Evaluation of the population dynamics of the forage legume (Lotus corniculatus), using matrix population models

The population dynamics of perennial crop plants are influenced by numerous factors, including management practices. Conditions in the field vary from year to year, and matrix population models are useful for evaluating population behaviour in relation to environmental variability. In Missouri, the stand persistence of birdsfoot trefoil ( Lotus corniculatus ), a perennial legume, is often limited by disease and poor seed production. A stage-based, matrix population model was developed to evaluate the population dynamics of birdsfoot trefoil in relation to clipping treatment. The plant growth stages represented in the model were seeds, seedlings, mature vegetative and reproductive plants. Two phases of population growth were evaluated in clipped and unclipped stands. Establishment-phase populations were characterized by relatively high mortality and low reproduction. Elasticity analysis indicated that growth of these populations was most sensitive to the survival of vegetative plants. Mature vegetative plants and seeds comprised the majority of surviving individuals in clipped and unclipped populations, respectively; however, establishment-phase populations under both management treatments tended toward extinction. Populations in the post-establishment phase of growth were characterized by relatively low mortality and high reproduction. Population growth in this phase of growth was most sensitive to seed production, and most individuals in these populations were at the seed stage.     

Forest-cutting rapidly improves the demographic status of Paeonia officinalis, a species threatened by forest closure

In the Mediterranean region, the spread and densification of woodlands and shrublands subsequent to rural depopulation is a critical issue for the conservation of open-habitat plant species. Our objective was to assess the effectiveness of forest management to reduce the negative impact of forest closure on the persistence of a protected herbaceous perennial species Paeonia officinalis. Using demographic surveys from 2003 to 2008 in a woodland, open and managed habitat clear-cutted for the aim of our study, we assessed the effect of forest opening on plant performance and population dynamics. In addition, we performed a shading experiment on reproductive plants to mimic canopy closure and study its impact on plant growth and fecundity. Based on quadrat surveys and matrix models, we showed that forest cutting induced a rapid increase in plant performance and population asymptotic growth rate. Indeed, within 2 years, plant size, flower, seed and ovule numbers as well as the plant stage distribution, asymptotic growth rates and elasticity patterns shifted from values similar to those in the woodland habitat to values similar to those in the open habitat. Similarly, artificially shaded reproductive plants regressed within 2 years towards the vegetative stage. For perennial plants which have a stage in their life-cycle which allows for individual survival under unfavourable conditions such as the vegetative stage for P. officinalis, such demographic plasticity may be fundamental for their long-term persistence in temporally heterogeneous environments. Our study highlights the need to mix an experimental approach with a mid-term demographic survey in order to design efficient conservation management strategies for declining populations of rare species.     

Life History Studies on the Genus Trillium (Liliaceae) III. Reproductive Biology of Six Sessile-flowered Species Occurring in the Southeastern United States with Special Reference to Vegetative Reproduction

Abstract Life history characteristics, e.g., stage class structures of natural populations and associated reproductive characteristics, were studied for six sessile-flowered, diploid Trillium (Liliaceae) species that are restricted to the Coastal Plain region of the southeastern United States.
These sessile-flowered species reproduce primarily by vegetative propagation. Leaf area measurements were used to categorize stage class distributions of natural populations. Populations propagating mainly by vegetative reproduction had non-sigmoidal, convex-shaped population structures with most plants being in the intermediate stage classes. Low numbers of individuals in smaller stage classes and an abundance of intermediate sized individuals are due to the fact that vegetative propagules are the primary method for maintenance of local populations.
Characteristics associated with sexual reproduction were also examined. Seed output averaged about 20 seeds per plant, except for T. lancifolium which produced 9.7 seeds on the average. Seed setting rates varied between 15.61–44.15% and mean seed weight varied from 4.89 to 10.75 mg. The dominance of vegetative versus sexual reproduction may be due to the fact that all six species occur in ecologically unstable flood plain habitats.     

