Electrophoretic examination of the population structure of brown trout, Salmo trutta L., from the Lough Neagh catchment, Northern Ireland

Samples of brown trout, Salmo trutia L., from 34 locations throughout the Lough Neagh system in north-east Ireland were electrophoretically examined for genetic variation at 28 enzyme loci. Patterns of allelic variation at 12 polymorphic loci indicated the existence of genetic differentiation within as well as among several river systems, suggesting the existence of multiple brown trout populations. Significant gene frequency differences were detected over distances as little as 3 km, demonstrating the propensity of this species for microgeographic genetic differentiation. This was confirmed by a hierarchical analysis of genetic variance, some 35% of among-sample variance being distributed within tributaries. Within Lough Neagh itself significant genetic differentiation was detected between two morphotypes (dollaghan and salmon-trout) and for one of these (dollaghan) among samples from different years and from different areas of the lough. This suggests the existence of genetically differentiated subpopulations of originating from separate river catchments.     

Allozyme and RAPD analysis of the genetic diversity and geographic variation in wild populations of the American chestnut (Fagaceae)

Genetic variation among 12 populations of the American chestnut (Castanea dentata) was investigated. Population genetic parameters estimated from allozyme variation suggest that C. dentata at both the population and species level has narrow genetic diversity as compared to other species in the genus. Average expected heterozygosity was relatively low for the population collected in the Black Rock Mountain State Park, Georgia (He = 0.096 +/- 0.035), and high for the population in east central Alabama (He = 0.196 +/- 0.048). Partitioning of the genetic diversity based on 18 isozyme loci showed that ~10% of the allozyme diversity resided among populations. Cluster analysis using unweighted pair-group method using arithmetric averages of Rogers' genetic distance and principal components analysis based on allele frequencies of both isozyme and RAPD loci revealed four groups: the southernmost population, south-central Appalachian populations, north-central Appalachian populations, and northern Appalachian populations. Based on results presented in this study, a conservation strategy and several recommendations related to the backcross breeding aimed at restoring C. dentata are discussed.     

Genetic differentiation of pink salmon oncorhynchus gorbuscha Walbaum in the Asian part of the range

Genetic variation at 19 allozyme (including 11 polymorphic) and 10 microsatellite loci was examined in the population samples of odd- and even-broodline pink salmon from the southern part of Sakhalin Island, Southern Kuril Islands, and the northern coast of the Sea of Okhotsk. The estimates of relative interpopulation component of genetic variation over the allozyme loci, per broodline, were on average 0.43% (GST), while over the microsatellite loci it was 0.26% (the theta(ST) coefficient, F-statistics based on the allele frequency variance), and 0.90% (the rho(ST) coefficient, R-statistics based on the allele size variance). The values of interlinear component constituted 2.34, 0.31, and 1.05% of the total variation, respectively. Using the allozyme loci, statistically significant intralinear heterogeneity was demonstrated among the regions, as well as among the populations of Southern Sakhalin Island. Multivariate scaling based on the allozyme data demonstrated regional clustering of the sample groups, representing certain populations during the spawning run or in different years. Most of the microsatellite loci examined were found to be highly polymorphic (mean heterozygosity > 0.880). The estimates of interlinear, interregional, and interpopulation variation over these loci in terms of theta(ST) values were substantially lower than in terms of rho(ST) values. Regional genetic differentiation, mostly expressed at the allozyme loci among the populations from the northern and southern parts of the Sea of Okhotsk (i.e., between the Sakhalin and Kuril populations), was less expressed at the microsatellite loci. The differentiation between these regions observed can be considered as the evidence in favor of a large-scale isolation by distance characterizing Asian pink salmon. It is suggested that in pink salmon, low genetic differentiation at neutral microsatellite loci can be explained by extremely high heterozygosity,of the loci themselves, as well as by the migration gene exchange among the populations (the estimate of the genetic migration coefficient inferred from the "private" allele data constituted 2.6 to 3.4%), specifically, by the ancient migration exchange, which occurred during postglacial colonization and colonization of the range.     

