genetic hybridization

..Now, new genetic evidence suggests that hybrid speciation, even without polyploidy, is more common in plants and also animals than we thought...

..We demonstrate the method on allozyme data from two species of hybridizing trout, as well as on two simulated data sets...

..This process has been a major driving force behind the divergence of the angiosperms and their biodiversity...

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..callipterus mtDNA lineages, probably still during the water level low stand, and that subsequently the invading mtDNA lineage spread throughout the lake...

..Our findings challenge long-standing assumptions on patterns of reproductive isolation in chipmunks and suggest that there may be other examples of hybridization among the 23 species of Tamias that occur in western North America...

..Such rapid sequence divergence is driven by positive selection and may contribute to reproductive isolation...

..These results demonstrate the utility of hybrid zones for identifying factors contributing to isolation and verify the prediction of increased resolution relative to controlled crosses...

..A large degree of correspondence between AFLP clustering and trophic types indicated fewer cases of parallel evolution of trophic ecomorphology than previously inferred from mitochondrial data...

..These results lend credence to the view that hybridization may provide the raw material for rapid adaptation and provide a simple explanation for niche divergence and phenotypic novelty often associated with hybrid lineages...

..The review offers a handful of glimpses into these complex dynamics...

..melanogaster mothers. Implications of our findings for understanding Haldane's rule-the observation that hybrid breakdown is often specific to the heterogametic sex-are also discussed...

..These findings suggest that we should use extreme caution when interpreting single gene genealogies as species phylogenies, especially for cpDNA and mtDNA...

..Synthetic F(1) hybrids between putative diploid progenitors are additive of their parental genomes, suggesting that polyploidization rather than hybridization induces genomic changes in Tragopogon...

..melanogaster females and males of its three closest relatives. The study of this locus may shed light on the genetic control of both speciation and development...

..In contrast, increased hybrid fitness can be most readily explained through the segregation of additive genetic factors, with epistasis playing a more limited role...

..Whether a similar scenario explains the introgression into Iberian L. europaeus remains unclear but it is possible that it hybridized with already introgressed L. granatensis...

..In addition, two genes, with critical roles in sex determination and micro RNA processing, Sxl and loqs, were identified as misexpressed in hybrid female heads, potentially contributing to hybrid incompatibility...

..Rapidly evolving heterochromatic DNA sequences may be driving the evolution of this incompatibility gene...

..Given the widespread occurrence of Wolbachia among insects, it thus appears that there are multiple ways by which these endosymbionts may directly and indirectly contribute to reproductive isolation and speciation...

..Since heterogeneity of natural environments is rapidly deteriorating in most biomes, the evolutionary ecology of speciation reversal ought to be fully integrated into conservation biology...

..Finally, species richness in plants is correlated with many biological and geohistorical factors, most of which increase ecological opportunities...

..Our results imply that speciation genes can be identified by comparing genomes of interfertile native and invading species pairs...

..Concentrating on the supposed major evolutionary units, we used nuclear ribosomal (ETS) and chloroplast (trnT-trnL) sequences in order to disentangle the phylogenetic relationships and to infer the origins of the polyploids...

..Here we provide firstly a historic perspective of hybridization research, secondly a novel attempt to assess the extent of hybridization among animals and thirdly an overview of the reviews and case studies presented in this theme issue...

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..Thus, when the benefits of mate choice vary, females may radically alter their mate selection in response to their own phenotype and their environment, even to the point of choosing males of other species...

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..We show that inbreeding has no effect on transposition in the strains used, concluding that hybridization significantly increases the Osvaldo transposition rate...

..Moreover, we find that cosegregation of shape differences in different elements corresponds to developmental, rather than functional, units...

..The study illustrates how species without postmating barriers to gene exchange can alternate between convergence and divergence when environmental conditions oscillate...

..simulans lineage. Because of this transposition, a fraction of hybrids completely lack JYAlpha and are sterile, representing reproductive isolation without sequence evolution...

..Therefore, the abundance of hybrid species among grass endophytes, and their prevalence in many host populations suggests a selective advantage of hybridization for the mutualistic endophytes...