Impact of land use intensity and temperature on the reproductive performance of <Emphasis Type="Italic">Dactylis glomerata</Emphasis> populations in the southeastern Alps

An understanding of the processes and environmental conditions governing spatial variation in reproductive performance of plants can provide important information about the factors characterizing plant community structure and influencing fitness in natural plant populations, especially in the context of climate and land use change. In this study, 60 mountain populations of Dactylis glomerata distributed along a fertilization regime in varying grassland hay meadows were evaluated. Variations in field management, climate, soil fertility, vegetation structure, population density and species richness on reproductive performance were examined. The results indicated that field management and soil nutrient availability are the main variables influencing population density and reproductive output of D. glomerata. Moreover, the results show the effect of temperature on seed mass and resource investment in reproduction. Climate and soil change suggest a morphological differentiation of reproductive traits: (i) individuals grown on sites with higher soil nutrient availability or nutrient supply have larger inflorescences with a greater number and heavier seeds; (ii) individuals grown on warmer sites have heavier seeds. We conclude that if the climate warms and increases land use intensification in hay meadows in the Alps, this will have a pronounced positive impact on the reproductive performance of D. glomerata. Moreover, it can be hypothesized that the migration potential of D. glomerata towards higher altitudes may be likely in the near future in response to accelerated climate change.     

Variation in reproductive modes and population genetic structures of a monocarpic perennial herb,Cardiocrinum cordatum,in relation to habitat fragmentation

Reproductive systems are recognized as having a profound influence on the extent and structure of genetic variation in plant populations. To investigate the spatiotemporal variation in the reproductive modes (sexual and vegetative reproduction) and population genetic structures of a monocarpic perennial herb, Cardiocrinum cordatum (liliaceae), we selected a variety of habitats (e.g. large forested area including primeval forest, small fragmented secondary forest, and so on) around Sapporo City, Japan. We conducted breeding experiments, monitored the fate and growth of marked individuals for 3 years, and also analyzed the spatiotemporal genetic variation of flowering plants within the populations using allozyme variation. Plants emasculated prior to anthesis produced mature fruits in all populations examined. However, seed production was significantly lower in the small fragmented populations, possibly because of the low availability of pollinators and subsequent pollen limitation. In these fragmented populations, the mature flowering plants tended to be more dependent on vegetative reproduction for their recruitment, because they can only produce flowers once in their lifetime. Genetic diversity using samples from mature flowering plants in each population was lower in the small fragmented populations than in the large populations. In addition, although genotypic compositions in the fragmented populations were more or less similar during the 3 years of the study, the dominant genotypes changed temporally and spatially every year in the large populations. The present study demonstrated that the reproductive features of C. cordatum can be altered in various environmental conditions, such as habitat fragmentation, and these changes considerably affected the population genetic structures and vice versa.     

How does herbivory affect individuals and populations of the perennial herb Paeonia officinalis?

In this study we quantified variability in foliage herbivory and pre-dispersal seed predation and its effects on plant performance and demography in populations of a rare and protected perennial herb, Paeonia officinalis. An individual-based survey was performed during four years in four populations, which contained plants in both open habitat and woodland. We detected marked spatial and temporal variation among and within populations in foliage herbivory (by insects) and pre-dispersal seed predation (by insects, rodents and Roe Deer). Foliage herbivory decreased with plant demographic stages in open habitats, from seedlings to reproductive individuals, but no significant trend was detected in woodland habitats. This may be due to different demographic origin of larger vegetative plants in this habitat. Depending on demographic stage, herbivory was higher in open habitats or not significantly different between habitats. This suggests differences in herbivore abundance in different habitats within sites. Pre-dispersal seed predation remained weak and did not depend on habitat. We did not detect any consequence of foliage herbivory on seedling mortality and individual growth in our study. Our results illustrate the need to investigate plant-herbivore interactions over several years in distinct populations in order to more accurately evaluate herbivore impact on plant population dynamics.     

Seed production and pre-dispersal reproductive losses in the narrow endemic <Emphasis Type="Italic">Euphorbia pedroi</Emphasis> (Euphorbiaceae)

Euphorbia pedroi is a narrow endemic species with three known populations located in coastal areas of western Portugal. This study focused on the reproductive biology of this species from flowering to dispersal, aiming to identify the factors causing decrease in seed production potential and to assess the spatio-temporal patterns of seed production at the individual and population levels. The abortion of reproductive structures, particularly seeds, represented a major fraction of losses in the potential seed production of E. pedroi. Moth larvae destroyed a variable proportion of cyathia in a large number of plants from the two populations regardless of their degree of isolation. Furthermore, generalist and specialist pre-dispersal seed predators were responsible for temporally variable seed losses unrelated with variables indicative of plant size and fecundity, and showing no consistency at the individual level. Specialist seed-wasps inflicted the highest losses to E. pedroi and their impact was intimately associated with the magnitude of yearly variation in seed production. This finding highlights the role of the inter-annual variation in seed production as a key feature in this plant-seed predator system. The effect of the two groups of seed predators on the reproductive output of E. pedroi was additive and those insects do not seem to exert an important selective pressure on the traits studied. The proportion of intact seeds produced by E. pedroi differed between locations, but not between individuals within each population, highlighting the major contribution of larger plants to the seed pool.     