Population studies on an endemic troglobitic beetle: geographical patterns of genetic variation, gene flow and genetic structure compared with morphometric data

Highly specialized obligatory cave beetles endemic to the French Pyrenees offer an opportunity to investigate the relative importance of environmental conditions and ecological characteristics on the organization of genetic variability, to describe the genetic structure of populations, and to assess the extent of gene flow between local populations in relation to geologic structure. Twenty-three geographically close populations of the beetle Speonomus hydrophilus occurring both in caves (reduced fluctuations in many abiotic parameters) and under the deepest layer of soil in mountains (more exposed to climatic variations) were studied. Significant genetic differentiation at 17 allozyme loci was found among populations in close proximity, as well as among those from distant parts of range. On a larger scale, genetic differences among populations appear to result from low dispersal rates between populations. The spatial patterning observed suggests that allozyme frequencies are not responding to environmentally controlled selection. Substantial genetic divergence (F(ST) = 0.112) occurred throughout the range, with important variation in levels of genetic variability (H: 0.065-0.184) among populations. A significant level of substructuring has occurred among the populations with four major geographic areas of similarity indicated. The substructuring of the species into regions suggests an influence of paleoclimatic gradient and paleoenvironment on the population's genetic structure. Also, founder effect and reduced gene flow appear to have influenced populations in the southeastern portion of the range.     

Genetic differentiation of pink salmon Oncorhynchus gorbuscha Walbaum in the Asian part of the range

Genetic variation at 19 enzyme (including 11 polymorphic) and 10 microsatellite loci was examined in the population samples of odd-and even-broodline pink salmon from the southern part of Sakhalin Island, Southern Kuril Islands, and the northern coast of the Sea of Okhotsk. The estimates of relative interpopulation component of genetic variation for the allozyme loci, per broodline, were on average 0.43% (G _ST), while over the microsatellite loci it was 0.26% (the ?_ST coefficient, F-statistics based on the allele frequency variance), and 0.90% (the ρ_ST coefficient, R-statistics based on the allele size variance). The values of interlinear component constituted 2.34, 0.31, and 1.05% of the total variation, respectively. Using the allozyme loci, statistically significant intralinear heterogeneity was demonstrated among the regions, as well as among the populations of southern Sakhalin. Multidimensional scaling based on the allozyme data demonstrated regional clustering of the sample groups, representing certain populations during the spawning run or in different years. Most of the microsatellite loci examined were found to be highly polymorphic (mean heterozygosity > 0.880). The estimates of interlinear, interregional, and interpopulation variation over these loci in terms of ?_ST values were substantially lower than in terms of ρ_ST values. Regional genetic differentiation, mostly expressed at the allozyme loci between the populations from the northern Sea of Okhotsk and the Sakhalin and Kuril group of populations, was less expressed at the microsatellite loci. The differentiation between these regions observed can be considered as the evidence in favor of a large-scale isolation by distance characterizing Asian pink salmon. It is suggested that in pink salmon, low genetic differentiation at neutral microsatellite loci can be explained by extremely high heterozygosity of the loci themselves, as well as by the migration gene exchange among the populations (the estimate of the gene migration coefficient inferred from the “private” allele data constituted 2.6 to 3.4%), specifically, by the ancient migration exchange, which occurred during postglacial colonization of the range     

Evolutionary implications of allozyme and RAPD variation in diploid populations of dioecious buffalograss Buchloë dactyloides

Buffalograss, Buchloë dactyloides, is widely distributed throughout the Great Plains of North America, where it is an important species for rangeland forage and soil conservation. The species consists of two widespread polyploid races, with narrowly endemic diploid populations known from two regions: central Mexico and Gulf Coast Texas. We describe and compare the patterns of allozyme and RAPD variation in the two diploid races, using a set of 48 individuals from Texas and Mexico (four population samples of 12 individuals each). Twelve of 22 allozyme loci were polymorphic, exhibiting 35 alleles, while seven 10-mer RAPD primers revealed 98 polymorphic bands. Strong regional differences were detected in the extent of allozyme polymorphism: Mexican populations exhibited more internal gene diversity (H_e= 0.20, 0.19) than did the Texan populations (H_e= 0.08, 0.06), although the number of RAPD bands in Texas (n= 62) was only marginally smaller than in Mexico (n= 68). F-statistics for the allozyme data, averaged over loci, revealed strong regional differentiation (mean F_RT=+ 0.30), as well as some differentiation among populations within regions (mean F_PR=+ 0.09). In order to describe and compare the partitioning of genetic variation for multiple allozyme and RAPD loci, we performed an Analysis of Molecular Variance (AMOVA). AMOVA for both allozyme and RAPD data revealed similar qualitative patterns: large regional differences and smaller (but significant) population differences within regions. RAPDs revealed greater variation among regions (58.4% of total variance) than allozymes (45.2%), but less variation among individuals within populations (31.9% for RAPDs vs. 45.2% for allozymes); the proportion of genetic variance among populations within regions was similar (9.7% for RAPDs vs. 9.6% for allozymes). Despite this large-scale concordance of allozyme and RAPD variation patterns, multiple correlation Mantel techniques revealed that the correlations were low on an individual by individual basis. Our findings of strong regional differences among the diploid races will facilitate further study of polyploid evolution in buffalograss.     

