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1.
The performance of hybrids relative to their parents is an important factor in speciation research. We measured the growth of 46 Saccharomyces yeast F1 interspecific and intraspecific hybrids, relative to the growth of each of their parents, in pairwise competition assays. We found that the growth of a hybrid relative to the average of its parents, a measure of mid‐parent heterosis, correlated with the difference in parental growth relative to their hybrid, a measure of phenotypic divergence, which is consistent with simple complementation of low fitness alleles in one parent by high fitness alleles in the other. Interspecific hybrids showed stronger heterosis than intraspecific hybrids. To manipulate parental phenotypic divergence independently of genotype, we also measured the competitive growth of a single interspecific hybrid relative to its parents in 12 different environments. In these assays, we not only identified a strong relationship between parental phenotypic divergence and mid‐parent heterosis as before, but, more tentatively, a weak relationship between phenotypic divergence and best‐parent heterosis, suggesting that complementation of deleterious mutations was not the sole cause of interspecific heterosis. Our results show that mating between different species can be beneficial, and demonstrate that competition assays between parents and offspring are a useful way to study the evolutionary consequences of hybridization. 相似文献
2.
Genetic differentiation along environmental clines is often observed as a result of interplay between gene flow and natural
selection. In order to understand the relative roles of these processes in shaping this differentiation, we designed a study
in which we used two approaches that have not previously been combined, the Q
ST–F
ST comparison and crossbreeding. We examined (1) interpopulation phenotypic and genetic (AFLP) variation, and (2) performance
of interpopulation hybrids in a common annual Senecio glaucus. Fitness of interpopulation hybrids (F1 and F2) was tested under simulated population natural conditions in terms of aridity
and analyzed for a relationship with (1) spatial distance and (2) environmental differences (amount of annual rainfall). While
phenotypic variation corresponded to the clinal changes in aridity along population locations, viz. narrower and longer leaves,
longer leaf outgrowths and advanced flowering in more arid environments, the F
ST < 0.1 calculated from AFLP data suggested intensive interpopulation gene flow, with little if any contribution of genetic
drift. Performance of hybrids in simulated natural environments revealed heterosis in F1, but a hybrid breakdown in F2 generation.
These effects were related to both the spatial distance between hybrid parents and their population rainfall differences.
The detected clinal phenotypic variation and outbreeding depression in F2 strongly support presence of aridity-induced clinal
natural selection, which is matched by the observed Q
ST ≫ F
ST. From this we conclude that Q
ST–F
ST comparison can detect effect of diversifying selection when patterns of phenotypic variation across sampled locations can
be reliably predicted from environmental variation. 相似文献
3.
The nature of two different SV40-transformed cell lines which are temperature sensitive (ts) for the expression of the transformed phenotype has been analysed by somatic cell hybridization. Ts 23A cells are temperature sensitive in their ability to grow in medium containing low serum; in hybrids between these cells and a standard SV40-transformed BALB/c 3T3 cell line, the mutation seems to be dominant, at least for some parameters. One hundred percent of the hybrid clones have a very low efficiency of plating in medium containing 1% serum, but only 50% of them show growth inhibition in mass culture under the same conditions. Ts H615 cells revert to a normal phenotype at 39 °C for most parameters of transformation. The mutation appears to be recessive, as the hybrids generally behave like transformed cells at 39 °C. However, the expression of this mutation is not completely suppressed, since DNA synthesis after confluence shows some degree of inhibition in the hybrids at 39 °C. A considerable variation in the behavior of individual hybrid clones and in the degree of inhibition of some parameters has been observed and is discussed in terms of possible mechanism(s) of transformation. 相似文献
4.
5.
