Changes In Genotype Frequencies Research Articles

Changes in allele and genotype frequencies of PrP gene in breeds of sheep in Slovakia between 2004 and 2015

The objective of the study was to analyze the changes in allele and genotype frequencies of PrP gene in auction purebred rams of various breeds in Slovakia between 2004 and 2015. Male genotyping was done within the National Scrapie Eradication Programme by the certified laboratories. Positive changes in all breeds were found during the analyzed period. As a result of strict positive selection for ARR allele and strict negative selection for VRQ and ARQ alleles in most numerous Improved Valachian (IV) and Tsigai (TS) breeds, 94.7 % (IV) and 95.7 % (TS) of animals were included in the first and second risk (R1 and R2) groups in 2015. Frequencies of ARR allele were above 0.9 in specialized meat breeds. In Lacaune breed, frequencies of ARR, ARQ and VRQ alleles were 0.896, 0.117 and 0.003 in 2015. All purebred East Friesian males were included in R1 and R2 groups in 2015.

Measuring microbial fitness in a field reciprocal transplant experiment.

Microbial fitness is easy to measure in the laboratory, but difficult to measure in the field. Laboratory fitness assays make use of controlled conditions and genetically modified organisms, neither of which are available in the field. Among other applications, fitness assays can help researchers detect adaptation to different habitats or locations. We designed a competitive fitness assay to detect adaptation of Saccharomyces paradoxus isolates to the habitat they were isolated from (oak or larch leaf litter). The assay accurately measures relative fitness by tracking genotype frequency changes in the field using digital droplet PCR (DDPCR). We expected locally adapted S.paradoxus strains to increase in frequency over time when growing on the leaf litter type from which they were isolated. The DDPCR assay successfully detected fitness differences among S.paradoxus strains, but did not find a tendency for strains to be adapted to the habitat they were isolated from. Instead, we found that the natural alleles of the hexose transport gene we used to distinguish S.paradoxus strains had significant effects on fitness. The origin of a strain also affected its fitness: strains isolated from oak litter were generally fitter than strains from larch litter. Our results suggest that dispersal limitation and genetic drift shape S.paradoxus populations in the forest more than local selection does, although further research is needed to confirm this. Tracking genotype frequency changes using DDPCR is a practical and accurate microbial fitness assay for natural environments.

Twenty years of artificial directional selection have shaped the genome of the Italian Large White pig breed.

In this study, we investigated at the genome-wide level if 20years of artificial directional selection based on boar genetic evaluation obtained with a classical BLUP animal model shaped the genome of the Italian Large White pig breed. The most influential boars of this breed (n=192), born from 1992 (the beginning of the selection program of this breed) to 2012, with an estimated breeding value reliability of >0.85, were genotyped with the Illumina Porcine SNP60 BeadChip. After grouping the boars in eight classes according to their year of birth, filtered single nucleotide polymorphisms (SNPs) were used to evaluate the effects of time on genotype frequency changes using multinomial logistic regression models. Of these markers, 493 had a PBonferroni <0.10. However, there was an increasing number of SNPs with a decreasing level of allele frequency changes over time, representing a continuous profile across the genome. The largest proportion of the 493 SNPs was on porcine chromosome (SSC) 7, SSC2, SSC8 and SSC18 for a total of 204 haploblocks. Functional annotations of genomic regions, including the 493 shifted SNPs, reported a few Gene Ontology terms that might underly the biological processes that contributed to increase performances of the pigs over the 20years of the selection program. The obtained results indicated that the genome of the Italian Large White pigs was shaped by a directional selection program derived by the application of methodologies assuming the infinitesimal model that captured a continuous trend of allele frequency changes in the boar population.

