共查询到20条相似文献,搜索用时 31 毫秒
1.
Five traits of early child development were studied in 656 infants from the day of birth till 2 years of age. The infants
selected for follow-up were born at 26–42 weeks of gestational age and with a birth weight accordingly ranging from 860 to
4560g. Analysis of variance was carried out for each of the following five traits which entailed the age at which a child:
1) turned himself over (turned); 2) sat unsupported for a few seconds (sat); 3) stood up (stood); 4) walked unsupported (walked);
and 5) cut its first tooth (tooth). The results of this survey show no significant sex differences in the age of initial occurrence
of any of the studied traits. Comparison with older siblings of the surveyed infants indicated a significant sibling resemblance
component for all 5 trais, with the respective intraclass correlation coefficients ranging between 0.34 and 0.53. Gestational
age and birth weight, but not “tooth”, appeared to be important messages of an infant's motor development, insofar as onset
of the studied traits. The separate correlations of “turned”, “sat”, “stood” and “walked” with gestational age or weight were
all negative and statistically highly significant.
Research Unit — Human Population Biology, Division of Anatomy and Anthropology 相似文献
2.
Takashi Torigoe 《Primates; journal of primatology》1987,28(4):497-506
A captive troop of Japanese monkeys (Macaca fuscata) was presented with a nylon rope, a wooden cube, and an iron tube, and their subsequent manipulations were observed in detail.
In total, 202 manipulation patterns were distinguished on the basis of three components: the actions performed, body-parts
used, and relations to other objects. The developmental changes in these modes of manipulation were analyzed cross-sectionally,
revealing four characteristics: (1) the most manipulative members of the troop were those aged 2–3 and 4–6 years old; (2)
most of the manipulatory repertoire appeared by 4–6 years old; (3) actions such as Roll, Rub, and Slide and the use of bodyparts
continued to increase in variety until 4–6 years old, while the variety of other actions showed plateaus after 2–3 years old
or an earlier age; and (4) secondary manipulations appeared at 1 year old and continued to increase in variety even after
4–6 years old. 相似文献
3.
Linghe Zeng William R. Meredith Jr. Osman A. Gutiérrez Deborah L. Boykin 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(1):93-103
Genetic improvement in yield and fiber quality is needed for worldwide cotton production. Identification of molecular markers
associated with fiber-related traits can facilitate selection for these traits in breeding. This study was designed to identify
associations between SSR markers and fiber traits using an exotic germplasm population, species polycross (SP), derived from
multiple crosses among Gossypium tetraploid species. The SP population underwent 11 generations of mixed random mating and selfing followed by 12 generations
of selfing. A total of 260 lines were evaluated for fiber-related traits under three environments in 2005 and 2006. Large
genotypic variance components in traits were identified relative to components of genotype × environment. Eighty-six primer
pairs amplified a total of 314 polymorphic fragments among 260 lines. A total of 202 fragments with above 6% allele frequency
were analyzed for associations. Fifty-nine markers were found to have a significant (P < 0.05, 0.01, or 0.001) association with six fiber traits. There were six groups identified within the population using structure
analysis. Allele frequency divergence among six groups ranged from 0.11 to 0.27. Of the 59 marker–trait associations, 39 remained
significant after correction for population structure and kinship using a mixed linear model. The effect of population sub-structure
on associations was most significant in boll weight among the traits analyzed. The sub-structure among the SP lines may be
caused by natural selection, the breeding method applied during development of inbred lines, and unknown factors. The identified
marker–trait associations can be useful in breeding and help determine genetic mechanisms underlying interrelationships among
fiber traits.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Very fine roots respond to soil depth: biomass allocation,morphology, and physiology in a broad-leaved temperate forest 总被引:1,自引:0,他引:1
Naoki Makita Yasuhiro Hirano Takeo Mizoguchi Yuji Kominami Masako Dannoura Hiroaki Ishii Leena Finér Yoichi Kanazawa 《Ecological Research》2011,26(1):95-104
Very fine roots (<0.5 mm in diameter) of forest trees may serve as better indicators of root function than the traditional
category of <2 mm, but how these roots will exhibit the plasticity of species-specific traits in response to heterogeneous
soil nutrients is unknown. Here, we examined the vertical distribution of biomass and morphological and physiological traits
of fine roots across three narrow diameter classes (<0.5, 0.5–1.0, and 1.0–2.0 mm) of Quercus serrata and Ilex pedunculosa at five soil depths down to 50 cm in a broad-leaved temperate forest. In both species, biomass and the allocation of very
fine roots were higher in the surface soil but lower below 10-cm soil depth compared to values for larger roots (0.5–2.0 mm).
