Article Addendum: The paradox of clonality and the evolution of self-incompatibility

In the January issue of New Phytologist Vallejo-Marín and O’Brien documented that in the genus Solanum (Solanaceae) clonality and self-incompatibility, a common genetic mechanism enforcing cross-fertilization, co-occur more often than expected by chance. Using a phylogenetic approach the authors showed that the statistical association between clonality and self-incompatibility persists even after taking into account phylogenetic relationships among species, uncertainty in the phylogenetic reconstruction, and associations between clonality and life history (annual/perennial). Vallejo-Marín and O’Brien suggest that clonality and self-incompatibility tend to co-occur because clonality, by allowing the persistence and propagation of a genotype in environments with limited pollinator or mate availability, reduces the selective pressure favoring the breakdown of self-incompatibility. In addition to promoting the maintenance of self-incompatibility, when clonality results in the spatial aggregation of genetically identical individuals, clonality may promote its breakdown by restricting pollen transfer between different genotypes. Here I call attention to these contradictory predictions of the effects of clonality on the evolution of self-incompatibility, and suggest that the outcome of this paradox depend on both the extent to which clonal propagation compensates for limited seed production, and on the extent to which clonality reduces pollen transfer between genotypes

Hybrid species are on the march – with the help of humans

First paragraph: Species that evolved far apart have been thrown together by worldwide transport, global warming, deforestation and farming. This is increasing the rate at which plant hybrids are being produced and these new species can dramatically affect local plants, animals and ecosystems. Access this article on The Conversation website: https://theconversation.com/hybrid-species-are-on-the-march-with-the-help-of-humans-5964

Revealed: the first ever flower, 140m years ago, looked like a magnolia

First paragraph: Although most species of plants on Earth have flowers, the evolutionary origin of flowers themselves are shrouded in mystery. Flowers are the sexual organs of more than 360,000 species of plants alive today, all derived from a single common ancestor in the distant past. This ancestral plant, alive sometime between 250m and 140m years ago, produced the first flowers at a time when the planet was warmer, and richer in oxygen and greenhouse gases than today. A time when dinosaurs roamed primeval landscapes

Genomics of invasion: Diversity and selection in introduced populations of monkeyflowers (Mimulus guttatus)

Global trade and travel is irreversibly changing the distribution of species around the world. Because introduced species experience drastic demographic events during colonization and often face novel environmental challenges from their native range, introduced populations may undergo rapid evolutionary change. Genomic studies provide the opportunity to investigate the extent to which demographic, historical and selective processes shape the genomic structure of introduced populations by analysing the signature that these processes leave on genomic variation. Here, we use next-generation sequencing to compare genome-wide relationships and patterns of diversity in native and introduced populations of the yellow monkeyflower (Mimulus guttatus). Genome resequencing data from 10 introduced populations from the United Kingdom (UK) and 12 native M.guttatus populations in North America (NA) demonstrated reduced neutral genetic diversity in the introduced range and showed that UK populations are derived from a geographic region around the North Pacific. A selective-sweep analysis revealed site frequency changes consistent with selection on five of 14 chromosomes, with genes in these regions showing reduced silent site diversity. While the target of selection is unknown, genes associated with flowering time and biotic and abiotic stresses were located within the swept regions. The future identification of the specific source of origin of introduced UK populations will help determining whether the observed selective sweeps can be traced to unsampled native populations or occurred since dispersal across the Atlantic. Our study demonstrates the general potential of genome-wide analyses to uncover a range of evolutionary processes affecting invasive populations

Selection through female fitness helps to explain the maintenance of male flowers

Andromonoecy, the production of both male and hermaphrodite flowers in the same individual, is a widespread phenomenon that occurs in approximately 4,000 species distributed in 33 families. Hypotheses for the evolution of andromonoecy suggest that the production of intermediate proportions of staminate flowers may be favored by selection acting through female components of fitness. Here we used the andromonoecious herb Solanum carolinense to determine the pattern of selection on the production of staminate flowers. A multivariate analysis of selection indicates that selection through female fitness favors the production of staminate flowers in at least one population. We conclude that this counterintuitive benefit of staminate flowers on female fitness highlights the importance of considering female components of fitness in the evolution of andromonoecy, a reproductive system usually interpreted as a "male" strategy

Riverbanks as battlegrounds: why does the abundance of native and invasive plants vary?

The abundance of invasive alien plants (IAPs) can vary dramatically over small spatial scales for reasons that are often unclear. Understanding these could offer key insights for containing invasions, accepting that eradication is often no longer feasible. This study investigated determinants of IAP cover on riverbanks, a well-known hotspot of invasion, using Impatiens glandulifera, a prolific invader across the Northern hemisphere, as a model species. Within this framework we included the potential for dominant native vegetation cover, mediated by favourable environmental conditions, to resist invasion by I. glandulifera through negative association. Our analyses, using structural equation modelling, showed that I. glandulifera is more sensitive to environmental conditions, than dominant native vegetation. High soil moisture was a key determinant of I. glandulifera cover, having negative effects across the riparian zone. Spatially, I. glandulifera and dominant native vegetation responded differently to environmental conditions. Sites with steeper banks had less dominant native vegetation at the water's edge, potentially favouring I. glandulifera cover through reduced competition. In general, greater abundance of dominant native vegetation presented a more invasion-resistan

