THE EFFECT OF DISTANCE FROM THE PARENTAL SITE ON OFFSPRING PERFORMANCE AND INBREEDING DEPRESSION IN IMPATIENS CAPENSIS: A TEST OF THE LOCAL ADAPTATION HYPOTHESIS

If microgeographic variation in selection within a natural plant population has resulted in local adaptation, then offspring fitness should decline with distance from the parental site. If outcrossed progeny are less well-adapted to the parental environment than inbred progeny, but perform better in environments different from that of the parent, then the fitness of inbred progeny relative to outcrossed progeny should decrease with dispersal distance from the parent. To test these predictions, we collected seedlings at 10-m intervals from a 40 times 40-m permanent grid in a natural population of Impatiens capensis, grew them in a greenhouse, and crossed them to produce outcrossed chasmogamous seeds. Seedlings from outcrossed chasmogamous and self-fertilized cleistogamous seeds were planted back into the source population in the original site of their maternal parents and in arcs 3 and 12 m from the parental location and censused weekly for survival and reproduction. The fitness of inbred offspring declined significantly and the magnitude of observed inbreeding depression increased with distance from the parental site, supporting the local adaptation hypothesis.     

Clonal and fine-scale genetic structure in populations of a restricted Korean endemic, Hosta jonesii (Liliaceae) and the implications for conservation

BACKGROUND AND AIMS: In plant populations the magnitude of spatial genetic structure of apparent individuals (including clonal ramets) can be different from that of sexual individuals (genets). Thus, distinguishing the effects of clonal versus sexual individuals in population genetic analyses could provide important insights for evolutionary biology and conservation. To investigate the effects of clonal spread on the fine-scale spatial genetic structure within plant populations, Hosta jonesii (Liliaceae), an endemic species to Korea, was chosen as a study species. METHODS: Using allozymes as genetic markers, spatial autocorrelation analysis of ramets and of genets was conducted to quantify the spatial scale of clonal spread and genotype distribution in two populations of H. jonesii. KEY RESULTS: Join-count statistics revealed that most clones are significantly aggregated at < 3-m interplant distance. Spatial autocorrelation analysis of all individuals resulted in significantly higher Moran's I values at 0-3-m interplant distance than analyses of population samples in which clones were excluded. However, significant fine-scale genetic structure was still observed when clones were excluded. CONCLUSIONS: These results suggest that clones enhance the magnitude of spatial autocorrelation due to localized clonal spread. The significant fine-scale genetic structure detected in samples excluding clones is consistent with the biological and ecological traits exhibited by H. jonesii including bee pollination and limited seed dispersal. For conservation purposes, genetic diversity would be maximized in local populations of H. jonesii by collecting or preserving individuals that are spaced at least 5 m apart.     

Microhabitat contributes to microgeographic divergence in threespine stickleback

Since the New Synthesis, most migration-selection balance theory has predicted that there should be negligible differentiation over small spatial scales (relative to dispersal), because gene flow should erode any effect of divergent selection. Nevertheless, there are classic examples of microgeographic divergence, which theory suggests can arise under specific conditions: exceptionally strong selection, phenotypic plasticity in philopatric individuals, or nonrandom dispersal. Here, we present evidence of microgeographic morphological variation within lake and stream populations of threespine stickleback (Gasterosteus aculeatus). It seems reasonable to assume that a given lake or stream population of fish is well-mixed. However, we found this assumption to be untenable. We examined trap-to-trap variation in 34 morphological traits measured on stickleback from 16 lakes and 16 streams. Most traits varied appreciably among traps within populations. Both between-trap distance and microhabitat characteristics such as depth and substrate explained some of the within-population morphological variance. Microhabitat was also associated with genotype at particular loci but there was no genetic isolation by distance, implying that heritable habitat preferences may contribute to microgeographic variation. Our study adds to growing evidence that microgeographic divergence can occur across small spatial scales within individuals’ daily dispersal neighborhood where gene flow is expected to be strong.     

