Vertically inherited microbiota and environment modifying behaviours conceal genetic variation in dung beetle life history.

Diverse organisms actively manipulate their (sym)biotic and physical environment in ways that feed back on their own development. However, the degree to which these processes affect microevolution remains poorly understood. The gazelle dung beetle both physically modifies its ontogenetic environment and structures its biotic interactions through vertical symbiont transmission.

Sexually transmitted mutualist nematodes shape host growth across dung beetle species.

Many symbionts are sexually transmitted and impact their host's development, ecology, and evolution. While the significance of symbionts that cause sexually transmitted diseases (STDs) is relatively well understood, the prevalence and potential significance of the sexual transmission of mutualists remain elusive. Here, we study the effects of sexually transmitted mutualist nematodes on their dung beetle hosts.

Plasticity, symbionts and niche construction interact in shaping dung beetle development and evolution.

Developmental plasticity is an important product of evolutionary processes, allowing organisms to maintain high fitness in the face of environmental perturbations. Once evolved, plasticity also has the potential to influence subsequent evolutionary outcomes, for example, by shaping phenotypic variation visible to selection and facilitating the emergence of novel trait variants. Furthermore, organisms may not just respond to environmental conditions through plasticity but may also actively modify the abiotic and (sym)biotic environments to which they themselves respond, causing plasticity to interact in complex ways with niche construction.

Utilizing geometric morphometrics to investigate gene function during organ growth: Insights through the study of beetle horn shape allometry.

Static allometry is a major component of morphological variation. Much of the literature on the development of allometry investigates how functional perturbations of diverse pathways affect the relationship between trait size and body size. Often, this is done with the explicit objective to identify developmental mechanisms that enable the sensing of organ size and the regulation of relative growth.

Vertically inherited microbiota and environment-modifying behaviors indirectly shape the exaggeration of secondary sexual traits in the gazelle dung beetle.

Many organisms actively manipulate the environment in ways that feed back on their own development, a process referred to as developmental niche construction. Yet, the role that constructed biotic and abiotic environments play in shaping phenotypic variation and its evolution is insufficiently understood. Here, we assess whether environmental modifications made by developing dung beetles impact the environment-sensitive expression of secondary sexual traits.

Assessing the evolutionary lability of insulin signalling in the regulation of nutritional plasticity across traits and species of horned dung beetles.

Nutrition-dependent growth of sexual traits is a major contributor to phenotypic diversity, and a large body of research documents insulin signalling as a major regulator of nutritional plasticity. However, findings across studies raise the possibility that the role of individual components within the insulin signalling pathway diverges in function among traits and taxa. Here, we use RNAi-mediated transcript depletion in the gazelle dung beetle to investigate the functions of forkhead box O (Foxo) and two paralogs of the insulin receptor (InR1 and InR2) in shaping nutritional plasticity in polyphenic male head horns, exaggerated fore legs, and weakly nutrition-responsive genitalia.

Strongly sexually dimorphic forelegs are not more condition-dependent than less dimorphic traits in .

Unlabelled: Directional sexual selection drives the evolution of traits that are most closely linked to reproductive success, giving rise to trait exaggeration and sexual dimorphism. Exaggerated structures are often costly and, therefore, thought to be expressed in a condition-dependent manner. Sexual selection theory thus predicts a direct link between directional sexual selection, sexual dimorphism, and sex-specific condition dependence.

Size rather than complexity of sexual ornaments prolongs male metamorphosis and explains sexual size dimorphism in sepsid flies.

Male sexual ornaments often evolve rapidly and are thought to be costly, thus contributing to sexual size dimorphism. However, little is known about their developmental costs, and even less about costs associated with structural complexity. Here, we quantified the size and complexity of three morphologically elaborate sexually dimorphic male ornaments that starkly differ across sepsid fly species (Diptera: Sepsidae): (i) male forelegs range from being unmodified, like in most females, to being adorned with spines and large cuticular protrusions; (ii) the fourth abdominal sternites are either unmodified or are converted into complex appendages; and (iii) male genital claspers range from small and simple to large and complex (e.

Developmental bias predicts 60 million years of wing shape evolution.

The degree to which developmental biases affect trait evolution is subject to much debate. Here, we first quantify fluctuating asymmetry as a measure of developmental variability, i.e.

Allometric plasticity and the evolution of environment-by-environment (E×E) interactions during a rapid range expansion of a dung beetle.

Plastic responses to environmental conditions may themselves depend on other environmental conditions, but how such environment-by-environment (E×E) interactions may impact evolution remains unclear. We investigate how temperature shapes the nutritional polyphenism in horn length in a beetle and test whether "allometric plasticity" (a form of E×E) predicts latitudinal differentiation during a rapid range expansion. Rearing populations under common garden conditions demonstrates that increased temperatures reduce the body size threshold separating two male morphs in all populations but also that the magnitude of temperature-dependent changes in allometry diverged across recently established populations.

Mixed support for an alignment between phenotypic plasticity and genetic differentiation in damselfly wing shape.

The relationship between genetic differentiation and phenotypic plasticity can provide information on whether plasticity generally facilitates or hinders adaptation to environmental change. Here, we studied wing shape variation in a damselfly (Lestes sponsa) across a latitudinal gradient in Europe that differed in time constraints mediated by photoperiod and temperature. We reared damselflies from northern and southern populations in the laboratory using a reciprocal transplant experiment that simulated time-constrained (i.

Developmental bias in the evolution and plasticity of beetle horn shape.

The degree to which developmental systems bias the phenotypic effects of environmental and genetic variation, and how these biases affect evolution, is subject to much debate. Here, we assess whether developmental variability in beetle horn shape aligns with the phenotypic effects of plasticity and evolutionary divergence, yielding three salient results. First, we find that most pathways previously shown to regulate horn length also affect shape.

