Evolution Of Plant Populations Research Articles

Induced responses contribute to rapid adaptation of Spirodela polyrhiza to herbivory by Lymnaea stagnalis

Herbivory-induced responses in plants are typical examples of phenotypic plasticity, and their evolution is thought to be driven by herbivory. However, direct evidence of the role of induced responses in plant adaptive evolution to herbivores is scarce. Here, we experimentally evolve populations of an aquatic plant (Spirodela polyrhiza, giant duckweed) and its native herbivore (Lymnaea stagnalis, freshwater snail), testing whether herbivory drives rapid adaptive evolution in plant populations using a combination of bioassays, pool-sequencing, metabolite analyses, and amplicon metagenomics. We show that snail herbivory drove rapid phenotypic changes, increased herbivory resistance, and altered genotype frequencies in the plant populations. Additional bioassays suggest that evolutionary changes of induced responses contributed to the rapid increase of plant resistance to herbivory. This study provides direct evidence that herbivory-induced responses in plants can be subjected to selection and have an adaptive role by increasing resistance to herbivores.

Evolution of plant drought strategies and herbivore tolerance after two decades of climate change.

Ongoing global warming, coupled with increased drought frequencies, together with other biotic drivers may have resulted in complex evolutionary adaptation. The resurrection approach, comparing ancestors raised from stored seeds with their contemporary descendants under common conditions, is a powerful method to test for recent evolution in plant populations. We used 21-26-yr-old seeds of four European plant species - Matthiola tricuspidata, Plantago crassifolia, Clinopodium vulgare and Leontodon hispidus - stored in seed banks together with re-collected seeds from their wild populations. To test for evolutionary changes, we conducted a glasshouse experiment that quantified heritable changes in plant responses to drought and simulated insect herbivory. In three out of the four studied species, we found evidence that descendants had evolved shorter life cycles through faster growth and flowering. Shifts in the osmotic potential and leaf dry matter content indicated that descendants also evolved increased drought tolerance. A comparison of quantitative genetic differentiation (QST ) vs neutral molecular differentiation (FST ) values, using double digest restriction-site associated DNA (ddRAD) genotyping data, suggested that directional selection, and therefore adaptive evolution, was underlying some of the observed phenotypic changes. In summary, our study revealed evolutionary changes in plant populations over the last decades that are consistent with adaptation of drought escape and tolerance as well as herbivory avoidance.

Evolutionary history of endangered and relict tree species Dipteronia sinensis in response to geological and climatic events in the Qinling Mountains and adjacent areas.

Geological and climatic events are considered to profoundly affect the evolution and lineage divergence of plant species. However, the evolutionary histories of tree species that have responded to past geological and climate oscillations in central China's mountainous areas remain mostly unknown. In this study, we assessed the evolutionary history of the endangered and relict tree species Dipteronia sinensis in the Qinling Mountains (QM) and adjacent areas in East Asia based on variations in the complete chloroplast genomes (cpDNA) and reduced‐genomic scale single nucleotide polymorphisms (SNPs). Population structure and phylogenetic analysis based on the cpDNA variations suggested that D. sinensis could be divided into two intraspecific genetic lineages in the eastern and western sides of the QM (EQM and WQM, respectively) in East Asia. Molecular dating suggested that the intraspecific divergence of D. sinensis occurred approximately 39.2 million years ago during the later Paleogene. It was significantly correlated with the orogeny of the QM, where the formation of this significant geographic barrier in the region may have led to the divergence of independent lineages. Bayesian clustering and demographic analysis showed that intraspecific gene flow was restricted between the EQM and WQM lineages. Isolation‐with‐migration analysis indicated that the two genetic lineages experienced significant demographic expansions after the Pleistocene ice ages. However, the genetic admixture was determined in some populations between the two lineages by the large scale of SNP variations due to DNA incompatibility, the large significant population size, and rapid gene flow of nuclear DNA markers. Our results suggest that two different conservation and management units should be constructed for D. sinensis in the EQM and WQM areas. These findings provide novel insights into the unprecedented effects of tectonic changes and climatic oscillations on lineage divergence and plant population evolution in the QM and adjacent areas in East Asia.