From horticultural plantings into wild populations: movement of pollen and genes in <Emphasis Type="Italic">Lobelia cardinalis</Emphasis>

The Southern Grassland biome in Brazil has long been neglected by the government and by the scientific community as well. Lack of studies about the effects of disturbance (mostly fire and grazing) on plant community and populations are the main hindrances for the future management plans, which complicates the conservation of this rich and unique biome. In this study, the population biology of a rosette species, Eryngium horridum (Apiaceae), has been investigated, in order to compare the effects of fire, grazing and abandonment. E. horridum is a very common species and many farmers consider it a nuisance. Two different areas were chosen for the study purposes: Morro Santana and the Research Center Pró-Mata. Areas under different types (fire and grazing) and disturbance histories were compared. Populations were analysed in plots of 25 m², divided in age-state classes (seedlings, young, adult and reproductive individuals). Both morphological and phenological traits have been investigated. Fire influenced populations in a direct way, whilst grazing showed an indirect effect. Seedlings were found only in areas excluded from disturbance for 3 years on Morro Santana. Due to this, seedling establishment might be more related to environmental conditions than to disturbance regimes. Young individuals were mainly found in recently burned areas, while adult individuals were dominant in areas excluded from disturbance. Additionally, individuals from E. horridum showed a great capacity of resprouting after plant damage. Reproductive individuals also showed the capacity of producing new rosettes after the death of the inflorescence axis. This strategy is probably of great importance for the survival of populations in areas excluded from disturbance. Therefore, vegetative reproduction seemed to be the most important strategy for the maintenance and survival of its populations, allowing longer population persistence over time, even in the absence of disturbance.     

Optimal management of the rare Gladiolus imbricatus in Estonian coastal meadows indicated by its population structure

Questions: What is the best grassland management regime for the threatened plant species Gladiolus imbricatus; is the stage structure of local populations a feasible indicator of the effect of changed management. Location: Coastal meadow system in southwestern Estonia. Methods : The effect of five management regimes was studied in a long‐term (three‐year) field experiment: (1) mowing in late July, (2) grazing by cattle, (3) grazing by sheep, (4) sheep grazing during the first year and mowing during subsequent years, (5) no management (control). Results: The population density increased significantly in response to the mowing treatment and to the mowing after sheep grazing treatment. The proportion of grazed plant individuals was higher in the sheep‐grazed than in the cattle‐grazed treatment. Generative and vegetative adult individuals of G. imbricatus were significantly more damaged by cattle herbivory than juveniles. All management regimes shifted the population structure towards a dynamic state where juvenile stages dominate, while the not managed control retained a regressive population structure. Conclusions: Population stage structure was a useful indicator of different management conditions, even in the case where population density did not differ. As indicated by population stage structure, the best management regime for G. imbricatus was either mowing in late July only, or alternation of grazing and mowing in different years.     

Interpreting reproductive allometry: Individual strategies of allocation explain size-dependent reproduction in plant populations

Size-dependent or allometric relationships between reproductive and vegetative size are extremely common in plant populations. Reproductive allometry where plant size differences are due to environmental variability has been interpreted both as an adaptive strategy of plant growth and allocation, and as the product of fixed developmental constraints. Patterns of development are crucial in defining reproductive allometry but development is not fixed across individuals. For example, environmental adversity (e.g. resource impoverishment) tends to favor reproduction at relatively small sizes – an adaptive response to environmental adversity. While small individuals may have lower reproductive output than large individuals, all plants should maximize their reproductive output and relative allocation to reproduction may be constant across sizes. Thus, where individual plants within a population initiate reproduction at different sizes, no significant reproductive allometry is an appropriate null expectation. Reproductive allometry occurs in plant populations where initiating reproduction at small sizes yields relatively high or low reproductive size at final development. Both of these outcomes are common in plant populations. Our interpretation of reproductive allometry combines previous adaptive and developmental constraint interpretations, and is the first to successfully explain the range of relationships in plant populations where relative allocation has been observed to increase, decrease or remain constant will increasing plant size.     