安徽黄山青冈种群遗传结构的空间自相关分析

以黄山－青冈（Ｃyclobalanopsis glauca)种群为例,研究了种群内等位基因的空间格局,在种群内,大多数等位基因的Moran'sI数大于期望值,但只有两个等位基因存在显著的正空间自相关;如果考虑不同的无性系分株时,大多数等位基因在短距离内存在显著的空间自相关。相关图表明不同距离间隔,Moran'sI指数变化无规律,表明没有哪个进化因子起决定作用,但无性系繁殖在空间自相关中起重要作用,尤其是在近距离。     

MACRO- AND MICROGEOGRAPHIC STRUCTURE OF A SPATIALLY SUBDIVIDED BEETLE SPECIES IN NATURE

Spatial subdivision of species can affect their population structure by allowing processes such as limited dispersal, spatial heterogeneity in selective pressures, small population sizes, and random events to operate. By studying species restricted to islands or “island” habitats, one can attempt to determine which of these factors have affected the current structure of the population. Collops georgianus (Coleoptera: Melyridae), a beetle species endemic to the “island” habitat of granitic rock outcrops, was chosen to see how its spatially subdivided distribution has affected its genetic structure. Its genetic structure was examined on both a macrogeographic and a microgeographic level using protein electrophoresis. Macrogeographically, 12 populations throughout its range were sampled. The discontinuous distribution of outcrops, and thus populations, throughout its range, has determined the connectivity of the populations. Significant variation in allele frequencies and substructuring (F_ST = 0.192) was found throughout the range, but there was no spatial autocorrelation. Microgeographically, in the central part of the range, where outcrops are denser and more continuously distributed in space, there was evidence of isolation by distance. Very little variation in allele frequencies was found, but a low but significant level of substructuring occurred among the populations. Comparison of disjunct and continuous populations microgeographically revealed no effect of disjunct distributions, although a significant effect of distance was detected. Effective population size variation among populations and between years, compounded with the effects of local extinctions, suggest that random processes such as drift and founder effects are important determinants of the population's genetic structure.     

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.     

Variation in fine‐scale genetic structure and local dispersal patterns between peripheral populations of a South American passerine bird

The distribution of suitable habitat influences natal and breeding dispersal at small spatial scales, resulting in strong microgeographic genetic structure. Although environmental variation can promote interpopulation differences in dispersal behavior and local spatial patterns, the effects of distinct ecological conditions on within‐species variation in dispersal strategies and in fine‐scale genetic structure remain poorly understood. We studied local dispersal and fine‐scale genetic structure in the thorn‐tailed rayadito (Aphrastura spinicauda), a South American bird that breeds along a wide latitudinal gradient. We combine capture‐mark‐recapture data from eight breeding seasons and molecular genetics to compare two peripheral populations with contrasting environments in Chile: Navarino Island, a continuous and low density habitat, and Fray Jorge National Park, a fragmented, densely populated and more stressful environment. Natal dispersal showed no sex bias in Navarino but was female‐biased in the more dense population in Fray Jorge. In the latter, male movements were restricted, and some birds seemed to skip breeding in their first year, suggesting habitat saturation. Breeding dispersal was limited in both populations, with males being more philopatric than females. Spatial genetic autocorrelation analyzes using 13 polymorphic microsatellite loci confirmed the observed dispersal patterns: a fine‐scale genetic structure was only detectable for males in Fray Jorge for distances up to 450 m. Furthermore, two‐dimensional autocorrelation analyzes and estimates of genetic relatedness indicated that related males tended to be spatially clustered in this population. Our study shows evidence for context‐dependent variation in natal dispersal and corresponding local genetic structure in peripheral populations of this bird. It seems likely that the costs of dispersal are higher in the fragmented and higher density environment in Fray Jorge, particularly for males. The observed differences in microgeographic genetic structure for rayaditos might reflect the genetic consequences of population‐specific responses to contrasting environmental pressures near the range limits of its distribution.     