When we applied these diameter classes, only very fine roots of Q. serrata exhibited significant changes in specific root length (SRL; m g−1) and root nitrogen (N) concentrations with soil depth, whereas the N concentrations only changed significantly in I. pedunculosa. The SRL and root N concentrations of larger roots in the two species did not significantly differ among soil depths. Thus,
very fine roots may exhibit species-specific traits and change their potential for nutrient and water uptake in response to
soil depth by plasticity in root biomass, the length, and the N in response to available resources. 相似文献
5.
W. C. Johnson L. E. Jackson O. Ochoa R. van Wijk J. Peleman D. A. St. Clair R. W. Michelmore 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(7):1066-1073
Wild plant species are often adapted to more stressful environments than their cultivated relatives. Roots are critical in
exploiting soil resources that enable plants to withstand environmental stresses, but they are difficult to study. Cultivated
lettuce (Lactuca sativa L.) and wild L. serriola L. differ greatly in both shoot and root characteristics. Approximately 100 F2:3 families derived from an interspecific cross were evaluated in greenhouse and field experiments. In the greenhouse, root
traits (taproot length, number of laterals emerging from the taproot, and biomass) and shoot biomass were measured 4 weeks
after planting. In the field, plants were grown for 9 weeks (close to harvest maturity of the cultivated parent); mild drought
stress was induced by withholding water for 1 week, and gravimetric moisture of soil was then determined for five depth increments
between 0–100 cm. The families were genotyped using codominantly scored AFLP markers distributed throughout the genome. Composite
interval mapping was used to analyze marker-trait associations. Quantitative trait loci were identified for differences between
wild and cultivated lettuce for root architectural traits and water acquisition. Thirteen QTL were detected that each accounted
for 28–83% of the phenotypic variation. The loci for taproot length (i.e., cm taproot length g–1 plant biomass) and the ability to extract water from deep in the soil profile co-localized in the genome. These coincident
loci were identified in separate experiments. The wild L. serriola is therefore a potential source of agriculturally important alleles to optimize resource acquisition by cultivated lettuce,
thereby minimizing water and fertilizer inputs and ultimately enhancing water quality.
Received: 25 February 2000 / Accepted: 31 March 2000 相似文献
6.
Natural DNA variation at candidate loci is associated with potato chip color, tuber starch content, yield and starch yield 总被引:1,自引:0,他引:1
Li L Paulo MJ Strahwald J Lübeck J Hofferbert HR Tacke E Junghans H Wunder J Draffehn A van Eeuwijk F Gebhardt C 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2008,116(8):1167-1181
Complex characters of plants such as starch and sugar content of seeds, fruits, tubers and roots are controlled by multiple
genetic and environmental factors. Understanding their molecular basis will facilitate diagnosis and combination of superior
alleles in crop improvement programs (“precision breeding”). Association genetics based on candidate genes is one approach
toward this goal. Tetraploid potato varieties and breeding clones related by descent were evaluated for 2 years for chip
quality before and after cold storage, tuber starch content, yield and starch yield. Chip quality is inversely correlated
with tuber sugar content. A total of 36 loci on 11 potato chromosomes were evaluated for natural DNA variation in 243 individuals.
These loci included microsatellites and genes coding for enzymes that function in carbohydrate metabolism or transport (candidate
loci). The markers were used to analyze population structure and were tested for association with the tuber quality traits.
Highly significant and robust associations of markers with 1–4 traits were identified. Most frequent were associations with
chip quality and tuber starch content. Alleles increasing tuber starch content improved chip quality and vice versa. With
two exceptions, the most significant and robust associations (q < 0.01) were observed with DNA variants in genes encoding enzymes that function in starch and sugar metabolism or transport.
