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1.
Paul Alibert Fabienne Fel-Clair Katerina Manolakou Janice Britton-Davidian Jean-Christophe Auffray 《Evolution; international journal of organic evolution》1997,51(4):1284-1295
The effects of hybridization on developmental stability and size of tooth characters were investigated in intersubspecific crosses between random-bred wild strains of the house mouse (Mus musculus domesticus and M. m. musculus). Fluctuating asymmetry (FA) and trait size were compared within and between parental, F1, backcross, and F2 hybrid groups. The relationship between FA and reproductive fitness within the F1 hybrids was also studied. The results indicated that both FA and character size levels differed significantly between the two subspecies. The F1 hybrids and the recombined groups (backcrosses and F2 hybrids) showed heterosis for both parameters. No significant differences in the FA of fertile and sterile F1 hybrid individuals were found. Comparison of the FA levels obtained in this study with those found in wild populations from the hybrid zone in Denmark showed that the levels of FA were lower in laboratory-bred samples than in the wild populations. This study provides further evidence that, in hybrids, the developmental processes underlying most of the morphological traits we studied benefit from a heterotic effect, despite the genomic incompatibilities between the two European house mice revealed by previous genetical and parasitological studies. 相似文献
2.
Sodhi M Mukesh M Ahlawat SP Sobti RC Gahlot GC Mehta SC Prakash B Mishra BP 《Biochemical genetics》2008,46(3-4):124-136
This study aims to assess the genetic diversity and population structure of two major zebu dairy breeds (Tharparkar and Rathi)
adapted to the arid region of Rajasthan state of India. Various variability estimates indicate the existence of sufficient
within-breed genetic diversity. Mean estimates of F-statistics are significantly different from zero: F
IS = 0.112 ± 0.029, F
IT = 0.169 ± 0.033, F
ST = 0.065 ± 0.017. The overall positive value of F
IS (0.112) and an F
IT value (0.169) that is more than the F
ST (0.065) indicate departure from random mating. The drift-based estimates reflect a moderate yet significant level of breed
differentiation between the Tharparkar and Rathi breeds. The evaluation of an exact test, showing that allele frequencies
across all the loci differed significantly, supports the population differentiation. This is paralleled by the outcome of
neighbor-joining clustering based on allele-sharing distance measures. The allocation of a high percentage of individuals
(95.7%) to their population of origin and correspondence analysis further substantiates the existence of a cohesive genetic
structure in both the breeds. 相似文献
3.
M. N. Shapturenko L. A. Tarutina L. A. Mishin A. V. Kilchevsky L. V. Khotyleva 《Russian Journal of Genetics》2014,50(2):123-130
The identification of perspective parental lines for the creation of high-yield hybrids is the most labor-consuming stage of selection, because it needs extensive trials of combining ability. Based on evaluation of the genetic divergence of the parental lines, the prediction accuracy of F1 hybrids performance was investigated. The value of the divergence was calculated using biometric and molecular methods, such as inter simple sequence repeats (ISSR) and random amplified polymorphic DNA (RAPD). Based on estimates of divergence, 10 lines were chosen for cyclic cross (scheme I) and testcross (scheme II). In most crosses, the F1 hybrids were significantly superior to the parents in the main economically valuable traits. The level of heterosis was higher among hybrids of scheme I. Analysis of the relationship between parental divergence and F1 performance showed that the hybrid productivity of scheme I was predetermined by ISSR divergence in 86%, and productivity was caused by RAPD divergence in 69%, whereas the F1 yield of scheme II was not related to the value of genetic distances. Since the values of DNA divergence were closely associated both with midparent level and F1 performance, we assumed that part of the polymorphic DNA fragments of the parental lines of scheme I is related to heterotic loci (HTL), which may be considered potential key markers for the heterotic selection of the sweet pepper. 相似文献
4.
