A developmental response to pathogen infection in Arabidopsis

We present evidence that susceptible Arabidopsis plants accelerate their reproductive development and alter their shoot architecture in response to three different pathogen species. We infected 2-week-old Arabidopsis seedlings with two bacterial pathogens, Pseudomonas syringae and Xanthomonas campestris, and an oomycete, Peronospora parasitica. Infection with each of the three pathogens reduced time to flowering and the number of aerial branches on the primary inflorescence. In the absence of competition, P. syringae and P. parasitica infection also increased basal branch development. Flowering time and branch responses were affected by the amount of pathogen present. Large amounts of pathogen caused the most dramatic changes in the number of branches on the primary inflorescence, but small amounts of P. syringae caused the fastest flowering and the production of the most basal branches. RPS2 resistance prevented large changes in development when it prevented visible disease symptoms but not at high pathogen doses and when substantial visible hypersensitive response occurred. These experiments indicate that phylogenetically disparate pathogens cause similar changes in the development of susceptible Arabidopsis. We propose that these changes in flowering time and branch architecture constitute a general developmental response to pathogen infection that may affect tolerance of and/or resistance to disease.     

Convergence in reduced body size,head size,and blood glucose in three island reptiles

Many oceanic islands harbor diverse species that differ markedly from their mainland relatives with respect to morphology, behavior, and physiology. A particularly common morphological change exhibited by a wide range of species on islands worldwide involves either a reduction in body size, termed island dwarfism, or an increase in body size, termed island gigantism. While numerous instances of dwarfism and gigantism have been well documented, documentation of other morphological changes on islands remains limited. Furthermore, we lack a basic understanding of the physiological mechanisms that underlie these changes, and whether they are convergent. A major hypothesis for the repeated evolution of dwarfism posits selection for smaller, more efficient body sizes in the context of low resource availability. Under this hypothesis, we would expect the physiological mechanisms known to be downregulated in model organisms exhibiting small body sizes due to dietary restriction or artificial selection would also be downregulated in wild species exhibiting dwarfism on islands. We measured body size, relative head size, and circulating blood glucose in three species of reptiles—two snakes and one lizard—in the California Channel Islands relative to mainland populations. Collating data from 6 years of study, we found that relative to mainland population the island populations had smaller body size (i.e., island dwarfism), smaller head sizes relative to body size, and lower levels of blood glucose, although with some variation by sex and year. These findings suggest that the island populations of these three species have independently evolved convergent physiological changes (lower glucose set point) corresponding to convergent changes in morphology that are consistent with a scenario of reduced resource availability and/or changes in prey size on the islands. This provides a powerful system to further investigate ecological, physiological, and genetic variables to elucidate the mechanisms underlying convergent changes in life history on islands.     

Assessing the effects of land-use change on plant traits, communities and ecosystem functioning in grasslands: a standardized methodology and lessons from an application to 11 European sites

BACKGROUND AND AIMS: A standardized methodology to assess the impacts of land-use changes on vegetation and ecosystem functioning is presented. It assumes that species traits are central to these impacts, and is designed to be applicable in different historical, climatic contexts and local settings. Preliminary results are presented to show its applicability. METHODS: Eleven sites, representative of various types of land-use changes occurring in marginal agro-ecosystems across Europe and Israel, were selected. Climatic data were obtained at the site level; soil data, disturbance and nutrition indices were described at the plot level within sites. Sixteen traits describing plant stature, leaf characteristics and reproductive phase were recorded on the most abundant species of each treatment. These data were combined with species abundance to calculate trait values weighed by the abundance of species in the communities. The ecosystem properties selected were components of above-ground net primary productivity and decomposition of litter. KEY RESULTS: The wide variety of land-use systems that characterize marginal landscapes across Europe was reflected by the different disturbance indices, and were also reflected in soil and/or nutrient availability gradients. The trait toolkit allowed us to describe adequately the functional response of vegetation to land-use changes, but we suggest that some traits (vegetative plant height, stem dry matter content) should be omitted in studies involving mainly herbaceous species. Using the example of the relationship between leaf dry matter content and above-ground dead material, we demonstrate how the data collected may be used to analyse direct effects of climate and land use on ecosystem properties vs. indirect effects via changes in plant traits. CONCLUSIONS: This work shows the applicability of a set of protocols that can be widely applied to assess the impacts of global change drivers on species, communities and ecosystems.     

