Many organisms assemble biological materials into architectures and tools that add and extend biological functions - with profound ecological effects, and inspiring human technologies. However, there is no general concept of how evolutionary bio-material innovation arises from both the physiological and the behavioural recombination of compounds. SuPerSilk aims to understand how mechanical super-performance evolves by disentangling the concerted effects of both physiological and behavioural factors on structure-function relationships, utilizing spiders and their silk products as a model system. Specifically, SuPerSilk will (1) determine if the diversification into different types of silk glands facilitated the evolvability of spider silk performance, (2) test if the behavioural combination of different spider silks into compound threads provides a fast track for the evolution of thread performance and an extension of performance limits, (3) test whether similar thread functions evolved via repeated or alternative pathways, and (4) establish a roadmap for the targeted bioprospecting of silk compounds with specific properties. Being the first project that will jointly track the evolution of base materials and their behaviourally assembled compound products, SuPerSilk will address a timely question in evolutionary biology: if and how the evolvability of physical traits can be modified by the evolution of novel behaviours and vice versa. The outcome will be a precedent for the integrative study of animal products that will establish a new line of research: evolutionary materials. In addition, by probing the structure-function relationship of behaviourally assembled silk composites, SuPerSilk will reinvigorate efforts to develop super-tough biofibres for industrial applications, a field that has stagnated in recent years, and enable the engineering of bio-fabrics with tailorable properties.

Female widow spiders are frequently cannibalistic, but males of the invasive brown widow spider Latrodectus geometricus can avoid being eaten by mating with immature females that never attack their mating partners. Although immature females are generally assumed unable to mate due to the lack of developed external genitalia, in this species they readily mate and produce offspring at maturity. Nevertheless, despite the benefits arising from immature mating, males consistently prefer to mate with adult, cannibalistic females. Sexual cannibalism is generally considered detrimental for the male, but in L. geometricus it represents a male adaptive strategy which brings advantages in terms of lower female propensity to re-mate. Therefore, its lack in immature mating may come at cost of paternity loss due to female re-mating. I suggests a trade-off between mating rate and reproductive assurance. In the proposed project, I will test the hypothesis that immature mating is costly for the male. I will investigate the mechanism of immature mating as well as ultimate fitness consequences for the male in terms of paternity. I will use a multidisciplinary approach, combining state-of-the-art behavioural, morphological and molecular methods. Utilizing the expertise and infrastructure in two excellent institutions: University of Greifswald and University of Toronto, I will enhance international collaboration and knowledge transfer among research teams. At the University of Greifswald, mating systems are studied by a combination of behavioural and morphological approaches. Using advanced tools to study and visualize internal structures crucial for understanding reproductive biology, I will characterize the morphological mechanisms and structures associated with immature mating. At the University of Toronto, I will use established husbandry infrastructure and molecular techniques to determine behavioural correlates of paternity, and links to female reproductive output.