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Most freshwater mussels (Bivalvia: Unionida) have larvae (glochidia in Margaritiferidae, Hyriidae and Unionidae) that are parasitic on fishes. Mechanisms of glochidia release and morphological features (size, shape, larval teeth, etc.) vary across taxa and geography. Among the Australasian Hyriidae, glochidia have been described from 12 of the 28 putative species. Alathyria pertexta Iredale, 1934 is a widespread species from subtropical/semitemperate south-eastern Queensland and northern New South Wales to the northern wet tropics of Queensland and southern New Guinea. Little information is available on its biology and its glochidia have not been described in detail. The aim of this study was to describe the glochidia of A. pertexta pertexta and the method of their release. Gravid females collected from Mary River, near Kenilworth, and Isaac River, north-west of Rockhampton, Queensland, released glochidia in ‘amorphous mucus conglutinates’, in which glochidia are released from exhalent siphons of females in a loose mucus matrix that dissociates in water, during the austral spring (August–October); they then hatched from vitelline membranes but remained tethered by a larval thread and began characteristically ‘winking’. Shells (n = 80) are subtriangular and scalene in shape, 268.1 µm long (±1.21, s.e.), 242.9 µm high (±1.22, s.e.) and have a hinge length of 191 µm (±0.63, s.e.). Larval teeth are spineless, S-shaped hooks with singular interlocking cusps on opposing valves. The surface of the apex and valve margins are crenulated, and valves are smooth and porous, held together by a hinge and a singular internal adductor muscle.
The food resource utilisation of six species of Banksia by the endangered Carnaby’s cockatoo (Calyptorhynchus latirostris) was investigated on the Swan coastal plain, Western Australia, over a 12-month period. The energy yield from the seeds harvested by the cockatoos was determined and the information was combined with data on the number of infructescences produced per hectare, the average seed yield per infructescence and the average rate of harvest of that species of seed by the cockatoos to calculate estimates of the number of infructescences required to support a single cockatoo per day under a range of scenarios. Over 65% of infructescences of each species of Banksia handled by the cockatoos were consumed for seed. Banksia sessilis had the largest number of infructescences and follicles manipulated by Carnaby’s cockatoos. The energy content of Banksia seed was 20–23 kJ g–1. Seed weight varied from 0.075 ± 0.016 (s.e.) g for B. attenuata to 0.007 ± 0.002 (s.e.) g for B. sessilis. The number of infructescences required to meet the birds’ daily energy intake ranged from 14 for B. grandis to 3821 for B. sessilis. The results have important implications for the continued capacity of the Swan coastal plain to support Carnaby’s cockatoos, for the future survival of obligate seeding Banksia spp. and for anthropogenic revegetation programs utilising Banksia spp.
The black-footed rock-wallaby (Petrogale lateralis) is the most widespread member of the endemic Australian macropodid genus Petrogale. Considerable morphological and genetic diversity within this species has long been recognised and P. lateralis is currently divided into three described subspecies (P. lateralis lateralis, P. l. pearsoni, P. l. hacketti) and two undescribed forms (MacDonnell Ranges race, West Kimberley race). Chromosomal, morphological, genic and genomic studies have demonstrated that these five taxa are closely related but distinguishable. Here, we formally name the MacDonnell Ranges race and the West Kimberley race as subspecies of P. lateralis.
Understanding the behavioural responses of animals to habitat change is vital to their conservation in landscapes undergoing restoration. Studies of animal responses to habitat restoration typically assess species presence/absence; however, such studies may be restricted in their ability to show whether restoration is facilitating the return of self-sustaining and functional fauna populations. We present a case study using VHF/GPS tracking of a young adult perentie (Varanus giganteus), to demonstrate the range of applications of the Time Local Convex Hull method of home-range construction in analysing the behavioural responses of fauna to habitat change and restoration. Presence/absence studies provide single point locations of an animal, and the Minimum Convex Polygon method provides an invariant estimate of habitat use across the whole home range. However, the Time Local Convex Hull method provides a useful method for assessing movement and behavioural responses of fauna to habitat change and restoration, and the specific habitat requirements for the long-term support of populations. The breadth and multidimensionality of data generated indicates strongly that understanding the complex interactions between animals and their environment is fundamental to their conservation in the face of ever-increasing rates of human-induced habitat change and degradation.
