Population structure of the intertidal copepod Tigriopus californicus as revealed by field manipulation of allele frequencies

Summary Allele frequencies in natural T. californicus populations were perturbed by introduction of copepods from neighboring differentiated populations. In five experiments, the Gpt ^F allele was introduced into single recipient pools at a frequency of approximately 20%. In each case, the introduced allele declined to low frequencies (<3%) in less than one month, apparently due to dilution by residents of other pools on the same outcrop. In a larger scale experiment, the Pgi ^F was introduced into four pools on a single small rock outcrop; all pools on the outcrop were subsequently monitored. While the allele frequency fell from approximately 40% to 10% during the first six weeks after the transplant, no further change in frequency was observed for the duration of the experiment (16 months). Within six weeks some spread of the allele to non-recipient pools on the same outcrop was observed; by eight months, allele frequencies in all pools on the outcrop were similar. Hence, despite the extensive turnover of subpopulations as single pools evaporate or are washed out, genetic homogeneity and stability of entire outcrops are maintained via extensive inter-pool gene flow; this contrasts sharply with the highly restricted levels of inter-outcrop gene flow.     

The Dagestan gene pool: Polymorphism of immunogenetic and biochemical markers in Kumyks

This study is a part of long-term investigations devoted to the analysis of the gene pool of Dagestan ethnic groups. The phenotype (in %), gene, and haplotype frequencies in Kumyk ethnic group are reported. A total of 39 alleles and six haplotypes of 14 loci (AB0, Rhesus, P, Levis, Kell, HP, GC, C’3, TF, 6PGD, GLO1, ESD, ACP, and PGM1) of immunobiochemical genetic marker systems were examined. Rare haplotypes of the Rhesus system were identified, including CDE in the Karabudakhkent population with the frequency of 0.030, and Cde and cdE in the Dorgeli population with the frequencies of 0.034 and 0.38, respectively. Similarly to the other ethnic populations of Dagestan examined, Kukyk populations carried rare, albeit typically “Caucasoid” gene ACP1 ^c of the AcP1 locus. The frequency of this allele in the two populations was similar, constituting 0.031 for Karabudakhkent and 0.032 for Dorgeli. In Kumyks, allele frequencies of the AB0, Rhesus, P, Lewis, Kell, HP, GC, C′3, TF, 6PGD, GLO1, ESD, ACP, but not PGM1, systems were similar to the mean allele frequencies at these loci observed in the other ethnic groups from the Dagestan, Caucasus, and the whole European historical ethnographic province. At the same time, the allele frequency values obtained were different from those for the populations of Kazakhstan, Central Asia, Siberia, and the Ruswsian Far East. Thus, the results obtained for classical genetic markers indicate that Kumyks are genetically closer to the indigenous populations of Dagestan than to Turkic-speaking populations. Analysis of the fit of the observed phenotype frequencies to the Hardy-Weinberg expectations showed that compared to other indigenous populations of Dagestan examined, in Kumyks the genetic state of the population upon random allele association was close to equilibrium. Probably, this state was determined by practical absence of the consanguineous marriages upon preservation of intra-aul endogamy.     

Frequency distributions for chloroplast genes in Chlamydomonas zygote clones: Evidence for random drift

Mitochondria and chloroplasts of eucaryotic cells contain populations of DNA molecules. In certain cases, e.g., the chloroplasts of Chlamydomonas reinhardtii and the mitochondria of Saccharomyces cerevisiae, organelles contributed by the two parents are known to fuse in the zygote, creating a single population of DNA molecules. In a cross, this population will include molecules of both parental genotypes. There is reason to suspect that organelle DNA molecules in this population are selected randomly for replication and recombination. This would result in random changes in the frequency of a particular allele or genotype within the organelle gene pool of a single zygote and also within its clone of progeny cells. A given gene frequency would increase in some zygote clones and decrease in others, analogous to random drift of gene frequencies in small Mendelian populations. To test this, we have examined the distribution of chloroplast gene frequencies among the zygote clones produced in each of a number of crosses of Chlamydomonas. These distributions are typically U or L shaped as predicted by the random drift hypothesis. They include uniparental zygote clones, in which a chloroplast allele from one parent has been fixed (frequency 100%) and the alternative allele from the other parent has been lost (frequency 0%). Among the remaining (biparental) zygote clones, there is a linear distribution of allele frequencies, showing a great increase in variance over the input frequencies. In these experiments both biparental and uniparental zygotes show a bias favoring chloroplast alleles from the mt⁺ (maternal) parent, and there is no statistically significant mode at the allele frequency of 0.5 corresponding to the equal input of alleles from the maternal and paternal (mt^?) parents. The observed distributions support the hypothesis that both uniparental inheritance and the high variance of allele frequencies among zygote clones are due to random drift of allele frequencies, coupled with a directional force which favors fixation of the maternal allele. In addition, statistical analysis of the data shows a strong but incomplete tendency for linked chloroplast markers to be fixed or lost together in uniparental zygotes. Possible cellular and molecular mechanisms for these observations are discussed.     

