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Arboreal lizards, especially species that inhabit flood-prone environments, have been poorly surveyed worldwide. We examined spatiotemporal patterns in arboreal lizard abundance and factors driving detection rates in floodplain environments using artificial bark covers, a non-destructive and cost-effective survey method. In total, 112 flexible, closed-cell foam bark covers were installed on eucalypt trees in 13 wetlands in the Murrumbidgee River floodplain of southern New South Wales, Australia, stratified by two inundation frequency treatments. Of four arboreal lizard species detected, the southern marbled gecko (Christinus marmoratus) (n = 41) and the tree dtella (Gehyra versicolor) (n = 8) were restricted to the mid-Murrumbidgee region, whereas the crevice skink (Egernia striolata) (n = 19) was restricted to the lower-Murrumbidgee region and did not co-occur with either gecko species. Mean detection rates of lizard species did not differ between frequently and infrequently inundated treatments but their abundance beneath covers varied significantly by month. For all detected lizard species, the presence/absence of the arachnid Holconia murrayensis represented a significant variable in explaining lizard occurrence patterns, particularly that of C. marmoratus. Artificial bark covers are a useful survey method for collecting distribution, abundance, and occupancy data on floodplain reptiles, although detection rates can be affected by the month, predator–prey interactions, and survey effort. Adopting passive, non-destructive reptile survey methods would greatly improve our knowledge of species’ distributions and abundance patterns in vegetation communities subject to disturbance events.
Kangaroos and other macropodoids stand out among mammals for their unusual hopping locomotion and body shape. This review examines the scaling of hind- and forelimb bones, and the primary ankle extensor muscles and tendons. We find that the scaling of the musculoskeletal system is sensitive to the phylogenetic context. Tibia length increases with positive allometry among most macropodoids, but negative allometry in eastern grey kangaroos and isometry in red kangaroos. Femur length decreases with stronger negative allometry in eastern grey and red kangaroos than among other macropodoids. Muscle masses scale with negative allometry in western grey kangaroos and with isometry in red kangaroos, compared to positive allometry in other macropodoids. We further summarise the work on the hopping gait, energetics in macropodoids, and stresses in the musculoskeletal system in an evolutionary context, to determine what trade-offs may limit locomotor performance in macropodoids. When large kangaroos hop, they do not increase oxygen consumption with speed, unlike most mammals, including small hopping species. We conclude that there is not enough information to isolate the biomechanical factors that make large kangaroos so energy efficient. We identify key areas for further research to fill these gaps.
Raine Island, located in the northern Great Barrier Reef, hosts the largest green turtle nesting aggregation in the world, but typically experiences low hatching success (20–60%, depending on the number of females visiting the island to nest). To determine whether the low hatching success of green turtle eggs at Raine Island might be explained by local sand characteristics, we investigated the physical properties of Raine Island sand and compared it to sand from other eastern coast Australian sea turtle nesting beaches that have high hatching success (>80%). We also measured the water, salt and organic material content of sand within nests at Raine Island to see whether any of these variables were correlated with the proportion of early embryo death or hatching success. The physical characteristics of Raine Island sand were similar to those of other eastern coast Australian nesting beaches, so it seems unlikely that inherent physical sand properties, water content, salt or organic matter explain the relatively low hatching success observed on Raine Island compared to other Australian green turtle nesting beaches. However, we found that nests that were inundated twice with seawater during spring high tides at the end of their first week of incubation experienced greater early development mortality and lower hatching success than did non-inundated nests, suggesting that embryos drowned during the inundation. Last, we found that hatching success declined towards the end of the nesting season, suggesting that the beach sand in the nesting areas of Raine Island changes in some way, and/or that egg quality decreases as the nesting season progresses.
Senescence is a decline in reproduction and survival rate with advancing age resulting from deterioration of somatic tissues and systems throughout the body. Age-related somatic changes (somatic ageing) have been studied extensively in vertebrates but are less well known in other animals, including insects. Since adult insects have very limited ability to repair their exoskeleton, somatic ageing could involve deterioration and discolouration of the cuticle. We investigated age-related changes in wing pigmentation and abdominal cuticle necrosis in females of the Australian leaf insect Phyllium monteithi. Adult females varied markedly in the extent and pattern of pigmentation on their bodies, and we found that pigment spots on the forewings increased in size with age in most individuals. As females aged, most individuals also exhibited increasing levels of abdominal cuticle necrosis, resulting in the loss of abdominal cuticle along the margin of the abdomen. Neither the extent of pigmentation nor cuticle loss were clearly associated with reduced fecundity or longevity in the protected laboratory environment, but it remains unknown whether these age-related changes have functional implications in the wild. Our results show that the P. monteithi exoskeleton undergoes complex changes with age, with potential implications for functional traits and fitness.
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