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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. [ABSTRACT FROM AUTHOR]

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 Statement: Predicting 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. [ABSTRACT FROM AUTHOR]

Premise of research. While climate change will affect all plant species, those in high-altitude habitats cannot move to a more suitable habitat and must therefore adjust to their new environment. To determine how floral traits associated with pollinator attraction may respond to environmental changes, we examine whether these traits are phenotypically plastic, whether genetic variation exists for these traits to enable adaptation, and whether phenotypic plasticity itself has a genetic basis. Methodology. In high-altitude habitats, climate models predict increases in temperature and in spring and early summer rainfall. We grew Aquilegia coerulea plants from three natural populations in two greenhouse rooms, each set at a different temperature, with two water regimes per room. There were 2 water regimes × 3 populations × 17 families × 3 or 4 plants in each room. We measured floral display size, flower size, flower color, and reward traits. We used linear mixed models to examine the effects of family, population, and water and their interactions on the different traits within each room. Pivotal results. All floral traits showed genetic variation either within or among populations. Many floral traits exhibited phenotypic plasticity in response to water, and genetic variation in phenotypic plasticity was identified for two traits. The number of flowers increased while spur length and reflectivity decreased between the cool-dry and the warm-wet treatments. Conclusions. All floral traits examined had the potential to adjust to the changes in water expected under anthropogenic climate change in high-altitude habitats. As the plant adjusts to the new environmental conditions, the potential roles of phenotypic plasticity versus selection on a trait mean vary among floral traits. We discuss the implications of these expected changes in floral traits on pollinators and plant fitness. [ABSTRACT FROM AUTHOR]

Abstract: 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. [ABSTRACT FROM AUTHOR]

Background and Aims: Interactions between species are especially sensitive to environmental changes. The interaction between plants and pollinators is of particular interest given the potential current global decline in pollinators. Reduced pollinator services can be compensated for in some plant species by self-pollination. However, if inbreeding depression is high, selfed progeny could die prior to reaching adulthood, leading to cryptic recruitment failure. Methods: To examine this scenario, pollinator abundance, pollen limitation, selfing rates and inbreeding depression were examined in 12 populations of varying disturbance levels in Sophora microphylla (Fabaceae), an endemic New Zealand tree species. Key Results: High pollen limitation was found in all populations (average of 58% reduction in seed production, nine populations), together with high selfing rates (61% of offspring selfed, six populations) and high inbreeding depression (selfed offspring 86% less fit, six populations). Pollen limitation was associated with lower visitation rates by the two endemic bird pollinators. Conclusions: The results suggest that for these populations, over half of the seeds produced are genetically doomed. This reduction in the fitness of progeny due to reduced pollinator service is probably important to population dynamics of other New Zealand species. More broadly, the results suggest that measures of seed production or seedling densities may be a gross overestimate of the effective offspring production. This could lead to cryptic recruitment failure, i.e. a decline in successful reproduction despite high progeny production. Given the global extent of pollinator declines, cryptic recruitment failure may be widespread. [ABSTRACT FROM AUTHOR]

Background and Aims Gynodioecy, the co-occurrence of female and hermaphroditic individuals, is thought to be an intermediate step between hermaphroditism and separate sexes, a major transition in flowering plants. Because retaining females in a population requires that they have increased seed fitness (to compensate for the lack of pollen fitness), factors that affect seed fitness are of great importance to the evolution of this mating system and have often been studied. However, factors negatively affecting female fitness are equally important and have been largely neglected. One such factor stems from female flowers being less attractive to insects than hermaphrodite flowers, thereby decreasing their relative fitness. Methods To test the severity and consequences of this type of pollinator discrimination in Geranium maculatum, experimental populations with the range of sex ratios observed in nature were created, ranging from 13 % to 42 % females. Pollinators were observed in order to measure the strength of discrimination, and pollen deposition and seed production of both sexes were measured to determine the fitness consequences of this discrimination. Additionally a comparison was made across the sex ratios to determine whether discrimination was frequency-dependent. Key Results It was found that female flowers, on average, were visited at half of the rate of hermaphrodite flowers, which decreased their pollen receipt and seed production. Additionally, females were most discriminated against when rare, due to both changes in the pollinators' behaviour and a shift in pollinator composition. Conclusions The results suggest that pollinator discrimination negatively affects females' relative fitness when they are rare. Thus, the initial spread of females in a population, the first step in the evolution of gynodioecy, may be made more difficult due to pollinator discrimination. [ABSTRACT FROM PUBLISHER]