Loci under selection during multiple range expansions of an invasive plant are mostly population specific, but patterns are associated with climate

Identifying the genes underlying rapid evolutionary changes, describing their function and ascertaining the environmental pressures that determine fitness are the central elements needed for understanding of evolutionary processes and phenotypic changes that improve the fitness of populations. It has been hypothesized that rapid adaptive changes in new environments may contribute to the rapid spread and success of invasive plants and animals. As yet, studies of adaptation during invasion are scarce, as is knowledge of the genes underlying adaptation, especially in multiple replicated invasions. Here, we quantified how genotype frequencies change during invasions, resulting in rapid evolution of naturalized populations. We used six fully replicated common garden experiments in Brazil where Pinus taeda (loblolly pine) was introduced at the same time, in the same numbers, from the same seed sources, and has formed naturalized populations expanding outward from the plantations. We used a combination of nonparametric, population genetics and multivariate statistics to detect changes in genotype frequencies along each of the six naturalization gradients and their association with climate as well as shifts in allele frequencies compared to the source populations. Results show 25 genes with significant shifts in genotype frequencies. Six genes had shifts in more than one population. Climate explained 25% of the variation in the groups of genes under selection across all locations, but specific genes under strong selection during invasions did not show climate-related convergence. In conclusion, we detected rapid evolutionary changes during invasive range expansions, but the particular gene-level patterns of evolution may be population specific.

FASTAptamer: A Bioinformatic Toolkit for High-throughput Sequence Analysis of Combinatorial Selections.

High-throughput sequence (HTS) analysis of combinatorial selection populations accelerates lead discovery and optimization and offers dynamic insight into selection processes. An underlying principle is that selection enriches high-fitness sequences as a fraction of the population, whereas low-fitness sequences are depleted. HTS analysis readily provides the requisite numerical information by tracking the evolutionary trajectory of individual sequences in response to selection pressures. Unlike genomic data, for which a number of software solutions exist, user-friendly tools are not readily available for the combinatorial selections field, leading many users to create custom software. FASTAptamer was designed to address the sequence-level analysis needs of the field. The open source FASTAptamer toolkit counts, normalizes and ranks read counts in a FASTQ file, compares populations for sequence distribution, generates clusters of sequence families, calculates fold-enrichment of sequences throughout the course of a selection and searches for degenerate sequence motifs. While originally designed for aptamer selections, FASTAptamer can be applied to any selection strategy that can utilize next-generation DNA sequencing, such as ribozyme or deoxyribozyme selections, in vivo mutagenesis and various surface display technologies (peptide, antibody fragment, mRNA, etc.). FASTAptamer software, sample data and a user's guide are available for download at http://burkelab.missouri.edu/fastaptamer.html.

Karakter Genetik Populasi Bedeng 61B Desa Wonokarto Kabupaten Lampung Timur Pasca Program Kolonisasi Pemerintah Belanda

Gene and genotype frequencies are important in a population characterizing. Based on the frequency of these gene and genotype, distinctiveness of population can be determined (Arisuryanti et al., 2007). Gene frequencies of population can be changed if there are evolutionary forces (the factors that play a role in changing the allele and genotype frequencies), such as, mutation, migration, non-random mating, genetic drift and natural selection (Arisuryanti & Daryono, 2007). Migration and genetic drift were thought to be a factor that changed alleles and genotype frequencies in the population of Lampung. Witrianto (2010) showed migration programs that were triggered by the Dutch government, it was called colonization. Therefore, in the population of Lampung, indication of changes in allele and genotype frequencies were need to be evaluated. The results showed that frequency of alleles IA, IB and IO in the population were 0.17; 0.21 and 0.62, respectively. Frequency of genotype IAIA, IAIO, IBIB, IBIO, IAIB and IOIO were 0.290; 0.2108; 0.0441; 0.2604; 0.0650 and 0.3800, respectively. Chi Square test showed that the value of X2 were 0,07 (X2 < α critical value at 5% for dF = 3). It can be concluded that alleles and genotype distribution of ABO blood system in the population were in accordance with Hardy Weinberg equilibrium law, so that the equilibrium legal status were applied in this population. Genetic drift and gene flow were not affected alleles and genotype changes. The process of microevolution were not occur in the population of people from the 61 B plot of Wonokarto village. Keywords: character of genetic population, post-colonization of Dutch government, the 61 B plot of Wonokarto village

Distribution of Hepatitis C virus genotypes among newly acquired HCV infections in British Columbia (2000-2013).