Frequency and effect of human apolipoprotein A-IV polymorphism on lipid and lipoprotein levels in an Icelandic population

Summary Human apolipoprotein A-IV (apo A-IV) exhibits a genetic polymorphism with two common alleles, A-IV¹ and A-IV², in Caucasian populations. We have investigated this polymorphism in the Icelandic population. The frequencies of the two alleles are significantly different from middel European populations with a higher frequency of the A-IV² allele (0.117 versus 0.077) occurring in Iceland. The alleles at the apo A-IV locus have significant effects on plasma high density lipoprotein cholesterol (HDL-C) and triglyceride levels. The average effect of the A-IV² allele is to raise HDL-C by 4.9 mg/dl and to lower triglyceride levels by 19.4mg/dl. We estimate that the genetic variability at the apo A-IV gene locus accounts for 3.1% of the total variability of HDL-C and for 2.8% of the total variability of triglycerides in the population from Iceland. This confirms and extends our previous observations on apo A-IV allele effects in Tyroleans in an independent population.     

SIMPLE GENETIC BASIS FOR IMPORTANT SOCIAL TRAITS IN THE FIRE ANT SOLENOPSIS INVICTA

Variation in queen phenotype and reproductive role in the fire ant Solenopsis invicta has been shown to have a simple genetic basis in a single introduced population in the United States. The evidence consists of an association between this variation and queen genotype at Pgm-3, a phosphoglucomutase-encoding gene. In the present study, we surveyed Pgm-3 allele and genotype frequencies in diverse populations from the native and introduced ranges of this ant to learn whether this simple genetic basis for reproductive traits is a general feature of the species or a genetic anomaly in introduced ants stemming from a recent bottleneck or the invasion of novel habitats. No egg-laying queens living in polygyne (multiple-queen) nests possessed the homozygous genotype Pgm-3^a/a in any of the study populations, yet nonreproductive females from such nests (workers as well as queens that had not yet initiated oogenesis) possessed this genotype at moderate frequencies. Remarkably, Pgm-3^a/a was the most common genotype among all classes of females, including egg-laying queens, in monogyne (single-queen) nests from all populations studied. Genotype proportions at Pgm-3 in polygyne populations typically departed strongly from the proportions expected under Hardy-Weinberg equilibrium, whereas those in monogyne populations did not. These patterns establish that a single mendelian gene influences queen reproductive role in S. invicta and that this gene uniformly is under strong directional selection in the polygyne social form only. Moreover, the perfect association of Pgm-3 genotype and reproductive role in all populations, combined with the known function of phosphoglucomutase in insect metabolism, suggest that this gene may directly influence queen phenotypes rather than merely serving as a marker for a linked gene that causes the effects.     

The dose effect ofma-l+ andry+ on xanthine dehydrogenase activity inDrosophila melanogaster

Summary Two loci,ma-l ⁺ andry ⁺, necessary for xanthine dehydrogenase activity inDrosophila melanogaster have been studied for dosage effects utilizing deficiencies and duplications induced for this purpose. Comparisons of one, two and three doses ofma-l ⁺ in the female or one and two doses in the male indicate that there is no increase in specific enzyme activity with dose. On the other hand, comparisons of one, two and three doses ofry ⁺ in the male and female reveal an increase in enzyme activity that is roughly proportional to dose. Since dosage ofry ⁺ is limiting, whereas that ofma-l ⁺ is not, the final concentration of xanthine dehydrogenase is shown to depend on the number of doses ofry ⁺.The implications of these findings with respect to the hypothesis of dosage compensation and to the mechanism of control of enzyme and protein concentration are discussed.Operated by Union Carbide Corporation for the U.S. Atomic Energy Commission.     

