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1.
Visualizing the pattern of variation using microsatellites within a Eucalyptus globulus forest on the island of Tasmania provided surprising insights into the complex nature of the fine-scale spatial genetic structure that resides in these forests. We used spatial autocorrelation and principal coordinate analysis to compare fine-scale genetic structure between juvenile and mature cohorts in a study area, 140 m in diameter, located within a typical, continuous E. globulus forest. In total, 115 juvenile and 168 mature individuals were genotyped with eight highly polymorphic microsatellite loci. There was no significant difference in the level of genetic diversity between cohorts. However, there were differences in the spatial distribution of the genetic variation. Autocorrelation analysis provided clear evidence for significant spatial genetic structure in the mature cohort and significant, but weaker, structure in the juvenile cohort. The spatial interpolation of principal coordinate axes, derived from ordination of the genetic distance matrix between individuals, revealed a spatially coherent family group which was evident in both cohorts. Direct comparison of the genetic structure within each cohort allowed visualization of a shift in the spatial distribution of genetic variation within the population of approximately 10 m. As the shift coincided with the direction of prevailing winds, it is hypothesized that this phenomenon is due to downwind dispersal of seeds and is indicative of the important role of prevailing winds in forcing eastward gene flow in these high-latitude forests. 相似文献
2.
J. Fernández M. A. Toro 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(6-7):1056-1064
A model using integer quadratic mathematical programming has been developed to control the inbreeding level (or genetic diversity)
through group coancestry in a selection programme for a forestry population structured in terms of maternal families coming
from different locations. A method to calculate the average group coancestry between- and within-families for these open-pollinated
populations is also proposed. This model has been applied to data from a breeding programme of Australian Eucalyptus globulus. The strategy proved to be effective as reductions of up to 50% for the group coancestry of the selected individuals were
reached with a loss of only 5% of the maximum attainable selection differential (corresponding to truncation selection).
Received: 14 October 1999 / Accepted: 26 July 2000 相似文献
3.
Identification of spatial genetic boundaries using a multifractal model in human population genetics 总被引:3,自引:0,他引:3
Xue F Wang J Hu P Ma D Liu J Li G Zhang L Wu M Sun G Hou H 《Human biology; an international record of research》2005,77(5):577-617
There are two purposes in displaying spatial genetic structure. One is that a visual representation of the variation of the genetic variable should be provided in the contour map. The other is that spatial genetic structure should be reflected by the patterns or the gradients with genetic boundaries in the map. Nevertheless, most conventional interpolation methods, such as Cavalli-Sforza's method in genography, inverse distance-weighted methods, and the Kriging technique, focus only on the first primary purpose because of their arbitrary thresholds marked on the maps. In this paper we present an application of the contour area multifractal model (CAMM) to human population genetics. The method enables the analysis of the geographic distribution of a genetic marker and provides an insight into the spatial and geometric properties of obtained patterns. Furthermore, the CAMM may overcome some of the limitations of other interpolation techniques because no arbitrary thresholds are necessary in the computation of genetic boundaries. The CAMM is built by establishing power law relationships between the area A (> or =rho) in the contour map and the value p itself after plotting these values on a log-log graph. A series of straight-line segments can be fitted to the points on the log-log graph, each representing a power law relationship between the area A (> or =rho) and the cutoff genetic variable value for rho in a particular range. These straight-line segments can yield a group of cutoff values, which can be identified as the genetic boundaries that can classify the map of genetic variable into discrete genetic zones. These genetic zones usually correspond to spatial genetic structure on the landscape. To provide a better understanding of the interest in the CAMM approach, we analyze the spatial genetic structures of three loci (ABO, HLA-A, and TPOX) in China using the CAMM. Each synthetic principal component (SPC) contour map of the three loci is created by using both Han and minority groups data together. These contour maps all present an obvious geographic diversity, which gradually increases from north to south, and show that the genetic differences among populations in different districts of the same nationality are greater than those among different nationalities of the same district. It is surprising to find that both the value of p and the fractal dimension alpha have a clear north to south gradient for each locus, and the same clear boundary between southern and northern Asians in each contour map is still seen in the zone of the Yangtze River, although substantial population migrations have occurred because of war or famine in the last 2,000 or 3,000 years. A clear genetic boundary between Europeans and Asians in each contour map is still seen in northwestern China with a small value of alpha, although the genetic gradient caused by gene flow between Europeans and Asians has tended to show expansion from northwestern China. From the three contour maps another interesting result can be found: The values of alpha north of the Yangtze River are generally less than those south of the Yangtze River. This indicates that the genetic differences among the populations north of the Yangtze River are generally smaller than those in populations south of the Yangtze River. 相似文献
4.