Characterization of newly acquired Hepatitis C virus (HCV) infections is important in order to understand the epidemiology and spread of HCV. To describe the Hepatitis C virus (HCV) genotype distribution of newly acquired HCV infections in the province of British Columbia for the period 2000-2013. A descriptive cross-sectional analysis of multi-year data on HCV genotypes. Time trends for the proportion of different HCV genotypes are presented only for newly acquired (incident) HCV infections. For acute cases, genotype 1a remains the dominant HCV type in circulation (50%), followed by genotype 3a (34%). HCV genotype 1b declined, while genotype 2 was relatively stable. Phylogenetically-related clusters of HCV strains were observed indicating a common source of infection. Enhanced hepatitis surveillance provides a mechanism for monitoring different HCV strains currently circulating in the community. While HCV genotype 1a continues to be the most prevalent, changes in the relative frequency of genotypes 1 and 3 have been observed. This may have important implications for the control and prevention of the infection.

Adaptation in flower form: a comparative evodevo approach.

Evolutionary developmental biology (evodevo) attempts to explain how the process of organismal development evolves, utilizing a comparative approach to investigate changes in developmental pathways and processes that occur during the evolution of a given lineage. Evolutionary genetics uses a population approach to understand how organismal changes in form or function are linked to underlying genetics, focusing on changes in gene and genotype frequencies within populations and the fixation of genotypic variation into traits that define species or evoke speciation events. Microevolutionary processes, including mutation, genetic drift, natural selection and gene flow, can provide the foundation for macroevolutionary patterns observed as morphological evolution and adaptation. The temporal element linking microevolutionary processes to macroevolutionary patterns is development: an organism's genotype is converted to phenotype by ontogenetic processes. Because selection acts upon the phenotype, the connection between evolutionary genetics and developmental evolution becomes essential to understanding adaptive evolution in organismal form and function. Here, we discuss how developmental genetic studies focused on key developmental processes could be linked within a comparative framework to study the developmental genetics of adaptive evolution, providing examples from research on two key processes of plant evodevo - floral symmetry and organ fusion - and their role in the adaptation of floral form.

Rise and Fall of a Hybrid Zone: Implications for the Roles of Aggression, Mate Choice, and Secondary Succession

Hybridization can be an important evolutionary force by generating new species and influencing evolution of parental species in multiple ways, including introgression and the consequences of hybrid vigor. Determining the ecological processes underlying evolution in hybrid zones is difficult however because it requires examining changes in both genotypic frequencies over time and corresponding ecological information, data that are rarely collected together. Here, we describe genetic and ecological aspects of a hybrid zone between the Eastern Fence Lizard, Sceloporus undulatus, and the Florida Scrub Lizard, Sceloporus woodi, occurring over at least 23 generations. The hybrid zone, discovered greater than 35 years ago using morphological characters, originally consisted of nearly even proportions of parental species and hybrids. Now, using genetic markers (species-diagnostic mtDNA sites and 6 nDNA microsatellite loci across a total of n = 117 individuals), we confirm not only that hybridization occurred but also that subsequent backcrossing has resulted in highly introgressed hybrids, with many hybrids containing mitochondrial DNA from one species on a nuclear DNA background of the other. Ecological aspects explaining these shifts in genetic composition include female mate choice, changes in habitat associated with secondary succession, and, most strongly, a hierarchy of male territorial advantage-ecological mechanisms likely to be involved in the emergence and disappearance of many animal hybrid zones. Our results suggest that genetic assimilation is not a significant threat to either species and that rather transient hybrid zones such as this may serve to increase genetic diversity and are candidates for causing genetic discordance in phylogeographic analyses.

Comparison of two molecular diagnostic tools for the quantification ofCrithidia bombi, a parasite of bumblebees