Maternal environment affects the genetic basis of seed dormancy in Arabidopsis thaliana.

The genetic basis of seed dormancy, a key life history trait important for adaptive evolution in plant populations, has yet been studied only using seeds produced under controlled conditions in greenhouse environments. However, dormancy is strongly affected by maternal environmental conditions, and interactions between seed genotype and maternal environment have been reported. Consequently, the genetic basis of dormancy of seeds produced under natural field conditions remains unclear. We examined the effect of maternal environment on the genetic architecture of seed dormancy using a recombinant inbred line (RIL) population derived from a cross between two locally adapted populations of Arabidopsis thaliana from Italy and Sweden. We mapped quantitative trait loci (QTL) for dormancy of seeds produced in the greenhouse and at the native field sites of the parental genotypes. The Italian genotype produced seeds with stronger dormancy at fruit maturation than did the Swedish genotype in all three environments, and the maternal field environments induced higher dormancy levels compared to the greenhouse environment in both genotypes. Across the three maternal environments, a total of nine dormancy QTL were detected, three of which were only detected among seeds matured in the field, and six of which showed significant QTL×maternal environment interactions. One QTL had a large effect on dormancy across all three environments and colocalized with the candidate gene DOG1. Our results demonstrate the importance of studying the genetic basis of putatively adaptive traits under relevant conditions.

Garcinia brasiliensis: insights into reproductive phenology and sexual system in a Neotropical environment

Sexual systems play a key role in the ecology and evolution of plant populations. Research on Garcinia L. has shown the occurrence of variations in the sexual systems of this genus, with some authors considering it as dioecious, and for some species as gynodioecious or androdioecious. The population of G. brasiliensis in the restinga of Marica is dioecious with two individuals characterized as monoecious. Anatomical analysis showed that one has pistillate and sterile staminate flowers, being an unusual female and the other has staminate and perfect flowers (functional pollen grains and ovules), being andromonoecious. In addition, field observations, controlled hand-pollinations, reproductive phenology and anatomical analysis showed no evidence of apomixis in this Neotropical species, different from that provided in the literature for paleotropical species. However, asexual reproduction occurs through ramets suggesting that in this environment of restinga the seedlings are subjected to considerable limitations, and vegetative propagation becomes an important alternative for the occupation of the environment. Flowering episodes occurred throughout the study period, featuring a subannual and long-lasting flowering pattern mainly due to multiple blooms of male plants. The floral characters observed in G. brasiliensis are often associated with a generalist pollination system. Apis mellifera and Trigona spinipes are the effective pollinators of G. brasiliensis flowers. Our findings provide new insights into the reproductive biology of Garcinia.

Species invasion alters local adaptation to soil communities in a native plant

Plant populations are often adapted to their local conditions, including abiotic factors as well as the biotic communities with which they interact. Soil communities, in particular, have strong effects on both the ecology and evolution of plant populations. Many invasive plant species alter the ecological relationships between native plants and soil communities; however, whether invaders also alter the evolutionary dynamics between native plants and soils is less well known. Here I show that populations of a native annual, Pilea pumila, shift from being maladapted to adapted to their local soil community with increasing history of invasion by Alliaria petiolata, an invader known to alter microbial communities. Additionally, native populations showed a signal of adaptation to soils of particular invasion stages, independent of local coevolutionary dynamics. These results suggest that invasive species affect not only the ecological, but also the evolutionary relationships of native species.

