Competition and body size in plants: the between-species trade-off for maximum potential versus minimum reproductive threshold size

Aims According to traditional theory, superior competitive ability in plants generally requires relatively large plant body size. Yet even within the most crowded vegetation, most resident species are relatively small; species size distributions are right-skewed at virtually every scale. We examine a potential explanation for this paradox: small species coexist with and outnumber large species because they have greater 'reproductive economy', i.e. they are better equipped—and hence more likely—to produce offspring despite severe size suppression from intense competition.Methods Randomly placed plots within old-field vegetation were surveyed across the growing season. Within each plot, the largest (MAX) and smallest (MIN) reproductive individuals of each resident species were collected for above-ground dry mass measurement. We tested three hypotheses: (i) smaller resident species (with smaller MAX size) have generally smaller reproductive threshold sizes; (ii) smaller resident species have greater 'reproductive economy', i.e. a smaller MIN relative to MAX reproductive plant size; and (iii) MIN size predicts plot occupancy (species abundance within the community) better than MAX size.Important findings The results supported the first and third, but not the second hypothesis. However, we could not reject the hypothesis that smaller species have greater reproductive economy, as it was not possible to record data for the largest potential plant size for each species—since even the largest (MAX) plants collected from our sampled plots were subjected to competition from neighbours under these natural field conditions. Importantly, contrary to conventional competition theory, more successful species (in terms of greater plot occupancy) had smaller minimum not larger (or smaller) maximum reproductive sizes. These results suggest that a small reproductive threshold size, commonly associated with relatively small potential body size, is generally more effective in transmitting genes into future generations when selection from neighbourhood crowding/competition is intense—at least within natural old-field vegetation. Accordingly, we propose a simple conceptual model that represents the basis for a fundamental paradigm shift in the predicted selection effects of crowding/competition on plant body size evolution.     

Revising traditional theory on the link between plant body size and fitness under competition: evidence from old‐field vegetation

The selection consequences of competition in plants have been traditionally interpreted based on a “size‐advantage” hypothesis – that is, under intense crowding/competition from neighbors, natural selection generally favors capacity for a relatively large plant body size. However, this conflicts with abundant data, showing that resident species body size distributions are usually strongly right‐skewed at virtually all scales within vegetation. Using surveys within sample plots and a neighbor‐removal experiment, we tested: (1) whether resident species that have a larger maximum potential body size (MAX) generally have more successful local individual recruitment, and thus greater local abundance/density (as predicted by the traditional size‐advantage hypothesis); and (2) whether there is a general between‐species trade‐off relationship between MAX and capacity to produce offspring when body size is severely suppressed by crowding/competition – that is, whether resident species with a larger MAX generally also need to reach a larger minimum reproductive threshold size (MIN) before they can reproduce at all. The results showed that MIN had a positive relationship with MAX across resident species, and local density – as well as local density of just reproductive individuals – was generally greater for species with smaller MIN (and hence smaller MAX). In addition, the cleared neighborhoods of larger target species (which had relatively large MIN) generally had – in the following growing season – a lower ratio of conspecific recruitment within these neighborhoods relative to recruitment of other (i.e., smaller) species (which had generally smaller MIN). These data are consistent with an alternative hypothesis based on a ‘reproductive‐economy‐advantage’ – that is, superior fitness under competition in plants generally requires not larger potential body size, but rather superior capacity to recruit offspring that are in turn capable of producing grand‐offspring – and hence transmitting genes to future generations – despite intense and persistent (cross‐generational) crowding/competition from near neighbors. Selection for the latter is expected to favor relatively small minimum reproductive threshold size and hence – as a tradeoff – relatively small (not large) potential body size.     