The requirements of diagnostic methods for the detection of parasites/pathogens are dependent on the overall aim of a study. Epidemiological studies tend to focus on presence/absence studies in order to unravel factors contributing to the spread of disease agents (Kleeman et al., 2002; Njiru et al., 2008; Erler et al., 2012). In contrast, studies driven by evolutionary questions might be interested in the parasite genotypes contributing to infections, in order to determine genotype by genotype interactions, local adaptation, and changes in genotype frequencies predicted by models like the Red Queen or the gene-for-gene theory for host-parasite co-evolution, the last being used mainly for plants (Flor, 1942; Bell, 1982; Decaestecker et al., 2007). Pathology studies, however, in different contexts (ecology and evolution) need the quantification of the infection rate of a host as the primary data. Due to technical advances, molecular diagnostic methods are increasingly used because of their cost effectiveness and reliability (Kelley et al., 2006; Leisova et al., 2006; Leblanc-Maridor et al., 2011). Microscopic methods are popular because very little advanced equipment is needed. However, when dealing with large samples [as in ecological studies (Salath e & Schmid-Hempel, 2011; Goulson et al., 2012)] microscopic methods require a long time to process each sample and to measure the infection rates, and this might result in increasing error rates over long periods of analyses (Pattyn et al., 2008; Lim et al., 2010). Molecular methods are more easily standardized, allowing for integrative studies andmeta-analyses. During the past years, declines of pollinators have been repeatedly reported (Biesmeijer et al., 2006; Ratnieks & Carreck, 2010; Cameron et al., 2011). Factors contributing to pollinator declines have been identified as habitat fragmentation (Murray et al., 2009; Winfree et al., 2009; Potts et al., 2010), pesticide usage (Gill et al., 2012; Henry et al., 2012; Stokstad, 2012;Whitehorn et al., 2012), and increasing parasite loads (Cox-Foster et al., 2007; vanEngelsdorp et al., 2009; Cameron et al., 2011). Thus, studies of parasites in insect pollinators are highly demanded, both from an epidemiological as well as an evolutionary point of view. Amajormodel system in evolutionary ecology of pollinators is the bumblebee (Bombus spec.) (Jordano, 1987). Bumblebees are important pollinators for crops and wild plants (Corbet et al., 1991; Lye et al., 2011; Graystock et al., 2013). Many of their biological aspects have been studied [sociality (Bourke & Ratnieks, 1999; LopezVaamonde et al., 2004; Huth-Schwarz et al., 2011), cognition (Skorupski & Chittka, 2006; Riveros & Gronenberg, 2009), ecology (Kremen et al., 2007), and host-parasite co-evolution (Schmid-Hempel, 1998)]. Bumblebees are eusocial insects with an annual life-cycle, whose colonies are founded by a single-mated queen. Their social life and low genetic diversity within a colony make them a prime target for parasites. Their social organization provides parasites with both a stable and rich environment (Schmid-Hempel, 1998). The low genetic variability within a colony, due to the single-mated and unique queen, allows parasites to easily infect an entire colony (Baer & SchmidHempel, 1999, 2001). One of the most widespread parasites in bumblebees is Crithidia bombi (Protozoa: Trypanosomatidae), a trypanosome gut parasite. Crithidia bombi decreases the chance of successful colony foundation *Correspondence: Bertrand Fouks, Institut fur Biologie,Molekulare Okologie,Martin-Luther-Universitat Halle-Wittenberg, HoherWeg 4, Halle (Saale) 06099, Germany. E-mail: bertrand.fouks@zoologie. uni-halle.de

Dramatic Changes in the Genotypic Frequencies of Target Insecticide Resistance in French Populations of &lt;I&gt;Myzus persicae&lt;/I&gt; (Hemiptera: Aphididae) Over the Last Decade

In 2001, although target site resistance against pyrethroids was wide-spread in clonal populations of Myzus persicae on oilseed rape in France (kdr), target site resistance against carbamates was rare. Starting in 2005, control failure by carbamates appeared. The current study was designed to document changes in insecticide-resistant genotype frequencies in France during the last decade. Two resistant genotypes (RGs) were dominant in populations in 2009-2010: RG1 with the kdr 1014F allele (16%), RG2 with the MACE 431F allele and the atypical s-kdr 918L allele (83%). The widespread prevalence of RG2 suggests that a substantial shift has occurred (allele 431F in < 2% individuals in 2001) presumably in response to agrichemicals. Analysis of neutral markers revealed that 2009-2010 populations were composed of two differentiated genetic pools (instead of one in 2001) and that RG2 was found in two divergent superclones of M. persicae. Possible explanations for these observed shifts in population structure and especially for the dramatic increase of the double mutant RG2 are discussed.

