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Introduction
Publications
Publications (204)
Climate is changing towards both higher average temperatures and more frequent and severe heat waves. Whereas numerous studies have investigated temperature effects on animal life histories, assessments of their immune function are limited. In the size- and colour-dimorphic black scavenger (or dung) fly Sepsis thoracica (Diptera: Sepsidae), we expe...
The male competition for fertilization that results from female multiple mating promotes the evolution of increased sperm numbers and can impact sperm morphology, with theory predicting that longer sperm can at times be advantageous during sperm competition. If so, males with longer sperm should sire more offspring than competitors with shorter spe...
Wolbachia bacteria are common endosymbionts of many arthropods found in gonads and various somatic tissues. They manipulate host reproduction to enhance their transmission and confer complex effects on fitness-related traits. Some of these effects can serve to increase the survival and transmission efficiency of Wolbachia in the host population. Th...
Further advancing black soldier fly (BSF) farming for waste valorisation and more sustainable global protein supplies critically depends on targeted exploitation of genotype-phenotype associations in this insect, comparable to conventional livestock. This study used a fully crossed factorial design of rearing larvae of four genetically distinct BSF...
Mosquito-borne diseases impose a high burden on human and animal health. Temperature strongly influences the physiology and life cycle of mosquitoes, but also the development and/or propagation of the pathogens they transmit. Thus, the vector capacity of mosquitoes depends strongly on temperature and their behavioural thermoregulation through micro...
Female and male reproductive traits co-evolve through pre- and post-copulatory sexual selection and sexual conflict. Although males typically transfer many sperm during copulation, only a small proportion reach the fertilization site because females often actively or passively reduce sperm number in their reproductive tract. Males may transfer acce...
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Ambient temperature strongly determines the behaviour, physiology, and life history of all organisms. The technical assessment of organismal thermal niches in form of now so-called thermal performance curves (TPC) thus has a long tradition in biological research. Nevertheless, several traits do not display the idealized, intuitive dome-...
Foraging provides the basis for animal reproduction, but requires energy and time to be sustained, entailing a trade-off. Whereas females should maximize their time foraging for resources, males should minimize their foraging time by optimizing time budgets to maximize their access to mating partners.
Mark-resight field studies are difficult and he...
Evidence for selective disadvantages of large body size remains scarce in general. Previous studies of the yellow dung fly Scathophaga stercoraria have demonstrated strong positive sexual and fecundity selection on male and female size. Nevertheless, the body size of flies from a Swiss study population has declined by ~10% 1993–2009. Given substant...
Because predator-prey interactions in nature are multifarious, linking phenomenological predation rates to underlying behavioral or ecological mechanisms is challenging. Size- and sex-specific predation has been implicated as a major selective force keeping animals small, directing the evolution of body size and sexual size dimorphism. We experimen...
In current times of global change, several sources of stress such as contaminants and high temperatures may act synergistically. The extent to which organisms persist in stressful conditions will depend on the fitness consequences of multiple simultaneously acting stressors and the genetic basis of compensatory genetic responses. Ivermectin is an a...
Background: The black soldier fly (Hermetia illucens) is the most promising insect candidate for nutrient-recycling through bioconversion of organic waste into biomass, thereby improving sustainability of protein supplies for animal feed and facilitating transition to a circular economy. Contrary to conventional livestock, genetic resources of
farm...
Background
The black soldier fly (Hermetia illucens) is the most promising insect candidate for nutrient-recycling through bioconversion of organic waste into biomass, thereby improving sustainability of protein supplies for animal feed and facilitating transition to a circular economy. Contrary to conventional livestock, genetic resources of farme...
Precise mechanisms underlying sperm storage and utilization are largely unknown, and data directly linking stored sperm to paternity remain scarce. We used competitive microsatellite PCR to study the effects of female morphology, copula duration and oviposition on the proportion of stored sperm provided by the second of two copulating males (S2) in...
Phenomenological and behavioural studies have greatly advanced the study of natural selection. Field studies of selection well appraise the natural situation, but is this also true for laboratory studies, which are typically more mechanistic? We compared precopulatory sexual selection (mating differential based on pairing success) in field and labo...
Temperature is an important determinant affecting the capacity of disease vectors like mosquitoes (Culicidae) to transmit disease agents. Although the impact of temperature on vector-borne disease dynamics has been studied intensively, the actual temperature encountered by the vector in a heterogeneous landscape is rarely taken into account. If dis...