Ecological fitness of a glyphosate-resistant Lolium rigidum population: Growth and seed production along a competition gradient

Repeated use of glyphosate has resulted in evolution of glyphosate-resistant Lolium rigidum populations in Australia. The relative growth, competitiveness and reproductive output of glyphosate resistant (R) and susceptible (S) L. rigidum phenotypes from a single population were compared in competition with wheat. Vegetative growth of R and S individuals was studied in response surface experiments in the glasshouse and seed production was measured using an additive neighbourhood design experiment conducted in pots outside during the normal growing season of L. rigidum in Australia. There were no significant differences in vegetative growth or competitiveness of the R and the S phenotypes. The mean weight of seeds produced by R plants was significantly greater than that produced by S individuals. In the absence of wheat and at low wheat densities, S plants produced more seeds than R plants. However, at higher crop densities, differences in seed production were not significant. This is the first study to compare components of fitness at key life history stages for glyphosate R and S phenotypes isolated from a single weed population. The results presented indicate important differences in resource allocation during the reproductive stage for R and S phenotypes. Subtle differences in life history strategies may be manipulated by agronomic management to exploit the potential ecological fitness costs of the R phenotype. Further studies are required to provide a greater understanding of the occurrence and extent of fitness costs associated with glyphosate resistance. This knowledge can then be incorporated into models that simulate resistance evolution to design management strategies to prevent and/or contain the spread of glyphosate resistance.     

Density and reproductive success in wild populations of Diplotaxis erucoides (Brassicaceae)

Summary One possible consequence of low population density, particularly in self-incompatible plants, is reproductive failure. I surveyed seed set per flower in two populations of the self-incompatible annual Diplotaxis erucoides (Brassicaceae) in Jerusalem, Israel. Widely spaced plants had lower fruit set and fewer seeds per filled silique than did plants growing close to conspecific neighbors. Such density-dependent reproductive success could help explain the maintanence of spatial patchiness in plant populations, and could also have implications for population dynamics of rare species.     

From over to undercompensation: Variable responses to herbivory during ontogeny of a Neotropical monocarpic plant

Empirical and theoretical work has suggested that plants can change their compensatory responses to herbivory as they develop. However, such a relationship is likely to be more complex than previously thought since the amount and type of damage a plant receives can also change as the plant develops. Here, we determined the survival, growth, and reproductive output of plants (Actinocephalus polyanthus) from different ontogenetic stages that received variable levels of natural or simulated herbivore damage. Juvenile plants and non‐reproductive adults in which leaves were damaged showed full vegetative compensation, whereas pre‐reproductive plants were not able to replace the lost leaves. However, these same pre‐reproductive plants produced more inflorescences and thus more seeds and seedlings than control plants. In contrast, damage to vegetative and/or reproductive structures during the reproductive phase resulted in a negative effect on seed and seedling production. Herbivory effects on plant survival, growth, and reproduction during the vegetative and pre‐reproductive phases were independent of the amount of damage. However, during reproduction, the magnitude of these effects was strongly influenced by the amount of damage and the reproductive stage of the plant at the time of the damage. In short, our results demonstrate that the survival, growth, and reproductive responses to herbivory of A. polyanthus can be dependent on the timing and/or intensity of damage. The reproductive response of A. polyanthus to our simulated herbivory treatments during the pre‐reproductive phase represents an example of overcompensation. Furthermore, it indicates that vegetative regrowth is not necessarily a driving factor for tolerance.     

Warm temperature conditions restrict the sexual reproduction and vegetative growth of the spring ephemeral <Emphasis Type="Italic">Gagea lutea</Emphasis> (Liliaceae)

The responses of reproduction and growth to climate warming are important issues to predict the fate of plant populations at high latitudes. Spring ephemerals inhabiting cool-temperate forests grow better under cool conditions, but how reproductive performance is influenced by warm weather is unclear. The phenological and physiological responses of reproduction and vegetative growth to warm temperature and light conditions were evaluated in the spring ephemeral Gagea lutea. Leaf and bract physiological activities, bulb growth, and seed production were compared among reproductive plants grown in forest, open, and greenhouse (GH; warming manipulation in the open site) plots. In vitro pollen germination ability was tested under various temperatures. In the GH, leaf and bract photosynthetic activities decreased rapidly at the fruiting stage, but dark respiration rates remained high, resulting in higher carbon exhaust in warm conditions. Both leaf and bract sizes and their longevities were reduced in the GH. Annual bulb growth was largest in the forest plot and smallest in the GH plot. Pollen germination was strongly inhibited at high temperature (30 °C). Fruit and seed productions were decreased only in the GH plot. Both vegetative and reproductive activities were negatively affected by warm temperature, resulting in less vegetative growth and lower seed-set, whereas an understory habitat was beneficial for vegetative growth and showed similar seed production to an open habitat over the experimental period. Decreasing population dynamics of spring ephemerals was predicted in response to future warming climate not only by growth inhibition but also by restriction of seed production.     