The relationship between individual seed quality and maternal plant body size in crowded herbaceous vegetation

Aims In most natural plant populations, there is a strong right-skewed distribution of body sizes for reproductive plants—i.e. the vast majority are relatively small, suppressed weaklings that manage not just to survive effects of crowding/competition and other hazards but also to produce offspring. Recent research has shown that because of their relatively large numbers, these relatively small resident plants collectively contribute most of the seed offspring production available for the population in the next generation. However, the success of these offspring will depend in part on their quality, e.g. reflected by seed size and resource content. Accordingly, in the present study, we used material from natural populations of herbaceous species to test the null hypothesis that there is no significant relationship between body size variation in resident plants—resulting from between-site variation in the intensity of crowding/competition—and variation in the mass or N content of their individual seeds.Methods Using populations of 56 herbaceous species common in eastern Ontario, total above-ground dry plant mass, mean mass per seed and mean nitrogen (N) content per seed were recorded for a sample of the largest resident plants and also for the smallest reproductive plants growing in local neighbourhoods with the most severe crowding/competition from near neighbours.Important findings Mass per seed was numerically smaller from the smallest resident plants for most study species, but with few exceptions, this was not significantly different (P> 0.05) from mass per seed from the largest resident plants. The results therefore showed no general effect of maternal plant body size on individual seed mass, or N content. This suggests that the reproductive output of the smaller half of the resident plant size distribution within these populations is likely to contribute not just most of the seed production available for the next generation but also seed offspring that are just as likely—on a per individual basis—to achieve seedling/juvenile recruitment success as the seed offspring produced by the largest resident plants. This conflicts with the traditional 'size-advantage' hypothesis for predicting plant fitness under severe competition, and instead supports the recent 'reproductive-economy-advantage' hypothesis, where competitive fitness is promoted by capacity to produce offspring that—despite severe body size suppression imposed by neighbour effects—in turn have capacity to produce grand-offspring.     

Offspring for the next generation: most are produced by small plants within herbaceous populations

Within crowded natural plant populations, the traditional prediction is that most of the offspring from which future generations are drawn will be contributed by the relatively few individuals belonging to the larger size classes. Yet, the extent to which this is true should depend on the extent to which the inevitably more numerous, but relatively small suppressed plants within the same population manage not only to survive suppression, but also to reproduce before death. We recorded the above-ground dry mass for mature reproductive plants from natural populations of 21 species of herbaceous angiosperms. The size distributions of these reproductive plants were all strongly right-skewed, and in every case, the vast majority of the estimated offspring production within the population was contributed by the three, four, or five smallest deciles of the plant size distribution. Our data suggest, in contrast with traditional theory, that most of the coexisting species within crowded vegetation are successful residents not because they are relatively large, but because they produce numerous descendants from numerous offspring that have ‘reproductive economy’—i.e. offspring with the ability, despite suppression to a very small size, to also produce offspring of their own for the next generation.     

Convergent evolution of seed dispersal by ants,and phylogeny and biogeography in flowering plants: A global survey

Seed dispersal is a fundamental life history trait in plants. Although the recent surge of interest in seed dispersal by ants (myrmecochory) has added greatly to knowledge on the ecology of seed dispersal and ant–plant mutualisms, myrmecochory also represents a unique opportunity to examine the links between seed dispersal and evolution in flowering plants. Here we review the taxonomic, phylogenetic and biogeographic distribution of myrmecochory in flowering plants. Myrmecochory is mediated by elaiosomes, i.e., lipid-rich seed appendages that attract ants and serve as rewards for dispersal. We surveyed the literature for evidence of elaiosomes in angiosperm plants to estimate the global prevalence of myrmecochory. We then searched the literature for phylogenetic reconstructions to identify myrmecochorous lineages and to estimate the minimum number of independent evolutionary origins of myrmecochory. We found that myrmecochory is present in at least 11 000 species or 4.5% of all species, in 334 genera or 2.5% of all genera and in 77 families or 17% of all families of angiosperm plants. We identified at least 101, but possibly up to 147, independent origins of myrmecochory. We estimated three or more origins in 13 families and found that at least half the genera are myrmecochorous in 10 families. Most myrmecochorous lineages were Australian, South African or northern temperate (Holarctic). A mapping of families containing myrmecochorous genera on a dated angiosperm supertree showed that myrmecochory has evolved in most of the major angiosperm lineages and that it is more frequent in younger families (crown group age <80 million years) than in older ones. We suggest that the relatively low physiological and energetic costs of producing an elaiosome and the consistent selective benefits of myrmecochory (dispersal, protection from seed predators and fire, safe and nutrient-rich microsites) explain the numerous evolutionary and developmental origins of myrmecochory in angiosperm plants, and we propose that elaiosomes thus provide one of the most dramatic examples of convergent evolution in biology.     