The involvement of Septate Junctions (SJs) in critical cellular functions that extend beyond their role as diffusion barriers in the epithelia and the nervous system has made the fruit‐fly an ideal model for the study of human diseases associated with impaired Tight Junction (TJ) function. In this study, we summarized current knowledge of the Droso...
Interspecific gene flow by hybridization may weaken species barriers and adaptive divergence, but can also initiate reinforcement of reproductive isolation trough natural and sexual selection. The extent of interspecific gene flow and its consequences for the initiation and maintenance of species barriers in natural systems remain poorly understood...
Organismal life histories evolve as syndromes, resulting in correlated evolutionary differentiation of key traits that ultimately aid in discerning species. Reproductive success depends both on the absolute body size of an individual and its size relative to the opposite sex: sexual size dimorphism. In an attempt to further elucidate their coexiste...
The cotton leafhopper, Amrasca biguttula (Ishida), a sucking insect pest of cotton and vegetables, is present throughout Southeast Asia. Patterns of molecular and morphological differentiation among A. biguttula populations collected from seven cotton growing areas of Punjab, Pakistan, were studied by sequencing the barcode region of the mitochondr...
Sexual selection is generally held responsible for the exceptional diversity in secondary sexual traits in animals. Mating system evolution is therefore expected to profoundly affect the covariation between secondary sexual traits and mating success. While there is such evidence at the interspecific level, data within species remain scarce. We here...
Sexual selection represents a potent force that can drive rapid population differentiation in traits related to reproductive success. Hence, sexual traits are expected to show greater population divergence than non‐sexual traits. We test this prediction by exploring patterns of morphological differentiation of the exaggerated fore femur (a male‐spe...
1.Thermal performance curves (TPCs) have been estimated in multiple ectotherm species to understand their thermal plasticity and adaptation and to predict the effect of global warming. However, TPCs are typically assessed under constant temperature regimes, so their reliability for predicting thermal responses in the wild where temperature fluctuat...
The evolutionary potential of organisms depends on the presence of sufficient genetic variation for traits subject to selection, as well as on the genetic covariances among them. While genetic variation ultimately derives from mutation, theory predicts the depletion of genetic (co)variation under consistent directional or stabilizing selection in n...
Because predator-prey interactions in nature are multifarious, linking phenomenological predation rates to the underlying behavioural or ecological mechanisms is challenging. Size- and sex-specific predation has been implicated as a major selective force keeping animals small, affecting the evolution of body size and sexual size dimorphism. We expe...
Because predator-prey interactions in nature are multifarious, linking phenomenological predation rates to the underlying behavioural or ecological mechanisms is challenging. Size- and sex-specific predation has been implicated as a major selective force keeping animals small, affecting the evolution of body size and sexual size dimorphism. We expe...
Seasonality is a key environmental factor that regularly promotes life history adaptation. Insects invading cold–temperate climates need to overwinter in a dormant state. We compared the role of temperature and photoperiod in dormancy induction in the laboratory, as well as winter survival and reproduction in the field and the laboratory, of 5 wide...
Coprophagous insect communities play a critical role in the decomposition of vertebrate dung and provide ecosystem functions fundamental to modern agriculture. While the ecology of dung beetles is rather well understood, niche differentiation in coprophagous flies is poorly studied. Sepsid flies (Diptera: Sepsidae) are a vital part of the European...
Although genetic and plastic responses are sometimes considered as unrelated processes, their phenotypic effects may often align because genetic adaptation is expected to mirror phenotypic plasticity if adaptive, but run counter to it when maladaptive. The magnitude and direction of this alignment has further consequences for both the tempo and mod...
Understanding why and how multiple species manage to coexist represents a primary goal of ecological and evolutionary research. This is of particular relevance for communities that depend on resource rich ephemeral habitats that are prone to high intra- and interspecific competition. Black scavenger flies (Diptera: Sepsidae) are common and abundant...
Sexual selection can displace traits acting as ornaments or armaments from their viability optimum in one sex, ultimately giving rise to sexual dimorphism. The degree of dimorphism should not only mirror the strength of sexual selection but also the net viability costs of trait maintenance at equilibrium. As the ability of organisms to bear exagger...
Ivermectin is a veterinary pharmaceutical widely applied against parasites of livestock. Being effective against pests, it is also known to have lethal and sublethal effects on non-target organisms. While considerable research demonstrates the impact of ivermectin residues in livestock dung on the development and survival of dung feeding insect lar...
Identifying the contribution of pre‐ and postzygotic barriers to gene flow is a key goal of speciation research. The widespread dung fly species Sepsis cynipsea and Sepsis neocynipsea offer great potential for studying the speciation process over a range of opportunities for gene exchange within and across sister species (cross‐continental allopatr...