The differences between two maize (Zea mays L.) inbred lines and their F1 hybrids in their response to chilling periods of various duration (1, 2, 3 or 4 weeks) and subsequent return to optimum temperatures were analysed by the measurement of the photosystem (PS) 1 and 2 activity, the photosynthetic pigments' content and the activity of antioxidant enzymes. The PS2 activity and the chlorophyll content decreased in plants subjected to 3 or 4 weeks of chilling, but not in those subjected to 1 or 2 weeks of chilling. This decrease was more pronounced in inbreds compared to their hybrids. The activity of superoxide dismutase did not much change with the increasing length of chilling period in the inbreds but decreased in the hybrids, the glutathione reductase activity increased in both types of genotypes but more in the inbred lines, while for ascorbate peroxidase and catalase the changes in parents-hybrids relationship did not show any specific trend. The PS1 activity and the carotenoids' content was not much affected. 相似文献
6.
Ali Mohammad Banaei Moghaddam Jörg Fuchs Tobias Czauderna Andreas Houben Michael Florian Mette 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,120(2):215-226
Arabidopsis accessions Col-0 and C24 and their reciprocal hybrids were employed as a model system to investigate the potential
relationship between changes in DNA methylation, chromatin structure, endopolyploidization and gene expression in heterotic
genotypes. Nucleolus size, endopolyploidization level and distribution of DNA and histone H3 methylation at the microscopic
level does not differ between parents and their hybrids. Methylation sensitive amplified polymorphism revealed a largely constant
pattern of DNA methylation (97% of signals analyzed) after intraspecific crosses. The parental expression profile of selected
genes was maintained in hybrid offspring. No correlation was found between expression pattern and DNA methylation levels at
restriction sites within 5′ regulatory regions. Thus, the results revealed only minor changes of chromatin properties and
other nuclear features in response to intraspecific hybridization in Arabidopsis thaliana. 相似文献
7.
The river floodplain species Rorippa amphibia, Rorippa sylvestris, and their hybrid Rorippa x anceps were studied here, with the aim of identifying potential species differences with respect to flooding tolerance, and of assessing their expression in F1 hybrids. Parents and their F1 hybrids were subjected to three flooding treatments mimicking natural conditions, and growth-related and leaf morphological traits were compared. In contrast to R. sylvestris, R. amphibia responded to waterlogging by forming specialized roots, and its growth was not reduced. These traits were dominantly expressed in hybrids. Both species and the hybrids established shoot growth over 2 wk of complete submergence. Only in R. sylvestris was this not at the expense of root biomass, suggesting that R. sylvestris can photosynthesize underwater. Rorippa sylvestris also showed a hyponastic response. Hybrids were intermediate to the parents in this respect. This study shows that phenotypic expression of parental traits in F1 hybrids is mostly additive, but can also be dominant. This suggests that a large overlap in habitat use of parents and hybrids is likely. If such an overlap occurs, the main evolutionary consequences of hybridization in Rorippa will be the introgression of genes, as the hybrids are fully fertile. 相似文献
8.
Patrick A. Vigueira Jacob F. Schaefer David D. Duvernell Brian R. Kreiser 《Evolutionary ecology》2008,22(1):55-70
We assessed prezygotic (probability of spawning) and postzygotic (hatching success) reproductive isolation among the three
ecologically and morphologically similar species in the Fundulus notatus species complex. We employed a multi-generation breeding experiment to test the hypotheses that karyotypic differences, body
size differences, or geographic isolation among populations will increase pre or postzygotic reproductive barriers. Overall,
prezygotic barriers were strong and postzygotic barriers weak in crosses of non-hybrid heterospecifics (F1 hybrid crosses)
while prezygotic barriers were weaker and postzygotic barriers stronger in crosses involving hybrid individuals (F2 hybrid
crosses and backcrosses). Prezygotic barriers among the two smaller species (Fundulus notatus and F. euryzonus) broke down rapidly; first generation hybrids spawned (F2 hybrid crosses and backcrosses) as frequently as parental forms
in intraspecific crosses. There was no increase in postzygotic barriers among species with cytogenetic differences. There
were increased prezygotic, but not postzygotic, barriers among geographically isolated populations of one species. While pure
males and females were just as likely to spawn with hybrids, some types of hybrid females suffered from increased sterility,
but not inviability, over hybrid males. Female sterility was only seen in hybrids with a Fundulus euryzonus parent, while other female hybrids produced viable eggs. 相似文献
9.
