermore, it is not known if existing tools that identify recent and strong positive selection from genomic sequences, in simple models of evolution, can detect recent positive selection when it operates on GRNs. Here, we propose a simulation framework, called EvoNET, that simulates forward-in-time the evolution of GRNs in a population. Since the population size is finite, random genetic drift is explicitly applied. The fitness of a mutation is not constant, but we evaluate the fitness of each individual by measuring its genetic distance from an optimal genotype. Mutations and recombination may take place from generation to generation, modifying the genotypic composition of the population. Each individual goes through a maturation period, where its GRN reaches equilibrium. At the next step, individuals compete to produce the next generation. As time progresses, the beneficial genotypes push the population higher in the fitness landscape. We examine properties of the GRN evolution such as robustness against the deleterious effect of mutations and the role of genetic drift. We confirm classical results from Andreas Wagner’s work that GRNs show robustness against mutations and we provide new results regarding the interplay between random genetic drift and natural selection.

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