Clinal variation in body size and related life history traits is common and has stimulated the postulation of several eco-geographical rules. Whereas some clinal patterns are clearly adaptive, the causes of others remain obscure. We investigated intra-specific body size, development time and female fecundity (egg size and number) clines across 13 E...
Geographic clines offer insights about putative targets and agents of natural selection as well as tempo and mode of adaptation. However, demographic processes can lead to clines that are indistinguishable from adaptive divergence. Using the widespread yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae), we examine quantitative geneti...
Sexual selection has 2 main components, female preference and male male competition, which can lead males to adopt alternative reproductive tactics to optimize their reproductive success. Two traits that significantly influence reproductive success are body size and coloration, as they can facilitate access to females through male contests or as fe...
Geographic variation in phenotypic traits is commonly correlated with spatial variation in the environment, e.g. seasonality and mean temperature, providing evidence that natural selection generates such patterns. In particular, both body size and egg size of ectothermic animals are commonly larger in northern climates, and temperature induces plas...
Predation is a major factor influencing the fitness and life history of animals. Two key traits affecting prey survival are body size and coloration. Sepsis thoracica males display a sigmoid relationship between these 2 traits, defining a size threshold above which investment in melanin drastically drops, producing small melanic (black) or large am...
Climatic conditions can be very heterogeneous even over small geographic scales, and are believed to be major determinants of the abundance and distribution of species and populations. Organisms are expected to evolve in response to the frequency and magnitude of local thermal extremes, resulting in local adaptation. Using replicate yellow dung fly...
Support for macroecological rules in insects is mixed, with potential confounding interrelations between patterns rarely studied. We here investigate global patterns in body and wing size, sexual size dimorphism and range size in common fruit flies (Diptera: Drosophilidae) and explore potential interrelations and the predictive power of Allen's, Be...
The biodiversity of agricultural land is usually measured via indicator species that can be recorded time- and cost-efficiently. Behind this approach lies the seldom-questioned assumption that these groups of organisms are good at reflecting the overall species diversity of a habitat. We tested this assumption by comparing the diversity of cow-dung...
Trade-offs allow individuals to optimize their fitness by tailoring the investment into different traits to variable environmental conditions, such as along geographical gradients. Trade-offs thus can help in adjusting to changing thermal and insolation profiles, especially in small ectotherms, whose body temperature typically follows environmental...
Sexual size dimorphism (SSD) can vary drastically across environments, demonstrating pronounced sex-specific plasticity. In insects, females are usually the larger and more plastic sex. However, the shortage of taxa with male-biased SSD hampers the assessment of whether the greater plasticity in females is driven by selection on size or represents...
Characterization of the phenotypic differentiation and genetic basis of traits that can contribute to reproductive isolation is an important avenue to understand the mechanisms of speciation. We quantified the degree of prezygotic isolation and geographical variation in mating behaviour among four populations of Sepsis neocynipsea that occur in all...
The relative importance of different evolutionary forces leading to morphological divergence during early stages of speciation is of central interest in biological research. We addressed this issue using the sister species S. cynipsea, which is restricted to Europe, and S. neocynipsea, which occurs in Europe and North America. The distinct ranges o...
Ultimate factors driving insect body size are rather well understood, while—apart from a few model species—the underlying physiological and developmental mechanisms received less attention. We investigate the physiological basis of adaptive size variation in the yellow dung fly Scathophaga stercoraria, which shows pronounced male-biased sexual size...
Life history trade-offs emerge when limited resources are allocated to multiple functions of an organism. Under highly competitive conditions trade-offs can result in alternative phenotypes that differ morphologically and physiologically. Such is the case in insect species that grow under high densities, where competition for resources but also the...
Taxonomic resolution or uncertainty poses an important problem in biodiversity research. Assessment of biodiversity at the species level is most informative and preferred, but requires effort and expertise. Alternatively, researchers often bin species into higher taxa because they are unable to recognize them, or to save money and time. Here we ana...
A Preprint reviewed and recommended by Peer Community Evolutionary Biology: http://dx.doi.org/10.24072/pci.evolbiol.100027 Evidence for selective disadvantages of large body size remains scarce in general. Previous phenomenological studies of the yellow dung fly Scathophaga stercoraria have demonstrated strong positive sexual and fecundity selectio...
Extreme weather events such as heat waves are becoming more frequent and intense. Populations can cope with elevated heat stress by evolving higher basal heat tolerance (evolutionary response) and/ or stronger induced heat tolerance (plastic response). However, there is ongoing debate about whether basal and induced heat tolerance are negatively co...