云南引种印楝实生种群的表型变异

为了揭示印楝(Azadirachta indica)实生种群表型变异程度和变异规律, 以云南引种印楝人工林为研究对象, 基于9个种群90个单株14个表型性状严格细致的测量, 采用单因素方差分析、巢式方差分析、相关分析、协方差主成分分析(S法)和非加权配对算术平均法(UPGMA)聚类分析等数理方法, 分析了种群的表型变异。结果表明: 印楝种内表型性状在种群间和种群内均存在着较丰富的差异, 种群内的变异大于种群间的变异, 种群间的分化相对较小。对表型性状进行的变异系数多重比较和协方差主成分分析(S法)均显示, 结实和种子化学成分相关性状的变异是造成印楝表型变异的主要来源。利用种群间欧氏距离进行的UPGMA聚类分析结果进一步表明, 印楝9个种群可以分为4类, 表型性状并没有严格依地理距离而聚类。研究结果为印楝的遗传改良工作奠定了基础, 为制定育种策略和人工经营对策提供了科学依据。     

皂荚南方天然群体种实表型多样性

以系统揭示表型变异程度和变异规律为目的, 对皂荚(Gleditsia sinensis)南方分布区的10个天然群体的11个种实性状进行了比较分析。采用方差分析、多重比较、相关分析等多种分析方法, 对群体间和群体内的表型多样性以及与地理、环境因子的相关性进行了讨论。方差分析结果表明; 皂荚果实、种子等性状在群体间和群体内存在丰富的变异, 11个性状在群体间、群体内均达显著差异; 荚果性状在群体间和群体内的变异均大于种子性状, 11个性状的平均表型分化系数为20.42%, 群体内的变异(32.28%)大于群体间的变异(7.19%), 群体内的变异是皂荚的主要变异来源; 皂荚各性状平均变异系数为11.20%, 变异幅度为4.55%-18.38%。群体间荚果的变异(14.75%)高于群体间种子变异(6.95%), 表明种子变异稳定性高。荚果和种子各性状之间多呈极显著或显著正相关, 表现为荚果越大, 则种子越大, 种子的千粒重也越大; 荚果表现为同地理经度的南北变异, 种子则表现为同地理纬度的东西变异。研究结果为进一步开展皂荚遗传育种、保护生物学研究和皂荚种质资源利用奠定了基础。     

Geographic components of linkage disequilibrium in natural populations of Escherichia coli

Geographic variation in the genetic structure of natural enteric populations of Escherichia coli was assessed at both the single-locus and dilocus levels from allozyme genotypes at 12 enzyme loci in 178 cell lines isolated from human hosts in Sweden, Iowa, and Tonga. Although there was significant heterogeneity in allele frequencies at six of the 12 loci, geographic variation accounted for only 2.0% of the total genetic diversity (HT = 0.518). Ohta's D-statistics were used to partition the total variance of dilocus linkage disequilibrium into within-population and between-population components. The observed total variance in disequilibrium (0.0339), averaged over 66 locus-pairs, was significantly greater than would be expected (0.0103) if alleles were randomly associated in an unstructured total population; and both within-locality and between-locality components made substantial contributions to the total variance. Half the locus-pairs exhibited the specific dual relationship among components expected when random factors are generating disequilibrium, but 20% of the locus-pairs showed the opposite relationship, reflecting systematic allele associations. The magnitude of dilocus disequilibrium apparently is unrelated to the chromosomal distance between loci. This and other evidence indicates that substitutive recombination rates in natural populations are sufficiently low to permit indirect periodic selection to play a prominent role in generating multilocus genetic structure.      