Evidence for intrachromosomal gene conversion in cultured mouse cells

In this report we present an experimental scheme that facilitates the study of homologous recombination between closely linked genes in cultured mammalian cells. Two different Xho I linker insertion mutants of the herpes simplex virus type 1 thymidine kinase (HTK) gene were introduced into mouse LTK^? cells as direct repeats on a plasmid carrying a dominant selectable marker. Following stabilization of these sequences in the recipient cell, selection for TK⁺ was applied to detect recombinational events between different TK^? genes. TK⁺ segregants were observed at a frequency of 10^?4–10^?5 in lines harboring both mutant genes. Control lines carrying only one type of mutant HTK gene yielded TK⁺ cells at frequencies of 10^?7 or less. Physical analysis of the TK⁺ segregants has revealed the presence of an apparently normal HTK gene that is resistant to Xho I endonuclease digestion in each TK⁺ line examined. Analyses of the TK gene pairs before and after recombination suggest that at least 50% of the recombinants are the result of nonreciprocal exchanges of genetic information, or gene conversion events.     

Origin,evolution, and population genetics of the selfish Segregation Distorter gene duplication in European and African populations of Drosophila melanogaster

Meiotic drive elements are a special class of evolutionarily “selfish genes” that subvert Mendelian segregation to gain preferential transmission at the expense of homologous loci. Many drive elements appear to be maintained in populations as stable polymorphisms, their equilibrium frequencies determined by the balance between drive (increasing frequency) and selection (decreasing frequency). Here we show that a classic, seemingly balanced, drive system is instead characterized by frequent evolutionary turnover giving rise to dynamic, rather than stable, equilibrium frequencies. The autosomal Segregation Distorter (SD) system of the fruit fly Drosophila melanogaster is a selfish coadapted meiotic drive gene complex in which the major driver corresponds to a partial duplication of the gene Ran‐GTPase activating protein (RanGAP). SD chromosomes segregate at similar, low frequencies of 1–5% in natural populations worldwide, consistent with a balanced polymorphism. Surprisingly, our population genetic analyses reveal evidence for parallel, independent selective sweeps of different SD chromosomes in populations on different continents. These findings suggest that, rather than persisting at a single stable equilibrium, SD chromosomes turn over frequently within populations.     

The effects of genetic drift during range expansion on geographical patterns of variation: a computer simulation of the colonization of Australia by Bufo marinus

A computer simulation is performed of allele frequency changes resulting from genetic drift at eleven loci during the probable course of colonization of Australia by populations of the Giant Toad, Bufo marinus. The history of twelve populations for which allele frequency data are available is modelled. Account is taken of the likely pattern of relationship among the populations, the effective size of the populations (as indicated by the observed variance of allele frequencies) and the probable isolation of the populations from each other following their separation. In all simulations, allele frequencies at some loci show a significant association with latitude while others do not. In six of ten simulations, there is a significant association between degree of variation at a locus and the presence of a latitudinal cline of allele frequencies. There are also indications of this kind of association in simulations of a uni-directional range expansion. These results demonstrate that such associations, which were also observed in the data from the actual populations, can result from genetic drift during a range expansion, and therefore cannot be taken as evidence of the action of natural selection.     

Genetic factors affecting allelic recombination at the histidine-3 locus ofNeurospora crassa

Summary In addition to the generec-4, other genetic factors affect the frequency of allelic recombination in thehis-3 locus. One dominant factor, designated asrec-6 ⁺, in association withrec-4 ⁺ causes greater reduction in prototrophic frequency than obtained withrec-4 ⁺ alone. The action ofrec 6 ⁺ in crosses recessive homozygous forrec-4 is not established at the present. The effect ofrec-6 ⁺ is recognised only with onehis-3 allele but not with another. Interaction ofrec-4 ⁺ orrec-4 with other genetic factors can give approximately ten fold variation in the prototrophic frequencies obtained with a pair of alleles. It is suggested that the control of the rate of mutations during meiosis might be one of the roles of the recombination genes.     

Hybridization between the fire-bellied toads Bombina bombina and Bombina variegata in the karst regions of Slovakia and Hungary: morphological and allozyme evidence

Geographic variability and genetic interactions in the contact zone between the fire-bellied toads, Bombina bombina and B. variegata, were studied using analysis of morphological and genetic variation in sixteen samples from the Slovak Karst and Aggtelek Karst regions. Genotype frequencies at four marker loci (Ldh-1, Mdh-1, Adk, Hem) demonstrate the existence of a hybrid zone with highly variable population structures. While some samples appear to represent panmictic hybrid populations, other samples are very heterogeneous. Pure individuals of both species occurred together with hybrids at one site. Habitat segregation among genetically differentiated demes probably causes this heterogeneity of population structures. Increased frequencies of the allele Ldh-1^M, which is present in low proportion in B. bombina south of the contact zone, were found in some hybrid populations.     