Geostatistical analysis of soil properties in a secondary tropical dry forest,St. Lucia,West Indies

Spatial variability of soil properties directly influences forest growth. However, spatial variation in soil properties has not been studied within tropical dry forests. As such, it is unclear whether soil properties, like moisture and N availability, display spatial variation at scales similar to that of other ecosystems. To gain insight into this variation, we established a 56 × 56 m sampling grid in tropical dry forest on the Caribbean island of St. Lucia. Samples collected at 4-m intervals were analyzed for forest floor mass, soil texture, pH, organic C, net N mineralization, net nitrification and available P. Geostatistical procedures were used to determine spatial autocorrelation of the aforementioned properties and processes. Semivariogram parameters were used in a block kriging procedure to produce spatial maps of soil properties. At the scale of our study, most soil properties exhibited spatial autocorrelation at distances of 24 m or less. Varying degrees of similarity were found between patterns of forest floor mass, organic C, net N mineralization, net nitrification and available P. No similarity was found between soil texture or pH and other properties. Fine-scale spatial patterns of net N mineralization and net nitrification are likely driven by overstory litter inputs, rather than variation in soil texture and water availability.     

MICROGEOGRAPHIC PATTERNS OF GENETIC AND MORPHOLOGICAL VARIATION IN SAVANNAH SPARROWS (PASSERCULUS SANDWICHENSIS)

Surveys of genetic population structure are often limited to large geographic scales because geographically close populations are indistinguishable. Genetic uniformity across adjacent demes can be interpreted as evidence for cohesion (panmixia) or recent divergence. However, poor genetic resolution at microgeographic scales can also arise from the use of overly conservative (slowly evolving) markers. This study examines the ability of hypervariable, minisatellite loci to discriminate among geographically close populations of Savannah sparrows (Passerculus sandwichensis) and to track morphological differentiation at a microgeographic scale (interregional distance < 55 km). Savannah sparrows breeding at five island and two mainland sites in the Bay of Fundy, New Brunswick, Canada, show concordant patterns of variation in external morphology (seven characters) and multilocus DNA fingerprinting profiles (S_xy): island sparrows are phenotypically larger and genetically more similar to each other than they are to mainland sparrows. This pattern of variation is consistent with both adaptive (natural selection) and nonadaptive (genetic drift) mechanisms of population divergence. Based on minisatellite diversity, the effective size of both island and mainland populations is 37, an estimate substantially lower than census population sizes. These data are discordant with observations of sparrow vagility and abundance and suggest a closer examination of microgeographic patterns in avian systems.     

Spatial genetic structure and frequency of interspecific hybridization in Platanthera aquilonis and P. dilatata (Orchidaceae) occurring in sympatry

Knowledge of genetic structure at different scales is necessary for evaluating the importance of interactions between the genome and environment and for inferring underlying processes that bring about evolutionary diversification. Here, genetic and morphological variation was assessed for 154 individuals of Platanthera aquilonis and P. dilatata in Maine, using RAPD and PCR-RFLP markers and measurements of five morphological traits to determine the prevalence of interspecific hybrids and underlying spatial genetic structure of the population. Both species co-mingled in the population, but clumping was observed. Platanthera aquilonis was more abundant, but genetic variation was lower (polymorphic loci [40%], expected heterozygosity [0.137]) than that of P. dilatata (P(p) = 72%; H(e) = 0.245). Interspecific hybrids were rare (eight individuals), and morphology was not consistently reliable for determining hybrid status even though the species differed significantly in several traits. Spatial autocorrelation analyses showed significant genetic structure at small distances for both species, most likely due to restricted seed dispersal. Platanthera aquilonis did not exhibit a pattern of spatial genetic structure consistent with other selfing species. This suggests that the species is facultative autogamous, which allows for limited production of hybrid individuals and reduces the strength of spatial genetic structure relative to P. dilatata.     