..Additional studies are needed in this group of lizards and in other codistributed groups to determine if Pleistocene climatic changes could be a general factor influencing the evolutionary history of a regional biota...

..We propose that the dosage-dependent regulation of chromatin could be a universal phenomenon affecting lethality in interspecies hybrids...

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..These results show that a lethal hybrid incompatibility has evolved as a by-product of adaptive protein evolution...

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..These results indicate that the regeneration of hybrid plants involves not only the integration of S. italica nuclear and organellar DNA, but also the genome complementation of T1 and T2...

..We analyze the behavior of these metrics by studying their least and largest values and when they achieve them. As a by-product of this study, we obtain tight bounds on the size of a tree-child time consistent phylogenetic network...

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..The aim of the present work was to analyse in more detail their geographical range in this region of overlap, to investigate intraspecific genetic variability and phylogeographic structure, and to search for possible hybrids...

..clevelandii is a diploid hybrid species derived from P. centranthifolius and P. spectabilis; and (iii) demonstrate that pollen-mediated gene flow via hummingbird vectors is prevalent in the hybrid complex...

..These chloroplast capture events, the first of which involved a now extinct haplotype, are the most likely explanation for the observed incongruencies between plastid and nuclear DNA markers...

..e. chimpanzees and gorillas) and most likely also our extinct, close relatives in the hominid lineage...

..Taken together, our results imply that even cryptic alien introgression can be highly mutagenic to a recipient plant genome...

..Results are discussed in the context of the broader question of how phenotypic diversity may be achieved in rapidly evolving systems...

..This finding confirms that inter-specific hybridization between wolves and dogs can occur in natural wolf populations. A possible correlation between hybridization and wolf population density and disturbance deserves further research...

..Our results also demonstrate that manipulation of DNA methylation can be sufficient to erect hybridization barriers, offering a potential mechanism for speciation and a means of controlling gene flow between species...

..The results of the bidimensional genomic scan showed that the genetic architecture was mainly additive or the experimental set-up did not have enough power to detect epistatic interactions...

..Other strategies, such as the use of exclusion primers, may detect rare parental repeat types in hybrids when previous hypotheses regarding the second parental species are lacking...

..muelleri). In this work, we examine the gene expression pattern in hybrid females of X. laevis x X. muelleri to determine if this asymmetrical pattern of expression also occurs in hybrid females...

..annuus and H. petiolaris. These results are consistent with the hypothesis that transgressive segregation of elemental uptake and leaf succulence contributed to the origin of salt adaptation in the diploid hybrid species H. paradoxus...

..These methods were complementary and provided comprehensive information about the genomic constitution of the plants produced...

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..The morphological similarity of most ant males, perhaps resulting from the lack of sexual conflict, may similarly contribute to the commoness of hybridization...

..A third was more likely to have heterozygote excess in ephemeral cattle ponds. These patterns indicate that admixture is influenced by complex genotype-by-environment interactions...

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..22) and UPK (1.11) indicated that marker-based selection could be relatively more efficient. The QTL on chromosome 1S for PEV was found to be most significant, where QTLs for hard endosperm starch concentration had been detected earlier...

..In turn, asexuality has permitted the perpetuation and establishment of ecologically divergent hybrid genotypes...

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..thaliana can be applied to gain insights into adaptive evolution of ecologically important traits and genome-wide processes, such as polyploidy, speciation and reticulate evolution, within and among Arabidopsis species...

..That is why the genetic skewness of hybrids becomes apparent at the skin level and corresponds to its manifestations at the organism level...

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..A combination of evolutionary processes, including incomplete lineage sorting as well as hybridization, may be responsible for the currently observed genetic patterns in hierofalcons...

..turgidum. Implications of our findings on how natural variation in the ability of Ae. tauschii to express those postzygotic reproductive phenotypes diversified and contributed to the speciation of T. aestivum are discussed...