Spatial genetic structure (SGS) results from the interplay of several demographical processes that are difficult to tease apart. In this study, we explore the specific effects of seed and pollen dispersal and of early postdispersal mortality on the SGS of a seedling cohort (N = 786) recruiting within and around an expanding pedunculate oak (Quercus robur) stand. Using data on dispersal (derived from parentage analysis) and mortality (monitored in the field through two growing seasons), we decompose the overall SGS of the cohort into its components by contrasting the SGS of dispersed (i.e. growing away from their mother tree) vs. nondispersed (i.e. growing beneath their mother tree) and initial vs. surviving seedlings. Patterns differ strongly between nondispersed and dispersed seedlings. Nondispersed seedlings are largely responsible for the positive kinship values observed at short distances in the studied population, whereas dispersed seedlings determine the overall SGS at distances beyond c. 30 m. The paternal alleles of nondispersed seedlings show weak yet significantly positive kinships up to c. 15 m, indicating some limitations in pollen flow that should further promote pedigree structures at short distances. Seedling mortality does not alter SGS, except for a slight increase in the nondispersed group. Field data reveal that mortality in this group is negatively density‐dependent, probably because of small‐scale variation in light conditions. Finally, we observe a remarkable similarity between the SGS of the dispersed seedlings and that of the adults, which probably reflects dispersal processes during the initial expansion of the population. Overall, this study demonstrates that incorporating individual‐level complementary information into analyses can greatly improve the detail and confidence of ecological inferences drawn from SGS. 相似文献
5.
Mesophyll structure has been associated with the photosynthetic performance of leaves via the regulation of internal light and CO(2) profiles. Differences in mesophyll structure and chlorophyll distribution within three ontogenetically different leaf types of Eucalyptus globulus ssp. globulus were investigated. Juvenile leaves are blue-grey in color, dorsiventral (adaxial palisade layer only), hypostomatous, and approximately horizontal in orientation. In contrast, adult leaves are dark green in color, isobilateral (adaxial and abaxial palisade), amphistomatous, and nearly vertical in orientation. The transitional leaf type has structural features that appear intermediate between the juvenile and adult leaves. The ratio of mesophyll cell surface area per unit leaf surface area (A(mes)/A) of juvenile leaves was maximum at the base of a single, adaxial palisade layer and declined through the spongy mesophyll. Chlorophyll a + b content showed a coincident pattern, while the chlorophyll a:b ratio declined linearly from the adaxial to abaxial epidermis. In comparison, the mesophyll of adult leaves had a bimodal distribution of A(mes)/A, with maxima occurring beneath both the adaxial and abaxial surfaces within the first layer of multiple palisade layers. The distribution of chlorophyll a + b content had a similar pattern, although the maximum ratio of chlorophyll a:b occurred immediately beneath the adaxial and abaxial epidermis. The matching distributions of A(mes)/A and chlorophyll provide further evidence that mesophyll structure may act to influence photosynthetic performance. These changes in internal leaf structure at different life stages of E. globulus may be an adaptation for increased xeromorphy under increasing light exposure experienced from the seedling to adult tree, similar to the characteristics reported for different species according to sunlight exposure and water availability within their native habitats. 相似文献
6.
Spatial autocorrelation (SA) methods were recently extended to detect local spatial autocorrelation (LSA) at individual localities. LSA statistics serve as useful indicators of local genetic population structure. We applied this method to 15 allele frequencies from 43 villages of a South American tribe, the Yanomama. Based on a network of links 相似文献
7.
AFLP genetic maps of Eucalyptus globulus and E. tereticornis 总被引:8,自引:0,他引:8
C. M. Marques J. A. Araújo J. G. Ferreira R. Whetten D. M. O’Malley B.-H. Liu R. Sederoff 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(6-7):727-737
Amplified fragment length polymorphism (AFLP) analysis is a rapid and efficient technique for detecting large numbers of
DNA markers in eucalypts. We have used AFLP markers in a two-way pseudo-testcross strategy to generate genetic maps of two
clones of different Eucalyptus species (E. tereticornis and E. globulus). Of 606 polymorphic fragments scored, 487 segregated in a 1 : 1 ratio, corresponding to DNA polymorphisms heterozygous in
one parent and null in the other. In the maternal E. tereticornis map, 268 markers were ordered in 14 linkage groups (919 cM); the paternal E. globulus map had 200 markers in 16 linkage groups (967 cM). Results from PGRI software were compared with MAPMAKER. The average density
of markers was approximately 1 per 3.9 cM. Framework markers were ordered with an average confidence level of 90%, covering
80–100% of the estimated Eucalyptus genome size. In order to investigate the homologies between the E. tereticornis and the E. globulus genetic linkage maps, we included 19 markers segregating 3 : 1 in the analysis. Some homeologous linkage groups were recognized.