Experimental Test of an Eco-Evolutionary Dynamic Feedback Loop between Evolution and Population Density in the Green Peach Aphid

An eco-evolutionary feedback loop is defined as the reciprocal impacts of ecology on evolutionary dynamics and evolution on ecological dynamics on contemporary timescales. We experimentally tested for an eco-evolutionary feedback loop in the green peach aphid, Myzus persicae, by manipulating initial densities and evolution. We found strong evidence that initial aphid density alters the rate and direction of evolution, as measured by changes in genotype frequencies through time. We also found that evolution of aphids within only 16 days, or approximately three generations, alters the rate of population growth and predicts density compared to nonevolving controls. The impact of evolution on population dynamics also depended on density. In one evolution treatment, evolution accelerated population growth by up to 10.3% at high initial density or reduced it by up to 6.4% at low initial density. The impact of evolution on population growth was as strong as or stronger than that caused by a threefold change in intraspecific density. We found that, taken together, ecological condition, here intraspecific density, alters evolutionary dynamics, which in turn alter concurrent population growth rate (ecological dynamics) in an eco-evolutionary feedback loop. Our results suggest that ignoring evolution in studies predicting population dynamics might lead us to over- or underestimate population density and that we cannot predict the evolutionary outcome within aphid populations without considering population size.

Association between Rho-kinase (ROCK2) gene polymorphisms and Behçet’s disease

Behçet's disease (BD) is a multi-systemic vasculitis. The aim of this study was to investigate the association between Rho-kinase (ROCK2) gene polymorphisms and patients with BD in a Turkish population. A total of 194 BD patients and 276 healthy controls with similar age and sex were included to this study. Polymorphisms were analyzed in genomic DNA using a BioMark 96.96 dynamic array system. mRNA from blood samples was extracted, and real-time polymerase chain reaction was performed for ROCK2 gene expression. There were marked changes in both genotype (TT, 41.8%; TA, 30.3%) and allele (T, 57%; A, 43%) frequencies for the rs35768389 (Asp601Val) polymorphism in patients compared with controls (TT, 64.6%; TA, 9.4%, P < 0.0001; T, 69.3%; A, 30.7%, P = 0.0004). Although CC genotype (52.0%) of rs1515219 polymorphism were more frequent, CT genotype (27.7%) were less frequent among the patients than controls (CC, 31.7%, CT, 44.6%, P = 0.0001). There was an increase in C allele (65.8% vs 54.0%) and decrease in T allele frequencies (34.2% vs 46.0%, P = 0.001) in patients. However, no associations were found with rs726843, rs2290156, rs965665, rs10178332, rs2230774, rs6755196, rs10929732, and rs34945852 polymorphisms. There was an increase in peripheral blood mRNA ROCK2 expressions in patients. This is the first study to examine the involvement of ROCK2 gene variation in the risk of incident BD. The results strongly suggest that ROCK2 gene polymorphisms may modify individual susceptibility to BD in the Turkish population.

A Field Experiment Demonstrating Plant Life-History Evolution and Its Eco-Evolutionary Feedback to Seed Predator Populations

The extent to which evolutionary change occurs in a predictable manner under field conditions and how evolutionary changes feed back to influence ecological dynamics are fundamental, yet unresolved, questions. To address these issues, we established eight replicate populations of native common evening primrose (Oenothera biennis). Each population was planted with 18 genotypes in identical frequency. By tracking genotype frequencies with microsatellite DNA markers over the subsequent three years (up to three generations, ≈5,000 genotyped plants), we show rapid and consistent evolution of two heritable plant life-history traits (shorter life span and later flowering time). This rapid evolution was only partially the result of differential seed production; genotypic variation in seed germination also contributed to the observed evolutionary response. Since evening primrose genotypes exhibited heritable variation for resistance to insect herbivores, which was related to flowering time, we predicted that evolutionary changes in genotype frequencies would feed back to influence populations of a seed predator moth that specializes on O. biennis. By the conclusion of the experiment, variation in the genotypic composition among our eight replicate field populations was highly predictive of moth abundance. These results demonstrate how rapid evolution in field populations of a native plant can influence ecological interactions.

The Role of Clonal Interference in the Evolutionary Dynamics of Plasmid-Host Adaptation

