Pieter A Arnold

• BSc (Hons), PhD
• Research Fellow at Australian National University

When leaves exceed their thermal threshold during heatwaves, irreversible damage to the leaf can accumulate. However, few studies have explored short-term acclimation of leaves to heatwaves that could help plants to prevent heat damage with increasing heatwave intensity. Here, we studied the heat tolerance of PSII (PHT) in response to a heatwave in...

Phenotypic plasticity and rapid evolution are fundamental processes by which organisms can maintain their function and fitness in the face of environmental changes. Here we quantified the plasticity and evolutionary potential of an alpine herb Wahlenbergia ceracea. Utilising its mixed-mating system, we generated outcrossed and self-pollinated famil...

Forecasts of vulnerability to climate warming require an integrative understanding of how species are exposed to, are damaged by, and recover from thermal stress in natural environments. The sensitivity of species to temperature depends on the frequency, duration, and magnitude of thermal stress. Thus, there is a generally recognised need to move b...

Background and Aims Many plants have some capacity for leaf thermoregulation via stomatal conductance (gsw), such that leaf temperature (Tleaf) is rarely coupled with air temperature (Tair). The difference between leaf and air temperature (thermal offset, ΔT) and the slope (thermal coupling strength, β) is mediated by interactions between the plant...

The increasing frequency and severity of heatwaves will intensify stress on plants. Given regional variation in heatwave exposure and expected differences in thermal tolerance between species it is unlikely that all plant species will be affected equally by climate change. However, little is currently known about variation in the responses of plant...

Phenotypic plasticity and rapid evolution are fundamental processes by which organisms can maintain their function and fitness in the face of environmental changes. Here we quantified the plasticity and evolutionary potential of an alpine herb Wahlenbergia ceracea . Utilising its mixed-mating system, we generated outcrossed and self-pollinated fami...

Metabolic cold adaptation, or Krogh's rule, is the controversial hypothesis that predicts a monotonically negative relationship between metabolic rate and environmental temperature for ectotherms living along thermal clines measured at a common temperature. Macrophysiological patterns consistent with Krogh's rule are not always evident in nature, a...

The Climate Variability Hypothesis (CVH) predicts that species from environments with more variable temperatures should have wide thermal tolerance breadth. We addressed this question in plants and asked which climate predictors (e.g., temperature, precipitation, variability/seasonality) best predict species thermal limits. Measures of low (T crit-...

Understanding the molecular basis of plant heat tolerance helps to predict the consequences of a warming climate on plant performance, particularly in vulnerable environments. Our current understanding comes primarily from studies in Arabidopsis thaliana and selected crops exposed to short and intense heat stress. In this study we sought to charact...

In seasonal environments, a high responsiveness of development to increasing temperatures in spring can infer benefits in terms of a longer growing season, but also costs in terms of an increased risk of facing unfavourable weather conditions. Still, we know little about how climatic conditions influence the optimal plastic response. Using 22 years...

By 2100, greenhouse gases are predicted to reduce ozone and cloud cover over the tropics causing increased exposure of organisms to harmful ultraviolet‐B radiation (UVBR). UVBR damages DNA and is an important modulator of immune function and disease susceptibility in humans and other vertebrates. The effect of UVBR on invertebrate immune function i...

Dispersal is a key component of life history that influences individual fitness, population dynamics and range expansion. Morphological traits that are functionally related to dispersal may change through the spatial sorting of phenotypes at population range edges and invasion fronts. Generally, since larger invertebrates are expected to have great...

Abstract Foundation seaweed species are experiencing widespread declines and localised extinctions due to increased instability of sea surface temperature. Characterising temperature thresholds are useful for predicting patterns of change and identifying species most vulnerable to extremes. Existing methods for characterising seaweed thermal tolera...

Climate warming may affect multiple aspects of plant life history, including important factors such as germination responses and the key trade‐off between offspring size and number. As a case study to address these concepts, we used an alpine plant (waxy bluebell, Wahlenbergia ceracea; Campanulaceae) that shows plasticity to warming in seed traits...