Limited pollen-mediated dispersal and partial self-incompatibility in the rare ironstone endemic Tetratheca paynterae subsp. paynterae increase the risks associated with habitat loss

Patterns of mating and dispersal are key factors affecting the dynamics, viability and evolution of plant populations. Changes in mating system parameters can provide evidence of anthropogenic impacts on populations of rare plants. Tetratheca paynterae subsp. paynterae is a critically endangered perennial shrub confined to a single ironstone range in Western Australia. Mining of the range removed 25% of plants in 2004 and further plants may be removed if the viability of the remaining populations is not compromised. To provide baseline genetic data for monitoring mining impacts, we characterised the mating system and pollen dispersal over two seasons in T. paynterae subsp. paynterae and compared mating system parameters with two other ironstone endemics, T. paynterae subsp. cremnobata and T. aphylla subsp. aphylla that were not impacted by mining. T. paynterae subsp. paynterae was the only taxon showing evidence of inbreeding (t m = 0.89), although hand pollination revealed pre-zygotic self-incompatibility limits the production of seed from self-pollen. In a year of lower fruit set (2005), the estimate of correlated paternity increased from 20 to 35%. Direct estimates of realised pollen dispersal, made by paternity assignment in two small populations where all adult plants were genotyped, revealed a leptokurtic distribution with 30% of pollen dispersed less than 3 m and 90% less than 15 m. Restricted pollen dispersal maintains the strong genetic structuring of the adult populations in succeeding generations. As a consequence of preferential outcrossing, any reduction in effective population size, flowering plant density and/or the abundance and activity of pollinators may impact negatively on population viability through reduced seed set, increased inbreeding and increased correlated paternity.

Anthony David Bradshaw. 17 January 1926 — 21 August 2008

Tony Bradshaw successfully straddled the divide between fundamental and applied science at a time when few achieved the feat. He made major contributions to our understanding of evolution in plant populations and of the significance of phenotypic plasticity, and then exploited those advances to develop new, science-based techniques for the restoration of degraded ecosystems. His discovery of the speed and local scale of evolution in grass populations remains one of the finest demonstrations of evolution in action, and he was one of the founders of the new discipline of restoration ecology.

Evolution in plant populations as a driver of ecological changes in arthropod communities

Heritable variation in traits can have wide-ranging impacts on species interactions, but the effects that ongoing evolution has on the temporal ecological dynamics of communities are not well understood. Here, we identify three conditions that, if experimentally satisfied, support the hypothesis that evolution by natural selection can drive ecological changes in communities. These conditions are: (i) a focal population exhibits genetic variation in a trait(s), (ii) there is measurable directional selection on the trait(s), and (iii) the trait(s) under selection affects variation in a community variable(s). When these conditions are met, we expect evolution by natural selection to cause ecological changes in the community. We tested these conditions in a field experiment examining the interactions between a native plant (Oenothera biennis) and its associated arthropod community (more than 90 spp.). Oenothera biennis exhibited genetic variation in several plant traits and there was directional selection on plant biomass, life-history strategy (annual versus biennial reproduction) and herbivore resistance. Genetically based variation in biomass and life-history strategy consistently affected the abundance of common arthropod species, total arthropod abundance and arthropod species richness. Using two modelling approaches, we show that evolution by natural selection in large O. biennis populations is predicted to cause changes in the abundance of individual arthropod species, increases in the total abundance of arthropods and a decline in the number of arthropod species. In small O. biennis populations, genetic drift is predicted to swamp out the effects of selection, making the evolution of plant populations unpredictable. In short, evolution by natural selection can play an important role in affecting the dynamics of communities, but these effects depend on several ecological factors. The framework presented here is general and can be applied to other systems to examine the community-level effects of ongoing evolution.

Elevated carbon dioxide concentrations indirectly affect plant fitness by altering plant tolerance to herbivory