The linkage data developed in these maps will be used to detect loci controlling commercially important traits.
Received: 17 July 1997 / Accepted: 13 October 1997 相似文献
8.
Realised gains in stand volume of Eucalyptus globulus Labill. families at 7–9 years were compared with gains predicted at 3.5 years. Gain predictions were based on height, diameter at breast height (DBH), sectional area, and stem volume for 153 full-sib families and 18 commercial checks in five-tree line plots on three West Australian sites. Single-site narrow-sense heritability estimates were 0.12–0.24 for height, 0.08–0.12 for DBH, 0.09–0.13 for sectional area, and 0.14–0.19 for stem volume. Genetic dominance effects were significant (p?<?0.05) in most cases, and the estimated dominance/additive genetic variance ratio was heterogeneous for height and DBH. Stand volume was measured for 93 of the same families and checks in 40-tree block plots on four sites. Heritability of stand volume was 0.25–0.76, with an across-sites estimate of 0.41. Dominance effects were statistically absent at two sites. Estimated region-wide additive genetic correlations between selection traits (in line plots) and stand volume (in block plots) ranged from 0.86 to 0.90. Estimated stand volume gain was 23 % of the mean for the best 12 % of families and 14 % of the mean for the best 24 % of families. Realised gain was under-estimated by predictions based on height, DBH, and sectional area, which had smaller coefficients of additive variation than did stem volume. It is concluded that although BLUP analysis of early-age height and DBH can provide for indirect selection on E. globulus stand volume, analysis of stem volume is required to predict genetic gain at an appropriate scale. 相似文献
9.
Rencoret J Gutiérrez A Nieto L Jiménez-Barbero J Faulds CB Kim H Ralph J Martínez AT Del Río JC 《Plant physiology》2011,155(2):667-682
Lignin changes during plant growth were investigated in a selected Eucalyptus globulus clone. The lignin composition and structure were studied in situ by a new procedure enabling the acquisition of two-dimensional nuclear magnetic resonance (2D-NMR) spectra on wood gels formed in the NMR tube as well as by analytical pyrolysis-gas chromatography-mass spectrometry. In addition, milled-wood lignins were isolated and analyzed by 2D-NMR, pyrolysis-gas chromatography-mass spectrometry, and thioacidolysis. The data indicated that p-hydroxyphenyl and guaiacyl units are deposited at the earlier stages, whereas the woods are enriched in syringyl (S) lignin during late lignification. Wood 2D-NMR showed that β-O-4' and resinol linkages were predominant in the eucalypt lignin, whereas other substructures were present in much lower amounts. Interestingly, open β-1' structures could be detected in the isolated lignins. Phenylcoumarans and cinnamyl end groups were depleted with age, spirodienone abundance increased, and the main substructures (β-O-4' and resinols) were scarcely modified. Thioacidolysis revealed a higher predominance of S units in the ether-linked lignin than in the total lignin and, in agreement with NMR, also indicated that resinols are the most important nonether linkages. Dimer analysis showed that most of the resinol-type structures comprised two S units (syringaresinol), the crossed guaiacyl-S resinol appearing as a minor substructure and pinoresinol being totally absent. Changes in hemicelluloses were also shown by the 2D-NMR spectra of the wood gels without polysaccharide isolation. These include decreases of methyl galacturonosyl, arabinosyl, and galactosyl (anomeric) signals, assigned to pectin and related neutral polysaccharides, and increases of xylosyl (which are approximately 50% acetylated) and 4-O-methylglucuronosyl signals. 相似文献
10.