Evolutionary divergence in directions of high phenotypic variance in the ostracode genus poseidonamicus

Trait variation and covariation are understood to influence the response of populations to natural selection on generational time scales, but their role, if any, in shaping long-term macroevolutionary divergence is still unclear. The present study uses the rich fossil record of the ostracode genus Poseidonamicus to reconstruct in great detail the evolutionary history of a set of landmark-based morphometric characters. This reconstruction included two kinds of evolutionary inferences: ancestor-descendant transitions among populations repeatedly sampled at the same location and divergence between lineages measured as independent contrasts on a phylogeny. This reconstructed history was then used to test if evolutionary changes were concentrated in directions (traits or combinations of traits) with high phenotypic variance. Two different statistics of association between evolution and variation tested the null hypothesis that evolutionary changes occur in random directions with respect to trait variability. The first of these measured the similarity between the directions of evolutionary change and the axis of maximum variance, and the second measured the degree to which evolutionary changes were concentrated in directions of high phenotypic variation. Randomization tests indicated that both kinds of evolutionary inferences (ancestor-descendant and phylogenetic contrasts) occurred preferentially in directions of high phenotypic variance (and close to the axis of maximal variation), suggesting that within-population variation can structure long-term divergence. This effect decayed after a few million years, but at least for one metric, never disappeared completely. These results are consistent with Schluter's genetic constraints model in which evolutionary trajectories on adaptive landscapes are deflected by variation within and covariation among traits.     

Enzyme Variability in the DROSOPHILA WILLISTONI Group. III. Amounts of Variability in the Superspecies, D. PAULISTORUM

The semispecies composing the superspecies, Drosophila paulistorum, have been analyzed for genetic variation at 17 enzyme loci. On the average a population of D. paulistorum is polymorphic for 55-67% of its loci and an average individual is heterozygous at 21% of its loci. The pattern of genetic variability found supports the hypothesis that allozyme variation is maintained in natural populations by some form of balancing selection. Evidence is presented which supports the hypothesis that glucose-metabolizing enzymes are less genetically variable than non-glucose-metabolizing enzymes. The known genetic relationships between the semispecies of D. paulistorum are discussed in the light of the frequencies of alleles at allozyme loci.     

Concordance of genetic divergence among sockeye salmon populations at allozyme, nuclear DNA, and mitochondrial DNA markers

Abstract.— We examined genetic variation at 21 polymorphic allozyme loci, 15 nuclear DNA loci, and mitochondrial DNA in four spawning populations of sockeye salmon ( Oncorhynchus nerka ) from Cook Inlet, Alaska, to test for differences in the patterns of divergence among different types of markers. We were specifically interested in testing the suggestion that natural selection at allozyme loci compromises the effectiveness of these markers for describing the amount and patterns of gene flow among populations. We found concordance among markers in the amount of genetic variation within and among populations, with the striking exception of one allozyme locus ( sAH ), which exhibited more than three times the amount of among-population differentiation as other loci. A consideration of reports of discordance between allozymes and other loci indicates that these differences usually result from one or two exceptional loci. We conclude that it is important to examine many loci when estimating genetic differentiation to infer historical amounts of gene flow and patterns of genetic exchange among populations. It is less important whether those loci are allozymes or nuclear DNA markers.     

ASSOCIATIONS BETWEEN ALLOZYME FREQUENCIES AND SOIL CHARACTERISTICS IN GAILLARDIA PULCHELLA (COMPOSITAE)

Selection favoring different alleles in different environments frequently has been suggested as an explanation for allozyme variation within and among populations. This hypothesis predicts that allozyme frequencies will be correlated with environmental variables. Previous studies on allozyme frequency-environment covariation in plants often have relied on qualitative assessments of the environment and have emphasized highly autogamous species. We have examined allozyme frequency-soil associations in Gaillardia pulchella, an obligately outcrossed annual plant, by regressing the frequencies of 15 common allozymes representing six polymorphic enzyme loci on principal components from a set of 20 quantitative soil variables. Fifty-one populations, representing four taxonomic varieties, were included in the analysis. Among the 26 populations representing the var. pulchella, allozymes Adh-2f and Pgm-1c were significantly associated with a block of highly inter-correlated soil characteristics which serve to discriminate between soils derived from calcareous vs. non-calcareous rock types. This geographically complex pattern of allozyme frequency-soil covariation is not likely to be spurious and, thus, indicates the presence of adaptively differentiated soil races, or ecotypes. However, these results are not sufficient to conclude that the allozyme frequency divergence between ecotypes was mediated by selection, either directly or through genetic hitchhiking. The pattern of allozyme frequency-soil covariation within var. pulchella was not found among the other taxonomic varieties. Patterns of genotype-environment covariation often may be recognizable only within geographically or environmentally restricted groups of populations because of the confounding influences of other environmental variables.     