We have been examining the importance of the root system on shoot growth and development using a developmentally disabled
hybrid of the common bean Phaseolus vulgaris L. Parental cultivars (P. Vulgaris cv. Redkloud of Mesoamerican origin, and P. vulgaris cv. Batt of Andean origin) grow normally, but crosses produce F1 hybrids exhibiting hybrid weakness associated with reduced
root and shoot growth. In this study, applications of benzylaminopurine (BAP) to roots of F1 hybrids increased the number
of root tips and leaves. Reciprocal grafting was used to study the effects of the root system on shoots. Grafting of roots
of the Mesoamerican cultivar onto shoots of F1 hybrids increased the cytokinin concentrations in leaves of F1 hybrids and
removed the characteristics associated with hybrid weakness. To determine whether factors in the xylem sap enhanced leaf growth,
leaf discs were incubated on sap collected from Mesoamerican and Andean cultivars. Sap from Mesoamerican plants enhanced the
growth of leaf discs excised from F1 hybrids more than sap collected from Andean cultivars. Estimates of the transport of
zeatin riboside (ZR)–type cytokinins from roots of F1 hybrids indicated that transport out of hybrid roots was reduced compared
with those transported out of Mesoamerican or Andean roots. Results suggest that ZR-type cytokinins are involved in hormonal
integration between roots and shoots of P. vulgaris and that one of the barriers to hybridization between Andean and Mesoamerican landraces is related to hormone transport.
Received October 15, 1998; accepted May 12, 1999 相似文献
10.
Andrea Šimková Michal Janáč Pavel Hyršl Vadym Krasnovyd Lukáš Vetešník 《Journal of fish biology》2021,98(4):1155-1171
Hybrid advantage, described as the superiority of hybrids in some traits over their parents and termed the “heterosis effect,” is widely documented in the case of reciprocal crosses of parental species (i.e., hybrids representing the F1 generation). In fish, high survival, fast growth and better health status have been widely documented in F1 hybrids. Nonetheless, the effects of interspecific hybridization on vigour, physiology and immunity-related traits in fish are largely unknown, especially concerning native systems of coexisting parental and hybrid genomes in the same habitat. The present study examined the potential physiological and immune aspects of hybrid heterosis by comparing condition status (measured especially by indexes), haematological profile, glucose concentration and selected parameters of non-specific and specific immunity between the evolutionarily divergent non-congeneric cyprinoid species Abramis brama and Rutilus rutilus and their hybrids representing the F1 generation, all of them caught in nature. Clear differences were documented for vigour-related, physiological and immune parameters between the two divergent species. Hybrids generally tended to express intermediate characters of the measured traits, likely generated by the evolutionary divergence of the hybridizing species; nonetheless, for some traits, hybrids exhibited a character that was more similar to one parental species than to the other. This was interpreted as the heterozygote advantage for F1 hybrids. It is suggested that a maternally inherited genetic background may potentially influence the expression of some branches of non-specific immunity or other aspects related to the fish health status. 相似文献
11.
Eduardo Crisol Ma. Liberty P. Almazan Peter W. Jones Finbarr G. Horgan 《Entomologia Experimentalis et Applicata》2013,147(1):18-32
Hybrid and pure‐line (inbred) rice [Oryza sativa L. (Poaceae)] varieties have distinct physiologies, particularly as related to their nutrient requirements. These differences could confound the results and interpretation of experiments that compare rice varieties grown in pots for their resistance and responses to herbivores. In this study, a series of experiments was conducted to identify potentially confounding interactions between pot size (soil volume), fertilizer regime, and the use of acetate insect cages with rice line type (hybrid, fertile parental inbred, and male sterile inbred) during bioassays with the brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae). The growth of hybrid rice was often limited (relatively low biomass and low grain production) compared to fertile inbred lines even in large pots (7 200 ml) and when grown without added fertilizer. Several interactions between the effects of growth conditions and line type were detected. Acetate cages caused a significant reduction in grain yield in hybrids, but not in inbreds, mainly resulting from a cage‐induced decrease in grain weight (smaller grains). Hybrids and male sterile lines often had higher root or above‐ground biomass in the largest caged pots compared with fertile inbred lines, but biomass was similar in smaller pots, indicating that the large pots allowed longer unimpeded growth of fertile inbreds, but not other line types. There were no interactions between the presence or absence of planthoppers with line type or experimental conditions. All line types were equally susceptible to planthoppers. Often the effects of planthopper feeding on plant fitness (i.e., tolerance) were apparent when plants were grown in large pots but not in small pots, particularly for hybrid lines and under high nitrogen regimes. On the basis of these results we recommend that researchers ensure that plants are not unequally stressed by inadequate growth conditions during comparative studies with herbivores on physiologically distinct rice varieties or rice species. We recommend the use of large pots (soil volume) and lower fertilizer levels with young, non‐reproductive plants during comparative bioassays with planthoppers. Field cages are recommended for hybrid‐inbred comparisons during older plant stages but these are subject to a range of other confounding variables. 相似文献
12.