Comparing linkage and linkage disequilibrium between loci provided evidence for the existence of large haplotype blocks in
the breeding materials analyzed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
7.
J. A. Buso F. J. B. Reifschneider L. S. Boiteux S. J. Peloquin 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(8):1311-1319
The 2n-pollen grains formed by first-division restitution without crossover (FDR-NCO) are unique breeding tools, since they
can transmit almost 100% of non-additive genetic effects from the parent to the progeny. FDR-NCO gametes are considered superior
to those formed by FDR with crossing over (FDR-CO), which can pass on to the progenies approximately 80% of the heterozygosity
and a large fraction of the epistasis. However, 2n-pollen formation by FDR-NCO mechanism requires the incorporation (in homozygous
condition) of at least two recessive alleles. In the present work, 40 tetraploid families derived from complete 4x-2x factorial
crosses were evaluated under short-day conditions to verify whether or not the postulated genetic superiority of FDR-NCO over
FDR-CO gametes holds true for eight quantitative traits in potato. Families were derived from crosses between four 4x commercial
cultivars, and a random sample of ten diploid Solanum phureja-haploid S. tuberosum hybrids producing 2n-pollen by either FDR-CO or FDR-NCO. The results indicated no significant superiority of FDR-NCO over
FDR-CO families for total tuber yield (TTY) and six other traits (haulm maturity – HM; plant vigor – PV; plant uniformity
– PU; eye depth – ED; number of tubers per hill – NTH; and commercial over total yield index – CTI). Based upon cytological
observations, the FDR-CO and FDR-NCO gametes are expected to be genetically equivalent for all loci between the centromeres
and the chromosomal site of maximum recombination. In our experiment, differences between FDR-CO- and FDR-NCO-derived progenies
were not observed for TTY. Therefore, our results can be interpreted as additional evidence for the hypothesis that genes
with major effect on TTY expression might have a physical location between centromeres and proximal crossovers in the potato
chromosomes. In addition, a similar trend was observed for HM, PV, and ED but apparently not for commercial yield – CY (i.e.,
tubers with more than 33 mm in diameter).
Received: 21 September 1998 / Accepted: 26 October 1998 相似文献
8.
Li X Yan W Agrama H Jia L Shen X Jackson A Moldenhauer K Yeater K McClung A Wu D 《Planta》2011,234(2):347-361
Yield is the most important and complex trait for genetic improvement in crops, and marker-assisted selection enhances the
improvement efficiency. The USDA rice mini-core collection derived from over 18,000 accessions of global origins is an ideal
panel for association mapping. We phenotyped 203 O. sativa accessions for 14 agronomic traits and identified 5 that were highly and significantly correlated with grain yield per plant:
plant height, plant weight, tillers, panicle length, and kernels/branch. Genotyping with 155 genome-wide molecular markers
demonstrated 5 main cluster groups. Linkage disequilibrium (LD) decayed at least 20 cM and marker pairs with significant LD
ranged from 4.64 to 6.06% in four main groups. Model comparisons revealed that different dimensions of principal component
analysis affected yield and its correlated traits for mapping accuracy, and kinship did not improve the mapping in this collection.
Thirty marker–trait associations were highly significant, 4 for yield, 3 for plant height, 6 for plant weight, 9 for tillers,
5 for panicle length and 3 for kernels/branch. Twenty-one markers contributed to the 30 associations, because 8 markers were
co-associated with 2 or more traits. Allelic analysis of OSR13, RM471 and RM7003 for their co-associations with yield traits
demonstrated that allele 126 bp of RM471 and 108 bp of RM7003 should receive greater attention, because they had the greatest
positive effect on yield traits. Tagging the QTLs responsible for multiple yield traits may simultaneously help dissect the
complex yield traits and elevate the efficiency to improve grain yield using marker-assisted selection in rice. 相似文献
9.
