Michael Ørsted

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• PhD
• Professor (Associate) at Aalborg University

The Spotted Wing Drosophila (Drosophila suzukii) is native to Southeast Asia. Since its first detection in 2008 in Europe and North America, it has been a pest to the fruit production industry as it feeds and oviposits on ripening fruit. Here we aim to model the potential geographical distribution of D. suzukii. We performed an extensive literature...

The relationship between population size, inbreeding, loss of genetic variation and evolutionary potential of fitness traits is still unresolved, and large-scale empirical studies testing theoretical expectations are surprisingly scarce. Here we present a highly replicated experimental evolution setup with 120 lines of Drosophila melanogaster havin...

Temperature tolerance is critical for defining the fundamental niche of ectotherms and researchers classically use either static (exposure to a constant temperature) or dynamic (ramping temperature) assays to assess tolerance. The use of different methods complicates comparison between studies and here we present a mathematical model (and R -script...

About 50 y ago, Crow and Kimura [ An Introduction to Population Genetics Theory (1970)] and Ohta and Kimura [ Genet. Res. 22, 201–204 (1973)] laid the foundations of conservation genetics by predicting the relationship between population size and genetic marker diversity. This work sparked an enormous research effort investigating the importance of...

It is becoming increasingly clear that microbial symbionts influence key aspects of their host’s fitness, and vice versa . This may fundamentally change our thinking about how microbes and hosts interact in influencing fitness and adaptation to changing environments. Here we explore how reductions in population size commonly experienced by threaten...

Temperatures in the Arctic currently rise at four times the global average, making it of utmost importance to understand the thermal biology of species in these sensitive environments. For arctic ectotherms in particular, thermal tolerance limits and adaptive potential are mostly unknown. Such knowledge is urgently needed to predict climate change...

Some insect species have been proposed as a sustainable alternative to traditional animal‐based food and feed sources. Optimisation of insect production can generally be achieved using two main approaches: optimising environmental conditions and improving traits of interest through selective breeding. These avenues are not inseparable as performanc...

Studies of ectotherm responses to heat extremes often rely on assessing absolute critical limits for heat coma or death (CTmax), however, such single parameter metrics ignore the importance of stress exposure duration. Furthermore, population persistence may be affected at temperatures considerably below CTmax through decreased reproductive output....

The thermal death time (TDT) model suggests that the duration an organism can tolerate thermal stress decreases exponentially as the intensity of the temperature becomes more extreme. This model has been used to predict damage accumulation in ectothermic animals and plants under fluctuating thermal conditions. However, the critical assumption of th...

The thermal death time (TDT) model suggests that the duration an organism can tolerate thermal stress decreases exponentially as the intensity of the temperature becomes more extreme. This model has been used to predict damage accumulation in ectotherm animals and plants under fluctuating thermal conditions. However, the critical assumption of the...

Studies of ectotherm responses to heat extremes often rely on assessing absolute critical limits for heat coma or death (CTmax), however, such single parameter metrics ignores the importance of stress exposure duration. Furthermore, population persistence may be affected at temperatures considerably below CTmax through decreased reproductive output...

Metabolic compensation has been proposed as a mean for ectotherms to cope with colder climates. For example, under the metabolic cold adaptation and the metabolic homeostasis hypotheses (MCA and MHH), it has been formulated that cold-adapted ectotherms should display both higher (MCA) and more thermally sensitive (MHH) metabolic rates (MRs) at lowe...

Metabolic compensation has been proposed as a mean for ectotherms to cope with colder climates. For example, under the metabolic cold adaptation/metabolic homeostasis hypotheses (MCA/MHH), it has been formulated that cold-adapted ectotherms should display higher/more thermally sensitive metabolic rates (MRs) at lower temperatures. However, whether...

Temperature affects the rate of all biochemical processes in ectotherms and is therefore critical for determining their current and future distribution under global climate change. Here we show that the rate of biological processes maintaining growth, homeostasis and ageing in the permissive temperature range increases by 7% per degree Celsius (med...