Dorothy A. Steane Natalie Conod Rebecca C. Jones René E. Vaillancourt Bradley M. Potts 《Tree Genetics & Genomes》2006,2(1):30-38
Eucalyptus globulus (Myrtaceae) is a forest tree native to southeastern Australia, but is grown globally for pulpwood and timber. Eight microsatellite
loci were used to determine the degree of selectively neutral differentiation between native populations of the geographic
races of E. globulus that are used in a national breeding programme. Spatial differentiation was detected among 340 samples from across the species
range (F
ST=0.09±0.02). Analysis of molecular variance showed that there was significant variation between the races, and an unweighted
pair group method with arithmetic mean analysis of Nei’s genetic distance between races showed that geographically proximal
races tended to be more closely related than geographically distant races. This contrasted markedly with analyses based on
quantitative genetic data, where some races appeared to be highly divergent from their geographically closest neighbours.
Comparison of racial differentiation based on quantitative (Q
ST) and molecular (F
ST) data suggested that at least five of the quantitative traits used for defining races of E. globulus have been influenced by natural selection, resulting in cases of both phenotypic divergence of parapatric races and phenotypic
convergence of allopatric races. We conclude that selectively neutral molecular markers are more useful than quantitative
genetic data for identifying the evolutionary affinities and lineages within E. globulus. However, both sources of information should be used in defining evolutionarily important units for conservation. The population
structure observed in E. globulus has important consequences for future association studies and may also affect breeding strategies if significant genome co-adaptation
has occurred. 相似文献
11.
We investigated the scale of genetic variation of purple needlegrass (Nassella pulchra), a species commonly used in California for grassland restoration. Common garden and field data revealed evidence of genetic
differentiation between two intermixed microhabitats characterized by differences in soil depth and community composition.
We assessed the genetic variation within a single population using randomly amplified polymorphic DNA (RAPD) data collected
from clusters of five individuals in 40 locations. We found no evidence for genetic structure at the whole population level.
At smaller spatial scales, however, we found strong evidence that genetic subdivision of the population occurs at the level
of the maternal neighborhood. We suggest that the interaction between widespread pollen dispersal and restricted seed dispersal
may be the primary factor generating these results; panmictic pollen dispersal will make detection of genetic patterning difficult
at larger spatial scales while limited seed dispersal will generate local genetic structure. As a result, the detection of
population genetic structure will depend on the spatial scale of analysis. Local selection gradients related to topography
and soil depth are also likely to play a role in structuring local genetic variation. Since N. pulchra is widely used in California in grassland and woodland habitat restoration, we suggest that, as a general rule, care should
be exercised in transferring germplasm for the purposes of conservation when little is known about the within-population genetic
subdivision of a plant species.
Received: 23 December 1996 / Accepted: 20 May 1997 相似文献
12.
José Alexandre Felizola Diniz-Filho João Vitor Barnez P. L. Diniz Thiago Fernando Rangel Thannya Nascimento Soares Mariana Pires de Campos Telles Rosane Garcia Collevatti Luis Mauricio Bini 《Genetica》2013,141(10-12):479-489
Several methods of spatial analyses have been proposed to infer the relative importance of evolutionary processes on genetic population structure. Here we show how a new eigenfunction spatial analysis can be used to model spatial patterns in genetic data. Considering a sample of n local populations, the method starts by modeling the response variable (allele frequencies or phenotypic variation) against the eigenvectors sequentially extracted from a geographic distance matrix (n × n). The relationship between the coefficient of determination (R 2) of the models and the cumulative eigenvalues, which we named the spatial signal-representation (SSR) curve, can be more efficient than Moran’s I correlograms in describing different patterns. The SSR curve was also applied to simulated data (under distinct scenarios of population differentiation) and to analyze spatial patterns in alleles from microsatellite data for 25 local populations of Dipteryx alata, a tree species endemic to the Brazilian Cerrado. The SSR curves are consistent with previous phylogeographical patterns of the species, revealing combined effects of isolation-by-distance and range expansion. Our analyses demonstrate that the SSR curve is a useful exploratory tool for describing spatial patterns of genetic variability and for selecting spatial eigenvectors for models aiming to explain spatial responses to environmental variables and landscape features. 相似文献
13.
Eucalyptus camaldulensis and E. tereticornis are closely related species commonly cultivated for pulp wood in many tropical countries including India. Understanding the genetic structure and linkage disequilibrium (LD) existing in these species is essential for the improvement of industrially important traits. Our goal was to evaluate the use of simple sequence repeat (SSR) loci for species discrimination, population structure and LD analysis in these species. Investigations were carried out with the most common alleles in 93 accessions belonging to these two species using 62 SSR markers through cross amplification. The polymorphic information content (PIC) ranged from 0.44 to 0.93 and 0.36 to 0.93 in E. camaldulensis and E. tereticornis respectively. A clear delineation between the two species was evident based on the analysis of population structure and species-specific alleles. Significant genotypic LD was found in E. camaldulensis, wherein out of 135 significant pairs, 17 pairs showed r(2)≥0.1. Similarly, in E. tereticornis, out of 136 significant pairs, 18 pairs showed r(2)≥0.1. The extent of LD decayed rapidly showing the significance of association analyses in eucalypts with higher resolution markers. The availability of whole genome sequence for E. grandis and the synteny and co-linearity in the genome of eucalypts, will allow genome-wide genotyping using microsatellites or single nucleotide polymorphims. 相似文献
14.