..Due to similarities in phenotype and ecology, and the joint evolutionary history of their mtDNA sequences, the taxonomic status of K. k. kob and K. k. thomasi as separate subspecies is called into question...

..The present, preliminary survey may raise questions about the species status of these particular populations and also about the nature of the biological species concept...

..To understand speciation and the maintenance of taxa as separate entities, we need information about natural hybridization and gene flow among species...

..guttatus population revealed that the hms1 locus is polymorphic and that the incompatibility allele appears to segregate at intermediate frequency, a pattern that is consistent with either genetic drift or natural selection...

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..We propose the occurrence of a gametophytic-specific process which leads to segregation distortion at the ggi1 locus associated with gynogenetic induction with incomplete penetrance...

..The closely linked microsatellite markers identified in this study can be used to genotype parental lines for Ne1 and Ne2 or to eliminate the two hybrid necrosis genes using marker-assisted selection...

..yakuba and D. santomea. These results provide the basis for future high-resolution mapping and ultimately, molecular cloning, of the interacting genes that contribute to hybrid sterility...

..The extent of interspecific genetic divergence underlying hybrid male sterility, especially in contrast with the low degree of inviability and female sterility, is far greater than expected from previous studies...

..This hypothesis not only explains Haldane's rule in a simple way, but also suggests that genomic conflicts play a major role in evolution and speciation...

..We also observed sympatry-associated sexual dysfunction in interspecific crosses, which was consistent with the existence of reinforcement mechanisms...

..Our results illustrate the importance of distinctly defining hybrid classes in studies of reproductive isolation. To our knowledge, this is the first such detailed evolutionary analysis in endangered fish taxa...

..Because hybridization is a widespread phenomenon in birds, many of these cases might be due to interspecific gene flow...

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..The possibility of close linkage at two loci remains, but the simpler one-locus model cannot be rejected in the absence of contrary evidence...

..Hence, considerable chromosomal differences do not seem to prevent extensive gene flow...

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..These results indicate that the endemic Sorbus taxa on Arran are the products of multiple and ongoing evolutionary events. This information must be incorporated into management policies for their future conservation...

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..Thus, each lake may be viewed as a different temporal snapshot taken throughout the gradual process of speciation...

..f. rufus populations. The remaining three individuals were found to contain only markers for E. albocollaris. These results indicate that the population at Andringitra is a hybrid population between E. albocollaris and E.f. rufus...

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..Given the age of H. anomalus (> 100 000 years bp), it may be that microsatellite evidence for recurrent speciation has been eroded by mutation and gene flow through pollen...

..A total of 52 microsatellites, 159 polymorphic AFLP markers and six SNPs were mapped using the Introgression Lines generated by [1]. Map location and markers' distribution are presented...

..alba- and S. fragilis-specific markers found in both parental combinations (on average, 65.3 vs 34.7%, respectively) supports the (phylogenetic) hypothesis that S. fragilis is derived from S. alba-like progenitors...

..In addition, the results show that hybrid infertility may facilitate the process of reinforcement and speciation...

..Among the 40 isolated CA microsatellites, we noted a preponderance of compound and frequently interleaved CA-TA repeats as well as a striking polarity at the 5' end of the repeats...

..Our findings suggest that multiple substitutions driven by natural selection may be a general phenomenon required to generate hybrid incompatibility alleles...

..None of the models available in the literature can account for all of the empirical patterns. However, modified versions of the models can do so. Ways of discriminating between the different models are then discussed...

..groups, identified by Multilocus Sequence Typing (MLST), and can be localized in the genome by comparative genetic hybridization (CGH). In order to test this hypothesis, we propose to: 1) Define the allelic diversity of 1000 S...

..available in genetic hybrids of the genus Xiphophorus, in which genetic factors can be manipulated through genetic hybridization of different Xiphophorus species. Recently, UV-inducible Xiphophorus melanoma models have been developed...

..We will perform laboratory studies of tolerance and preference to understand these anomalies. Our results may be relevant to understanding the origin of species in other animal groups, including humans. ..

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..We will perform laboratory studies of tolerance and preference to understand these anomalies. Our results may be relevant to understanding the origin of species in other animal groups, including humans. ..