P. Y. Jui T. M. Choo K. M. Ho T. Konishi R. A. Martin 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(5):549-556
A study was conducted on a two-row/six-row cross of barley to (1) determine the yield potential, (2) detect epistasis and
genetic correlations, (3) estimate the heritabilities of six agronomic traits, and (4) study the effect of the V locus on the agronomic traits in the barley cross. The effects of five other marker loci (Re2, s, R, Est1, and Est5) on the six agronomic traits were also studied. One hundred and ninety doubled-haploid (DH) lines were derived from a ‘Leger’/CI9831
cross using the bulbosum method. The DH lines and the two parents were tested for grain yield, test weight, seed weight, plant
height, lodging, and heading/maturity at two locations in Eastern Canada in 1993. Additive×additive epistasis and genetic
correlations were detected for some of the agronomic traits. Many of the heritability estimates were high; however, significant
progress in yield improvement would be difficult to achieve because of a low mean yield of the DH lines. Under the growing
conditions in Eastern Canada, six-row lines outyielded two-row by 20–27%. Six-row lines, however, were associated with low
test weight, low seed weight, and severe lodging. Some two-row lines yielded higher than the two-row parent CI9831, but none
of the six-row lines yielded higher than the six-row parent ‘Leger’. The R, s, and Est5 loci were associated with the six agronomic traits, but the Est1 locus was apparently not associated with the agronomic traits. The effect of the Re2 locus was probably due to its close linkage with the V locus. Further studies are needed to determine if superior six-row lines can be developed from two-row/six-row crosses.
Received: 19 September 1996 / Accepted: 18 October 1996 相似文献
10.
Summary Mound-shaped algal banks and associated bioclastic deposits have been investigated on the Apulian shelf, SE Italy, off Capo
d’Otranto and Santa Maria di Leuca within a bathymetric range of 53–60m water depth. The bioclastic deposits form different
sand-gravel skeletal assemblages; each one characterised by different associations and occurrence of prevailing organisms
in relation to substratum types. These deposits lie on a lee shore and form rhodalgal and bryomol relict-modern deposits which
originate from the banks’ erosion by means of bottom currents and storms. These play a significant role in reworking bottom
preventing colonization by a sessile stabilizing bottom community, and mobile deposits prevent large encrustations. Sediments
are thus characterised by a variable taphonomical preservation state and time-averaging as shown by the occurrence of abraded
bryozoan growth forms. The banks, sub-circular in shape, display a maximum diameter of 70 m and 1–2m relief. Their position
on the shelf coincides with the present day 50 m isobath and it is assumed to correspond to a paleoshore such as that which
formed in the Holocene during the transgression following the last ice age. Living counterparts of these banks occur today
north of the study area at 10–30 m water depth. 相似文献
11.
Three categories of wetland assessment methods have been recognized by the United States Environmental Protection Agency,
including Level 1—Landscape-scale Assessment; Level 2—Rapid Field Methods; and Level 3—Intensive Biological and Physico–Chemical
Measures. This study incorporates wetland assessment methods for each assessment level, including the Level 1 Landscape Development
Intensity (LDI) index, Level 2 Wetland Rapid Assessment Procedure (WRAP), and Level 3 Florida Wetland Condition Index (FWCI).
Using a neighborhood analysis in Geographic Information Systems (GIS), an LDI index map was created using 1995 land use, creating
a calculated LDI index value for each 30 m2 area in Florida. Level 1–3 assessment procedures were employed at 193 palustrine emergent (n = 75) and forested (n = 118) wetlands. Significant correlations were found among the multiple Level 1–3 assessment procedures using the nonparametric
Spearman’s correlation coefficient for pair-wise comparisons of LDI and WRAP, LDI and diatom FWCI, WRAP and diatom FWCI, LDI
and macrophyte FWCI, WRAP and macrophyte FWCI, LDI and macroinvertebrate FWCI, and WRAP and macroinvertebrate FWCI (|r| > 0.50, P < 0.01). Defining the relationship between Level 1–3 assessment methods may be used to estimate the more intensive and species
assemblage-specific Level 3 FWCI assessment scores for wetlands with Level 1 or Level 2 scores. Inferences can then be made
as to wetland condition based on established correlations with intensive assessment methods. 相似文献
12.