Premise of research. Changes in the abiotic environment can influence plant mating systems through phenotypic changes in floral traits that affect selfing. Herkogamy (spatial separation of male and female functions within a flower), dichogamy (temporal separation), and total flower number affect within- (autogamy) and/or among- (geitonogamy) flower selfing. We examined the potential effects of environmental changes associated with global warming on herkogamy, dichogamy, and number of flowers per plant and discussed the impacts on the mating system in a high-altitude species, Aquilegia coerulea. Methodology. In the high-altitude habitats in which this species grows, global warming is expected to increase both temperature and spring precipitation in the form of rain. We grew plants from 17 families from each of three natural populations of A. coerulea at two temperature and two water treatments, leading to 692 experimental plants (2 temperature × 2 water × 3 populations × 17 families × 3-4 individuals per family). We measured herkogamy and dichogamy, recorded total flower number for each plant, and examined variation in floral traits due to genes and the environment. Pivotal results. Herkogamy, dichogamy, and total flower number-traits known to influence selfing rate- were all phenotypically plastic in response to changes in water or temperature. Genetic variation for all three traits was detected within and/or among populations. Conclusions. On the basis of our results, we predict that the increase in total flower number as a plastic response to global warming will have the strongest influence on the selfing rate and increase the level of geitonogamous selfing. Because inbreeding depression is high in A. coerulea, selection will act to reduce floral display in order to reduce inbreeding depression, but there will be a balance between the negative impact of inbreeding depression and the advantage provided by large floral displays in attracting pollinators. [ABSTRACT FROM AUTHOR]

• Populations containing both females and hermaphrodites (dimorphic) are generally found in drier sites than those with only hermaphrodites (monomorphic). The sex-differential plasticity hypothesis (SDP) suggests that this is caused by hermaphrodites reducing allocation to seeds in harsh environments, allowing female establishment. We proposed that a similar process could explain sex distribution within populations. • We compared light availability and soil moisture between sites of three monomorphic and three dimorphic populations of Geranium maculatum and between microsites occupied by females and hermaphrodites within populations. We also correlated seed production in dimorphic populations with environmental measures. • We found that dimorphic and monomorphic populations occurred in sites with similar soil moisture but within two dimorphic populations females occurred in drier microsites than hermaphrodites, as predicted by the SDP hypothesis. Contrary to the predictions, hermaphrodites’ seed production was not influenced by the environment. Rather, females’ seed production was correlated with environmental conditions in two populations, although the direction of the correlation differed between populations. • Our results suggest that in this species, the SDP hypothesis does not explain sex distribution among or within populations. However, microsite environments may influence the distribution of sexes within a population and potentially aid in maintaining gynodioecy. [ABSTRACT FROM AUTHOR]

Plant species with separate genders often exhibit gender differences in traits related to reproductive allocation. In gynodioecious species, females often produce more seeds than do hermaphrodites, leading to a higher reproductive cost. The mechanisms that allow females to meet the high costs of reproduction are currently under debate. In this study, we test the hypothesis that there are genetically based gender differences in physiological traits that enable females to finance these costs through higher photosynthetic carbon gain in the gynodioecious perennial Geranium maculatum. Females and hermaphrodites were compared in a greenhouse study that minimized environmental and selfing rate differences between the genders. We found that females produced smaller flowers but more of them and more fruits than did hermaphrodites. However, genders did not differ in their seed number, seed mass, fruit set, and reproductive allocation. In addition, genders did not differ in photosynthetic rate (A), leaf N, and water use efficiency inferred from leaf carbon isotope ratio (δ13C). Overall, G. maculatum shows no genetically based gender differences for most of the reproductive traits or any of the physiological traits measured. Our results suggest that for G. maculatum, the gender fitness differences previously identified in natural populations may be caused by gender differences in microhabitat and/or selfing rate. [ABSTRACT FROM AUTHOR]

Premise of the Study: Microsatellite markers were developed for New Zealand species of Corybas (Orchidaceae) to investigate population genetics and species delimitation. Methods and Results: From sequencing a total genomic DNA library (using Illumina MiSeq), we developed 22 microsatellite markers for C. obscurus. The di‐ and trinucleotide repeat loci were initially trialed on individuals representing seven Corybas taxa (C. "rimutaka," C. confusus, C. hypogaeus, C. macranthus, C. obscurus, C. trilobus, and C. walliae) and had one to eight alleles per locus. Twelve polymorphic markers were further tested on six Corybas populations from three of the seven taxa (C. obscurus, C. "rimutaka," and C. trilobus). Observed and expected heterozygosities ranged from 0–1 and 0–0.859, respectively. The utility of these 12 loci was further validated in five related Corybas species (C. hypogaeus, C. obscurus, C. vitreus, C. walliae, and C. "rimutaka"; 38 individuals) representing populations from across the North and South Islands. The average value for genetic diversity among populations (FST) of 0.439 shows differentiation among species. Conclusions: These markers will be useful for future studies aimed at delimiting species boundaries and examining the genetic diversity of the New Zealand Corybas species. [ABSTRACT FROM AUTHOR]