Sexual size dimorphism (SSD) arises when the net effects of natural and sexual selection on body size differ between the sexes. Quantitative SSD variation between taxa is common, but directional intraspecific SSD reversals are rare. We combined micro- and macroevolutionary approaches to study geographic SSD variation in closely related black scaven...
Cattle treated with the veterinary parasiticide ivermectin (IVM) fecally excrete residues. Here we report the exposition and dissipation characteristics of these residues in dung of IVM-treated cattle, and in soil beneath this dung, on pastures including Canada, France, Switzerland, and The Netherlands. Residues were quantified for dung collected f...
To detect the relative importance of selective and neutral processes leading to population differentiation, we contrast spatial differentiation patterns in wing morphology (shaped by drift and viability selection) and male foreleg femur morphology (under putative sexual selection) with those in neutral genetic markers. We scored 16 wing landmarks and...
Environmental stressors can have unintended negative effects on beneficial organisms. Testing environmental effects of pharmaceutical residues is therefore often mandated in form of single-species ecotoxicological laboratory tests, yet differential sensitivity of species can ultimately disturb the entire community. A more realistic approach is to d...
The application of veterinary medical products (VMPs) to livestock can impact soil organisms in manure-amended fields or adversely affect organisms that colonize dung pats of treated animals, and potentially retard the degradation of dung on pastures. For this reason, the authorization process for VMPs in the European Union includes a requirement f...
The authorization of veterinary medicinal products (VMP) requires that they be assessed for non-target effects in the environment. Numerous field studies have assessed these effects on dung organisms. However, few studies have examined effects on soil-dwelling organisms, which might be exposed to VMP residues released during dung degradation. We co...
In biodiversity assessments, especially of small-bodied organisms for which taxonomic expertise is lacking, identification by genetic barcoding may be a cost-effective and efficient alternative to traditional identification of species by morphology, ecology and behavior. Here we test the feasibility and accuracy of such an approach using dung insec...
By degrading the dung of livestock that graze on pastures, coprophilous arthropods accelerate the cycling of nutrients to maintain pasture quality. Many veterinary medicinal products (VMPs), such as ivermectin (IVM), are excreted unchanged in the dung of treated livestock. These residues can be insecticidal and may reduce the function (i.e., dung-d...
The evolution of the vast diversity of floral volatiles is little understood, although they serve fundamental functions, such as pollinator attraction and herbivore deterrence. Floral volatiles are often species specific, yet highly variable and sensitive to environmental factors. To date, nothing is known about the heritability of floral volatiles...
Uncovering genetic responses to selection in wild populations typically requires tracking individuals over generations and use of animal models. Our group monitored the body size of one Swiss Yellow Dung Fly (Scathophaga stercoraria; Diptera: Scathophagidae) field population over 15 years, including intermittent common garden rearing in the laborat...
Registration of veterinary medical products (VMPs) includes the provision that field tests may be required to assess potential non-target effects associated with the excretion of product residues in dung of treated livestock (Phase II, Tier B testing). However, regulatory agencies provide no guidance on the format of these tests. Here, we report de...
Veterinary medical product residues can cause severe damage in the dung ecosystem. Depending on the manner of application and the time after treatment, the excreted concentration of a given pharmaceutical varies. The popular anthelmintic drug ivermectin (IVM) can be applied to livestock in several different ways and is faecally excreted over a peri...
The plant and insect communities of many summer pastures in the Swiss Alps are changing as they become encroached by woody plants. To understand the implications for overall biodiversity, we need to determine how different taxonomic groups respond to shrub encroachment. We investigated effects of encroachment upon species diversity of vascular plan...
Sexual size dimorphism (SSD), a difference in body size between sexes, is common in many taxa. In insects, females are larger than males in >70% of all taxa in most orders. The fruit fly, Drosophila melanogaster is one prominent model organism to investigate SSD since its clear and representative female-biased SSD and its growth regulation are well...
Elevational gradients influence the distribution and abundance of species drastically and can lead to variation in community composition. Although coprophagous flies are of ecological and economic importance, their biodiversity and distribution are largely neglected. We studied the impact of steep elevational gradients and geography on the distribu...
Organisms can respond to and cope with stressful environments in a number of ways including
behavioural, morphological and physiological adjustments. To understand the role of behavioural traits
in thermal adaptations we compared heat resistance, locomotor (walking and flying) activity, flight
performance and morphology of three European population...