Stomatal conductance and transpiration were measured concurrently in an irrigated Eucalyptus globulus Labill. plantation. Canopy stomatal conductance, canopy boundary layer conductance and the dimensionless decoupling coefficient (Ω) were calculated (a) summing the conductance of three canopy layers (gc) and (b) weighting the contribution of foliage according to the amount of radiation received (gc′). Canopy transpiration was then calculated from gc and gc′ for Ω = 1 (Eeq), Ω = 0 (Eimp) and by weighting Eeq and Eimp using Ω (EΩ). Eeq, Eimp and EΩ were compared to transpiration estimated from measurements of heat pulse velocity. The mean value of Ω was 0·63. Transpiration calculated using gc and assuming perfect coupling (12·5 ± 0·9 mmol m?2 s?1) significantly overestimated measured values (8·7 ± 0·8 mmol m?2 s?1). Good estimates of canopy transpiration were obtained either (a) calculating EΩ separately for the individual canopy layers or (b) treating the canopy as a single layer and using gc′ in a calculation of Eimp (Ω = 0). The latter approach only required measurement of stomatal conductance at a single canopy position but would be unsuitable for use in combined models of canopy transpiration and assimilation. It should however, be suitable for estimating transpiration in forests regardless of the degree of coupling. 相似文献
15.
Maximum stomatal conductance to water vapour and CO2 ( g wmax , g cmax , respectively), which are set at the time of leaf maturity, are determined predominantly by stomatal size ( S ) and density ( D ). In theory, many combinations of S and D yield the same g wmax and g cmax , so there is no inherent correlation between S and D , or between S , D and maximum stomatal conductance. However, using basic equations for gas diffusion through stomata of different sizes, we show that a negative correlation between S and D offers several advantages, including plasticity in g wmax and g cmax with minimal change in epidermal area allocation to stomata. Examination of the relationship between S and D in Eucalyptus globulus seedlings and coppice shoots growing in the field under high and low rainfall revealed a strong negative relationship between S and D , whereby S decreased with increasing D according to a negative power function. The results provide evidence that plasticity in maximum stomatal conductance may be constrained by a negative S versus D relationship, with higher maximum stomatal conductance characterized by smaller S and higher D , and a tendency to minimize change in epidermal space allocation to stomata as S and D vary. 相似文献
16.
Estimating impacts of poison operations using mark-recapture analysis and population viability analysis: an example with New Zealand robins (
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《新西兰生态学杂志》2011,25(1):29-38
Several recent studies have used "roll calls"—searches for individually-marked birds—to assess impacts of aerial poison operations on non-target species. Roll calls have advantages over methods such as 5-minute bird counts, call counts, and dead body counts, but roll calls are based on the assumption that detection rates are 100%, or that detection rates are constant over time and space. They also require more than one group of birds, at a poisoned and unpoisoned site for example, for valid statistical comparisons. With minor adjustment of field methods, however, a series of surveys can be treated as a mark-recapture experiment, allowing powerful analysis without such restrictive assumptions. Survival and detection rates can be estimated independently for each time interval, and alternative models fitted to the data for factors affecting those rates. Using the software package MARK, we analyzed data for New Zealand robins (Petroica australis) on Tiritiri Matangi Island to estimate impact of an aerial brodifacoum operation conducted in September 1993 to eradicate kiore (Rattus exulans). The population was established by translocations in 1992 and 1993, and consisted of 40 birds at the time of the operation. Taking seasonal and yearly variation in detection and survival rates into account, we estimate that 11% of robins (4-5 birds) died as a result of the poison. There was strong evidence that survival probability was lower immediately after the operation, despite the small number of birds disappearing. The poison effect was confined to the interval from September-October 1993, including the first two weeks after the poison drop, and survival for subsequent monthly intervals was consistent with the normal summer rate. Using simulation modelling based on our data from the population, we predict that the operation set population growth back by about one year but had no longer-term impact. 相似文献
17.