Starch gel electrophoretic analyses of crude seed extracts of Cucurbita ecuadorensis, C. maxima, their F1 and F2, and three of the four possible interspecific backcrosses reveal that the genus is polymorphic for alpha-naphthyl acetate esterases (Est) and leucine aminopeptidase (LAP). The two electrophoretic forms of both Est and LAP are controlled by codominant alleles. The two loci do not exhibit linkage. Neither the LAP nor the Est phenotypes exhibit a significant deviation from the expected 1:1 ratio in interspecific backcrosses when the donor parent alleles are transmitted through female gametes, but there is a significant deviation for Est when transmission is through male gametes. Differential gametic selection involving the Est-1 locus suggests structural differences between the genomes of the parental species for the chromosomal region in which this locus occurs. No structural differences are indicated between the parental genomes for the chromosome region bearing the Lap-1 locus. 相似文献
5.
Molecular divergence and hybrid performance in rice 总被引:42,自引:0,他引:42
Qifa Zhang Y. J. Gao M. A. Saghai Maroof S. H. Yang J. X. Li 《Molecular breeding : new strategies in plant improvement》1995,1(2):133-142
This study was undertaken to determine the relationship between genetic distance of the parents based on molecular markers and F1 performance in a set of diallel crosses involving eight commonly used parental lines in hybrid rice production. The F1s and their parents were measured for five traits including heading date, plant height, straw weight, grain yield and biomass. The parental lines were assayed for DNA polymorphisms using two classes of markers: 140 probes for restriction fragment length polymorphisms (RFLPs) and 12 simple sequence repeats (SSRs), resulting in a total of 105 polymorphic markers well spaced along the 12 rice chromosomes. SSRs detected more polymorphism than RFLPs among the eight lines. A cluster analysis based on marker genotypes separated these eight lines into three groups which agree essentially with the available pedigree information. Correlations were mostly low between general heterozygosity based on all the markers and F1 performance and heterosis. In contrast, very high correlations were detected between midparent heterosis and specific heterozygosity based on the markers that detected significant effects for all the five traits; these correlations may have practical utility in predicting heterosis. The analyses also suggest the existence of two likely heterotic groups in the rice germplasm represented by these eight lines. 相似文献
6.
A probit analysis of the dosage-response of two isolates of Spodoptera frugiperda to a single nuclear polyhedrosis virus revealed a greater than 5-fold difference in the LD50. The response of F1 progeny of reciprocal crosses between the two parental isolates demonstrated that resistance to the virus is not sex-linked. The LD50 values of F1 and F2 backcrosses suggest that the major variation in resistance is due to a single gene or genes that lack dominance. 相似文献
7.
E. F. Legner 《BioControl》1991,36(1):1-18
Estimates of the minimum number of genetic loci governing expressions of gregarious oviposition inMuscidifurax raptorellus Kogan & Legner were enabled by the verification of recombinant males, which were secured from virgin hybrid females, formed
by crossing cohorts from solitary and gregarious populations. Examinations of parasitization behavior in female progeny that
had F1 male fathers indicated the presence of hybrids among the males. Estimates of gene number, made on the basis of variances
in P1, F1, F2 and backcross progeny, and by observing behavior in second and third order backcrosses, ranged from two to 19, with most
between two and five. However, backcrossing data suggested that at least eight loci were actively segregating for this characteristic.
Semi-dominance of the solitary trait (D=0.63 to 0.84), and unequal gene effects probably caused these gene estimated to be
lower than the actual number. Estimates of the coefficient of heritability, in the broad sense based on parental and F1 and F2 variances indicated that variability of gregarious behavior in the experimental environment was influenced >60% by genotypic
factors, offspring-parent regression analyses gave estimates >38%.
相似文献
8.