Genetic structure of age classes in Camellia japonica (Theaceae)

Camellia japonica L. (Theaceae), an insect- and bird-pollinated, broad-leaved evergreen tree, is widely distributed in Japan and the southern Korean peninsula. The species has a relatively even age distribution within populations, which may influence the spatial genetic structure of different age classes relative to species with typical L-shaped age distributions. To determine whether the internal spatial genetic structure found in seedlings and young individuals carries over into adults, we used allozyme loci, F-statistics, spatial autocorrelation statistics (Moran's I), and coancestry measures to examine changes in genetic structure among seven age classes in a population (60-m x 100-m area) in southern Korea. In seedlings, weak but significant positive values of Moran's I-statistics and coancestry measures were found for distances less than 14 m, which is consistent with a mechanism of limited seed dispersal combined with overlapping seed shadows. This spatial structure, however, dissipates in older age classes, and in adults genetic variation has an essentially random spatial distribution. Morisita's index of dispersion of individuals in each age class showed that seedlings and juveniles are more highly clustered than are older individuals. These results suggest that self-thinning changes the spatial relationships of individuals, and thus genotypes. A multilocus estimate of FST (0.008) shows a small but statistically significant difference in allele frequencies among age classes. In summary, intrapopulation genetic structure within and among age classes of C. japonica was significant but weak. Despite presumably limited seed dispersal, weak spatial genetic structure in juveniles suggests overlapping seed shadows followed by self-thinning during recruitment. The present study also demonstrates that studies of spatial genetic structure focusing on limited numbers of generations may not be sufficient to reveal the entire picture of genetic structure in populations with overlapping generations.     

MICROGEOGRAPHIC LINEAGE ANALYSIS BY MITOCHONDRIAL GENOTYPE: VARIATION IN THE COTTON RAT (SIGMODON HISPIDUS)

We evaluate the use of mitochondrial DNA (mtDNA) genetic markers to describe population structure and matrilineal kinship on a microgeographic scale. An analysis of restriction site variation in 134 cotton rats (Sigmodon hispidus) collected from a 3.2 hectare field revealed significant spatial and temporal heterogeneity in frequencies of mtDNA genotypes among nest sites. Inspection of particular genotypes provided additional information about minimum numbers of female lineages (family units) per nest site, and the possible matrilineal affiliations of individuals. However, since shared genotypes are not necessarily synapomorphs having arisen within the study area, conclusions about dispersal must remain reserved. Study of the maternally-transmitted mtDNA genome offers novel perspectives on the meaning of microgeographic population structure.     

Population genetic structure of the medicinal plant Vitex rotundifolia in China: implications for its use and conservation

Vitexrotundifolia L.is an important plant species used in traditional Chinese medicine.For its efficient use and conservation,genetic diversity and clonal variation of V.rotundifolia populations in China were investigated using inter-simple sequence repeat markers.Fourteen natural populations were included to estimate genetic diversity,and a large population with 135 individuals was used to analyze clonal variation and fine-scale spatial genetic structure.The overall genetic diversity (GD) of V.rotundifolia populations in China was moderate (GD=0.190),with about 40% within-population variation.Across all populations surveyed,the average within-population diversity was moderate (P = 22.6%; GD = 0.086).A relatively high genetic differentiation (Gst=0.587)among populations was detected based on the analysis of molecular variance data.Such characteristics of V.rotundifolia are likely attributed to its sexual/asexual reproduction and limited gene flow.The genotypic diversity (D=0.992) was greater than the average values of a clonal plant,indicating its significant reproduction through seedlings.Spatial autocorrelation analysis showed a clear within-population structure with gene clusters of approximately 20 m.Genetic diversity patterns of V.rotundifolia in China provide a useful guide for its efficient use and conservation by selecting particular populations displaying greater variation that may contain required medicinal compounds,and by sampling individuals in a population at >20 m spatial intervals to avoid collecting individuals with identical or similar genotypes.     

THE INFLUENCE OF DENSITY AND SEX ON PATTERNS OF FINE-SCALE GENETIC STRUCTURE

Natal philopatry is expected to limit gene flow and give rise to fine-scale spatial genetic structure (SGS). The banner-tailed kangaroo rat ( Dipodomys spectabilis ) is unusual among mammals because both sexes are philopatric. This provides an opportunity to study patterns of local SGS faced by philopatric and dispersing animals. We evaluated SGS using spatial genetic autocorrelation in two D. spectabilis populations (Rucker and Portal) over a 14-year temporal series that covered low, medium, and high population densities. Significantly positive autocorrelation values exist up to 800 m at Rucker and 400 m at Portal. Density was negatively associated with SGS (low >medium >high), and suggests that increases in density are accompanied by greater spatial overlap of kin clusters. With regard to sex-bias, we find a small but significant increase in the SGS level of males over females, which matches the greater dispersal distances observed in females. We observed variation in SGS over the ecological time scale of this study, indicating genetic structure is temporally labile. Our study is the first temporal exploration of the influence of density and sex on spatial genetic autocorrelation in vertebrate populations. Because few organisms maintain discreet kin clusters, we predict that density will be negatively associated with SGS in other species.     

