School of BioSciences - Research Publications
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ItemNo Preview AvailableChallenges and opportunities for innovation in bioinformed sustainable materials(SPRINGERNATURE, 2023-10-04)Abstract Nature provides a rich source of information for the design of novel materials; yet there remain significant challenges in the design and manufacture of materials that replicate the form, function, and sustainability of biological solutions. Here, we identify key challenges and promising approaches to the development of materials informed by biology. These challenges fall into two main areas; the first relates to harnessing biological information for materials innovation, including key differences between biological and synthetic materials, and the relationship between structure and function. We propose an approach to materials innovation that capitalizes on biodiversity, together with high-throughput characterization of biological material architectures and properties, linked to environmental and ecological context. The second area relates to the design and manufacture of bioinformed materials, including the physical scale of material architectures and manufacturing scale up. We suggest ways to address these challenges and promising prospects for a bioinformed approach to materials innovation.
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ItemExposure to thermal extremes favors higher solar reflectivity in intertidal gastropods(CELL PRESS, 2022-12-22)During low tides, intertidal animals can be exposed to extreme temperatures that can exceed the animals' thermal limits. Reflectance of solar radiation could be critical to prevent overheating for animals exposed to the sun; however, most studies ignore near-infrared (NIR) wavelengths that comprise approximately half of solar energy. Here, we conduct a phylogenetically controlled analysis to test whether the reflectivity of intertidal gastropod species is associated with solar exposure. Gastropods from exposed microhabitats had greater shell total reflectivity than those from sheltered microhabitats. Dry shells of gastropods from exposed microhabitats had higher NIR reflectivity even after controlling for UV-visible reflectivity, supporting selection for thermal benefits independent of visual benefits. Using thermal imaging, we also demonstrated that gastropods with high shell reflectivity had lower heating rate in natural conditions than those with low shell reflectivity. Together, these studies show that reflectivity can play a crucial role in thermoregulation in extreme environments.
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ItemNo Preview AvailableDisentangling thermal from alternative drivers of reflectance in jewel beetles: A macroecological study(WILEY, 2023-03)Abstract Aim To predict future colour–climate relationships, it is important to distinguish thermal drivers of reflectance from other evolutionary drivers. We aimed to achieve this by comparing relationships between climate and coloration in ultraviolet–visible (UV–Vis) and near‐infrared (NIR) light, separately. Location Samples were distributed primarily across Australia and North America, with some from Africa and Asia. Major taxa studied Coleoptera: Buprestidae. Methods We used jewel beetles as models to identify climatic drivers of reflectance, because jewel beetles have highly diverse coloration and a wide distribution and are often active in hot conditions. Specifically, we tested the association between climate, body size and reflectance using a phylogenetic comparative analysis for three wavebands (UV–Vis, NIR and total). Results Reflectance of jewel beetles was more strongly predicted by body size than by climate. NIR reflectance and total reflectance were not associated with climate, but larger beetles had higher NIR reflectance. For UV–Vis reflectance, small beetles were darker in warmer and more humid environments, whereas there was no association with climate for large beetles. Main conclusions Our study suggests that variation in reflectance of jewel beetles is not driven by thermal requirements and highlights the importance of considering NIR reflectance when evaluating explanations of the effects of colour on thermoregulation.
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ItemInsect visual sensitivity to long wavelengths enhances colour contrast of insects against vegetation(NATURE PORTFOLIO, 2022-01-19)The sensitivity of animal photoreceptors to different wavelengths of light strongly influence the perceived visual contrast of objects in the environment. Outside of the human visual wavelength range, ultraviolet sensitivity in many species provides important and behaviourally relevant visual contrast between objects. However, at the opposite end of the spectrum, the potential advantage of red sensitivity remains unclear. We investigated the potential benefit of long wavelength sensitivity by modelling the visual contrast of a wide range of jewel beetle colours against flowers and leaves of their host plants to hypothetical insect visual systems. We find that the presence of a long wavelength sensitive photoreceptor increases estimated colour contrast, particularly of beetles against leaves. Moreover, under our model parameters, a trichromatic visual system with ultraviolet (λmax = 355 nm), short (λmax = 445 nm) and long (λmax = 600 nm) wavelength photoreceptors performed as well as a tetrachromatic visual system, which had an additional medium wavelength photoreceptor (λmax = 530 nm). When we varied λmax for the long wavelength sensitive receptor in a tetrachromatic system, contrast values between beetles, flowers and leaves were all enhanced with increasing λmax from 580 nm to at least 640 nm. These results suggest a potential advantage of red sensitivity in visual discrimination of insect colours against vegetation and highlight the potential adaptive value of long wavelength sensitivity in insects.
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ItemNo Preview AvailableHeating rates are more strongly influenced by near-infrared than visible reflectance in beetles(COMPANY BIOLOGISTS LTD, 2021-10)Adaptations to control heat transfer through the integument are a key component of temperature regulation in animals. However, there remain significant gaps in our understanding of how different optical and morphological properties of the integument affect heating rates. To address these gaps, we examined the effect of reflectivity in both ultraviolet-visible and near-infrared wavelengths, surface rugosity (roughness), effective area (area subjected to illumination) and cuticle thickness on radiative heat gain in jewel beetles (Buprestidae). We measured heating rate using a solar simulator to mimic natural sunlight, a thermal chamber to control the effects of conduction and convection, and optical filters to isolate different wavelengths. We found that effective area and reflectivity predicted heating rate. The thermal effect of reflectivity was driven by variation in near-infrared rather than ultraviolet-visible reflectivity. By contrast, cuticle thickness and surface rugosity had no detectable effect. Our results provide empirical evidence that near-infrared reflectivity has an important effect on radiative heat gain. Modulating reflectance of near-infrared wavelengths of light may be a more widespread adaptation to control heat gain than previously appreciated.
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ItemCracks in the mirror hypothesis: High specularity does not reduce detection or predation risk(WILEY, 2022-01)Abstract Some animals, including certain fish, beetles, spiders and Lepidoptera chrysalises, have such shiny or glossy surfaces that they appear almost mirror‐like. A compelling but unsubstantiated hypothesis is that a highly specular or mirror‐like appearance enhances survival by reflecting the surrounding environment and reducing detectability. We tested this hypothesis by asking human participants to wear a mobile eye‐tracking device and locate highly realistic mirror‐green and diffuse‐green replica beetles against a variety of backgrounds in a natural forest environment. We also tested whether a mirror‐like appearance enhances survival to wild predators by monitoring the survival of mirror‐green and diffuse‐green replica beetles in a forested habitat and an open habitat. Human participants showed no difference in the detection probability or detection latency of mirror versus diffuse replica beetles, indicating that mirror‐like appearance does not impair prey capture. The field predation experiment found no difference in survival between the mirror and diffuse replica beetles in forested environments. Similarly, there was no difference in survival when beetles were deployed in the open habitat where there is no background to reflect, indicating that predators detect and do not actively avoid mirror‐like beetles. Our results suggest that a mirror‐like appearance does not reduce attack by predators. Instead, highly specular, mirror‐like surfaces may have evolved for an alternate visual function or as a secondary consequence of selection for a non‐visual function, such as thermoregulation. A free Plain Language Summary can be found within the Supporting Information of this article.