Understanding the mechanisms that determine the development of a bilaterally symmetrical trait is crucial to the interpretation
of patterns of fluctuating asymmetry (FA). Experimental and theoretical studies have indicated that feedback mechanisms both
within and between developing traits, may participate in the developmental control of asymmetry. This study provides evidence
that naturally occurring patterns of FA are affected by interactions between different traits. We found positive between‐trait
correlations in signed FA values for tibia lengths on different legs, but not between wing and tibia FA in two moth species.
Further research should investigate if trait functionality is related to this presumed correlated development. An extension
of the Rashevsky–Turing model of morphogenesis further showed that correlations between the signed FA values can be generated
by feedback mechanisms that regulate growth patterns between traits. We argue that such feedback mechanisms can be expected
to be widespread and show that between‐trait correlations in the unsigned FA then become confounded with correlations in the
signed FA. In addition, correlated development appeared to invalidate the use of the hypothetical repeatability to translate
correlations between the unsigned FA values into correlations in the presumed underlying developmental instability. In conclusion,
the presence of an organism‐wide asymmetry, which are most frequently found in morphologically integrated traits, may be even
less common than previously thought.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
The ectomycorrhizal (ECM) colonisation of seedling Sitka spruce (Picea sitchensis) was examined in an uneven-aged plantation forest in southern Scotland. The extent of ECM colonisation of individual seedlings
was 43.8–97.2%, with an overall mean of 80.3 ± 1.1%. A total of 13 ECM morphotypes were differentiated, with 1–4 ECM types
colonising an individual seedling. ECM colonisation was dominated by a single species, Tylospora
fibrillosa, which accounted for 72.4–97.7% of the ECM colonisation recorded, on a plot mean basis. Other ECM types appeared to be distributed
very patchily, only two types (Lactarius sp. and Mycelium radicis atrovirens Melin) exceeding a mean of 10% colonisation in any one plot. No significant correlations were recorded between ECM colonisation
and seedling growth, or between ECM colonisation and soil pH, loss-on-ignition, or water content.
Accepted: 16 October 1997 相似文献
14.
Guohua Yang Sansi Tu Shaoqing Li Lingling Feng Jin Kong Hui Li Yangsheng Li 《Frontiers of Biology in China》2008,3(4):443-448
A population of 117 doubled haploid (DH) lines derived from the cross of Zhaiyeqing 8 (indica)× Jingxi 17 (japonica) was employed to map quantitative trait loci (QTL) underlying four physiological traits related to chlorophyll contents of
the flag leaf. There were significantly positive correlations among chlorophyll a, chlorophyll b and chlorophyll a + b content.
Chlorophyll a/b ratio was significantly negatively correlated with chlorophyll b content. These four traits were normally
distributed with transgressive segregation, suggesting that they were controlled by multiple minor genes. A total of 11 QTLs
were detected for the four traits and they lay on six chromosomes. Each of them explained 9.2%–19.6% of the phenotypic variations,
respectively. Of these, two QTLs controlling chlorophyll a content were mapped on chromosomes 2 and 5; four QTLs underlying
chlorophyll b content were mapped on chromosomes 2, 3, 5 and 9; three QTLs underlying chlorophyll a + b amount were mapped
on chromosomes 3, 5 and 9; two QTLs underlying chlorophyll a/b ratio were mapped on chromosomes 6 and 11. The intrinsic relationship
among the four traits and the practical implication in rice breeding are discussed.
__________
Translated from Journal of Wuhan University (Science Edition), 2006, 52(6): 751–756 [译自: 武汉大学学报(理学版)] 相似文献
15.
16.