The manifestation of hybrid vigor with regard to the inheritance of body weight was established as a postweaning phenomenon in rats. Liver weight gain generally corresponded to body weight gain and also reflected hybrid vigor. The protein/DNA ratios of the chromatin from livers of inbred and heterotic hybrid male rats were found to increase with increasing age in growing rats. Hybrid chromatin had higher protein/DNA ratios throughout the age range studies. The difference between hybrids and inbreds were greatest in the early postweaning stages of growth and maturation. The RNA/DNA ratios of chromatin from livers of inbred and hybrid male rats were also found to exhibit trends within certain developmental periods.This investigation was supported by matching Federal and West Virginia State funds from the Hatch 190 grant and is published with the approval of the Director of the Agricultural Station as Scientific Paper No. 1293. 相似文献
13.
Douglas W. Drury Ross C. Ehmke Victoria N. Jideonwo Michael J. Wade 《Ecology and evolution》2013,3(7):1992-2001
When hybrid inviability is an indirect by‐product of local adaptation, we expect its degree of severity between pairs of populations to vary and to be sensitive to the environment. While complete reciprocal hybrid inviability is the outcome of the gradual process of local adaptation, it is not representative of the process of accumulation of incompatibility. In the flour beetle, Tribolium castaneum, some pairs of populations exhibit complete, reciprocal F1 hybrid incompatibility while other pairs are fully or partially compatible. We characterize this naturally occurring variation in the degree and timing of expression of the hybrid incompatible phenotype to better understand the number of genes or developmental processes contributing to speciation. We assessed the morphological and developmental variation in four Tribolium castaneum populations and their 12 possible F1 hybrids at each life‐history stage from egg to adult. We find that the rate of hybrid larval development is affected in all interpopulation crosses, including those eventually producing viable, fertile adults. Hybrid incompatibility manifests early in development as changes in the duration of instars and diminished success in the transition between instars are relative to the parent populations. Parent populations with similar developmental profiles may produce hybrids with disrupted development. The degree and timing of expression of hybrid inviability depends upon populations crossed, direction of the cross, and environment in which hybrids are raised. Our findings suggest that the coordinated expression of genes involved in transitional periods of development is the underlying cause of hybrid incompatibility in this species. 相似文献
14.
浙江红花油茶(Camellia chekiangoleosa)种仁含油率和油酸含量高,广宁红花油茶(C. semiserrata)具有较强的生长势和抗性。为了利用浙江红花油茶和广宁红花油茶的优点,培育优良种质材料,该研究对浙江红花油茶与广宁红花油茶的45个F1杂交子代进行表型性状分析,以掌握杂交子代的表型性状情况,同时利用SSR标记对其进行杂种真伪鉴定,并筛选可用于油茶杂交子代鉴定的SSR标记。结果表明:(1)浙江红花油茶 × 广宁红花油茶的F1子代表现为树形高大、生长迅速且其叶脉、萼片、柱头均倾向于父本广宁红花油茶的性状,而花和叶片形态等性状与母本浙江红花油茶接近,叶片颜色与大小等特征介于双亲特征之间。(2)从32个SSR标记中筛选出了8个可区分双亲且能明确杂交子代来源的完全互补型标记,用于开展杂交子代鉴定,其中7个标记杂种鉴定效率高达100%,1个标记杂种鉴定效率为55.56%; 8个标记相互补充鉴定出45个杂交子代全是真杂种。(3)8个SSR标记对杂交子代进行的鉴定能力验证表明,利用这些SSR标记鉴定油茶杂交子代是可行的。该研究结果为油茶物种间的杂交育种提供了参考,同时也为后续油茶物种间的杂交子代SSR标记鉴定提供了依据。 相似文献
15.