QUICKSERV: a service quality assessment tool for the quick-service restaurant industry

Purpose - The purpose of this study is to empirically develop and validate a practical, consistent and specific scale to assess perceived service quality at the service encounter at quick-service restaurants (QSRs). Design/methodology/approach - Development and validation of the scale involved a five-stage process. Data were collected from 430 customers of a QSR belonging to an international brand located in Barcelona. Surveys were applied immediately after the service encounter, using the face-to-face method. The scale development procedure involved exploratory and confirmatory factor analyses. Findings - The results suggest a specific and parsimonious measurement scale, whose structure comprises 14 items in four dimensions. In contrast to previous studies, this study identified the appropriateness of splitting the interaction quality dimension into two single dimensions, one focusing on the interaction time and other on staff-customer interaction. Furthermore, these indicate that a speedy service, pleasant treatment and food quality are the most valued attributes in QSR. Practical implications - This scale is a useful instrument to administer and assure service quality standards within QSR management systems. Its practical approach and short survey length ease data collection, considering that customers spend short amounts of time in this type of restaurant. Furthermore, it could also be used by franchisors and restaurant operators as a tool to monitor continuing compliance with service quality standards. Originality/value - The resulting scale introduces a novel four-factor structure with high goodness of fit to effectively measure customers' perceived service quality in QSRs, where the ease of use and speed of gathering client responses are a key factor for successful implementation

Neonicotinoid pesticide limits improvement in buzz pollination by bumblebees

Neonicotinoid pesticides have been linked to global declines of beneficial insects such as bumblebees. Exposure to trace levels of these chemicals causes sub-lethal effects, such as reduced learning and foraging efficiency. Complex behaviours may be particularly vulnerable to the neurotoxic effects of neonicotinoids. Such behaviours may include buzz pollination (sonication), in which pollinators, usually bees, use innate and learned behaviours to generate high-frequency vibrations to release pollen from flowers with specialised anther morphologies. This study assesses the effect of field-realistic, chronic exposure to the widely-used neonicotinoid thiamethoxam on the development of sonication buzz characteristics over time, as well as the collection of pollen from buzz-pollinated flowers. We found that the pollen collection of exposed bees improved less with increasing experience than that of unexposed bees, with exposed bees collecting between 47% and 56% less pollen by the end of 10 trials. We also found evidence of two distinct strategies for maximising pollen collection: (1) extensions to the duration of individual buzzes and (2) extensions of the overall time spent buzzing. We find new complexities in buzz pollination, and conclude that the impacts of field-realistic exposure to a neonicotinoid pesticide may seriously compromise this important ecosystem service

Quantifying the potential of 'on-farm' seed priming to increase crop performance in developing countries. A meta-analysis

Low-input agriculture in marginal areas of developing countries faces considerable challenges during crop development. A key stage in crop growth is seed germination, which is often constrained by abiotic factors such as low water potential, high temperatures and soil crusting, which can result in poor establishment. This is exacerbated by low soil fertility, salinity, drought, pests and diseases, which ultimately leads to reduced yields. Over the last 20 years, the potential of 'on-farm' seed priming, a traditional, low-cost technique, consisting of soaking seeds in water prior to sowing, has been applied to different crops and conditions with varying degrees of success. To understand the significance of this potentially transformative agronomic strategy, we have conducted a global meta-analysis of on-farm seed priming by quantifying (i) the rate of emergence, (ii) final emergence and (iii) total yield from 44 published papers on 17 crops across 10 countries. Our results show that on-farm seed priming has a significantly positive effect on crop performance: seeds emerge 22% faster, with an increased final emergence of 11%, with total yields 21% higher than conventionally sown seeds. Furthermore, sub-group analyses demonstrated that on-farm seed priming is more advantageous under stressful abiotic conditions with case studies categorized as being either 'nutrient deficient', 'salinity-stressed' or 'dry climates' gaining the highest yield improvements (22–28%). On-farm seed priming can be particularly beneficial to resource-poor farmers working in low-input agricultural systems where yield potential is limited by intrinsically stressed agronomic environments. Here, we demonstrate for the first time that on-farm seed priming is perfectly adapted to local situations in developing countries. Our results provide the evidence that on-farm seed priming could be effectively adopted by resource-poor farmers as a strategy to increase food security in some of the most marginal agricultural areas

Simulated seed predation reveals a variety of germination responses of neotropical rain forest species

Seed predation, an omnipresent phenomenon in tropical rain forests, is an important determinant of plant recruitment and forest regeneration. Although seed predation destroys large amounts of the seed crop of numerous tropical species, in many cases individual seed damage is only partial. The extent to which partial seed predation affects the recruitment of new individuals in the population depends on the type and magnitude of alteration of the germination behavior of the damaged seeds. We analyzed the germination dynamics of 11 tropical woody species subject to increasing levels of simulated seed predation (0–10% seed mass removal). Germination response to seed damage varied considerably among species but could be grouped into four distinct types: (1) complete inability to germinate under damage ≥1%, (2) no effect on germination dynamics, (3) reduced germination with increasing damage, and (4) reduced final germination but faster germination with increasing damage. We conclude that partial seed predation is often nonlethal and argue that different responses to predation may represent different proximal mechanisms for coping with partial damage, with potential to shape, in the long run, morphological and physiological adaptations in tropical, large-seeded species