ABSTRACTPromiscuous plasmids replicate in a wide range of bacteria and therefore play a key role in the dissemination of various host-beneficial traits, including antibiotic resistance. Despite the medical relevance, little is known about the evolutionary dynamics through which drug resistance plasmids adapt to new hosts and thereby persist in the absence of antibiotics. We previously showed that the incompatibility group P-1 (IncP-1) minireplicon pMS0506 drastically improved its stability in novel host Shewanella oneidensis MR-1 after 1,000 generations under antibiotic selection for the plasmid. The only mutations found were those affecting the N terminus of the plasmid replication initiation protein TrfA1. Our aim in this study was to gain insight into the dynamics of plasmid evolution. Changes in stability and genotype frequencies of pMS0506 were monitored in evolving populations of MR-1 (pMS0506). Genotypes were determined by sequencing trfA1 amplicons from individual clones and by 454 pyrosequencing of whole plasmids from entire populations. Stability of pMS0506 drastically improved by generation 200. Many evolved plasmid genotypes with point mutations as well as in-frame and frameshift deletions and duplications in trfA1 were observed in all lineages with both sequencing methods. Strikingly, multiple genotypes were simultaneously present at high frequencies (>10%) in each population. Their relative abundances changed over time, but after 1,000 generations only one or two genotypes dominated the populations. This suggests that hosts with different plasmid genotypes were competing with each other, thus affecting the evolutionary trajectory. Plasmids can thus rapidly improve their stability, and clonal interference plays a significant role in plasmid-host adaptation dynamics.

Single nucleotide polymorphisms in β-tubulin selected in Onchocerca volvulus following repeated ivermectin treatment: Possible indication of resistance selection

The control of onchocerciasis or river blindness by mass treatment of the population with ivermectin (IVM) has been a great success until now, so that in certain foci its elimination has become feasible. However, after more than 20 years of repeated IVM mass treatment, the disease still persists in many endemic countries. Sub-optimal responses and genetic changes have been reported in Onchocerca volvulus populations under high IVM pressure but more work is needed to determine whether resistance is developing. The situation needs to be urgently clarified to preserve the achievements of onchocerciasis control programs. In this study, O. volvulus adult worms were collected from the same individuals, before IVM exposure and following three years of annual or three-monthly treatments at 150μg/kg or 800μg/kg. Four single nucleotide polymorphisms (SNPs) occurring in the β-tubulin gene of these parasites were investigated. We found changes in genotype frequencies in O. volvulus β-tubulin gene associated with IVM treatments. The SNP at position 1545 (A/G) showed a significant increase in frequency of the less common nucleotide in the female worms following treatment. After 13 three-monthly treatments, female worm homozygotes with the less common genotype, prior to treatment, increased in frequency. The selected homozygotes, as well as heterozygotes, appeared to be less fertile (without or with very few embryonic stages in their uteri) than the wild-type homozygotes. These results provide additional evidence for genetic selection and strengthen the warning that selection for IVM resistance may be occurring in some O. volvulus populations.

Association Between Thr21Met and Ser89Asn Polymorphisms of the Urotensin-II (UTS2) Gene, Diabetes Mellitus, and Diabetic Retinopathy

Purpose: To evaluate possible role of the UTS2 gene polymorphisms (Thr21Met and Ser89Asn) in the genetic susceptibility to diabetic retinopathy (DR) in a Turkish population.Methods: Total number of 280 patients with DR (nonproliferative DR 170 and proliferative DR 110), 291 nondiabetic healthy controls, and 113 diabetic controls (without DR) were included to this study. The detection of UTS2 gene polymorphisms was achieved with PCR-RFLP technique. The Discovery Studio 2.1 program was used for molecular modeling analysis.Results: Thr21Met (T21M) and Ser89Asn (S89N) polymorphisms of the UTS2 gene were associated with the risk of developing diabetes and DR. M21M genotype frequencies were high in PDR (8.9% in diabetic control vs. 54.6% in PDR, P = 0.0092) group. Increases in 21M allele frequency (52.7% in diabetic control vs. 76.4% in PDR, P < 0.0001) frequency in PDR group were detected. However, there were no changes in genotype and allele frequencies for T21M in NPDR group. There were decreases in the S89N genotype (23.9% in diabetic control vs. 13.5%) and 89N allele frequencies (11.9% in diabetic control vs. 6.8%) in NPDR group. However, S89S genotype (76.1% in diabetic control vs. 86.4%) and 89S allele frequencies (88.1% in diabetic control vs. 93.2%) were high in NPDR group. Three haplotypes (MN, MS and TS) were associated with NPDR patients (P < 0.001), but only MN (P < 0.001) and TS haplotypes (P = 0.018) were associated in PDR group. Molecular modeling analysis showed that these two polymorphisms changed the 3D structure of UTS2, and provided interactions with neighboring residues.Conclusion: The associations between Thr21Met and Ser89Asn polymorphisms in the UTS2 gene and DR strongly suggest that these SNPs may be an important a risk factor for the development of DR in Caucasians, and could be candidate markers for earlier diagnosis and targets for DR therapy.

