Predictability of biotic stress structures plant defence evolution

To achieve ecological and reproductive success, plants need to mitigate a multitude of stressors. The stressors encountered by plants are highly dynamic but typically vary predictably due to seasonality or correlations among stressors. As plants face physiological and ecological constraints in responses to stress, it can be beneficial for plants to evolve the ability to incorporate predictable patterns of stress in their life histories. Here, we discuss how plants predict adverse conditions, which plant strategies integrate predictability of biotic stress, and how such strategies can evolve. We propose that plants commonly optimise responses to correlated sequences or combinations of herbivores and pathogens, and that the predictability of these patterns is a key factor governing plant strategies in dynamic environments.</p

Energy expenditure during egg laying is equal for early and late breeding free-living female great tits

In many bird populations, variation in the timing of reproduction exists but it is not obvious how this variation is maintained as timing has substantial fitness consequences. Daily energy expenditure (DEE) during the egg laying period increases with decreasing temperatures and thus perhaps only females that can produce eggs at low energetic cost will lay early in the season, at low temperatures. We tested whether late laying females have a higher daily energy expenditure during egg laying than early laying females in 43 great tits (Parus major), by comparing on the same day the DEE of early females late in their laying sequence with DEE of late females early in their egg laying sequence. We also validated the assumption that there are no within female differences in DEE within the egg laying sequence. We found a negative effect of temperature and a positive effect of female body mass on DEE but no evidence for differences in DEE between early and late laying females. However, costs incurred during egg laying may have carry-over effects later in the breeding cycle and if such carry-over effects differ for early and late laying females this could contribute to the maintenance of phenotypic variation in laying dates

Peering into the dark (ages) with low-frequency space interferometers: Using the 21-cm signal of neutral hydrogen from the infant universe to probe fundamental (Astro)physics.

The Dark Ages and Cosmic Dawn are largely unexplored windows on the infant Universe (z ~ 200-10). Observations of the redshifted 21-cm line of neutral hydrogen can provide valuable new insight into fundamental physics and astrophysics during these eras that no other probe can provide, and drives the design of many future ground-based instruments such as the Square Kilometre Array (SKA) and the Hydrogen Epoch of Reionization Array (HERA). We review progress in the field of high-redshift 21-cm Cosmology, in particular focussing on what questions can be addressed by probing the Dark Ages at z > 30. We conclude that only a space- or lunar-based radio telescope, shielded from the Earth's radio-frequency interference (RFI) signals and its ionosphere, enable the 21-cm signal from the Dark Ages to be detected. We suggest a generic mission design concept, CoDEX, that will enable this in the coming decades

Intra-specific variation in plant associated herbivore communities is phylogenetically structured in Brassicaceae

As a result of co-evolution between plants and herbivores, related plants often interact with similar herbivore communities. Variation in plant-herbivore interactions is determined by variation in underlying functional traits and by ecological and stochastic processes. Hence, typically only a subset of possible interactions is realized on individual plants. We show that insect herbivore communities assembling on individual plants are structured by plant phylogeny among twelve species in two phylogenetic lineages of Brassicaceae. This community sorting to plant phylogeny was retained when splitting the community according to herbivore feeding guilds. Relative abundance of herbivores as well as the size of the community structured community dissimilarity among plant species. Importantly, the amount of intra-specific variation in realized plant-herbivore interactions is also phylogenetically structured. We argue that variability in realized interactions that is not directly structured by plant traits is ecologically relevant and must be considered in the evolution of plant defences.Our Excel sheet contains a Read-Me file explaining the abbreviations, usage, and type of data collected. The Ecology Letters manauscript has a detailed methods section that outlines data collection and methodology. We appreciate notification of data re-use. Please use the contact Daan.Mertens@wur. nl and/or [email protected] Funding provided by: European Research CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000781Award Number: 677139Data originates from a common garden field-experiment, recording plant phenotype and herbivore communities on individual plants. Community development on plants was surveyed from 4-week-old plants until seed set. To allow the community to fully develop, insects were identified in situ to the highest taxonomic resolution possible (species or family level). The Ecology Letters manauscript has a detailed methods section that outlines data collection and methodology. Field observations: Raw herbivore abundance observations of herbivores individual plants. Observations present cumulative abundance over all monitoring rounds (see detailed methodology in the Ecology Letters manuscript). Phenotypic parameters: Plant height (measured from the ground to the top of the plant), diameter (measured as the distance between the two most distal leaves), length of the largest leaf, number of true leaves, and number of flowering branches. We present the maximum observed parameter values for each plant individual to represent its specific phenotype. Phylogeny: Phylogenetic dissimilarity among 12 brassicaceous plant species, based on ITS (see detailed methodology in the Ecology Letters manuscript)

Intra-specific variation in plant associated herbivore communities is phylogenetically structured in Brassicaceae

As a result of co-evolution between plants and herbivores, related plants often interact with similar herbivore communities. Variation in plant-herbivore interactions is determined by variation in underlying functional traits and by ecological and stochastic processes. Hence, typically only a subset of possible interactions is realized on individual plants. We show that insect herbivore communities assembling on individual plants are structured by plant phylogeny among twelve species in two phylogenetic lineages of Brassicaceae. This community sorting to plant phylogeny was retained when splitting the community according to herbivore feeding guilds. Relative abundance of herbivores as well as the size of the community structured community dissimilarity among plant species. Importantly, the amount of intra-specific variation in realized plant-herbivore interactions is also phylogenetically structured. We argue that variability in realized interactions that is not directly structured by plant traits is ecologically relevant and must be considered in the evolution of plant defences

Local and systemic effect of azadirachtin on host choice and feeding activity of Macrosiphum rosae on rose plants

Many studies in the last decades addressed the antifeedant and repellent effects of neem (Azadirachta indica)-based pesticides on arthropod herbivores with azadirachtin as the leading active ingredient. However, results for aphids regarding repellence and feeding were often contradictory and mainly based on laboratory studies with self-made neem extracts in high concentrations. Moreover, no data are available on the presence of azadirachtin in the phloem of treated plants—the tissue that most aphids feed on. We investigated how the application of the commercial neem product NeemAzal-T/S onto only one plant half (upper or lower) affects nymphs of the aphid Macrosiphum rosae in clip cages on the untreated plant half. Results for aphid mortality indicate that active ingredients of NeemAzal-T/S are translocated both upwards and downwards in rose plants and that active ingredients are transported in the phloem. Furthermore, we investigated whether NeemAzal-T/S has a repellent or antifeedant effect on M. rosae. A choice test in the greenhouse as well as the quantification of honeydew excretion and electrical penetration graph analysis do not show differences in settling or feeding on untreated and NeemAzal-T/S-treated rose plants. Collectively, our data show that the effect of approved concentrations of NeemAzal-T/S on M. rosae is based on the toxicity after feeding on treated plants, not on starvation