Intertidal population genetic dynamics at a microgeographic seascape scale

The intertidal community is among the most physically harsh niches on earth, with highly heterogeneous environmental and biological factors that impose strong habitat selection on population abundance, genetic connectivity and ecological adaptation of organisms in nature. However, most genetic studies to date have concentrated on the influence of basin-wide or regional marine environments (e.g. habitat discontinuities, oceanic currents and fronts, and geographic barriers) on spatiotemporal distribution and composition of intertidal invertebrates having planktonic stages or long-distance dispersal capability. Little is known about sessile marine organisms (e.g. seaweeds) in the context of topographic tidal gradients and reproductive traits at the microgeographic scale. In this issue of Molecular Ecology, Krueger-Hadfield et al. ( 2013a ) implemented an elaborate sampling strategy with red seaweed (Chondrus crispus) from a 90-m transect stand near Roscoff and comprehensively detected genome-scale genetic differentiation and biases in ploidy level. This study not only revealed that tidal height resulted in genetic differentiation between high- and low-shore stands and restricted the genetic exchange within the high-shore habitat, but also demonstrated that intergametophytic nonrandom fertilization in C. crispus can cause significant deviation from Hardy–Weinberg equilibrium. Such new genetic insights highlight the importance of microgeographic genetic dynamics and life history characteristics for better understanding the evolutionary processes of speciation and diversification of intertidal marine organisms.     

QUANTITATIVE GENETICS OF FITNESS TRAITS IN A WILD POPULATION OF PHLOX

To determine if the evolution of fitness traits in the annual plant, Phlox drummondii, is constrained by lack of genetic variation, we calculated the heritability and genetic correlation of 16 traits in a field population. Full- and half-sib families of seeds were generated in the greenhouse and planted back into the study population. Of 855 seeds that germinated, 609 survived to produce fruit. For each plant we measured several aspects of plant size and three components of female fecundity: total number of fruits produced, number of seeds per fruit, and mass of individual seeds. Heritability of traits ranged from 0.00 to 0.15. Several traits showed significant levels of additive genetic variance, but we found no evidence of additive genetic variance in components of female fecundity and no evidence of negative genetic correlation between fitness traits. These results suggest that evolution in this population would be constrained by lack of heritable variation in fitness traits.     

浙江天台山甜槠种群遗传结构的空间自相关分析

采用空间自相关分析方法对浙江天台山亚热带常绿阔叶林优势种甜槠种群全部个体及不同年龄级个体的小尺度空间遗传结构进行了分析,以探讨甜槠种群内遗传变异的分布特征及其形成机制。根据11个ISSR引物所提供的多态位点,经GenAlEx 6软件计算地理坐标和遗传距离矩阵在10个距离等级下的空间自相关系数。在样地内,甜槠种群内个体在空间距离小于10 m时存在显著的正空间遗传结构,其X-轴截矩为9.945。甜槠种群的空间遗传结构与其种子短距离传播和广泛的花粉传播有关。Ⅰ年龄级、Ⅱ年龄级和III年龄级个体在空间距离小于10 m时存在显著的正空间遗传结构,其X-轴截矩分别为11.820、9.746和9.792。当距离等级为5 m时,其空间自相关系数r分别为0.068、0.054和0.070。Ⅳ年龄级个体在所有空间距离等级中均不存在显著的空间遗传结构。甜槠是多年生、长寿命植物,自疏作用是导致IV年龄级个体空间遗传结构消失的主要原因。     

The structure of phenotypic variation in gender and floral traits within and among populations of Spergularia marina (Caryophyllaceae)