MORPHOLOGICAL RATES OF ANGIOSPERM SEED SIZE EVOLUTION

The evolution of seed size among angiosperms reflects their ecological diversification in a complex fitness landscape of life‐history strategies. The lineages that have evolved seeds beyond the upper and lower boundaries that defined nonflowering seed plants since the Paleozoic are more dispersed across the angiosperm phylogeny than would be expected under a neutral model of phenotypic evolution. Morphological rates of seed size evolution estimated for 40 clades based on 17,375 species ranged from 0.001 (Garryales) to 0.207 (Malvales). Comparative phylogenetic analysis indicated that morphological rates are not associated with the clade's seed size but are negatively correlated with the clade's position in the overall distribution of angiosperm seed sizes; clades with seed sizes closer to the angiosperm mean had significantly higher morphological rates than clades with extremely small or extremely large seeds. Likewise, per‐clade taxonomic diversification rates are not associated with the seed size of the clade but with where the clade falls within the angiosperm seed size distribution. These results suggest that evolutionary rates (morphological and taxonomic) are elevated in densely occupied regions of the seed morphospace relative to lineages whose ecophenotypic innovations have moved them toward the edges.     

Seed size predicts global effects of small mammal seed predation on plant recruitment

Recent studies demonstrate that by focusing on traits linked to fundamental plant life‐history trade‐offs, ecologists can begin to predict plant community structure at global scales. Yet, consumers can strongly affect plant communities, and means for linking consumer effects to key plant traits and community assembly processes are lacking. We conducted a global literature review and meta‐analysis to evaluate whether seed size, a trait representing fundamental life‐history trade‐offs in plant offspring investment, could predict post‐dispersal seed predator effects on seed removal and plant recruitment. Seed size predicted small mammal seed removal rates and their impacts on plant recruitment consistent with optimal foraging theory, with intermediate seed sizes most strongly impacted globally – for both native and exotic plants. However, differences in seed size distributions among ecosystems conditioned seed predation patterns, with relatively large‐seeded species most strongly affected in grasslands (smallest seeds), and relatively small‐seeded species most strongly affected in tropical forests (largest seeds). Such size‐dependent seed predation has profound implications for coexistence among plants because it may enhance or weaken opposing life‐history trade‐offs in an ecosystem‐specific manner. Our results suggest that seed size may serve as a key life‐history trait that can integrate consumer effects to improve understandings of plant coexistence.     

Understanding angiosperm diversification using small and large phylogenetic trees

How will the emerging possibility of inferring ultra-large phylogenies influence our ability to identify shifts in diversification rate? For several large angiosperm clades (Angiospermae, Monocotyledonae, Orchidaceae, Poaceae, Eudicotyledonae, Fabaceae, and Asteraceae), we explore this issue by contrasting two approaches: (1) using small backbone trees with an inferred number of extant species assigned to each terminal clade and (2) using a mega-phylogeny of 55473 seed plant species represented in GenBank. The mega-phylogeny approach assumes that the sample of species in GenBank is at least roughly proportional to the actual species diversity of different lineages, as appears to be the case for many major angiosperm lineages. Using both approaches, we found that diversification rate shifts are not directly associated with the major named clades examined here, with the sole exception of Fabaceae in the GenBank mega-phylogeny. These agreements are encouraging and may support a generality about angiosperm evolution: major shifts in diversification may not be directly associated with major named clades, but rather with clades that are nested not far within these groups. An alternative explanation is that there have been increased extinction rates in early-diverging lineages within these clades. Based on our mega-phylogeny, the shifts in diversification appear to be distributed quite evenly throughout the angiosperms. Mega-phylogenetic studies of diversification hold great promise for revealing new patterns, but we will need to focus more attention on properly specifying null expectation.     