Global environmental changes, such as rising atmospheric CO(2) concentrations, have a wide range of direct effects on plant physiology, growth, and fecundity. These environmental changes also can affect plants indirectly by altering interactions with other species. Therefore, the effects of global changes on a particular species may depend on the presence and abundance of other community members. We experimentally manipulated atmospheric CO(2) concentration and amounts of herbivore damage (natural insect folivory and clipping to simulate browsing) to examine: (1) how herbivores mediate the effects of elevated CO(2) (eCO(2)) on the growth and fitness of Arabidopsis thaliana; and (2) how predicted changes in CO(2) concentration affect plant resistance to herbivores, which influences the amount of damage plants receive, and plant tolerance of herbivory, or the fitness consequences of damage. We found no evidence that CO(2) altered resistance, but plants grown in eCO(2) were less tolerant of herbivory-clipping reduced aboveground biomass and fruit production by 13 and 22%, respectively, when plants were reared under eCO(2), but plants fully compensated for clipping in ambient CO(2) (aCO(2)) environments. Costs of tolerance in the form of reduced fitness of undamaged plants were detected in eCO(2) but not aCO(2) environments. Increased costs could reduce selection on tolerance in eCO(2) environments, potentially resulting in even larger fitness effects of clipping in predicted future eCO(2) conditions. Thus, environmental perturbations can indirectly affect both the ecology and evolution of plant populations by altering both the intensity of species interactions as well as the fitness consequences of those interactions.

Patterns of plant sexual systems in subtropical evergreen broad-leaved forests in Ailao Mountains, SW China

Aims Sexual systems influence many components of the ecology and evolution of plant populations and have rarely been documented in subtropical evergreen broad-leaved forests (SEBLF). Here we report frequency distribution and ecological correlates of plant sexual systems in SEBLF at Ailao Mountains, and compare our results with that of tropical and cool temperate forests. Methods We examine the sexual systems of 703 species of woody angiosperms belonging to 103 families and 296 genera based on a comprehensive survey of SEBLF at Ailao Mountains Natural Reserve. Information of plant sexual systems and ecological traits were mainly based on published literatures and specimens as well as our field observations. The associations between plant sexual system and ecological traits were assessed with chi-square tests. Important findings Among these species, 60.2% were hermaphroditic, 15.8% were monoecious and 24.0% were dioecious. The percentage of dioecious sexual system among tree species (22.2%) in SEBLF was comparable to those of tropical tree floras, but much higher than those of temperate forests at North America. The percentage of monoecious sexual system among tree species (30.1%) in SEBLF was higher than that of tropical tree floras, but much lower than those of temperate forests at North America. Monoecy was significantly associated with the tree growth form and was relatively common in temperate genera. Dioecy was significantly associated with fleshy fruits and monoecy was significantly associated with dry fruit type in SEBLF. The high percentage of diclinous sexual systems (monoecy and dioecy) in SEBLF may be associated with the origin of the flora and the prevalence of relatively small inconspicuous flowers of the forests in the Oriental Region.

New Phytologist evolves and strengthens

<i>New Phytologist</i> evolves and strengthens

Two-generation analysis of pollen flow across a landscape V: a stepwise approach for extracting factors contributing to pollen structure.

Patterns of pollen dispersal are central to both the ecology and evolution of plant populations. However, the mechanisms controlling either the dispersal process itself or our estimation of that process may be influenced by site-specific factors such as local forest structure and nonuniform adult genetic structure. Here, we present an extension of the AMOVA model applied to the recently developed TWOGENER analysis of pollen pool structure. This model, dubbed the Stepwise AMOVA (StAMOVA), focuses on determining to what extent ecological, demographic, and/or environmental factors influence the observed genetic variation in spatially separated pollen pools. The analysis is verified for efficacy, using an extensive battery of simulations, illustrating: (1) how nonuniform adult genetic structure influences the differentiation of spatially separated pollen pools, and (2) how effectively the Stepwise analysis performs in carrying out the appropriate corrections. Finally, the model is applied to a Quercus alba data set, from which we have prior evidence that the adult genetic structure is nonuniformly distributed across the sampling landscape. From this data set, we show how the Stepwise model can be applied to remove the effects of spatial adult genetic structure on pollen pool differentiation and contrast these results with those derived from the original TWOGENER analysis.