Son Le Christopher E. Harwood A. Rod Griffin Son H. Do Thinh H. Ha Wickneswari Ratnam René E. Vaillancourt 《Tree Genetics & Genomes》2017,13(5):102
We used a set of 16 SSR markers to check the identity of pure-species and hybrid clones in Vietnam’s Acacia auriculiformis, Acacia mangium, and acacia hybrid (A. mangium × A. auriculiformis) breeding programs. The statistics package HIest, applied to a large synthesized population, enabled accurate allocation of genotypes to the two pure species, F1 and F2 inter-specific hybrids and backcrosses, based on estimates of hybridity and heterozygosity. The hybridity status of putatively pure A. mangium and A. auriculiformis clones in adjacent clonal seed orchards was checked. Four out of 100 clones selected as A. mangium were found to be backcrosses (A. mangium × F1 inter-specific hybrid) while out of 96 clones selected as A. auriculiformis, two were F1 hybrids and two were backcrosses (A. auriculiformis × F1 hybrid). The markers were then applied to check the hybridity status of 160 putative acacia F1 hybrid genotypes that had been selected on morphological criteria from open-pollinated progenies collected from A. auriculiformis and A. mangium parents. Many selections based on morphology were found to be mistaken. Only thirteen of 63 clones originating from A. auriculiformis mothers were F1 hybrids, four were backcrosses, and the remaining 46 were pure A. auriculiformis. Fewer mistakes were evident for clones selected from A. mangium mothers, with 82 out of 89 clones confirmed as F1 hybrids, three as backcrosses, and four as pure A. mangium. The occurrence of F1 hybrids and backcrosses in pure-species seed orchards and their progeny shows that inter-species contamination is an issue requiring management in both pure-species and in hybrid breeding of these species in Vietnam. Examination of genetic distances among verified clones showed patterns of relatedness that were consistent with pedigree records. Implications for resource management as well as for breeding and clonal selection strategies are considered. 相似文献
9.
Leo S. Luckinbill Michael J. Clare Walter L. Krell William C. Cirocco Paula A. Richards 《Evolutionary ecology》1987,1(1):37-46
Summary Although many different physiological and biochemical changes characterize the process of senescence, little is understood of the genetic elements that determine its age of onset. We provide here the first estimates of the number of genetic factors that extend longevity inDrosophila melanogaster. Life span was measured in F1, F2 and backcrosses of true-breeding long and short-lived stocks ofD. melanogaster, established by selection. Estimates of the number of effective factors delaying senescence range from about 0.3 to 1.5, indicating control by a single factor. The distribution of longevity shows this to arise as selection acts on the short-lived parental stock. Life span is extended at the cost of early fecundity. 相似文献
10.
11.
JW Kijas JE Miller T Hadfield R McCulloch E Garcia-Gamez LR Porto Neto N Cockett 《PloS one》2012,7(7):e41508
Domestic animals are unique in that they have been organised into managed populations called breeds. The strength of genetic divergence between breeds may vary dependent on the age of the breed, the scenario under which it emerged and the strength of reproductive isolation it has from other breeds. In this study, we investigated the Gulf Coast Native breed of sheep to determine if it contains lines of animals that are sufficiently divergent to be considered separate breeds. Allele sharing and principal component analysis (PCA) using nearly 50,000 SNP loci revealed a clear genetic division that corresponded with membership of either the Florida or Louisiana Native lines. Subsequent analysis aimed to determine if the strength of the divergence exceeded that found between recognised breed pairs. Genotypes from 14 breeds sampled from Europe and Asia were used to obtain estimates of pair-wise population divergence measured as F
ST. The divergence separating the Florida and Louisiana Native (F
ST = 6.2%) was approximately 50% higher than the average divergence separating breeds developed within the same region of Europe (F
ST = 4.2%). This strongly indicated that the two Gulf Coast Native lines are sufficiently different to be considered separate breeds. PCA using small SNP sets successfully distinguished between the Florida and Louisiana Native animals, suggesting that allele frequency differences have accumulated across the genome. This is consistent with a population history involving geographic separation and genetic drift. Suggestive evidence was detected for divergence at the poll locus on sheep chromosome 10; however drift at neutral markers has been the largest contributor to the genetic separation observed. These results document the emergence of populations that can be considered separate breeds, with practical consequences for bio-conservation priorities, animal registration and the establishment of separate breed societies. 相似文献
12.
Todd Hatfield 《Environmental Biology of Fishes》1997,49(1):63-69
This paper describes patterns of developmental asymmetry in a limnetic-benthic stickleback species pair from Paxton Lake, British Columbia. Three gill raker characters and one armor character were compared among full-sib parental crosses and their hybrids (F1, F2 and backcrosses). All crosses displayed asymmetry, but no differences in mean or fluctuating asymmetry were detected among laboratory-reared crosses. When wild-caught limnetics and benthics were included in the analyses significant differences in FA among groups were detected in gill raker length and plate number. The effect appears to be solely due to wild-caught benthics, though the reasons for their greater asymmetry are unknown. The patterns in laboratory-reared crosses suggest that asymmetry is unlikely to promote reproductive isolation between the parental species. 相似文献
13.