We sampled four wild populations of the highly autogamous Spergularia marina (Caryophyllaceae) in California to detect and to measure the magnitude of within- and among-population sources of phenotypic variation in gender and floral traits. From flowers and fruits collected from field and greenhouse-raised plants, we measured ovule number, seed number, mean seed mass, pollen production (greenhouse families only), mean pollen grain volume (greenhouse families only), anther number, anther/ovule ratio, pollen/ovule ratio (estimated using different flowers for pollen than for ovules; greenhouse families only), petal number, and petal size. Using greenhouse-raised genotypes, variation among maternal families nested within populations was evaluated for each trait to determine whether populations differ in the degree of maternally transmitted phenotypic variation. For each population, we used 15 greenhouse-raised maternal families to estimate the broad-sense heritability and genetic coefficient of variation of each floral trait. The magnitude and statistical significance of broad-sense heritability estimates were trait- and population-specific. Each population was characterized by a different combination of floral traits that expressed significant maternally transmitted (presumably genetic) variation under greenhouse conditions. Flowers representing two populations expressed low levels of maternally transmitted variation (three or fewer of nine measured traits exhibited significant maternal family effects on phenotype), while flowers representing the other two populations exhibited significant maternal family effects on phenotype for five or more traits. Our ability to detect statistically significant differences among the four populations depended upon the conditions under which plants were grown (field vs. greenhouse) and on the floral trait observed. Field-collected flowers exhibited significant differences among population means for all traits except anther number. Flowers sampled from greenhouse-raised maternal families differed among populations for all traits except ovule number, seed number, and petal size. We detected negligible evidence that genetic correlations constrain selection on floral traits in Spergularia marina.     

Spatial genetic structure of two sympatric neotropical palms with contrasting life histories

The spatial genetic structure within sympatric populations of two neotropical dioecious palm species with contrasting life histories was characterized to evaluate the influence of life history traits on the extent of genetic isolation by distance. Chamaedorea tepejilote is a common wind-pollinated arboreal understory palm. Chamaedorea elatior is an uncommon climbing subcanopy palm with entomophilous pollination syndrome. A total of 59 allozyme alleles for C. tepejilote and 53 alleles for C. elatior was analyzed using both unweighted (Iu) and weighted (Iw) Moran's I spatial autocorrelation statistics. The spatial genetic structure detected within these populations is consistent with those reported for highly dispersed plants. A significance test for differences between mean Moran's I-coefficients revealed less spatial genetic structure within the C. tepejilote population than that in the C. elatior population. Adjacent individuals of C. elatior exhibited significant spatial genetic autocorrelation (Iu=0.039, Iw=0.034), indicating a Wright's neighborhood size of about 100 individuals. For C. tepejilote, nonrandom genetic distribution among nearest neighbors was detected, even from small spatial autocorrelation values (Iu=0.008, Iw=0.009), consistent with a neighborhood size of about 300 individuals. For both species, seed dispersal, mortality among life cycle stages, overlapping generations, and contrasting traits of mating and reproduction influence the standing spatial genetic structure within populations.     

Quantitative genetic variation in a population of Crepis tectorum subsp. pumila (Asteraceae)

Quantitative genetic variation was assessed in a population of Crepis tectorum subsp. pumila , a winter annual confined to calcareous grassland on the Baltic island of öland (SE Sweden). Plants from 40 maternal sibships were grown in a greenhouse and scored for a large number of traits representing all stages of the life cycle. The study included several characters that have been subject to ecotypic differentiation as well as traits known to be under current selection. Highly significant family differences were found for all but one character, suggesting that past selection was too weak to eliminate the genetic variability of characters presumed to be adaptive and there is a potential for further adaptive change in most traits. Two additional traits treated as qualitative were also found to differ significantly among families. A parallel cultivation experiment showed that the extent of population divergence in a quantitative trait was positively correlated with the amount of inter- family variation, implying stability of the relative variability for substantial periods of time, a possible reflection of phenotypic constraints being expressed both within and between populations. Additional data indicated that genetic trade-offs among traits under simultaneous selection, year-to- year variation in selection in combination with a long-lived seed bank, and genotype × environment interactions, could prevent the erosion of genetic variability in some characters connected with fitness.