Fitness costs of herbicide resistance across natural populations of the common morning glory, Ipomoea purpurea

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134117/1/evo13016_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134117/2/evo13016.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134117/3/evo13016-sup-0001-FigS1.pd

Variable inbreeding depression may explain associations between the mating system and herbicide resistance in the common morning glory

Inbreeding depression is a central parameter underlying mating system variation in nature and one that can be altered by environmental stress. Although a variety of systems show that inbreeding depression tends to increase under stressful conditions, we have very little understanding across most organisms how the level of inbreeding depression may change as a result of adaptation to stressors. In this work we examined the potential that inbreeding depression varied among lineages of Ipomoea purpurea artificially evolved to exhibit divergent levels of herbicide resistance. We examined inbreeding depression in a variety of fitness‐related traits in both the growth chamber and in the field, and paired this work with an examination of gene expression changes. We found that, while inbreeding depression was present across many of the traits, lineages artificially selected for increased herbicide resistance often showed no evidence of inbreeding depression in the presence of herbicide, and in fact, showed evidence of outbreeding depression in some traits compared to nonselected control lines and lineages selected for increased herbicide susceptibility. Further, at the transcriptome level, the resistant selection lines had differing patterns of gene expression according to breeding type (inbred vs. outcrossed) compared to the control and susceptible selection lines. Our data together indicate that inbreeding depression may be lessened in populations that are adapting to regimes of strong selection.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/170936/1/mec15852.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/170936/2/mec15852_am.pd

Microsatellite Markers for the New Zealand Endemic Tree <i>Fuchsia excortica</i>ta (Onagraceae)

Premise of the study: Microsatellite markers were developed from a New Zealand endemic understory tree, Fuchsia excorticata, to investigate factors affecting the mating system. Methods and Results: Using 454 pyrosequencing, 48 microsatellite markers were developed and tested for polymorphism within populations. Twelve of these microsatellite loci were identified as being polymorphic within at least three populations and consistently amplified in the four populations tested. These primers amplified di-, tri-, and tetranucleotide repeats with 1–10 alleles per population. Conclusions: These results indicate the utility of microsatellite loci for future mating system and population genetic studies in F. excorticata

Data from: Mating system contributes only slightly to female maintenance in gynodioecious Geranium maculatum (Geraniaceae)

Gynodioecy, the co-occurrence of female and hermaphroditic individuals within a population, is an important intermediate in the evolution of separate sexes. The first step, female maintenance, requires females to have higher seed fitness compared with hermaphrodites. A common mechanism thought to increase relative female fitness is inbreeding depression avoidance, the magnitude of which depends on hermaphroditic selfing rates and the strength of inbreeding depression. Less well studied is the effect of biparental inbreeding on female fitness. Biparental inbreeding can affect relative female fitness only if its consequence or frequency differs between sexes, which could occur if sex structure and genetic structure both occur within populations. To determine whether inbreeding avoidance and/or biparental inbreeding can account for female persistence in Geranium maculatum, we measured selfing and biparental inbreeding rates in four populations and the spatial genetic structure in six populations. Selfing rates of hermaphrodites were low and did not differ significantly from zero in any population, leading to females gaining at most a 1–14% increase in seed fitness from inbreeding avoidance. Additionally, although significant spatial genetic structure was found in all populations, biparental inbreeding rates were low and only differed between sexes in one population, thereby having little influence on female fitness. A review of the literature revealed few sexual differences in biparental inbreeding among other gynodioecious species. Our results show that mating system differences may not fully account for female maintenance in this species, suggesting other mechanisms may be involved

Cost of resistance data and analysis

This folder contains the data and analysis scripts to recreate the results and figures in the manuscript titled "Fitness costs of herbicide resistance across natural populations of the common morning glory". There is a README file in the folder containing more information

Data from: Fitness costs of herbicide resistance across natural populations of the common morning glory, Ipomoea purpurea

Although fitness costs associated with plant defensive traits are widely expected, they are not universally detected, calling into question their generality. Here we examine the potential for life history trade-offs associated with herbicide resistance by examining seed germination, root growth, and above-ground growth across 43 naturally occurring populations of Ipomoea purpurea that vary in their resistance to RoundUp®, the most commonly used herbicide worldwide. We find evidence for life history trade-offs associated with all three traits; highly resistant populations had lower germination, shorter roots and smaller above-ground size. A visual exploration of the data indicated that the type of trade-off may differ among populations. Our results demonstrate that costs of adaptation may be present at stages other than simply the production of progeny in this agricultural weed. Additionally, the cumulative effect of costs at multiple life cycle stages can result in severe consequences to fitness when adapting to novel environments

Tree with branch lengths

This file contains the tree data with branch lengths obtained via bladj. See paper for more details

Data from: Not all weeds are created equal: a database approach uncovers differences in the sexual system of native and introduced weeds

Weedy species provide excellent opportunities to examine the process of successful colonization of novel environments. Despite the influence of the sexual system on a variety of processes from reproduction to genetic structure, how the sexual system of species influences weediness has received only limited consideration. We examined the hypothesis that weedy plants have an increased likelihood of being self-compatible compared with nonweedy plants; this hypothesis is derived from Baker's law, which states that species that can reproduce uniparentally are more likely to successfully establish in a new habitat where mates are lacking. We combined a database of the weed (weedy/nonweedy) and introduction status (introduced/native) of plant species found in the USA with a database of plant sexual systems and determined whether native and introduced weeds varied in their sexual systems compared with native and introduced nonweeds. We found that introduced weeds are overrepresented by species with both male and female functions present within a single flower (hermaphrodites) whereas weeds native to the USA are overrepresented by species with male and female flowers present on a single plant (monoecious species). Overall, our results show that Baker's law is supported at the level of the sexual system, thus providing further evidence that uniparental reproduction is an important component of being either a native or introduced weed

Adaptive and maladaptive expression plasticity underlying herbicide resistance in an agricultural weed

Plastic phenotypic responses to environmental change are common, yet we lack a clear understanding of the fitness consequences of these plastic responses. Here, we use the evolution of herbicide resistance in the common morning glory (Ipomoea purpurea) as a model for understanding the relative importance of adaptive and maladaptive gene expression responses to herbicide. Specifically, we compare leaf gene expression changes caused by herbicide to the expression changes that evolve in response to artificial selection for herbicide resistance. We identify a number of genes that show plastic and evolved responses to herbicide and find that for the majority of genes with both plastic and evolved responses, plastic responses appear to be adaptive. We also find that selection for herbicide response increases gene expression plasticity. Overall, these results show the importance of adaptive plasticity for herbicide resistance in a common weed and that expression changes in response to strong environmental change can be adaptive.Impact StatementPredicting whether and how organisms will adapt to environmental change is a crucial goal. However, this goal can be complicated because environmental change can alter traits, in a process called plasticity. The extent and fitness consequences of plasticity will have important effects on the adaptive process. In this study, we use adaptation to herbicide in the agricultural weed, the common morning glory, as a model for understanding the extent and fitness consequences of plasticity in gene expression. We find evidence that gene expression plasticity is adaptive in the presence of herbicide, suggesting that understanding plasticity is crucial for understanding how organisms adapt to new environments.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/168444/1/evl3241.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168444/2/evl3241_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168444/3/evl3241-sup-0003-figureS3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168444/4/evl3241-sup-0001-figureS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168444/5/evl3241-sup-0002-figureS2.pd