Squamate hatchling size and the evolutionary causes of negative offspring size allometry

Although fecundity selection is ubiquitous, in an overwhelming majority of animal lineages, small species produce smaller number of offspring per clutch. In this context, egg, hatchling and neonate sizes are absolutely larger, but smaller relative to adult body size in larger species. The evolutionary causes of this widespread phenomenon are not fully explored. The negative offspring size allometry can result from processes limiting maximal egg/offspring size forcing larger species to produce relatively smaller offspring (‘upper limit’), or from a limit on minimal egg/offspring size forcing smaller species to produce relatively larger offspring (‘lower limit’). Several reptile lineages have invariant clutch sizes, where females always lay either one or two eggs per clutch. These lineages offer an interesting perspective on the general evolutionary forces driving negative offspring size allometry, because an important selective factor, fecundity selection in a single clutch, is eliminated here. Under the upper limit hypotheses, large offspring should be selected against in lineages with invariant clutch sizes as well, and these lineages should therefore exhibit the same, or shallower, offspring size allometry as lineages with variable clutch size. On the other hand, the lower limit hypotheses would allow lineages with invariant clutch sizes to have steeper offspring size allometries. Using an extensive data set on the hatchling and female sizes of > 1800 species of squamates, we document that negative offspring size allometry is widespread in lizards and snakes with variable clutch sizes and that some lineages with invariant clutch sizes have unusually steep offspring size allometries. These findings suggest that the negative offspring size allometry is driven by a constraint on minimal offspring size, which scales with a negative allometry.     

Phylogenetic Composition of Angiosperm Diversity in the Cloud Forests of Mexico

Several members of the most ancient living lineages of flowering plants (angiosperms) inhabit humid, woody, mostly tropical habitats. Here we assess whether one of these forest types, the cloud forests of Mexico (CFM), contain a relatively higher proportion of phylogenetically early-diverging angiosperm lineages. The CFM houses an extraordinary plant species diversity, including members of earliest-diverging angiosperm lineages. The phylogenetic composition of CFM angiosperm diversity was evaluated through the relative representation of orders and families with respect to the global flora, and the predominance of phylogenetically early- or late-diverging lineages. Goodness-of-fit tests indicated significant differences in the proportional local and global representation of angiosperm clades. The net difference between the percentage represented by each order and family in the CFM and the global flora allowed identification of clades that are overrepresented and underrepresented in the CFM. Early-diverging angiosperm orders and families were found to be neither over- nor underrepresented in the CFM. A slight predominance of late-diverging phylogenetic levels among overrepresented clades, however, was encountered in the CFM. The resulting pattern suggests that cloud forests provide habitats where the most ancient angiosperm lineages have survived in the face of accumulating species diversity belonging to phylogenetically late-diverging lineages.     

Dark diversity in dry calcareous grasslands is determined by dispersal ability and stress‐tolerance

Temperate calcareous grasslands are characterized by high levels of species richness at small spatial scales. Nevertheless, many species from a habitat‐specific regional species pool may be absent from local communities and represent the ‘dark diversity’ of these sites. Here we investigate dry calcareous grasslands in northern Europe to determine what proportion of the habitat‐specific species pool is realized at small scales (i.e. how the community completeness varies) and which mechanisms may be contributing to the relative sizes of the observed and dark diversity. We test whether the absence of particular species in potentially suitable grassland sites is a consequence of dispersal limitation and/or a low ability to tolerate stress (e.g. drought and grazing). We analysed a total of 1223 vegetation plots (1 × 1 m) from dry calcareous grasslands in Sweden, Estonia and western Russia. The species co‐occurrence approach was used to estimate the dark diversity for each plot. We calculated the maximum dispersal distance for each of the 291 species in our dataset by using simple plant traits (dispersal syndrome, growth form and seed characteristics). Large seed size was used as proxy for small seed number; tall plant height and low S‐strategy type scores were used to characterise low stress‐tolerance. Levels of small‐scale community completeness were relatively low (more species were absent than present) and varied between the grasslands in different geographic areas. Species in the dark diversity were generally characterized by shorter dispersal distances and greater seed weight (fewer seeds) than species in the observed diversity. Species within the dark diversity were generally taller and had a lower tolerance of stressful conditions. We conclude that, even if temperate grasslands have high levels of small‐scale plant diversity, the majority of potentially suitable species in the regional species pool may be absent as a result of dispersal limitation and low stress‐tolerance.     