Whole-Genome Characterization of Embryonic Stage Inbreeding Depression in a Selfed Loblolly Pine Family

Inbreeding depression is important in the evolution of plant populations and mating systems. Previous studies have suggested that early-acting inbreeding depression in plants is primarily due to lethal alleles and possibly epistatic interactions. Recent advances in molecular markers now make genetic mapping a powerful tool to study the genetic architecture of inbreeding depression. We describe a genome-wide evaluation of embryonic viability loci in a selfed family of loblolly pine (Pinus taeda L.), using data from AFLP markers from an essentially complete genome map. Locus positions and effects were estimated from segregation ratios using a maximum-likelihood interval mapping procedure. We identified 19 loci showing moderately deleterious to lethal embryonic effects. These loci account for >13 lethal equivalents, greater than the average of 8.5 lethal equivalents reported for loblolly pine. Viability alleles show predominantly recessive action, although potential overdominance occurs at 3 loci. We found no evidence for epistasis in the distribution of pairwise marker correlations or in the regression of fitness on the number of markers linked to deleterious alleles. The predominant role of semilethal alleles in embryonic inbreeding depression has implications for the evolution of isolated populations and for genetic conservation and breeding programs in conifers.

Seed predation, pathogen infection and life-history traits in Brassica rapa.

Herbivory and disease can shape the evolution of plant populations, but their joint effects are rarely investigated. Families of plants of Brassica rapa (Brassicaceae) were grown from seeds collected in two naturalized populations in an experimental garden. We examined leaf infection by the fungus Alternaria, seed predation by a gall midge (Cecidomyiidae) and plant life-history traits. Plants from one population had heavier seeds, were more likely to flower, had less fungal infection, had more seed predation and were more fecund. Fungal infection score and seed predation rate increased with plant size, but large plants still had the greatest number of undamaged fruits. Spatial heterogeneity in the experimental garden was significant; seed predation rate and fecundity varied among blocks. An apparent tradeoff existed between susceptibility to disease and seed predation: plants with the highest fungal infection score had the lowest seed predation rate. Alternaria infection varied between populations, but the disease had no effect on fecundity. Seed predation did reduce fecundity. Damaged fruits had 31.4% fewer intact seeds. However, evidence for additive genetic variation in resistance to seed predation was weak. Therefore, neither disease nor seed predation was likely to be a strong agent of genetically based fecundity selection.

Goat herbivory and plant phenology in a Mediterranean shrubland of northern Baja California

Two years of monthly observations of the feeding behaviour of goats on the northern Baja California coastal shrubland, made by the bite-count method, indicate that eight shrub species, plus all herbs grouped in a single category, comprise about 80% of their diet, although 27 other species were consumed occasionally. Five phenological stages were detected in the plant communities throughout the year and an extremely close relationship was observed between them and the feeding patterns of the goats, with flowering herbs dominating during the wet season, a diversified group of species contributing during the transition, and very specific shrubs, usually bearers of dried pods or plants with delayed phenology, sustaining the individuals during the dry season. In general, leaf initiation and flowering were the most preferred phenological stages. The feeding behaviour appears to be unrelated to the protein content of the different phenological stages. Such close links between the feeding behaviour of ruminants and the phenological stages of plant communities have profound implications in range management, in meeting the nutritional budgets appropriate to the animals, and in the study of range-plant conservation aspects, particularly the evolution of plant populations under various intensities of stress.

Reproductive Hierarchies in Erodium: Effects of Variation in Plant Density and Rainfall Distribution

Reproductive hierarchies in even—aged plant monocultures often reflect the dynamics of intraspecific competition and, by their influence on effective population number, can alter significantly the relative importance of genetic drift in the evolution of plant populations. In experimental populations of Erosium boytrs and E. brachycarpum, I examined the interactive effects of intraspecific competition and rainfall variability on the development of reproductive hierarchies in these annual species. Reproductive inequality within monocultures of both species increased with increasing plant density and plant productivity, as measured by seed production, was determined by rainfall distribution. The magnitude of reproductive inequality was dependent on the interaction of sowing density, reproductive inequality was greatest in populations that experienced early autumn precipitation and lowest in populations exposed to drought during flowering. In contrast, at the lowest sowing density there was no significant effect or rainfall pattern on reproductive inequality. Effective population number was relatively insensitive to increases in population density because of increased inequality in reproduction at higher population densities. Reproductive variance could be a major contributor to drift variance in dense populations of both Erodium species.