Development and evolution of character displacement.

Character displacement occurs when competition for either resources or successful reproduction imposes divergent selection on interacting species, causing divergence in traits associated with resource use or reproduction. Here, we describe how character displacement can be mediated either by genetically canalized changes (i.e., changes that reflect allelic or genotype frequency changes) or by phenotypic plasticity. We also discuss how these two mechanisms influence the tempo of character displacement. Specifically, we suggest that, under some conditions, character displacement mediated by phenotypic plasticity might occur more rapidly than that mediated by genetically canalized changes. Finally, we describe how these two mechanisms may act together and determine character displacement's mode, such that it proceeds through an initial phase in which trait divergence is environmentally induced to a later phase in which divergence becomes genetically canalized. This plasticity-first hypothesis predicts that character displacement should be generally mediated by ancestral plasticity and that it will arise similarly in multiple, independently evolving populations. We conclude by highlighting future directions for research that would test these predictions.

Relationships between spatio‐temporal environmental and genetic variation reveal an important influence of exogenous selection in a pupfish hybrid zone

The importance of exogenous selection in a natural hybrid zone between the pupfishes Cyprinodon atrorus and Cyprinodon bifasciatus was tested via spatio-temporal analyses of environmental and genetic change over winter, spring and summer for three consecutive years. A critical influence of exogenous selection on hybrid zone regulation was demonstrated by a significant relationship between environmental (salinity and temperature) and genetic (three diagnostic nuDNA loci) variation over space and time (seasons) in the Rio Churince system, Cuatro Ciénegas, Mexico. At sites environmentally more similar to parental habitats, the genetic composition of hybrids was stable and similar to the resident parental species, whereas complex admixtures of parental and hybrid genotypic classes characterized intermediate environments, as did the greatest change in allelic and genotypic frequencies across seasons. Within hybrids across the entire Rio Churince system, seasonal changes in allelic and genotypic frequencies were consistent with results from previous reciprocal transplant experiments, which showed C.bifasciatus to suffer high mortality (75%) when exposed to the habitat of C.atrorus in winter (extreme temperature lows and variability) and summer (abrupt salinity change and extreme temperature highs and variability). Although unconfirmed, the distributional limits of C.atrorus and C.atrorus-like hybrids appear to be governed by similar constraints (predation or competition). The argument favouring evolutionary significance of hybridization in animals is bolstered by the results of this study, which links the importance of exogenous selection in a contemporary hybrid zone between C.atrorus and C.bifasciatus to previous demonstration of the long-term evolutionary significance of environmental variation and introgression on the phenotypic diversification Cuatro Ciénegas Cyprinodon.

Temporal Changes in Genetic Variation of Boll Weevil (Coleoptera: Curculionidae) Populations, and Implications for Population Assignment in Eradication Zones

Abstract An existing microsatellite genotype database has been used for several years in population genetic assignment analyses of boll weevils, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), captured in eradication zones. It is important to update it in case of changes in genotype frequency at any of the locations over time. Such changes at neutral loci could be caused by drift, immigration, or population bottlenecks. We examined allele frequency distribution for 10 microsatellite loci to determine genetic differentiation among 10 boll weevil populations sampled from Texas and Mexico in 2009. In addition, temporal changes in genetic composition were examined in the eight populations for which samples were available from previous years. Substantial levels of spatial genetic structure were observed, with the 10 populations clustering as four major groups. Pairwise FST estimates in 2009 samples ranged from 0.001 (College Station-Cameron) to 0.492 (College Station-Ojinaga). There was little change in genetic profiles over time at four of the eight locations. Thus, for those four locations, genotype and allele frequency data can be pooled over the two sample dates, which will provide greater statistical power in future population assignment tests. However, genetic profiles changed substantially at Ojinaga, and to a lesser extent at Uvalde, Cameron, and Rosales, so the 2009 genotype data should be substituted in future analyses. Finally, populations from two new locations, Brownsville and Lockhart, TX, were sampled, genotyped, and added to the database. The addition of Lockhart is particularly important given its surprisingly high differentiation from the relatively nearby populations of Cameron and Uvalde.