Growth rate mediates hidden developmental plasticity of female yellow dung fly reproductive morphology in response to environmental stressors.

Understanding how environmental variation influences even cryptic traits is important to clarify the roles of selection and developmental constraints in past evolutionary divergence and to predict future adaptation under environmental change. Female yellow dung flies (Scathophaga stercoraria) typically have three sperm storage compartments (3S), but occasionally four (4S). More spermathecae are thought to be a female adaptation facilitating sperm sorting after mating, but the phenotype is very rare in nature.

Secondary Sexual Trait Melanization in "Black" Scavenger Flies: Nutritional Plasticity and Its Evolution.

AbstractThe black scavenger fly exhibits polyphenic development resulting in alternate small black and large amber male morphs. Although the behavior, ecology, and physiology of both morphs are being scrutinized, the evolutionary origins of the nutritional polyphenism remain poorly understood. I here use a comparative approach to study variation in the degree of melanization of the forefemur-a secondary sexual trait.

Evolutionary and plastic variation in larval growth and digestion reveal the complex underpinnings of size and age at maturation in dung beetles.

Age and size at maturity are key life-history components, yet the proximate underpinnings that mediate intra- and interspecific variation in life history remain poorly understood. We studied the proximate underpinnings of species differences and nutritionally plastic variation in adult size and development time in four species of dung beetles. Specifically, we investigated how variation in insect growth mediates adult size variation, tested whether fast juvenile growth trades-off with developmental stability in adult morphology and quantified plastic responses of digestive systems to variation in food quality.

Comprehensive thermal performance curves for yellow dung fly life history traits and the temperature-size-rule.

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-shaped TPC, and in practice assessments often do not cover the entire realistic or natural temperature range of an organism.

mediates species-, sex-, environment- and trait-specific exaggeration of size and shape.

Context-dependent trait exaggeration is a major contributor to phenotypic diversity. However, the genetic modifiers instructing development across multiple contexts remain largely unknown. We use the arthropod tibia, a hotspot for segmental differentiation, as a paradigm to assess the developmental mechanisms underlying the context-dependent structural exaggeration of size and shape through nutritional plasticity, sexual dimorphism and segmental differentiation.

A role for sex-determination genes in life history evolution? Doublesex mediates sexual size dimorphism in the gazelle dung beetle.

An organism's fitness depends strongly on its age and size at maturation. Although the evolutionary forces acting on these critical life history traits have been heavily scrutinized, the developmental mechanisms underpinning intraspecific variation in adult size and development time remain much less well-understood. Using RNA interference, I here show that the highly conserved sex-determination gene doublesex (dsx) mediates sexual size dimorphism (SSD) in the gazelle dung beetle Digitonthophagus gazella.

Evolution and plasticity of morph-specific integration in the bull-headed dung beetle .

Developmental and evolutionary processes underlying phenotypic variation frequently target several traits simultaneously, thereby causing covariation, or integration, among phenotypes. While phenotypic integration can be neutral, correlational selection can drive adaptive covariation. Especially, the evolution and development of exaggerated secondary sexual traits may require the adjustment of other traits that support, compensate for, or otherwise function in a concerted manner.

Metals by Micro-Scale Additive Manufacturing: Comparison of Microstructure and Mechanical Properties.

Many emerging applications in microscale engineering rely on the fabrication of 3D architectures in inorganic materials. Small-scale additive manufacturing (AM) aspires to provide flexible and facile access to these geometries. Yet, the synthesis of device-grade inorganic materials is still a key challenge toward the implementation of AM in microfabrication.

Rapid differentiation of plasticity in life history and morphology during invasive range expansion and concurrent local adaptation in the horned beetle Onthophagus taurus.

Understanding the interplay between genetic differentiation, ancestral plasticity, and the evolution of plasticity during adaptation to environmental variation is critical to predict populations' responses to environmental change. However, the role of plasticity in rapid adaptation in nature remains poorly understood. We here use the invasion of the horned beetle Onthophagus taurus in the United States during the last half century to study the contribution of ancestral plasticity and post-invasion evolution of plastic responses in rapid population differentiation.

Evolution of multivariate wing allometry in schizophoran flies (Diptera: Schizophora).

The proximate and ultimate mechanisms underlying scaling relationships as well as their evolutionary consequences remain an enigmatic issue in evolutionary biology. Here, I investigate the evolution of wing allometries in the Schizophora, a group of higher Diptera that radiated about 65 million years ago, by studying static allometries in five species using multivariate approaches. Despite the vast ecological diversity observed in contemporary members of the Schizophora and independent evolutionary histories throughout most of the Cenozoic, size-related changes represent a major contributor to overall variation in wing shape, both within and among species.

Notch signaling patterns head horn shape in the bull-headed dung beetle Onthophagus taurus.

Size and shape constitute fundamental aspects in the description of morphology. Yet while the developmental-genetic underpinnings of trait size, in particular with regard to scaling relationships, are increasingly well understood, those of shape remain largely elusive. Here we investigate the potential function of the Notch signaling pathway in instructing the shape of beetle horns, a highly diversified and evolutionarily novel morphological structure.

Sublethal effects of the parasiticide ivermectin on male and female reproductive and behavioural traits in the yellow dung fly.

The veterinary pharmaceutical ivermectin is commonly used against parasites of livestock. Excreted in dung it can have lethal and sublethal effects on non-target organisms developing in and living around cattle dung. Research in this realm typically investigates the impact of pharmaceuticals on dung-feeding insects by looking at juvenile development and survival, while fitness effects of adult exposure are largely neglected.