Studies on Plant Demography, A Festschrift for John L. Harper.

Contributors. Foreword. Preface. Profile of John L. Harper. Scientific Publications of John L. Harper Dynamics and Evolution of Plant Populations in Natural or Seminatural Environments: Past, Present and Future: Studies on the Population Dynamics of Some Long-lived Trees, J. Ogden. Plant Demography: A Community-level Interpretation, J. Sarukhan, D. Pinero and M. Martinez-Ramos. Fires and Emus: The Population Ecology of Some Woody Plants in Arid Australia, J.C. Nobel. Differences in Life Histories between Two Ecotypes of Plantago lanceolata L., J.M. van Groenendael. Variation and Differentiation in Population of Trifolium repens in Permanent Pastures, . Disasters and Catastrophies in Populations of Halimione portulacoides, Ad H.L. Huiskes and A.W. Stienstra. Establishment and Peri-establishment Mortality, R.E.L. Naylor. Population Biology and the Conservation of Rare Species, H.J. Harvey. Biology of Invasive and Weedy Species: Invading Plants: Their Potential Contribution to Population Biology, R.N. Mack. Proso Millet (Panicum miliaceum L.): A Crop and a Weed, P.B. Cavers and M.A. Bough. Population Dynamics of a Few Exotic Weeds in North-east India, R.S. Tripathi. Weeds and Agriculture: A Question of Balance, B.R. Trenbath. The Demographic Interpretation of Plant Form: Application to Plant Competition and Production: On the Astogeny of Six-cornered Clones: An Aspect of Modular Construction, A.D. Bell. The Importance of Plant form as a Determining Factor in Competition and Habitat Exploitation, P.H. Lovell and P.J. Lovell. Modular Demography and Form in Silver Birch, M. Jones. Modular Demography and Growth Patterns of Two Annual Weeds (Chenopodium album L. and Spergula arvenis L.) in Relation to Flowering, L. Maillette. A Modular Approach to Tree Production, M. Franco. Plant Interference: The Effects of Neighbours: Plant Responses to Crowding, A.R. Watkinson. The Thinning Rule and Its Application to Mixtures of Plant Populations, J. White. The Influence of Pathogens and Predators on Plant Populations: Pathogens and the Genetic Structure of Plant Populations, J.J. Burdon. Sex Ratios, Clonal Growth and Herbivory in Rumex acetosella, J.L. Doust and L.L. Doust. The Role of Grazing Animal, R. Dirzo. Plant Reproductive Biology: Islands and Dioecism: Insights from the Reproductive Ecology of Pandanus tectorius in Polynesia, P.A. Cox. The Meaning and Measurement of Reproductive Effort in Plants, F.A. Bazzaz and E.G. Reekie. Index.

Book reviews

Book Reviewed in this articleBirds of the North Solomons. Wau Ecology Institute Handbook No. 8 Don HaddenAn Atlas of Distribution of the Freshwater Fish Families of the World Tim M. BerraEstimating the Size of Animal Populations J. G. Blower, L. M. Cook &amp; J. A. BishopThe Ecology of Pests: Some Australian Case Histories R.L. Kitching and R.E. Jones (eds)Demography and Evolution in Plant Populations Edited by Otto Solbrig, Botanical Monographs Volume 15

Demography and Evolution in Plant Populations. Otto T. Solbrig , J. H. Burnett , H. G. Baker , H. Beevers , F. R. Whatley

Previous articleNext article No AccessNew Biological BooksDemography and Evolution in Plant Populations. Otto T. Solbrig , J. H. Burnett , H. G. Baker , H. Beevers , F. R. Whatley Steven N. HandelSteven N. Handel Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 56, Number 4Dec., 1981 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/412467 Copyright 1981 Stony Brook Foundation, Inc.PDF download Crossref reports no articles citing this article.