High allozyme diversity and unidirectional linear migration patterns within a population of tetraploid Isoetes sinensis, a rare and endangered pteridophyte

Isoetes sinensis (Isoetaceae), an aquatic quillwort which occurs only in two fragmented sites of China as an allotetraploid, is critically endangered. Genetic variation among eight subpopulations of I. sinensis was examined in the Xin’an River (119°14′–15′E, 29°28′N) by using allozyme polymorphism. Eighteen loci of 10 enzyme systems were examined and used for the analysis of population genetic parameters. As expected for allotetraploids, fixed heterozygosity was found at four loci. A high level of genetic diversity was observed in the population, with mean number of alleles per loci of 1.8, and mean percentage of polymorphic loci of 55.6%, which were much higher than the average values in fern species. The genetic variation within each subpopulation was not positively correlated with its size, which may be explained by high gene flow (Nm = 2.57), clonal reproduction and fixed heterozygosity of allopolyploid. The I. sinensis population contained high clonal diversity (PD = 0.39, D = 0.95), indicating the successful seedling recruitment of the population. Significant positive relationship was detected between clonal diversity and the size of subpopulation. Partitioning the genetic diversity indicated that 91.1% of the genetic variation was within subpopulations and only 8.9% existed among subpopulations. The migration pattern of I. sinensis along the Xin’an River is best explained by a source–sink model, but with unidirectional gene flow among subpopulations underlined by hydrochoric force. The results were then discussed in relation to both in situ and ex situ conservation efforts of the population.     

Allozyme and morphological variation in two subspecies of Dryas octopetala (Rosaceae)in Alaska

The Alaskan endemic shrub Dryas octopetala ssp. alaskensis and its circumpolar conspecific ssp. octopetala are adapted to closely adjacent habitats in alpine areas of Alaska. These alpine areas form geographically disjunct "islands" among which there are limited opportunities for gene flow. Allozyme electrophoresis and a common garden experiment were used to examine genetic variation between subspecies and among disjunct populations of each subspecies. Overall, allozyme variation in D. octopetala is low with little differentiation among populations or between subspecies. Morphological differences, however, are greater between subspecies than among populations within subspecies. Divergence for a few morphological and life-history characters has apparently occurred in response to strong selection, but without divergence at allozyme loci. The ancestors of both subspecies of D. octopetala in Alaska were isolated during the Pleistocene in the glacial refugia of Alaska and Yukon, which may explain low overall variation. Dryas. o. alaskensis is thought to be a Pleistocene derivative of ssp. octopetala, which may account for the low allozyme divergence between subspecies. Recent restriction to alpine areas may explain the low differentiation among disjunct populations.     

Phenotypic, maximum genetic, and special environmental variability in prehistoric human populations

The phenotypic variance (V(P)) may be divided into the genetic variance (V(G)), the general environmental variance (V(Eg)), and the special environmental variance (V(Es)). The latter is estimated through repeatability calculation (b). This value is considered the upper limit of heritability and represents maximum genetic variance proportion (V(Gm) = V(G) + V(Eg)) in relation to V(P) (b = (V(G) + V(Eg))/V(P)). This process allows an improved determination of biological relationships among groups from estimators maximizing the genetic information of quantitative characters. Two hundred and thirty-seven individuals inhabiting the northern coast of Chile for 4,000 years were taken as a sample. Measurement was made of six metric characters at both sides of the cranium. Special environmental values (es) were obtained by regression. The difference between these values and the phenotypic values (p) consists in the genetic values plus the general environmental values (g + eg). A mean b value of 0.83 indicated that V(Es) represents 17% of V(P). The results showed: 1) high stability of the maximum genetic variance in time and space, 2) high correlation between the biological relationships model, the phenotypic model, and the maximum genetic model, and 3) random distribution of the nongenetic variation, as expected from the quantitative genetics theory. These results support the use of phenotypic data for the interpretation of the evolution history of prehistoric populations.     