Subterranean termites build underground tunnels for foraging. The obtained food is transported to the nest through these tunnels, and consumed to maintain the termite colony. In this process, termites can cause damage to wooden structures. To develop effective control strategies to reduce termite damage, it is important to know the sizes of the termite populations in the tunnels. In this study, we proposed a method for estimating the termite population size using the spatial statistic indices including fractal dimension (FD), local density (LD), and join count statistic (JCS) for the tunnel patterns. However, the method needs further improvement to be applied in field conditions. For the method, we generated 8,000 tunnel pattern images (1,000 images for each N) using an agent-based model based on experimental data. Here, N (= 3, 4, ..., 10) represents the number of termites participating in tunnel construction in the simulation. Subsequently, we calculated the FD, LD and JCS values of the tunnel pattern and trained and verified the k-nearest neighbors (KNN) algorithm, using 5,600 and 2,400 images, respectively. The population size (N) was estimated based on the FD, LD and JCS using the KNN algorithm. The estimated accuracy for all N was 60% to 97% in the range of k = 1 to 300. If the model for tunnel pattern generation includes heterogeneous environmental conditions, the proposed method could be used to effectively estimate the actual number of termite populations. Finally, we briefly discuss the challenges affecting our model, and how these could be overcome. 相似文献
18.
We analysed the change of spatial genetic structure (SGS) of reproductive individuals over time in an expanding Pinus halepensis population. To our knowledge, this is the first empirical study to analyse the temporal component of SGS by following the dynamics of successive cohorts of the same population over time, rather than analysing different age cohorts at a single time. SGS is influenced by various factors including restricted gene dispersal, microenvironmental selection, mating patterns and the spatial pattern of reproductive individuals. Several factors that affect SGS are expected to vary over time and as adult density increases. Using air photo analysis, tree-ring dating and molecular marker analysis we reconstructed the spread of reproductive individuals over 30 years beginning from five initial individuals. In the early stages, genotypes were distributed randomly in space. Over time and with increasing density, fine-scale (< 20 m) SGS developed and the magnitude of genetic clustering increased. The SGS was strongly affected by the initial spatial distribution and genetic variation of the founding individuals. The development of SGS may be explained by fine-scale environmental heterogeneity and possibly microenvironmental selection. Inbreeding and variation in reproductive success may have enhanced SGS magnitude over time. 相似文献
19.
Bayesian approaches for the analysis of population genetic structure: an example from Platanthera leucophaea (Orchidaceae) 总被引:3,自引:0,他引:3
We describe four extensions to existing Bayesian methods for the analysis of genetic structure in populations: (i) use of beta distributions to approximate the posterior distribution of f and theta(B); (ii) use of an entropy statistic to describe the amount of information about a parameter derived from the data; (iii) use of the Deviance Information Criterion (DIC) as a model choice criterion for determining whether there is evidence for inbreeding within populations or genetic differentiation among populations; and (iv) use of samples from the posterior distributions for f and theta(B) derived from different data sets to determine whether the estimates are consistent with one another. We illustrate each of these extensions by applying them to data derived from previous allozyme and random amplified polymorphic DNA surveys of an endangered orchid, Platanthera leucophaea, and we conclude that differences in theta(B) from the two data sets may represent differences in the underlying mutational processes. 相似文献
20.
Abstract
- 1 Objectives of this study were to examine (i) between‐provenance variation in susceptibility to insects in Eucalyptus globulus and (ii) relationships between insect damage and tree growth. We planted seedlings of 18 provenances of E. globulus from south‐east Australia in a field trial and measured tree growth and insect damage.
- 2 Christmas beetles Anoplognathus spp. were the dominant herbivores during this experiment, and 99% of trees were affected by them. Defoliation of individual trees by Anoplognathus spp. ranged from 0% to 85%.
- 3 The main results of this study were that: (i) provenances of E. globulus from Tasmania and the Bass Strait islands, which had previously shown resistance to autumn gum moth Mnesampela privata and leaf blister sawfly Phylacteophaga froggatti tended to be resistant to Anoplognathus spp.; (ii) mean tree volume was reduced by herbivory; and (iii) the volume‐based performance ranking of provenances changed depending on the probability of insect outbreaks.
- 4 Fast‐growing provenances should be planted in optimal growing areas for E. globulus with low probability of insect outbreaks. However, in suboptimal growing areas, planting slightly slower growing but more resistant provenances is likely to result in greater output than planting fast‐growing provenances when the probability of insect outbreaks is high.