..The proposed research will focus on phenotypes in each of these three categories, subjecting each to a gene mapping protocol. ..

..The proposed study is relevant to public health because studies of Drosophila fertility can be applied to understanding the genetics of human fertility. ..

..We will perform laboratory studies of tolerance and preference to understand these anomalies. Our results may be relevant to understanding the origin of species in other animal groups, including humans. ..

..The proposed work represents an important step toward understanding the contribution of hybridization to adaptive evolution and speciation. ..

..Our long-term goal is to understand how animal species, including humans, arise by uncovering the genetic causes of speciation. ..

..simulans as well as several other Drosophila species will greatly enhance both the technical feasibility and the potential impact of this proposal as a model for testing functional consequences of sequence divergence. ..

..Understanding the consequences of the evolutionary patterns of these genes will help to reveal how species including humans maintain a functionally coherent genome. ..

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..This project will identify novel genes and physiological pathways affecting osteoporosis and examine how genetic and environmentally-based obesity affects bone mass, morphology and biomechanical function. ..

..Backcrossing with SM/J will be used to narrow the QTL interval for strain loss and to produce a new strain, carrying the unusual phenotypes of SM/J without requiring enforced heterozygosity at the agouti locus. ..

..Backcrossing with SM/J will be used to narrow the QTL interval for strain loss and to produce a new strain, carrying the unusual phenotypes of SM/J without requiring enforced heterozygosity at the agouti locus. ..

..These studies will increase our knowledge of the important physiological effects of dietary fat, including the genetic variants responsible for individual variations in response to a high fat diet. ..

..All female specific transcripts will be explored for their possible involvement in gametic interactions and ultimately species divergence. ..

..Since we are concentrating on hybrid inviability, some of our work will involve characterizing previously unstudied viability-essential genes and gene interactions that have functions required in all eukaryotes, including humans. ..

..I will also analyze the population dynamics and molecular evolution of the incompatibility alleles to ask whether they have adaptive value to the parental strains. ..

..The methods developed will be applicable in comparative analysis of other genomes, including those of humans and their primate relatives. ..

..These studies will increase our knowledge of the important physiological effects of dietary fat, including the genetic variants responsible for individual variations in response to a high fat diet. ..

..The outcome of these experiments will be a better understanding of the genetic, molecular, and cellular processes responsible for variation in limb growth with consequences for our understanding of pathologies of growth. ..

..This project will identify novel genes and physiological pathways affecting osteoporosis and examine how genetic and environmentally-based obesity affects bone mass, morphology and biomechanical function. ..

..We will test whether animals subjected to relatively poor pre- and neonatal environments respond more strongly to the high fat diet. We will map quantitative trait loci for these genetic maternal effects and their interaction with diet. ..

..In addition to positional cloning of the QTLs, congenic strains will be formed for each QTL and will be tested, along with the LGxSM recombinant inbred strains for a variety of obesity-related traits. ..

..This project will be the first to detect and map genes specifically affecting response to a high fat diet. ..

..The outcome of these experiments will be a better understanding of the genetic, molecular, and cellular processes responsible for variation in limb growth with consequences for our understanding of pathologies of growth. ..

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..These genic sRNAs may be responsible for sporadic gene methylation (epialleles) in ddm1. Cancer cells have similar changes in DNA methylation, which may use the same mechanism. ..

..These genic sRNAs may be responsible for sporadic gene methylation (epialleles) in ddm1. Cancer cells have similar changes in DNA methylation, which may use the same mechanism. ..

..Transposable elements and other repeats are common to all of these genomes, and may hold the key to epigenetic mechanisms of gene regulation and chromosome function. ..

..From these studies we hope to define the effective solar wavelength boundaries of melanoma, identify the class of DNA damage critical to CMM and elucidate the role of DNA repair in tumor suppression. ..

..Preliminary data suggests this mechanism is conserved in Arabidopsis. We will use each system to explore the ancient role of heterochromatin in chromosome biology. ..

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