S. W. Hussain W. M. Williams D. R. Woodfield J. G. Hampton 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(6-7):821-831
The objective of the current research was to generate a ploidy series of backcross progenies from a single triploid (2n=3x=24)
Trifolium repens×T. nigrescens F1 hybrid (3x H-6909-5). The 3x H-6909-5 plant was highly sterile and produced no seeds from approximately 3000 reciprocal backcrosses
to both parental species. Chromosome doubling by an in vitro colchicine method resulted in a marked increase in fertility.
Pollen stainability was increased from 9.9% in 3x H-6909-5 to an average of 89.2% (range 87.7–90.9%) in the three chromosome-doubled
6x H-6909-5 plants. Subsequent backcrosses of 6x H-6909-5 and interbreeding of backcross derivatives resulted in an array
of fertile hybrids at 4x, 5x and 7x levels and some aneuploids. The occurrence of 7x BC1F1 progeny from the T. repens×6x H-6909-5 (4x×6x) cross is the first unequivocal evidence of functional female 2n gametes in white clover. Meiotic pairing
in F1 and BC1F1 progeny indicated the presence of allosyndetic pairing, suggesting that genetic exchange between the two species is possible.
Received: 17 October 1996 / Accepted: 8 November 1996 相似文献
14.
Myburg AA Griffin AR Sederoff RR Whetten RW 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2003,107(6):1028-1042
Comparative genetic mapping in interspecific pedigrees presents a powerful approach to study genetic differentiation, genome evolution and reproductive isolation in diverging species. We used this approach for genetic analysis of an F1 hybrid of two Eucalyptus tree species, Eucalyptus grandis (W. Hill ex Maiden.) and Eucalyptus globulus (Labill.). This wide interspecific cross is characterized by hybrid inviability and hybrid abnormality. Approximately 20% of loci in the genome of the F1 hybrid are expected to be hemizygous due to a difference in genome size between E. grandis (640 Mbp) and E. globulus (530 Mbp). We investigated the extent of colinearity between the two genomes and the distribution of hemizygous loci in the F1 hybrid using high-throughput, semi-automated AFLP marker analysis. Two pseudo-backcross families (backcrosses of an F1 individual to non-parental individuals of the parental species) were each genotyped with more than 800 AFLP markers. This allowed construction of de novo comparative genetic linkage maps of the F1 hybrid and the two backcross parents. All shared AFLP marker loci in the three single-tree parental maps were found to be colinear and little evidence was found for gross chromosomal rearrangements. Our results suggest that hemizygous AFLP loci are dispersed throughout the E. grandis chromosomes of the F1 hybrid.Communicated by O. Savolainen 相似文献
15.
Hybridization phenomena in anurans have traditionally been studied through morphological comparisons, under the assumption that various hybrids (e.g., F1‘s, backcrosses) are predictably intermediate to parental species. We critically evaluate this assumption by examining morphology in genetically categorized hybrids between the treefrogs Hyla cinerea and H. gratiosa. A total of 202 frogs from a hybridizing population in Alabama were assayed for allozyme and mitochondrial DNA genotype and for a large suite of osteological characters. Discriminant analyses demonstrated distinct morphological separation between the genetically “pure” parental species. Morphometric analyses of genetically identified hybrids showed: 1) an extreme range of phenotypic expression within F1 and backcross classes, and 2) no apparent directional parental bias on the F1 phenotype. Had morphology alone been used as a guide, over 40 percent of the individuals with known hybrid ancestry would have been misclassified as “pure” parental species, and about 25 percent of the backcross individuals would not have been distinguished from F1‘s. These results exemplify the utility of joint comparisons of morphology and genotypic constitution in studies of natural hybridization, and they emphasize the limitations inherent in describing hybrid classes solely by morphological criteria. 相似文献
16.
