Gene flow from transgenic crops can introduce novel traits into related species, but the ecological importance of this process is unknown. Here, we report first empirical evidence that wild plants benefit a bacterial transgene under uncaged, natural conditions. Cultivated sunflower (Helianthus annuus) known to hybridize frequently with (H. in western and midwestern United States. We studied crop-developed Bacillus thuringiensis (Bt) transgene, cry1Ac, backcrossed populations. Lepidopteran...

Herbivore damage is generally detrimental to plant fitness, and the evolutionary response of populations can involve either increased resistance or tolerance. While characters that contribute resistance, such as secondary chemicals trichomes, are relatively well understood, a plant's ability tolerate have received much less attention. Using Helianthus annuus (wild sunflower) simulated Haplorhynchites aeneus (head-clipping weevil) model system, we examined morphological developmental...

▪ Abstract Ecological risks associated with the release of transgenic crops include nontarget effects crop and escape transgenes into wild populations. Nontarget can be two sorts: (a) unintended negative on species that do not reduce yield (b) greater persistence in feral Conventional agricultural methods, such as herbicide pesticide application, have large well-documented effects. To extent more specific target effects, may fewer The populations, via hybridization introgression, could lead...

• Premise of the study: Pathogens are thought to regulate host populations. In agricultural crops, virus infection reduces yield. However, in wild plants little is known about spatial and temporal patterns prevalence. Thus, pathogen effects on plant population dynamics unclear. Prevalence data provide necessary background for (1) evaluating size (2) improving risk assessment virus‐resistant transgenic crops. Methods: We used ELISA RT‐PCR survey Cucurbita pepo populations over 4 years five...

Although most plants experience herbivory by several insect species, there has been little empirical work directed toward understanding plant responses to these simultaneous selection pressures. In an experiment in which flea beetles (Phyllotreta cruciferae) and diamondback moths (Plutella xylostella) was manipulated a factorial design, I found that for resistance herbivores is not independent Brassica rapa. Specifically, the effect of beetle damage on B. rapa fitness depends amount moth...

Although there is considerable evidence indicating that herbivory detrimental to plant fitness, some recent studies of the evolution resistance have concluded insects do not impose selection on their host plants. A previously untested assumption underlies most insect distribution patterns are controlled directly by effects genotype preference and performance. The experiments described here explicitly tested this using specialist herbivore Uroleucon tissoti (Homoptera: Aphididae) its Solidago...

Polyploidy has played an important role in angiosperm diversification, but how polyploidy contributes to reproductive isolation remains poorly understood. Most work focused on postzygotic barriers, and the influence of ploidy differences prezygotic barriers is understudied. To address these gaps, we quantified hybrid occurrence, interspecific self-compatibility differences, contributions multiple pre- between diploid Erythronium mesochoreum (Liliaceae) its tetraploid congener albidum....

Microorganisms are ubiquitous and thought to regulate host populations. Although microorganisms can be pathogenic affect components of fitness, few studies have examined their effects on wild plant As individual traits might not contribute equally changes in population growth rate, it is essential examine the entire life cycle determine how dynamics. In this study, we used data from common garden experiments with plants three Cucurbita pepo populations exposed virus treatments. These were...

Seed banks are critically important for disturbance specialist plants because seeds of these species germinate only in disturbed soil. Disturbance and seed depth affect the survival germination probability bank, which turn population dynamics. We develop a density-dependent stochastic integral projection model to evaluate effect soil disturbances on plant dynamics with an emphasis mimicking how vertically redistribute within bank. perform simulation analysis frequency mean population's...

Premise Whole‐genome duplication (polyploidy) is an important force shaping flowering‐plant evolution. Ploidy‐specific plant–pollinator interactions represent community‐level biotic that can lead to nonrandom mating and the persistence of mixed‐ploidy populations. Methods At a naturally occurring diploid–tetraploid contact zone autopolyploid desert shrub Larrea tridentata , we combined flower phenology analyses, collections bees on plants known cytotype, flow cytometry analyses bee‐collected...

The demand for methods to translate information between spatial scales (i.e. size of observational units and the total area study) has intensified given increased recognition that empirical data collection practical applications occur at ranging from individual organisms landscapes. For example, there been considerable interest in “scaling‐down” have successful predicting fine‐scale species’ distributions coarse‐scale distributional maps. Here, we describe application scaling‐down estimation...

Summary 1. Most population dynamics studies are geographically restricted, yet species ranges large. We performed multiyear roadside surveys of the sunflower, Helianthus annuus , at two locations that differ in precipitation (eastern Kansas, KS; western Nebraska, NE). Our goals were to (i) document if there was geographic variation and evaluate role habitat variables landscape matrix; (ii) determine likely amount occupiable (iii) explore seed banks dynamics. 2. Geographical variation:...

The hybrid bridge hypothesis suggests that plant hybrids “bridge” the genetic gap between actual and potential host species, that, for this reason, herbivorous insects are more likely to evolve an expanded range in presence of hybrids. While intuitively appealing, has two implicit assumptions: phenotypic gaps hosts limit range, characters controlling use additively inherited Evaluation these assumptions operation is relatively uncommon. In addition, not been well integrated into existing...

At Arapaho Prairie, in the sandhills of western Nebraska, dioecious annual Croton texensis (Euphorbiaceae) exhibits biased sex ratios. Moreover, direction bias changes from year to year: 1994 study population was significantly female biased, 1995 and 1996 it male 1997 1998 ratio did not differ 1 : 1. Such variation observed plants is frequently attributed environmental determination (ESD), which favored by natural selection if rate fitness gain across an gradient greater for one than other....

Summary 1. Two ecological risks associated with the use of transgenic crops are transgene movement into wild populations and effects on non‐target organisms, such as pollinators. Despite importance pollinators, their contribution to global food supply, little is known about how they affected by crops. Pollinator preferences affect plant mating patterns; thus understanding pollinators will aid in movement. 2. Honey bee squash visit number duration were recorded conventional virus‐resistant...

Abstract. The aphids Uroleucon tissoti and U.nigrotuberculatum both exhibit significantly aggregated distribution patterns across clumps of their common host plant Solidago altissima , the tall goldenrod. However, is more than U.tissoti . We tested hypothesis that goldenrod genotype‐by‐U.tissoti genotype interactions for aphid performance characters could partially account this difference. Only one we measured showed a significant genotype‐bygenotype interaction; therefore it unlikely such...