Fungal pathogen species richness: why do some plant species have more pathogens than others?

Variation among plant species in the number of associated herbivore and pathogen species is predicted to fit a species-area relationship in which the area or biomass embodied by a plant species is a function of individual size and geographic range size. This hypothesis is tested using published estimates of geographic range, individual size, and species richness of fungal pathogens for 490 plant species occurring in the United States and controlling for sampling intensity and phylogenetic effects. The number of pathogens found on a plant species increases with the metrics of area and/or habitat diversity of plant species, and their effects are similar between gymnosperm and angiosperm lineages. The strength of this pattern across a diverse set of plant lineages suggests that accumulation and persistence of pathogen species on plant species are governed by similar processes among temperate plants.     

不同生活型被子植物功能性状与基因组大小的关系

基因组大小在被子植物物种之间存在着巨大的变异, 但目前对不同生活型被子植物功能性状与基因组大小的关系缺乏统一的认识。本研究基于被子植物245科2,226属11,215个物种的基因组大小数据, 探讨了不同生活型物种种子重量、最大植株高度和叶片氮、磷含量4个功能性状与基因组大小之间的关系。结果表明, 被子植物最大植株高度和种子重量与基因组大小间的关系在草本和木本植物中存在显著差异。草本植物最大植株高度与基因组大小的关系不显著, 但种子重量与其呈极显著的正相关关系。木本植物最大植株高度与基因组大小显著负相关, 但种子重量与其关系不显著。木本植物叶片氮含量与基因组大小呈显著正相关, 但其他生活型植物的叶片氮、磷含量与基因组大小均无显著相关性。本研究表明被子植物功能性状与基因组大小的相关性在不同生活型间存在差异, 这为深入研究植物多种功能性状和植物生活型与基因组大小的权衡关系在植物演化和生态适应中的作用提供了重要依据。     

Influence of seed size on performance of non-native annual plant species in a novel community at two planting densities

Climate warming enables plant species to migrate to higher latitudes and altitudes. Within Europe, the Mediterranean harbours many species that might expand their ranges towards Western Europe. Small seed size may facilitate dispersal, however, it may impair establishment of the range-expanding plant species in the novel vegetation. In a greenhouse experiment, we examined effects of average seed size of Mediterranean plant species on their establishment in a mixed community of Western European plant species. Applying two levels of densities of the natives and a herbivory treatment, we tested how seed size is linked to response in plant growth and fitness in novel vegetation. While all non-native plant species showed a negative response to increased planting density, species with small seeds showed a less negative response. This effect persisted under herbivory. Our data suggest that small-seeded non-native plant species may tolerate competitive pressure from novel plant communities better than large-seeded species, so that small seed size may confer a higher probability of establishment of non-native species in novel communities.     

The evolutionary diversification of seed size: using the past to understand the present

The Devonian origin of seed plants and subsequent morphological diversification of seeds during the late Paleozoic represents an adaptive radiation into unoccupied ecological niche space. A plant's seed size is correlated with its life-history strategy, growth form, and seed dispersal syndrome. The fossil record indicates that the oldest seed plants had relatively small seeds, but the Mississippian seed size envelope increased significantly with the diversification of larger seeded lineages. Fossil seeds equivalent to the largest extant gymnosperm seeds appeared by the Pennsylvanian, concurrent with morphological diversification of growth forms and dispersal syndromes as well as the clade's radiation into new environments. Wang's Analysis of Skewness indicates that the evolutionary trend of increasing seed size resulted from primarily passive processes in Pennsylvanian seed plants. The distributions of modern angiosperms indicate a more diverse system of active and some passive processes, unbounded by Paleozoic limits; multiple angiosperm lineages independently evolved though the upper and lower bounds. Quantitative measures of preservation suggest that, although our knowledge of Paleozoic seeds is far from complete, the evolutionary trend in seed size is unlikely to be an artifact of taphonomy.     