Cis-transcriptional variation in maize inbred lines B73 and Mo17 leads to additive expression patterns in the F1 hybrid 总被引:2,自引:0,他引:2
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Microarray analysis of gene expression patterns in immature ear, seedling, and embryo tissues from the maize inbred lines B73 and Mo17 identified numerous genes with variable expression. Some genes had detectable expression in only one of the two inbreds; most of these genes were detected in the genomic DNA of both inbreds, indicating that the expression differences are likely caused by differential regulation rather than by differences in gene content. Gene expression was also monitored in the reciprocal F1 hybrids B73xMo17 and Mo17xB73. The reciprocal F1 hybrid lines did not display parental effects on gene expression levels. Approximately 80% of the differentially expressed genes displayed additive expression patterns in the hybrids relative to the inbred parents. The approximately 20% of genes that display nonadditive expression patterns tend to be expressed at levels within the parental range, with minimal evidence for novel expression levels greater than the high parent or less than the low parent. Analysis of allele-specific expression patterns in the hybrid suggested that intraspecific variation in gene expression levels is largely attributable to cis-regulatory variation in maize. Collectively, our data suggest that allelic cis-regulatory variation between B73 and Mo17 dictates maintenance of inbred allelic expression levels in the F1 hybrid, resulting in additive expression patterns. 相似文献
16.
17.
Tomato pollen development: stages sensitive to chilling and a natural environment for the selection of resistant genotypes 总被引:2,自引:0,他引:2
Abstract The time during which pollen development is most sensitive to chilling was investigated. Five cultivars of tomato (Lycopersicon esculentum Mill.) bearing flower buds at different stages of development were kept at 7°C for 1 week under 12-h light periods, during which time growth stopped. After returning the plants to minimum temperatures of 18°C, the presence of chromatin in the pollen was assessed daily as the flowers reached anthesis. The results suggested that there are two stages of acute sensitivity to cold during pollen development, each of which results in cold-stressed plants having pollen empty of chromatin. The first and most sensitive stage is about 11.2 d (SE = 0.3 d) before anthesis, and this is followed by a second stage of sensitivity about 5.6±0.2 d before anthesis. Flowers that had wholly developed under simulated natural temperatures that decreased diurnally from a maximum of 18°C to a minimum of 7°C also had defective pollen, but pollen of normal appearance was regained within 14°d on return to higher temperatures. Plants of L. esculentum, and a form (LA 1363) of the wild species L. hirsutum from high altitudes in the Andes, as well as F1 and F3 generations of their hybrid, were grown to the flowering stage at an altitude of 600 m in Hawaii and then grown for a further 30°d at 2000 m, where night temperature was below 10°C. The high altitude environment severely affected the quality of pollen produced and its release from the stamen in L. esculentum, but not in L. hirsutum LA 1363. The results with the hybrids suggested that such tropical mountain environments can be used as a natural phytotron in the selection of chilling resistance that is only expressed in the mature plant. 相似文献
18.