Shoo fly don't bother me: Flies track social primates and carry viable anthrax

Flies—a small name for an enormous taxonomic group of over 110,000 described species that have unique ecological roles. Nonbiting flies ingest organic material in faecal matter or carrion, which is rich in microbes and nutrients that benefit both adults and their offspring (maggots). These are often referred to as “filth flies” because they are often pests in human settlements and responsible for the spread of enteric pathogens. Filth flies associate with human populations; however, whether this association is simply due to the presence of organic waste produced, or if flies move with social groups remains unknown. In this issue of Molecular Ecology, Gogarten et al. (2019) use a unique combination of field methods and molecular tools to show that filth flies (predominantly Muscidae [house flies] and Calliphoridae [blow flies]) associate and move with social nonhuman primate (NHP) groups (mangabeys and chimpanzees) for up to 12 days and over 1 km. Filth flies captured near these groups were found to have pathogen DNA on them from the causative agents of sylvatic anthrax and yaws. Furthermore, the authors were able to show that the anthrax bacteria on the flies was viable. Previous research emphasized sylvatic anthrax as a major conservation threat to wildlife at this field site (Hoffmann et al., 2017), highlighting the significance of filth flies as potential vectors of anthrax. The authors present a suite of methods and approaches that utilize flies to better understand rainforest biodiversity, pathogen transmission potential, and filth fly‐host associations. This work represents new directions and opportunities to integrate entomology into field research and exploit the natural history of flies to understand the pathogen landscape and address outstanding questions in ecology and evolution.     

Erratum to: Systemic Gene Delivery Protects the Photoreceptors in the Retinal Degeneration Slow Mouse

Neurochemical Research -     

Evolutionary physiology at 30+: Has the promise been fulfilled?

Three decades ago, interactions between evolutionary biology and physiology gave rise to evolutionary physiology. This caused comparative physiologists to improve their research methods by incorporating evolutionary thinking. Simultaneously, evolutionary biologists began focusing more on physiological mechanisms that may help to explain constraints on and trade-offs during microevolutionary processes, as well as macroevolutionary patterns in physiological diversity. Here we argue that evolutionary physiology has yet to reach its full potential, and propose new avenues that may lead to unexpected advances. Viewing physiological adaptations in wild animals as potential solutions to human diseases offers enormous possibilities for biomedicine. New evidence of epigenetic modifications as mechanisms of phenotypic plasticity that regulate physiological traits may also arise in coming years, which may also represent an overlooked enhancer of adaptation via natural selection to explain physiological evolution. Synergistic interactions at these intersections and other areas will lead to a novel understanding of organismal biology.     

A Highly Social,Land‐Dwelling Fish Defends Territories in a Constantly Fluctuating Environment

The Pacific leaping blenny (Alticus arnoldorum) is a marine fish that has made a highly successful transition to land. We report an extensive field study on the behavior of this remarkable fish and how it has coped with life on land. The fish occurs in great abundance above the waterline along the rocky coastlines of Micronesia. We found them to be terrestrial in all aspects of their adult daily life, but heavily constrained by large fluctuations in both tide and temperature with almost all activity limited to a brief period at mid‐tide. Despite this, the fish were highly social and data were consistent with males defending exclusive territories on land. A variety of metrics – the use of visual displays, the allometry of ornaments, and sexual dimorphism – further imply sexual selection on both sexes was strong. Despite being restricted to an extremely narrow habitable zone in which conditions change constantly, the Pacific leaping blenny is remarkably adapted to life on land and rarely returned to water. The genus is unique among the living fishes in its degree of terrestriality and serves as a useful model of the constraints and adaptations that accompany major ecological transitions.