THE INTENSITY OF SELECTION ACTING ON THE COUCH POTATO GENE—SPATIAL–TEMPORAL VARIATION IN A DIAPAUSE CLINE

Cosmopolitan populations of Drosophila melanogaster have co‐opted a form of reproductive diapause to overwinter in northern populations. Polymorphism in the couch potato gene has been implicated in genetic variation for this diapause trait. Using a collection of 20 populations from Florida to Canada and 11 collections from 3 years in a Pennsylvania orchard, we estimated the allele frequencies for 15 single nucleotide polymorphisms (SNPs) in the couch potato gene. These include the specific polymorphism associated with diapause inducability. We find that the SNP polymorphism, 48034(A/T), is correlated with latitude and its frequencies are predicted by the incidence of diapause trait. We find that the clinal patterns for cpo SNPs sampled in 1997 are similar to the same SNPs sampled in 2009–2010. SNPs that show apparent associations with cpo expression are also clinal with the low‐expression allele increasing in frequency, as would be predicted from functional knockout studies of cpo. Finally, we see a significant pattern where the frequency of the diapause‐causing allele drops in frequency during the summer season, consistent with the drop in the incidence of the diapause trait. The selection required to drive this response is large, roughly 24% to 59% per generation depending on the degree of dominance.     

Distribution of Two Asian-Related Coding SNPs in the MC1R and OCA2 Genes

Very little is known about the genes and mechanisms affecting skin lightening in Asian populations. In this study, two coding SNPs, c.G1129A (R163Q) at the MC1R (melanocortin 1 receptor) gene and c.A1962G (H615R) at the OCA2 (oculocutaneous albinism type II) gene, were investigated in a total of 1,809 individuals in 16 populations from various areas. The Q163 and R615 alleles prevailed almost exclusively in East and Southeast Asian populations. Wright’s F _ST was 0.445 for R163Q and 0.385 for H615R among the 16 populations. The frequency of the Q163 allele was higher in Northeast Asians than in Southeast Asians. The frequency of the R615 allele was highest in South China and unlikely to be associated with levels of ultraviolet radiation. This allele may be a good marker to study the genetic affinity among East Asians because of its restricted distribution and marked difference in allele frequency.     

Constitutive and barbital-induced expression of the Cyp6a2 allele of a high producer strain of CYP6A2 in the genetic background of a low producer strain

The levels of one or more cytochrome P450 (CYP) enzymes and the respective mRNAs are found to be higher in insecticide-resistant insects than in susceptible insects. To understand better how insects regulate the levels of CYPs, we examined the expression of the Cyp6a2 gene in various strains of Drosophila melanogaster. We also took a transgenic approach to understand the molecular mechanisms that are involved in strain variation of Cyp6a2 expression. RNA blot analysis showed that the constitutive expression of Cyp6a2 varies from strain to strain; the level of CYP6A2 mRNA is barely detectable in the underproducer ry⁵⁰⁶ strain, whereas it is very high in the overproducer 91-R and MHIII-D23 strains. The long terminal repeat (LTR) of mobile element 17.6 that is found in the 3′ untranslated region (UTR) of the Cyp6a2 gene of some strains does not appear to have any role on the steady-state CYP6A2 mRNA level. We also found that the Cyp6a2 gene is inducible by barbital in 91-R, ry⁵⁰⁶ as well as 91-C, which carries an LTR insertion. To examine the genetic background of the underproducer ry⁵⁰⁶ strain with respect to Cyp6a2 expression, we transformed the ry⁵⁰⁶ strain with the Cyp6a2 allele of the overproducer 91-R strain (Cyp6a2-91R) and measured the constitutive and barbital-induced expression of the Cyp6a2-91R transgene in the transformed flies. The Cyp6a2-91R transgene carrying 129 bp of DNA upstream of the ATG codon did not show any constitutive or barbital-induced expression in the ry⁵⁰⁶ host genome. However, transgenes with 1331 and 985 bp upstream DNA showed similar levels of constitutive expression that were higher than that of the endogenous Cyp6a2 gene of the ry⁵⁰⁶ host strain, but lower than the expression of the same gene in the 91-R strain. Both these transgenes, with 1331 and 985 bp upstream DNA, also showed induction with 0.1 M barbital. DNA sequence analysis revealed that in both 91-R and ry⁵⁰⁶, the upstream DNA between +1 and −985 bp contains a distal and a proximal group of three potential barbie boxes, i.e. cis-elements that are thought to be involved in barbiturate-mediated induction of CYP genes. Except for four bases located near the distal cluster of barbie boxes and two other bases, the base sequence of the upstream DNA is identical in ry⁵⁰⁶ and 91-R strains. These results suggest that the underproducer ry⁵⁰⁶ strain has the trans-regulatory factors to support constitutive and induced expression of the Cyp6a2-91R allele carrying DNA between −129 and −1331 bp regions. Possible reasons for low constitutive expression of the endogenous Cyp6a2 gene and moderate level of expression of the Cyp6a2-91R allele in the ry⁵⁰⁶ genetic background are discussed.     