Taichi A. Suzuki Michael W. Nachman 《Evolution; international journal of organic evolution》2015,69(9):2468-2481
In mammals, intrinsic postzygotic isolation has been well studied in males but has been less studied in females, despite the fact that female gametogenesis and pregnancy provide arenas for hybrid sterility or inviability that are absent in males. Here, we asked whether inviability or sterility is observed in female hybrids of Mus musculus domesticus and M. m. musculus, taxa which hybridize in nature and for which male sterility has been well characterized. We looked for parent‐of‐origin growth phenotypes by measuring adult body weights in F1 hybrids. We evaluated hybrid female fertility by crossing F1 females to a tester male and comparing multiple reproductive parameters between intrasubspecific controls and intersubspecific hybrids. Hybrid females showed no evidence of parent‐of‐origin overgrowth or undergrowth, providing no evidence for reduced viability. However, hybrid females had smaller litter sizes, reduced embryo survival, fewer ovulations, and fewer small follicles relative to controls. Significant variation in reproductive parameters was seen among different hybrid genotypes, suggesting that hybrid incompatibilities are polymorphic within subspecies. Differences in reproductive phenotypes in reciprocal genotypes were observed and are consistent with cyto‐nuclear incompatibilities or incompatibilities involving genomic imprinting. These findings highlight the potential importance of reduced hybrid female fertility in the early stages of speciation. 相似文献
19.
Time of flower anthesis in a day is thought to evolve in response to the time of pollinator activities. We studied blooming and withering time in natural populations of daylily (Hemerocallis fulva), nightlily (Hemerocallis citrina) and their hybrids, and also in an artificially obtained array of the F1 hybrids. Blooming time of H. fulva varied from 4:30 to 7:30 and H. citrina varied from 16:30 to 20:30. In a natural hybrid population, blooming time and withering time showed discontinuous bimodal distribution in spite that morphological traits of flowers showed continuous unimodal variation. Most F1 hybrids showed diurnal flowering. These findings indicate that only a few genes have strong phenotypic effect on the determination of flowering time in Hemerocallis, and suggest that the evolution from a H. fulva-like ancestor to H. citrina was not a continuous process by accumulation of minute mutations. 相似文献
20.
Heterosis for horticultural traits in Broccoli 总被引:4,自引:0,他引:4
Hale AL Farnham MW Nzaramba MN Kimbeng CA 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,115(3):351-360
Over the last three decades, broccoli (Brassica oleracea L., Italica Group) hybrids made by crossing two inbred lines replaced open-pollinated populations to become the predominant
type of cultivar. The change to hybrids evolved with little or no understanding of heterosis or hybrid vigor in this crop.
Therefore, the purpose of the present study was to determine levels of heterosis expressed by a set of hybrids derived by
crossing relatively elite, modern inbreds (n = 9). An additional objective was to determine if PCR-based marker derived genetic similarities among the parents can be
useful to predict heterosis in this crop. Thirty-six hybrids derived from a diallel mating design involving nine parents were
evaluated for five horticultural characters including the head characteristics of head weight, head stem diameter, and maturity
(e.g., days from transplant to harvest), and the plant vigor characteristics of plant height, and plant width in four environments.
A total of 409 polymorphic markers were generated by 24 AFLP, 23 SRAP and 17 SSR primer combinations. Euclidean distances
between parents were determined based on phenotypic traits. About half of the hybrids exhibited highparent heterosis for head
weight (1–30 g) and stem diameter (0.2–3.5 cm) when averaged across environments. Almost all hybrids showed highparent heterosis
for plant height (1–10 cm) and width (2–13 cm). Unlike other traits, there was negative heterosis for maturity, indicating
that heterosis for this character in hybrids is expressed as earliness. Genetic similarity estimates among the nine parental
lines ranged from 0.43 to 0.71 and were significantly and negatively correlated with highparent heterosis for all traits except
for stem diameter and days from transplant to harvest. Euclidean distances were not correlated with heterosis. With modern
broccoli inbreds, less heterosis was observed for head characteristics than for traits that measured plant vigor. In addition,
genetic similarity based on molecular markers was more highly correlated with plant vigor characteristics than head traits.
Unlike with molecular marker-based estimates of genetic similarity, euclidean distance determined using phenotypic trait data
was not predictive of heterosis. In conclusion, this study has documented heterosis in Brassica oleracea L., and the ability to predict heterosis in this crop using molecular marker-based estimates of genetic similarity among
parents used in producing the hybrid.
The contents of this publication do not necessarily reflect the views or policies of the USDA, nor does the mention of trade
names, commercial products, or organizations imply endorsement by the US Government. The cost of publishing this paper was
defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked as advertisement
solely to indicate this fact. 相似文献