Climate change presents many challenges for plants, a major one of which is the steady increase in the temperatures that plants are exposed to during germination, growth and reproduction. Generating a more complete understanding of the capacity for plants to respond and of the role that phenotypic plasticity plays in facilitating species' responses...

Phenotypic plasticity index (PI), the slope of reaction norm (K) and relative distances plasticity index (RDPI), the most commonly used estimators, have occasionally been found to generate different plasticity rankings between groups (species, populations, cultivars or genotypes). However, no effort has been made to determine how frequent this inco...

Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions and moisture availability during winter. It also affects the growing season’s start and end, and plant access to moisture and nutrients. Here, we review the current knowledge of the snow cover’s role for vegetation, p...

Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions, and moisture availability during winter. It also affects the growing season’s start and end, and plant access to moisture and nutrients. Here, we review the current knowledge of the snow cover’s role for vegetation,...

High‐phenotypic plasticity has long been considered as a characteristic promoting exotic plant invasions. However, the results of the studies testing this hypothesis are still inconsistent. Overlooking the effects of species resource requirements and environmental resource availability may be the main reasons for the ambiguous conclusions. Here, we...

When seeking to inform and improve prevention efforts and policy, it is important to be able to robustly synthesize all available evidence. But evidence sources are often large and heterogeneous, so understanding what works, for whom, and in what contexts can only be achieved through a systematic and comprehensive synthesis of evidence. Many barrie...

Seasonal snow is among the most important factors governing the ecology of many terrestrial ecosystems, but rising global temperatures are changing snow regimes and driving widespread declines in the depth and duration of snow cover. Loss of the insulating snow layer will fundamentally change the environment. Understanding how individuals, populati...

Explaining variation in the fitness of organisms is a fundamental goal in evolutionary ecology. Maintenance energy metabolism is the minimum energy required to sustain biological processes at rest (resting metabolic rate: RMR) and is proposed to drive or constrain fitness of animals; however, this remains debated. Hypotheses have been proposed as t...

Global warming may pose a serious threat to seed germination and establishment in alpine ecosystems, given that temperature is a primary factor in stimulating seed germination and regulating changes in seed dormancy. However, to date, little is known about the relative importance of temperatures experienced by parents versus by the seeds (after dis...

Plant thermal tolerance is a crucial research area as the climate warms and extreme weather events become more frequent. Leaves exposed to temperature extremes have inhibited photosynthesis and will accumulate damage to PSII if tolerance thresholds are exceeded. Temperature-dependent changes in basal chlorophyll fluorescence (T-F0) can be used to i...

Climate change is generating both sustained trends in average temperatures and higher frequency and intensity of extreme events. This poses a serious threat to biodiversity, especially in vulnerable environments, like alpine systems. Phenotypic plasticity is considered to be an adaptive mechanism to cope with climate change in situ, yet studies of...

Understanding plant thermal tolerance is fundamental to predicting impacts of extreme temperature events that are increasing in frequency and intensity across the globe. Extremes, not averages, drive species evolution, determine survival and increase crop performance. To better prioritize agricultural and natural systems research, it is crucial to...

Synthesis of evidence from the totality of relevant research is essential to inform and improve prevention efforts and policy. Given the large and usually heterogeneous evidence available,reaching a thorough understanding of what works, for whom, and in what contexts, can only be achieved through a systematic and comprehensive synthesis of evidence...

Plant thermal tolerance is a crucial research area as the climate warms and extreme weather events become more frequent. We developed and tested a high-throughput method for measuring photosynthetic critical thermal limits at low ( CT MIN ) and high ( CT MAX ) temperatures to achieve pragmatic and robust measures of thermal tolerance limits using a...

The current policy has the world on track to experience around 3°C of warming by 2100. The responses of organisms to our warming world will be mediated by changes in physiological processes, including metabolic rate. Metabolic rate represents the energetic cost of living, and is fundamental to understanding the energy required to sustain population...

Seasonal snow is among the most important factors governing the ecology of many terrestrial ecosystems, but rising global temperatures are changing snow regimes and driving widespread declines in the depth and duration of snow cover. Loss of the insulating snow layer will fundamentally change the environment – far more than incremental temperature...