Hong Ni Xing Feng Yong Gong Lu-yang Tao Xi-ru Wu 《Biological trace element research》2011,143(1):320-331
It has been reported that autophagy and zinc transporters (ZnTs) both play the key roles in excitotoxicity, which is associated
with cognitive deficits following developmental seizures. However, the influence of autophagy on acute phase ZnTs expression
has never been studied. The present study sought to investigate the contribution of an autophagy inhibitor (3-methyladenine,
3-MA) on the regulation of ZnTs, microtubule-associated protein 1A/1B light chain 3 (LC3), and beclin-1 expression in rat
hippocampus following recurrent neonatal seizures. We examined the expression of ZnT1∼ZnT3, LC3, and beclin-1 at 1.5, 3, 6,
and 24 h after the last seizures using real-time RT-PCR and Western blot methods, respectively. The results showed that there
were upregulated expressions of ZnT-1, ZnT-2, LC3, and beclin-1 of RS group. Pretreatment with 3-MA remarkably attenuated
seizure-induced ZnT-1, ZnT-2, LC3, and beclin-1 increase. Additionally, linear correlations could be observed between LC3–Beclin1,
LC3–ZnT-2, Beclin1–ZnT2, Beclin1–ZnT3, and among ZnT1∼ZnT3 in control group, while the linear correlations could be observed
between LC3–Beclin1, Beclin1–ZnT2, and Beclin1–ZnT3 in RS group. These results demonstrate, for the first time, that there
exists an interaction of Zn2+ with autophagic signals that are immediately activated in hippocampus after recurrent neonatal seizures, which might play
a key role in neonatal seizure-induced excitotoxicity. 相似文献
17.
Fine root vertical distribution and temporal dynamics in mature stands of two enset (Enset ventricosum Welw Cheesman) clones 总被引:2,自引:0,他引:2
Quantification of the role of fine roots in the biological cycle of nutrients necessitates understanding root distribution,
estimating root biomass, turnover rate and nutrient concentrations, and the dynamics of these parameters in perennial systems.
Temporal dynamics, vertical distribution, annual production and turnover, and nitrogen use of fine roots (≤2 mm in diameter)
were studied in mature (5-year-old) stands of two enset (Ensete ventricosum) clones using the in-growth bag technique. Live fine root mass generally decreased with increasing depth across all seasons
except the dry period. Except for the dry period, more than 70% of the fine root mass was in the above 0-20 cm depth, and
the fine root mass in the upper 0–10 cm depth was significantly higher than in the lowest depth (20–30 cm). Live fine root
mass showed a seasonal peak at the end of the major rainy season but fell to its lowest value during the dry or short rainy
season. The difference between the peak and low periods were significant (p ≤ 0.05). Fine root nitrogen (N) use showed significant seasonal variation where the mean monthly fine root N use was highest
during the major rainy season. There were significant effects on N use due to depths and in-growth periods, but not due to
clones. Enset fine root production and turnover ranged from 2,339 to 2,451 kg ha−1 year−1 and from 1.55 to 1.80 year−1, respectively. Root N return, calculated from fine root turnover, was estimated at 64–65 kg ha−1 year−1. Fine root production, vertical distribution and temporal dynamics may be related to moisture variations and nutrient (N)
fluxes among seasons and along the soil depth. The study showed that fine root production and turnover can contribute considerably
to the carbon and nitrogen economy of mature enset plots. 相似文献
18.
Jose Alberto Ram��rez-Valiente Fernando Valladares Antonio Delgado Huertas S. Granados Ismael Aranda 《Tree Genetics & Genomes》2011,7(2):285-295
Increased drought severity is expected in the Mediterranean Basin over the twenty-first century, but our understanding of
the potential of most forest tree species to cope with it remains uncertain. In this study, (1) we examined the potential
effects of long-term selection and the capacity to respond to future changes in selective pressures in three populations of
cork oak (Quercus suber L.). For this purpose, we evaluated the response to dry conditions of 45 open-pollinated trees originating from populations
in Morocco, Portugal, and Spain. Growth, leaf size, specific leaf area (SLA), carbon isotope discrimination (Δ13C), leaf nitrogen content (Nmass), and total chlorophyll content (Chlmass) were measured in 9-year-old plants. (2) We also investigated the relationships between functional traits and aboveground
growth by regression models. Plants presenting larger and more sclerophyllous leaves (low SLA and high leaf thickness) exhibited
higher growths, with results suggesting that these traits are subjected to divergent selection in this species. Heritability
estimates were moderately high for Δ13C (0.43 ± 0.25–0.83 ± 0.31) and stem diameter (0.40 ± 0.15–0.71 ± 0.28) for the tree populations. For the rest of the traits
(except for annual growth), heritability values varied among populations, particularly for height, leaf size, leaf thickness,
and Nmass. Our results suggest that natural selection has led to local adaptations and has also affected the genetic variance intrapopulation
in these cork oak populations, although studies with a higher number of populations should be carried out across different
years. Additionally, the absence of significant genetic correlations and the fact that correlated traits did not undergo opposing
selection provided little evidence for constraints on evolution caused by genetic correlations. 相似文献
19.