Allozyme variation among natural populations of Holopedium gibberum (Crustacea; Cladocera)

• 1 Holopedium gibberum, from twenty lakes in Rhode Island and Maine, were examined for allozyme variation at five loci to determine the pattern and degree of generic variation among sites and the genetic structure within individual lakes.
• 2 There were significant differences in allele frequencies among sites. Most populations were fixed for a particular allele at each locus. Only five lakes had polymorphic populations.
• 3 Polymorphic populations showed significant deviation from expected Hardy-Weinberg genotype frequencies. In each case, there was an excess of homozygotes.
• 4 Two lakes were examined for intra-lake allele frequency differences. In one lake there were no differences. The other lake exhibited significant allele frequency differences between stations at the north and south ends of the lake.
• 5 Populations were examined for the frequency distribution of composite genotypes over three loci. Most populations were dominated by one or two genotypes.
• 6 The results suggest sporadic sexual recruitment and a high degree of genetic isolation among these populations of H. gibberum. In these respects they resemble the permanent pond populations of Daphnia magna examined by Hebert (1974a).

     

Latitudinal cline in allele length provides evidence for selection in a circadian rhythm gene

Divergent natural selection across a heterogeneous landscape can drive the evolution of locally adapted populations in which phenotypic variation is fine‐tuned to the environment. At the molecular level, such processes can be inferred by identifying correlations between genetic variation and environmental variables. We demonstrate that allele length and allele frequency at a regulatory circadian rhythm gene, OtsClock1b, are highly correlated (R² = 0.86, P = 1.25 × 10^?5) with latitude (a surrogate for photoperiod) in kokanee, the freshwater resident form of sockeye salmon (Oncorhynchus nerka). Two OtsClock1b alleles were identified that differed in length by seven amino acids, with the frequency of the shorter allele increasing from 50% in southern British Columbia (49°N) to complete fixation in Alaska (62°N). No such associations were detected for neutral microsatellite loci. In addition, a kokanee population sampled from Kamchatka, Russia (55°N) fits within the North American latitudinal cline, suggesting that this pattern may be convergent across large longitudinal spatial scales. This correlation provides evidence that natural selection rather than demographic processes may drive the distribution of genetic variation at OtsClock1b in kokanee. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 869–877.     

Frequency Distribution of Esterase-5 Alleles in Two Populations of DROSOPHILA PSEUDOOBSCURA

Statistical tests comparing allele frequencies in natural populations with those predicted by various theories of genic variation depend critically on the accurate enumeration of alleles. This study used a series of five sequential electrophoretic conditions to characterize the allele frequency distributions of esterase-5 in two large population samples of Drosophila pseudoobscura from California. In Standard chromosome lines 12 electromorphs were discriminated using a single electrophoretic condition. When four additional criteria were used, the number of electromorphs increased to 41, 33 in one population and 22 in the other. Both populations had the same two alleles in high frequency, with other alleles present in frequencies of 6% or less. Although each population had a number of unique alleles, a χ² contingency test demonstrated no significant genetic divergence between them. A statistical comparison of allele frequencies in both populations with that predicted by neutral models suggests that the individual and combined distributions deviate from neutrality in the direction of purifying selection.—Sex-Ratio chromosomes differed markedly from Standard chromosomes in both allelic content and diversity. In 32 Sex-Ratio chromosomes from one population only three alleles were found, all of which were detected under the initial "standard" electrophoretic conditions. Moreover, none of these alleles was found in the Standard chromosome lines.     

