School of BioSciences - Research Publications
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ItemCorrelates of extinction risk in Australian squamate reptiles(Wiley, 2021-09-01)
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ItemHidden limbs in the "limbless skink" Brachymeles lukbani: Developmental observations.(Wiley, 2021-09)Reduced limbs and limblessness have evolved independently in many lizard clades. Scincidae exhibit a wide range of limb-reduced morphologies, but only some species have been used to study the embryology of limb reduction (e.g., digit reduction in Chalcides and limb reduction in Scelotes). The genus Brachymeles, a Southeast Asian clade of skinks, includes species with a range of limb morphologies, from pentadactyl to functionally and structurally limbless species. Adults of the small, snake-like species Brachymeles lukbani show no sign of external limbs in the adult except for small depressions where they might be expected to occur. Here, we show that embryos of B. lukbani in early stages of development, on the other hand, show a truncated but well-developed limb with a stylopod and a zeugopod, but no signs of an autopod. As development proceeds, the limb's small size persists even while the embryo elongates. These observations are made based on external morphology. We used florescent whole-mount immunofluorescence to visualize the morphology of skeletal elements and muscles within the embryonic limb of B. lukabni. Early stages have a humerus and separated ulna and radius cartilages; associated with these structures are dorsal and ventral muscle masses as those found in the embryos of other limbed species. While the limb remains small, the pectoral girdle grows in proportion to the rest of the body, with well-developed skeletal elements and their associated muscles. In later stages of development, we find the small limb is still present under the skin, but there are few indications of its presence, save for the morphology of the scale covering it. By use of CT scanning, we find that the adult morphology consists of a well-developed pectoral girdle, small humerus, extremely reduced ulna and radius, and well-developed limb musculature connected to the pectoral girdle. These muscles form in association with a developing limb during embryonic stages, a hint that "limbless" lizards that possess these muscles may have or have had at least transient developing limbs, as we find in B. lukbani. Overall, this newly observed pattern of ontogenetic reduction leads to an externally limbless adult in which a limb rudiment is hidden and covered under the trunk skin, a situation called cryptomelia. The results of this work add to our growing understanding of clade-specific patterns of limb reduction and the convergent evolution of limbless phenotypes through different developmental processes.
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ItemGenomic insights into a population of introduced European rabbits Oryctolagus cuniculus in Australia and the development of genetic resistance to rabbit hemorrhagic disease virus(WILEY, 2021-03-16)The European rabbit (Oryctolagus cuniculus) is one of the most devastating invasive species in Australia. Since the 1950s, myxoma virus (MYXV) and rabbit haemorrhagic disease virus (RHDV) have been used to manage overabundant rabbit populations. Resistance to MYXV was observed within a few years of the release. More recently, resistance to lethal RHDV infection has also been reported, undermining the efficiency of landscape-scale rabbit control. Previous studies suggest that genetic resistance to lethal RHDV infection may differ locally between populations, yet the mechanisms of genetic resistance remain poorly understood. Here, we used genotyping by sequencing (GBS) data representing a reduced representation of the genome, to investigate Australian rabbit populations. Our aims were to understand the relationship between populations and identify possible genomic signatures of selection for RHDV resistance. One population we investigated had previously been reported to show levels of resistance to lethal RHDV infection. This population was compared to three other populations with lower or no previously reported RHDV resistance. We identified a set of novel candidate genes that could be involved in host-pathogen interactions such as virus binding and infection processes. These genes did not overlap with previous studies on RHDV resistance carried out in different rabbit populations, suggesting that multiple mechanisms are feasible. These findings provide useful insights into the different potential mechanisms of genetic resistance to RHDV virus which will inform future functional studies in this area.
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ItemEnvironmental correlates of morphological diversity in Australian geckos(Wiley, 2021-05-01)
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ItemPlant communities, populations and individuals have distinct responses to short-term warming and neighbour biomass removal in two montane grasslands(WILEY, 2021-03-02)AIMS: Climate change will impact plant communities and populations but also individual plant performance. Most predictive models of community responses to climate change ignore individual‐level biotic interactions despite their known importance for community diversity and functioning. Here, we consider plant fitness and diversity responses to climate change associated factors at three organisational levels: communities, populations and individual plants, to increase our understanding of how plant communities respond to climate change. LOCATION: Montane grassland, Tasmania, Australia. METHODS: In two plant communities, we manipulated temperature using open‐top chambers and removed random and dominant species biomass. Two years after experimental manipulations, we assessed the impact of treatments on species diversity, community‐ and population‐level functional traits and individual plant fitness. RESULTS: Species diversity was affected by warming in one of the two communities, while community‐level functional trait diversity metrics were unaffected by treatments. Mean community trait values were strongly impacted by dominant species biomass removal in both communities, notably increasing specific leaf area (SLA) and specific root length. SLA showed the strongest population‐level trait response, with higher values found in warmed plots and lower values found in dominant species biomass removal plots. Neighbours had a stronger competitive effect on individual plant fitness in warmed compared to unwarmed conditions at the higher‐elevation site and facilitation was common in both communities. CONCLUSIONS: We demonstrated that over short time scales, plant communities respond to experimental warming and biomass removal across multiple organisational levels. Competitive and facilitative interactions played a significant role in determining fitness outcomes, but competitive interactions dominated under warmed conditions. We highlight the importance of local‐scale biotic interactions in mediating individual responses to warming and recommend their inclusion in future studies of how climate change will impact the long‐term structure and function of plant communities through short‐term impacts on individual plant fitness.
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ItemNo Preview AvailableImpact of COVID-19 Pandemic on Cardiovascular Testing in Asia(Elsevier BV, 2021-09)
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ItemNo Preview AvailableNature-based solutions for atoll habitability(ROYAL SOC, 2022-07-04)Atoll societies have adapted their environments and social systems for thousands of years, but the rapid pace of climate change may bring conditions that exceed their adaptive capacities. There is growing interest in the use of 'nature-based solutions' to facilitate the continuation of dignified and meaningful lives on atolls through a changing climate. However, there remains insufficient evidence to conclude that these can make a significant contribution to adaptation on atolls, let alone to develop standards and guidelines for their implementation. A sustained programme of research to clarify the potential of nature-based solutions to support the habitability of atolls is therefore vital. In this paper, we provide a prospectus to guide this research programme: we explain the challenge climate change poses to atoll societies, discuss past and potential future applications of nature-based solutions and outline an agenda for transdisciplinary research to advance knowledge of the efficacy and feasibility of nature-based solutions to sustain the habitability of atolls. This article is part of the theme issue 'Nurturing resilient marine ecosystems'.
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ItemNo Preview AvailableInvasive chameleons released from predation display more conspicuous colors(AMER ASSOC ADVANCEMENT SCIENCE, 2022-05-01)Conspicuous social and sexual signals are predicted to experience pronounced character release when natural selection via predation is relaxed. However, we have few good examples of this phenomenon in the wild and none in species with dynamic color change. Here, we show that Jackson's chameleons inadvertently introduced from Kenya to Hawaii (Oahu), where there are no coevolved, native lizard predators, experienced pronounced character release of color signals. Hawaiian chameleons displayed more conspicuous social color signals than Kenyan chameleons during male contests and courtship, were less cryptic in response to bird and snake predators, and showed greater change between display and antipredator color states. Hawaiian chameleon display colors were also more conspicuous in their local than ancestral habitats, consistent with local adaptation of social signals. These results demonstrate that relaxed predation pressure can result in character release of dynamic social signals in introduced species experiencing strong sexual selection.