Upper thermal limits (CTmax) are frequently used to parameterize the fundamental niche of ectothermic animals and to infer biogeographical distribution limits under current and future climate scenarios. However, there is considerable debate associated with the methodological, ecological and physiological definitions of CTmax. The recent (re)introdu...

The thermal-death-time (TDT) model has proven highly consistent in describing upper thermal limits in ectotherms through space and time. TDT model parameterization could thus yield new insights into the associations between heat tolerance, acclimation strategies, and species distribution in a range of animal models, including ants. In this study, w...

It is becoming increasingly clear that microbial symbionts influence key aspects of their host’s fitness, and vice versa. This may fundamentally change our thinking about how microbes and hosts interact in influencing fitness and adaptation to changing environments. Here we explore how reductions in population size commonly experienced by threatene...

One solution to alleviate the detrimental genetic effects associated with reductions in population size and fragmentation is to introduce immigrants from other populations. While the effects of this genetic rescue on fitness traits are fairly well known, it is less clear to what extent inbreeding depression and subsequent genetic rescue affect beha...

Understanding how environmental factors affect the thermal tolerance of species is crucial for predicting the impact of thermal stress on species abundance and distribution. To date, species' responses to thermal stress are typically assessed on laboratory-reared individuals and using coarse, low-resolution, climate data that may not reflect microh...

BACKGROUND The global pest spotted winged drosophila (Drosophila suzukii) continues to have a significant economic impact on fruit production in areas where it is established, in addition to newly invaded ranges. Management activities spanning national biosecurity responses to farm‐scale pest control are limited by the inability to predict the timi...

Temperature tolerance is critical for defining the fundamental niche of ectotherms and researchers classically use either static (exposure to a constant temperature) or dynamic (ramping temperature) assays to assess tolerance. The use of different methods complicates comparison between studies and here we present mathematical model (and R -scripts)...

Knowledge of the genetic basis underlying variation in response to environmental exposures or treatment is important in many research areas. For example, knowing the set of causal genetic variants for drug response could revolutionize personalized medicine. We used Drosophila melanogaster to investigate the genetic signature underlying behavioral v...

Habitat fragmentation and small population sizes can lead to inbreeding and loss of genetic variation, which can potentially cause inbreeding depression and decrease the ability of populations to adapt to altered environmental conditions. One solution to these genetic problems is the implementation of genetic rescue, which re-establishes gene flow...

Most organisms experience variable and sometimes suboptimal environments in their lifetime. While stressful environmental conditions are normally viewed as a strong selective force, they can also impact directly on the genetic basis of traits such as through environment-dependent gene action. Here, we used the Drosophila melanogaster Genetic Refere...

Trait variation is normally separated into genetic and environmental components, yet genetic factors also control the expression of environmental variation, encompassing plasticity across environmental gradients and within-environment responses. We defined four components of environmental variation: plasticity across environments, variability in pl...

Strong sexual dimorphism is commonly observed across species and, e.g., trade-offs between reproduction and maintenance are thought to explain this dimorphism. Here we test how the metabolic and functional phenotypic responses to varying types of environmental stress differ in male and female Drosophila melanogaster (Diptera: Drosophilidae), and ho...

Multiple environmental factors acting in concert can interact and strongly influence population fitness and ecosystem composition. Studies investigating interactions usually involve only two environmental factors; most frequently a chemical and another abiotic factor such as a stressful temperature. Here we investigate the effects of three environm...

Daphnia magna is a widely used model organism for aquatic toxicity testing. In the present study, we investigated the hydrolytic enzyme activity of D. magna after exposure to toxicant stress. In vivo enzyme activity was quantified using 15 fluorogenic enzyme probes based on 4-methylumbelliferyl or 7-amino-4-methylcoumarin. Probing D. magna enzyme a...