红皮云杉群体遗传多样的研究

在红皮云杉(Picea korainesis)分布区内,选取了有代表性的长白山及其支脉张广才岭、老爷岭、完达山,小兴安岭,大兴安岭,大兴安岭向内蒙古高原过渡地带以及锡霍特山脉的12个群体,运用群体遗传学、生理遗传学、森林遗传学以及林木育种的理论和方法,利用主成分和分层聚类分析等多种统计分析方法,从表型和分子水平等多层次较为系统地研究了红皮云杉群体内、群体间的变异,同时探讨了各种亲代、后代特征以及等位酶与生态环境因子之间的关系。,首次从亲代生物系统学特征,后代苗木形态、生长、生物量和矿物质元素等对红皮云杉群体遗传变异进行了研究,结果表明,红皮云杉具有丰富的遗传变异,群体内变异大于群体间变异;红皮云杉12个群体11个酶系统21个位点中约有27.2%的基因位点是多态的,群体间的变异量只占总变异量的15.2%,84.8%的变异存在于群体内。红皮云杉群体等位酶多态位点的比率在云杉属中处于较低的水平,群体间的分化与云杉其它树种相比处于较高的水平。等位酶与形态等具有相似的变异趋势。根据红皮云杉气候、亲代及后代特征群体区划结果,我们认为红皮云杉种子区划为:长白山种子区(Ⅰ);老爷岭、张广才岭、完达山种子区(Ⅱ);小兴安岭种子区(Ⅲ);大兴安岭北部种子区(Ⅳ);大兴安岭西南部种子区(Ⅴ);锡霍特山脉种子区(Ⅵ)。     

Levels of genetic polymorphism: marker loci versus quantitative traits.

Species are the units used to measure ecological diversity and alleles are the units of genetic diversity. Genetic variation within and among species has been documented most extensively using allozyme electrophoresis. This reveals wide differences in genetic variability within, and genetic distances among, species, demonstrating that species are not equivalent units of diversity. The extent to which the pattern observed for allozymes can be used to infer patterns of genetic variation in quantitative traits depends on the forces generating and maintaining variability. Allozyme variation is probably not strictly neutral but, nevertheless, heterozygosity is expected to be influenced by population size and genetic distance will be affected by time since divergence. The same is true for quantitative traits influenced by many genes and under weak stabilizing selection. However, the limited data available suggest that allozyme variability is a poor predictor of genetic variation in quantitative traits within populations. It is a better predictor of general phenotypic divergence and of postzygotic isolation between populations or species, but is only weakly correlated with prezygotic isolation. Studies of grasshopper and planthopper mating signal variation and assortative mating illustrate how these characters evolve independently of general genetic and morphological variation. The role of such traits in prezygotic isolation, and hence speciation, means that they will contribute significantly to the diversity of levels of genetic variation within and among species.     

QUANTITATIVE GENETICS OF SIZE,SHAPE, LIFE-HISTORY,AND FRUIT CHARACTERISTICS OF THE SEED-HETEROMORPHIC COMPOSITE HETEROSPERMA PINNATUM. I. VARIATION WITHIN AND AMONG POPULATIONS

We document phenotypic and genetic variation within and among populations of the seed heteromorphic species Heterosperma pinnatum Cav. (Compositae) in the production of seed morphs and in a variety of life-history and morphological characteristics that might be correlated with seed and head traits. Each trait is found to have significant genetic variance in most or, usually, all populations. Significant among-population genetic variation exists for all traits except number of achenes per head and seedling shape, although some traits have much less genetic variation among than within populations. Number and percentage of intermediate achenes per head, total number of achenes per head, and lengths of central and peripheral achenes had little among-population genetic variation compared to within-population variation. Most traits had slightly less genetic variation among than within populations; however, some traits (percentage of central achenes, length of awns, date that the first flowering head opened, date that the first fruiting head opened, and death date) had more among-population genetic variation. The proportions of achene morphs produced had high broad-sense heritabilities and high among-population genetic variance, except in the case of intermediate achenes. All phenological variables had high among-population genetic variation. Within-population heritabilities were high for dates of first flowering head and fruiting head but low for death date and reproductive interval. Family and population means measured in the greenhouse for traits having high broad-sense heritability or among-population genetic variance were closely correlated with field means for the corresponding families or populations. The amounts of phenotypic variation were similar for traits that were measured in both the field and the greenhouse. These lines of evidence suggest that greenhouse results provide reasonable estimates of genetic variation in the field for this species. Numerous studies have reported variation in the proportion of seed morphs for different heteromorphic-seeded species and have discussed adaptive scenarios for the evolution of seed proportions; however, our investigation is one of only a few that have documented the amount of phenotypic and genetic variation within and among populations.