Ants Sow the Seeds of Global Diversification in Flowering Plants

Background

The extraordinary diversification of angiosperm plants in the Cretaceous and Tertiary periods has produced an estimated 250,000–300,000 living angiosperm species and has fundamentally altered terrestrial ecosystems. Interactions with animals as pollinators or seed dispersers have long been suspected as drivers of angiosperm diversification, yet empirical examples remain sparse or inconclusive. Seed dispersal by ants (myrmecochory) may drive diversification as it can reduce extinction by providing selective advantages to plants and can increase speciation by enhancing geographical isolation by extremely limited dispersal distances.

Methodology/Principal Findings

Using the most comprehensive sister-group comparison to date, we tested the hypothesis that myrmecochory leads to higher diversification rates in angiosperm plants. As predicted, diversification rates were substantially higher in ant-dispersed plants than in their non-myrmecochorous relatives. Data from 101 angiosperm lineages in 241 genera from all continents except Antarctica revealed that ant-dispersed lineages contained on average more than twice as many species as did their non-myrmecochorous sister groups. Contrasts in species diversity between sister groups demonstrated that diversification rates did not depend on seed dispersal mode in the sister group and were higher in myrmecochorous lineages in most biogeographic regions.

Conclusions/Significance

Myrmecochory, which has evolved independently at least 100 times in angiosperms and is estimated to be present in at least 77 families and 11 000 species, is a key evolutionary innovation and a globally important driver of plant diversity. Myrmecochory provides the best example to date for a consistent effect of any mutualism on large-scale diversification.     

Death without sex—the ‘problem of the small’ and selection for reproductive economy in flowering plants

Most of the resident plants within vegetation fail to leave descendants because of death without sex—i.e. sexual reproduction fails (zero fecundity), primarily because of relatively small plant size. I propose that this ‘problem of the small’ represents one of the principal driving forces of evolution by natural selection, and that the main product of this selection is ‘reproductive economy’, manifested by several plant traits that are widely distributed among angiosperms: sexual maturity at a relatively young age and small size, relatively small seed size, selfing (including through mixed mating), and of particular interest here, clonality. In non-clonal species, an offspring develops from a zygote into a single ‘rooted unit’, i.e. a distinct vascular transition point between live shoot and root tissue. Clonal species can produce an indeterminate number of these rooted unit offspring asexually, all as products of a single zygote. Clonality is a common strategy in angiosperms because it confers a potential two-fold fitness benefit—especially in relatively small species—by promoting longevity of the zygote product, while at the same time providing a fecundity supplement (through asexual multiplication of rooted units), thereby allowing offspring production economically, i.e. without requiring large adult size, and without even requiring the fertilization of ovules. The primary fitness benefit from clonality, therefore, is that the somatic product of a zygote can effectively avoid an intrinsic limitation predicted for all non-clonal plants: the trade-off between longevity and the potential rate of offspring/descendant production. These major fitness benefits of clonality are explored in considering why clonality is less common in larger species, why the largest species (trees) generally do not have the longest-lived zygote product, and in re-assessing traditional and recent views concerning the loss of sex in clonal plants, the predicted trade-off between the size and number of clonal offspring, and the predicted trade-off between sexual and asexual reproduction.     