Weather and herbivores influence fertility in the endangered fern Botrychium multifidum (S.G. Gmel.) Rupr

Fluctuations in local weather conditions and other stochastic processes are important factors affecting species population persistence. We studied two differently sized populations of the rare and declining fern species Botrychium multifidum for 4 and 5 years, respectively. Individually marked plants in permanent plots were followed to detect trends in population size, reproductive success and dormancy in relation to local precipitation and temperature. Our applied logistic regression model suggests that the shortage of precipitation during summer decreases fertility in the next year in both populations. Invertebrate herbivory of the fertile part of the plant additionally diminishes the output of spores. We found the population size to be stable with a very low percentage of each population composed of juvenile plants. Stochastic processes and low recruitment could easily lead to the extinction of these populations.     

Climate change impacts on the conservation outlook of populations on the poleward periphery of species ranges: A case study of Canadian black‐tailed prairie dogs (Cynomys ludovicianus)

Given climate change, species' climatically suitable habitats are increasingly expected to shift poleward. Some imperilled populations towards the poleward edge of their species' range might therefore conceivably benefit from climate change. Interactions between climate and population dynamics may be complex, however, with climate exerting effects both indirectly via influence over food availability and more directly, via effects on physiology and its implications for survival and reproduction. A thorough understanding of these interactions is critical for effective conservation management. We therefore examine the relationship between climate, survival and reproduction in Canadian black‐tailed prairie dogs, a threatened keystone species in an imperilled ecosystem at the northern edge of the species' range. Our analyses considered 8 years of annual mark–recapture data (2007–2014) in relation to growing degree days, precipitation, drought status and winter severity, as well as year, sex, age and body mass. Survival was strongly influenced by the interaction of drought and body mass class, and winter temperature severity. Female reproductive status was associated with the interaction of growing degree days and growing season precipitation, with spring precipitation and with winter temperature severity. Results related to body mass suggested that climatic variables exerted their effects via regulation of food availability with potential linked effects of food quality, immunological and behavioural implications, and predation risk. Predictions of future increases in drought conditions in North America's grassland ecosystems have raised concerns for the outlook of Canadian black‐tailed prairie dogs. Insights gained from the analyses, however, point to mitigating species management options targeted at decoupling the mechanisms by which climate exerts its negative influence. Our approach highlights the importance of understanding the interaction between climate and population dynamics in peripheral populations whose viability might ultimately determine their species' ability to track climatically suitable space.     

Climate change shifts population structure and demographics of an alpine herb,Anemone narcissiflora ssp. sachalinensis (Ranunculaceae), along a snowmelt gradient

Alpine ecosystems, characterized by cold climates and short growing seasons, are thought to be most vulnerable to climate change. Warmer temperatures and earlier snowmelt extend the growing season length and increase drought stress for alpine plants, resulting in changes to their distribution. Anemone narcissiflora ssp. sachalinensis is a perennial herb that grows in the alpine snow-meadows of northern Japan. In the last few decades, its distribution has shifted toward later snowmelt habitat in the Taisetsu Mountains of Hokkaido. We recorded demographic data for this species at early, middle and late snowmelt habitats over four years (2009–2012), and constructed transition matrix models to evaluate how demographic parameters and population growth rate vary between local habitats along a snowmelt gradient. The proportion of reproductive plants was low and seed production was limited in the early snowmelt habitat, with drier soil conditions, in comparison to the middle and late snowmelt habitats, with moist soil conditions. Evidence of the transition from small plants to those in the reproductive stage was limited in the early snowmelt habitat, suggesting that growth was inhibited; the local population in this habitat was estimated to be sustained by seed migration from later snowmelt habitats. These results indicate that advancing snowmelt under climate change may decrease the reproductive activity and population growth rate of snow-meadow plants if seed migration from later snowmelt populations is limited, resulting in the extinction of local populations.     