Xin-Cheng Zhao Yun-Hua Yan Chen-Zhu Wang 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2006,192(10):1037-1047
Two sibling species, Helicoverpa assulta and Helicoverpa armigera both use (Z)-9-hexadecenal and (Z)-11-hexadecenal as their sex pheromone components but in almost reversed ratios, 93:7 and 3:97, respectively. H. assulta and H. armigera males performed upwind flight in response to the H. assulta sex pheromone blend (93:7). H. armigera responded strongly to the H. armigera blend (3:97), whereas H. assulta males remained inactive upon exposure to this blend. Both species gave clear dose-dependent electrophysiological responses to (Z)-11-hexadecenal. However, (Z)-9-hexadecenal evoked strong dose-dependent electrophysiological responses in H. assulta males but not in H. armigera. The two male F1 hybrids exhibited similar behavioral responses to two sex pheromone blends and electrophysiological responses to two pheromone components as H. armigera males. This indicated that H. armigera genes appear dominant in determining the behavioral response and electrophysiological responses. Behavioral and electrophysiological responses of backcrosses of male F1 hybrids (H. armigera female × H. assulta male) with female H. assulta and H. armigera were close to that of H. assulta and H. armigera, respectively. However, backcrosses of female F1 hybrids (H. assulta female × H. armigera male) with male H. assulta and H. armigera showed reduced behavioral responses but normal electrophysiological responses compared to males of the respective parental line. 相似文献
17.
Genetic structure of a hybrid zone between two violets,Viola rossii Hemsl. and V. bissetii Maxim.: dominance of F1 individuals in a narrow contact range
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The genetic composition of a hybrid zone can provide insight into the evolution of diversification in plants. We carried out morphological and amplified fragment length polymorphism analyses to investigate the genetic composition of a hybrid zone between two violets, Viola bissetii Hemsl. and Viola rossii Maxim. Our aim was to clarify the formation and maintenance of hybrids between these Viola species. We found that most hybrid individuals (V. bissetii × V. rossii) were of the F1 generation, with a few of the F2 generation. We found no backcrosses. The scarcity of post‐F1 hybrids indicates that a species barrier is established between the parental species. The F1‐dominated hybrid zone occupied only a narrow, intermediate ecotone between the parental habitats, suggesting that selection by environmental factors against hybrids may help to maintain the current conditions in this hybrid zone. 相似文献
18.
P. S. Ruban E. P. Cunningham P. M. Sharp 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,76(1):136-142
Summary The relationship between heterozygosity and the expression of heterosis at two different nutrition levels was investigated using Drosophila melanogaster. Average daily egg production and egg hatchability were measured in two parental strains and in F1, F2 and reciprocal backcross generations. Heterosis was more pronounced in the poor nutritional conditions. Two electrophoretic markers used to estimate the level of heterozygosity in F2 and backcrosses revealed an excess of heterozygous genotypes. Quantitative genetic effects (an additive line effect and individual and maternal heterosis) were estimated for both traits in the two environments. Although this model gave a reasonable fit in most cases, some epistatic interaction would have to be invoked in order to explain fully the results. 相似文献
19.
T. M. Choo 《Genetics》1981,99(3-4):525-540
By using a doubled-haploid population derived from F2 plants, additive and additive x additive genetic variances, as well as the number of segregating genes, can be estimated. An F2-derived doubled-haploid population may contain almost 50% more of the best recombinant than an F1-derived population. However, the best recombinant occurs in the same frequency in the two populations when there is no linkage between genes. The difference in the frequency of the best recombinant between F2- and F3-derived populations is small. This implies that the doubled-haploid method using F2 plants provides only slightly less opportunity for recombination than the conventional breeding methods of self-pollinating crops. In the absence of additive epistasis, a weighted mean of recombination values can be estimated using an F2-derived population and its parental lines. When additive epistasis is present, it can be estimated from doubled-haploid populations derived from two backcrosses. Studies on the linkage of quantitative characters are needed for determining whether doubled haploids should be produced from F2 or from F1 plants in a breeding program. 相似文献
20.
We analyzed polymorphism in the parental lines GK26 and Mo17 and testers Od221MV, Od308MV, and Od329 using SSR-analysis. Recombinant inbred lines (RILs) from populations F4 and F6 were genotyped at ten polymorphic loci. Allelic compositions and allele frequencies at microsatellite loci were investigated in parental lines and testers, and the best highly heterotic hybrids and their molecular genetic formulae were derived. The allelic composition of microsatellites were investigated in RILs and high-yield hybrids for the best combining ability parameters. 相似文献