Accuracy of Genomic Selection in a Rice Synthetic Population Developed for Recurrent Selection Breeding

Genomic selection (GS) is a promising strategy for enhancing genetic gain. We investigated the accuracy of genomic estimated breeding values (GEBV) in four inter-related synthetic populations that underwent several cycles of recurrent selection in an upland rice-breeding program. A total of 343 S_2:4 lines extracted from those populations were phenotyped for flowering time, plant height, grain yield and panicle weight, and genotyped with an average density of one marker per 44.8 kb. The relative effect of the linkage disequilibrium (LD) and minor allele frequency (MAF) thresholds for selecting markers, the relative size of the training population (TP) and of the validation population (VP), the selected trait and the genomic prediction models (frequentist and Bayesian) on the accuracy of GEBVs was investigated in 540 cross validation experiments with 100 replicates. The effect of kinship between the training and validation populations was tested in an additional set of 840 cross validation experiments with a single genomic prediction model. LD was high (average r² = 0.59 at 25 kb) and decreased slowly, distribution of allele frequencies at individual loci was markedly skewed toward unbalanced frequencies (MAF average value 15.2% and median 9.6%), and differentiation between the four synthetic populations was low (F_ST ≤0.06). The accuracy of GEBV across all cross validation experiments ranged from 0.12 to 0.54 with an average of 0.30. Significant differences in accuracy were observed among the different levels of each factor investigated. Phenotypic traits had the biggest effect, and the size of the incidence matrix had the smallest. Significant first degree interaction was observed for GEBV accuracy between traits and all the other factors studied, and between prediction models and LD, MAF and composition of the TP. The potential of GS to accelerate genetic gain and breeding options to increase the accuracy of predictions are discussed.     

Empirical Distributions of F ST from Large-Scale Human Polymorphism Data

Studies of the apportionment of human genetic variation have long established that most human variation is within population groups and that the additional variation between population groups is small but greatest when comparing different continental populations. These studies often used Wright’s F _ST that apportions the standardized variance in allele frequencies within and between population groups. Because local adaptations increase population differentiation, high-F _ST may be found at closely linked loci under selection and used to identify genes undergoing directional or heterotic selection. We re-examined these processes using HapMap data. We analyzed 3 million SNPs on 602 samples from eight worldwide populations and a consensus subset of 1 million SNPs found in all populations. We identified four major features of the data: First, a hierarchically F _ST analysis showed that only a paucity (12%) of the total genetic variation is distributed between continental populations and even a lesser genetic variation (1%) is found between intra-continental populations. Second, the global F _ST distribution closely follows an exponential distribution. Third, although the overall F _ST distribution is similarly shaped (inverse J), F _ST distributions varies markedly by allele frequency when divided into non-overlapping groups by allele frequency range. Because the mean allele frequency is a crude indicator of allele age, these distributions mark the time-dependent change in genetic differentiation. Finally, the change in mean-F _ST of these groups is linear in allele frequency. These results suggest that investigating the extremes of the F _ST distribution for each allele frequency group is more efficient for detecting selection. Consequently, we demonstrate that such extreme SNPs are more clustered along the chromosomes than expected from linkage disequilibrium for each allele frequency group. These genomic regions are therefore likely candidates for natural selection.     

Influence of BMI on level of circulating progenitor cells

Obesity complicates a number of diseases through mechanisms that are poorly defined. Mobilization and recruitment of progenitor cells to pathological sites is an important factor in disease progression. Here, we analyzed the influence of obesity on the systemic circulation of CD34⁺ cell populations and correlated frequencies of cells displaying previously established cell marker signatures with the BMI. Comparative analysis of peripheral blood mononuclear cells (PBMC) from 12 nonobese (BMI <30 kg/m²) and 14 obese (BMI >30 kg/m²) disease‐free donors by flow cytometry revealed that obesity is associated with a fivefold increased frequency of circulating progenitor cells (CPC), a population consisting of hematopoietic and endothelial precursors. Our data also indicate that obesity is associated with increased frequency of circulating mesenchymal stromal progenitor cells (MSC). In contrast, the frequencies of mature endothelial cells (EC) and CD34‐bright leukocytes are unaffected by obesity. Combined, our results indicate that obesity promotes mobilization of progenitor cells, which may have clinical relevance.