Understanding the spatial structure of populations is important in developing effective management options for threatened species, and for managing habitat connectivity for metapopulation function, and for demographic and genetic heterogeneity. We used genetic information to investigate the structure of populations of the quokka, Setonix brachyurus, in south-west Western Australia. We hypothesised that movement between known populations would be relatively rare and result in significant genetic structuring. Genetic analyses from 412 adult individuals at 14 nuclear markers (microsatellite) from 33 sampling locations identified structure, diversity and spatial separation of quokkas across their mainland distribution and on two islands. We identified nine inferred (K = 9) populations of quokka that would be otherwise difficult to define with standard ecological techniques. The highest genetic diversity was evident in a large central population of quokka in the southern forest area and genetic diversity was lower at the peripheries of the distribution. The Rottnest Island population contained 70% of the genetic diversity of the mainland populations but the genetic diversity of animals on Bald Island was markedly lower. Populations of quokka in the northern jarrah forest were the only ones to show evidence of recent or long-term population bottlenecking. Of particular interest was the recently identified population at the Muddy Lakes area (the only remaining locality on the Swan Coastal Plain), which was identified as being genetically associated with the southern forest population. Overall, spatial and population cluster analysis showed small insular populations in the northern jarrah forest area, but in the southern forests there appears to be a large panmictic population.
Detailed information on life history and ecology is essential for successful conservation and management. However, we have relatively little detailed data on the life history and ecology of most small lizard species, relative to other vertebrates, especially those that have undergone recent taxonomic changes. We studied the ecology of the elegant snake-eyed skink (Cryptoblepharus pulcher), a lizard that occurs on trees, fences, walls, and rock outcroppings in eastern Australia that spans temperate to tropical environments. In our temperate-zone study population living in natural habitat, individuals are active year-round, and gravid females were found during the months of September through December. Sexual maturity is reached in 12 months, lifespan is at least three years, and clutch size is typically two eggs. In laboratory incubation experiments, larger eggs were more likely to hatch. Low incubation temperatures (averaging 23 ± 7.5°C versus high temperatures averaging 26 ± 7.5°C) increased incubation duration significantly (range 56–72 days versus 40–51 days) and reduced the body size of hatchlings significantly (17.8 mm versus 18.7 mm snout–vent length). Skinks sheltered beneath small rocks that were not shared simultaneously with predatory snakes, and that reached average temperatures that were up to 3°C warmer during the day than unused rocks. Preferred microhabitats include substrates of rock or soil, and the largest rocks were occasionally shared by up to four individuals of all body size/sex combinations (5.8% of observations were shared, 30.2% of individual rocks were shared). Our study expands upon knowledge of the widespread genus Cryptoblepharus by providing detailed life history and ecological information on C. pulcher that can serve as a baseline for future studies.
Amphibian tadpoles are generally considered to be herbivores or plant-based detritivores that occupy lower trophic levels within freshwater aquatic communities. However, tadpoles are known to incorporate a variety of animal products within their diets as well. There are also many examples of tadpole species occupying higher trophic levels as opportunistic predators of conspecifics and other animals. In this paper, I describe the opportunistic predation of mosquito larvae by tadpoles of the sandpaper frog, Lechriodus fletcheri. Field observations revealed that L. fletcheri tadpoles actively preyed on mosquito larvae at the surface of the water column, using a series of swimming-to-gliding motions to hunt. This swimming routine may be effective for catching mosquito larvae, which respond to water vibrations to evade predation, allowing tadpoles to effectively become ‘invisible’ to the larvae during periods when tail motions are ceased. Given that L. fletcheri tadpoles have a non-specialised omnivorous diet, these findings indicate that the tadpoles of some species have the ability to take up multiple ecological roles within freshwater systems, including as opportunistic predators.
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