Synthesizing evidence is an essential part of scientifc progress, but it is often done in a slow and uncoordinated manner, sometimes producing misleading conclusions. Here, we propose the idea of an ‘open synthesis community’ to resolve this pressing issue.

An understanding of how sublethal exposure to phosphine affects an organism’s respiration is important for predicting its effects on activities depending on a reliable energy source including movement. After treatment with the appropriate sublethal doses of phosphine (LC10), both resistant and susceptible Tribolium castaneum beetles suffered reduct...

Plants tolerate temperature extremes within physiological limits before they can no longer photosynthesise and begin to incur damage. We can measure the critical thermal limits of leaves using many different methods. But how do variations within a measurement method affect estimates of thermal tolerance limits? Can we make valid interspecific compa...

Organisms vary widely in size, from microbes weighing 0.1 pg to trees weighing thousands of megagrams — a 1021-fold range similar to the difference in mass between an elephant and the Earth. Mass has a pervasive influence on biological processes, but the effect is usually non-proportional; for example, a tenfold increase in mass is typically accomp...

Phenotypic plasticity is frequently assumed to be an adaptive mechanism by which organisms cope with rapid changes in their environment, such as shifts in temperature regimes owing to climate change. However, despite this adaptive assumption, the nature of selection on plasticity within populations is still poorly documented. Here, we performed a s...

Plant biology is experiencing a renewed interest in the mechanistic underpinnings and evolution of phenotypic plasticity that calls for a re‐evaluation of how we analyse phenotypic responses to a rapidly changing climate. We suggest that dissecting plant plasticity in response to increasing temperature needs an approach that can represent plasticit...

1. Temperature plays a fundamental role in the dynamics of host–pathogen interactions. Wolbachia is an endosymbiotic bacteria that infects about 40% of arthropod species, which can affect host behaviour and reproduction. Yet, the effect of Wolbachia on host thermoregulatory behaviour is largely unknown, despite its use in disease vector control pro...

Temperature plays a fundamental role in the dynamics of host-pathogen interactions. Wolbachia is an endosymbiotic bacteria that infects about 40% of arthropod species, which can affect host behaviour and reproduction. Yet, the effect of Wolbachia on host thermoregulatory behaviour is largely unknown, despite its use in disease vector control progra...

Individuals vary in their ability to disperse. Much of this variation can be described by covarying phenotypic traits that are related to dispersal (constituting the ‘dispersal phenotype’ or ‘dispersal syndrome’), but the nature of the associations among these traits is not well understood. Unravelling the associations among traits that potentially...

The natural dispersal of Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) has been emulated in the laboratory for more than 50 years, using a simple dispersal apparatus. This has typically comprised of a starting container (initial resource or patch) connected by tubing, which contains thread for the animals to climb into a tube and hence to...

The cerambycid beetles comprise a diverse family that includes many economically important pests of living and dead trees. Pheromone lures have been developed for cerambycids in many parts of the world, but to date, have not been tested in Australia. In this study, we tested the efficacy of several pheromones, identified from North American and Eur...

Transitioning between life stages involves significant changes to the physiology, structural morphology, biochemistry and behaviour of an organism. Eclosion, metamorphosis and the onset of sexual maturity have consequences for the life history evolution of an organism by initiating reproductive and dispersal-related behaviours that are both energet...

Understanding viral dynamics in arthropods is of great importance when designing models to describe how viral spread can influence arthropod populations. The endosymbiotic bacterium Wolbachia spp., which is present in up to 40% of all insect species, has the ability to alter viral dynamics in both Drosophila spp. and mosquitoes, a feature that in m...

Behavioural fever is a widely conserved response to infection. The host increases body temperature (Tb) by altering their preferred temperature (Tp), generating a fever and delaying or avoiding pathogen-induced mortality. This response is not ubiquitous in insects, however, though few studies have investigated this response to viral infection. Here...

An extensively used model system for investigating anti-pathogen defence and innate immunity involves Drosophila C virus (DCV) and Drosophila melanogaster. While there has been a significant effort to understand infection consequences at molecular and genetic levels, an understanding of fundamental higher-level physiology of this system is lacking....