Temperature effects on forest herbs assessed by warming and transplant experiments along a latitudinal gradient

Slow‐colonizing forest understorey plants are probably not able to rapidly adjust their distribution range following large‐scale climate change. Therefore, the acclimation potential to climate change within their actual occupied habitats will likely be key for their short‐ and long‐term persistence. We combined transplant experiments along a latitudinal gradient with open‐top chambers to assess the effects of temperature on phenology, growth and reproductive performance of multiple populations of slow‐colonizing understorey plants, using the spring flowering geophytic forb Anemone nemorosa and the early summer flowering grass Milium effusum as study species. In both species, emergence time and start of flowering clearly advanced with increasing temperatures. Vegetative growth (plant height, aboveground biomass) and reproductive success (seed mass, seed germination and germinable seed output) of A. nemorosa benefited from higher temperatures. Climate warming may thus increase future competitive ability and colonization rates of this species. Apart from the effects on phenology, growth and reproductive performance of M. effusum generally decreased when transplanted southwards (e.g., plant size and number of individuals decreased towards the south) and was probably more limited by light availability in the south. Specific leaf area of both species increased when transplanted southwards, but decreased with open‐top chamber installation in A. nemorosa. In general, individuals of both species transplanted at the home site performed best, suggesting local adaptation. We conclude that contrasting understorey plants may display divergent plasticity in response to changing temperatures which may alter future understorey community dynamics.     

Clumped planting arrangements improve seed production in a revegetated eucalypt woodland

The arrangement of plants within revegetated sites is rarely considered an important characteristic of these communities. However, in natural systems, plant spatial arrangements can influence a range of ecological processes, including pollination and seed set. Pollinators tend to preferentially visit larger and/or more closely spaced populations, with plants in these populations generally receiving more outcrossed pollen, resulting in increased seed set and better quality seed. Similar trends may occur in revegetated populations, but little is known about the influence of planting arrangement on seed production in restored systems. Here, we quantified the effect of plant abundance (number of conspecifics within 100 m) and distance to nearest reproductive conspecific on the level of seed set for six eucalypt species (n = 422 trees in total) in 1 year and for one of these species (Eucalyptus leucoxylon), across three additional years. Seed number per fruit was highly variable both between individuals and within individuals across years. Despite this variability, there was a consistent trend of higher seed production (seed number per fruit) when another reproductive conspecific was within 20 m. In contrast, plant abundance had little influence on seed production. Further investigation of nearest neighbor arrangements found the distance to either the first, second, third, or fourth reproductive neighbors were the key predictors of seed production. Therefore, revegetation designs that consider plant spacing and aggregation, rather than only planting to overall density criteria (i.e. trees/ha), at least for the eucalypts studied here, has the potential to improve seed production in revegetated populations.     

TEMPORAL VARIATION OF FLOWER AND FRUIT SIZE IN RELATION TO SEED YIELD IN CELANDINE POPPY (CHELIDONIUM MAJUS; PAPAVERACEAE)

Ecological and evolutionary studies typically consider variation in single reproductive characters in isolation, without considering how they might be correlated with other reproductive and vegetative characters. In our study, we examined temporal patterns of variation and correlation in flower diameter and fruit length during a reproductive phase in two Massachusetts populations of the herb, Chelidonium majus. We also examined the relationships of such variation to measurements of seed yield components (mean seed weight and number per fruit) and aspects of plant vegetative size. Most of the variation in the sizes of reproductive characters occurred within individual plants, instead of among plants or between populations. Flower and fruit sizes as well as seed number per fruit declined significantly during the season in both populations. Only mean seed size per fruit was relatively stable for individual plants in both populations. Conserving resources by a gradual reduction in the size of reproductive characters over the season may be a strategy for maternal plants to continue seed production. The strong, persistent patterns of correlation between certain characters, such as flower and fruit size, in spite of extensive phenotypic plasticity, was interpreted as indirect evidence for developmental correlation. Furthermore, vegetatively larger plants produced not only more flowers and fruits, but also consistently larger flowers and fruits. The results emphasize that variation in fitness characters, such as seed size and number, should not be viewed in isolation from vegetative characters, flower, and fruit sizes in ecological and evolutionary studies, if the goal is to understand the mechanisms of natural selection in wild populations.