R. K. Gumber B. Schill W. Link E. v. Kittlitz A. E. Melchinger 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(3-4):569-580
Determining the genetic potential of a base population from the properties of their parental lines would improve the efficiency
of a breeding program. In the present study, we investigated whether the means of the parents and the genetic distance determined
from RAPD data (GD) or multivariate analysis (Mahalanobis D2), mid-parent heterosis (MPH), and the absolute difference between means of the parents (∣P1−P2∣) can be used for predicting the means and genetic variances (σ^2
g
) of F3:4 lines derived from different crosses in faba beans. The material comprised 18 intra- and 18 inter-pool crosses among lines
from the Minor, Major, and Mediterranean germplasm pools. Fifty F3:4 lines from each cross were evaluated for days to anthesis, plant height, seeds per plant, and seed yield in German (GE) and
Mediterranean (ME) environments. GD estimates between parent lines ranged from 0.38 to 0.58, while D2 ranged from 45.5 to 134.7. Correlations between means of the parents and F3:4 lines were highly significant for most traits. Estimates of σ2
g
for all traits showed non-significant correlations with MPH, GD, D2. In one ME, ∣P1−P2∣ had significant associations with σ^2
g
for seed yield and days to anthesis. The predicted usefulness of crosses, defined as the sum of the population mean and selection
responses, was most closely associated with the means of F3:4 lines. We conclude from this study that the means of F3:4 lines can be predicted from the means of the parents, whereas the prediction of genetic variance is still an unsolved problem
Received: 12 December 1997 / Accepted: 13 July 1998 相似文献
20.
A facies analysis of the epicontinental marine Cenomanian sediments of northern Germany shows the presence of 17 facies types (FTs, including several subtypes) which can be assigned to three facies associations: 1) an inner shelf facies association (FT 1–8) with high amounts of terrigenous material and/or high-energy depositional features, 2) a middle shelf facies association (FT 9–15) of predominantly calcareous sediments with moderate amounts of generally fine siliciclastics, and 3) an outer shelf facies association (FT 16–17) of low-energy, fine-grained, pure limestones. These three facies associations roughly correspond to the well-known lithological units of the Cenomanian of northern Germany, i.e., the Essen Greensand/Cenomanian Marls complex, the Pläner Limestones, and the Poor rhotomagense Limestones. The sediments were deposited on a northward-dipping homoclinal ramp with more-or-less shoreline-parallel facies belts. The sediment composition on this ramp-like shelf was a function of the varying importance of three different sediment sources: 1) terrigenous input from the south (Rhenobohemia), generally fining/decreasing in a proximal–distal (i.e., S–N) direction; 2) production of skeletal grains, mainly by macrobenthic organisms; and 3) settling of planktic carbonate (mainly calcispheres and calcareous nannofossils). In response to decreasing water energy with increasing water depth, the seaward decreasing terrigenous influence, and increasing planktic carbonate production, increasingly finer and more calcareous sediments were deposited in a proximal–distal transect. This rather straightforward picture was slightly modified by highest carbonate accumulation rates (planktic and benthic) on the middle shelf, forming a mid-shelf depocenter (fossiliferous, calcisphere-rich Pläner Limestones). Time-transgressive, southward-directed onlap of this biosedimentary system during the Cenomanian caused a significant retreat of the coastline towards the south and a retrogradational stacking of facies belts, explaining the broadly similar facies development and lithology of Cenomanian successions across northern Germany. The boundaries of the lithological units, however, tend to be considerably diachronous in a distal–proximal transect. In the late Middle and early Late Cenomanian, a final drowning and facies levelling (“oceanization”) is indicated by the widespread deposition of uniform calcareous nannofossil mudstones (Poor rhotomagense Limestones). 相似文献