Size distributions and dispersions along a 485-year chronosequence for sand dune vegetation

Using a sand dune chronosequence that spans 485 years of primary succession, we collected nearest-neighbor vegetation data to test two predictions associated with the traditional "size-advantage" hypothesis for plant competitive ability: (1) the relative representation of larger species should increase in later stages of succession; and (2) resident species that are near neighbors should, over successional time, become more similar in plant body size and/or seed size than expected by random assembly. The first prediction was supported over the time period between mid to later succession, but the second prediction was not; that is, there was no temporal pattern across the chronosequence indicating that either larger resident species, or larger seeded resident species, increasingly exclude smaller ones from local neighborhoods over time. Rather, neighboring species were generally more different from each other in seed sizes than expected by random assembly. As larger species accumulate over time, some relatively small species are lost from later stages of succession, but species size distributions nevertheless remain strongly right-skewed-even in late succession-and species of disparate sizes are just as likely as in early succession to coexist as immediate neighbors. This local-scale coexistence of disparate sized neighbors might be accounted for-as in traditional interpretations-in terms of species differences in "physical-space-niches" (e.g., involving different rooting depths), combined with possible facilitation effects. We propose, however, that this coexistence may also occur because competitive ability involves more than just a size advantage, with traits associated with survival (tolerance of intense competition) and fecundity (offspring production despite intense competition) being at least equally important.     

Plant traits in response to raising groundwater levels in wetland restoration: evidence from three case studies

Question: Is raising groundwater tables successful as a wetland restoration strategy? Location: Kennemer dunes, The Netherlands; Moksloot dunes, The Netherlands and Bullock Creek fen, New Zealand. Methods: Generalizations were made by analysing soil dynamics and the responsiveness of integrative plant traits on moisture, nutrient regime and seed dispersal in three case studies of re wetted vs. control wetlands with the same actual groundwater levels. Soil conditions included mineral (calcareous and non‐calcareous) soils with no initial vegetation, mineral soils with established vegetation and organic soils with vegetation. Results: The responsiveness of traits to raised groundwater tables was related to soil type and vegetation presence and depended on actual groundwater levels. In the moist‐wet zone, oligotrophic species, ‘drier’ species with higher seed longevity occupied gaps created by vegetation dieback on rewetting. The other rewetted zones still reflected trait values of the vegetation prevalent prior to rewetting with fewer adaptations to wet conditions, increased nutrient richness and higher seed longevity. Moreover, ‘eutrophic’ and ‘drier’ species increased at rewetted sites, so that these restored sites became dissimilar to control wetlands. Conclusions: The prevalent traits of the restored wetlands do not coincide with traits belonging to generally targeted plant species of wetland restoration. Long‐term observations in restored and control wetlands with different groundwater regimes are needed to determine whether target plant species eventually re vegetate restored wetlands.     

Genome size scaling through phenotype space

Background and Aims: Early observations that genome size was positively correlatedwith cell size formed the basis of hypothesized consequencesof genome size variation at higher phenotypic scales. This scalingwas supported by several studies showing a positive relationshipbetween genome size and seed mass, and various metrics of growthand leaf morphology. However, many of these studies were undertakenwith limited species sets, and often performed within a singlegenus. Here we seek to generalize the relationship between genomesize and the phenotype by examining eight phenotypic traitsusing large cross-species comparisons involving diverse assemblagesof angiosperm and gymnosperm species. These analyses are presentedin order of increasing scale (roughly equating to the numberof cells required to produce a particular phenotypic trait),following the order of: cell size (guard cell and epidermal),stomatal density, seed mass, leaf mass per unit area (LMA),wood density, photosynthetic rate and finally maximum plantheight. Scope: The results show that genome size is a strong predictor of phenotypictraits at the cellular level (guard cell length and epidermalcell area had significant positive relationships with genomesize). Stomatal density decreased with increasing genome size,but this did not lead to decreased photosynthetic rate. At higherphenotypic scales, the predictive power of genome size generallydiminishes (genome size had weak predictive power for both LMAand seed mass), except in the interesting case of maximum plantheight (tree species tend to have small genomes). There wasno relationship with wood density. The general observation thatspecies with larger genome size have larger seed mass was supported;however, species with small genome size can also have largeseed masses. All of these analyses involved robust comparativemethods that incorporate the phylogenetic relationships of species. Conclusions: Genome size correlations are quite strong at the cellular levelbut decrease in predictive power with increasing phenotypicscale. Our hope is that these results may lead to new mechanistichypotheses about why genome size scaling exists at the cellularlevel, and why nucleotypic consequences diminish at higher phenotypicscales.