Dr John Gould

Many plants exploit the ability of animals to move in order to disperse their pollen and seeds. Despite the growing understanding of the role animals play in the reproductive lives of plants, there are few examples of amphibians contributing to these processes. We report on an Australian tree frog, Litoria fallax, interacting with and likely moving seeds of the broad-leaved cumbungi, Typha orientalis, over short distances via external transport. Field observations revealed both juvenile and adult L. fallax individuals carrying typha seeds, which were adhered to the skin on the feet, legs, belly and dorsum. Approximately 30% of observed frogs were found to be carrying 1¿14 seeds at a time. The small size and specialised fibre tufts of typha seeds, which enable them to be primarily dispersed by wind, also make them susceptible to being unintentionally picked up and transported by L. fallax as they move through aquatic environments. The moist surfaces of frogs, coupled with their presence in freshwater systems that can be dominated by typha, create favourable conditions for seed attachment. These findings highlight a previously unknown interaction between an amphibian and a plant that enables seed dispersal, supporting the need for further exploration into unexpected plant vectors.

Many animals create their own microhabitats that are not naturally present in the environment, such as nests and burrows, which are extended phenotypes that perform tasks related to survival and reproduction. Animals may be able to avoid the costs of implementing their own extended phenotypes by exploiting those already created by other species, including structures that are not actively in use or abandoned. Herein, we report on the striped marsh frog, Limnodynastes peronii, from Australia utilizing crayfish burrows for depositing their egg clutches. Field observations revealed large numbers of recently hatched L. peronii tadpoles in two flooded burrows likely created by the hunter hairy crayfish, Cherax setosus, near an ephemeral wetland pond on Kooragang Island, Australia that had partially dried. Our observations indicate that L. peronii may opportunistically exploit crayfish burrows which, when flooded, become suitable aquatic sites for breeding. These small waterbodies may provide fitness benefits to offspring, reducing exposure to aquatic predators found in naturally occurring aquatic systems but at the expense of increasing competition and cannibalism among confined siblings. These burrows may provide suitable microhabitat refuge during droughts, and breeding habitat for amphibians when other typical breeding habitats may not exist due to wetland drying. This is an example of an amphibian using an extended phenotype of a crustacean for the purposes of reproduction, revealing a unique interaction between these species that has not been reported.

Aim: Changes to the extent and severity of wildfires driven by anthropogenic climate change are predicted to have compounding negative consequences for ecological communities. While there is evidence that severe weather events like drought impact amphibian communities, the effects of wildfire on such communities are not well understood. The impact of wildfire on amphibian communities and species is likely to vary, owing to the diversity of their life-history traits. However, no previous research has identified commonalities among the amphibians at most risk from wildfire, limiting conservation initiatives in the aftermath of severe wildfire. We aimed to investigate the impacts of the unprecedented 2019¿2020 black summer bushfires on Australian forest amphibian communities. Location: Eastern coast of New South Wales, Australia. Methods: We conducted visual encounter surveys and passive acoustic monitoring across 411 sites within two regions, one in northeast and one in southeast New South Wales. We used fire severity and extent mapping in two multispecies occupancy models to assess the impacts of fire on 35 forest amphibian species. Results: We demonstrate a negative influence of severe fire extent on metacommunity occupancy and species richness in the south with weaker effects in the north¿reflective of the less severe fires that occurred in this region. Both threatened and common species were impacted by severe wildfire extent. Occupancy of burrowing species and rain forest specialists had mostly negative relationships with severe wildfire extent, while arboreal amphibians had neutral relationships. Main Conclusion: Metacommunity monitoring and adaptive conservation strategies are needed to account for common species after severe climatic events. Ecological, morphological and life-history variation drives the susceptibility of amphibians to wildfires. We document the first evidence of climate change-driven wildfires impacting temperate forest amphibian communities across a broad geographic area, which raises serious concern for the persistence of amphibians under an increasingly fire-prone climate.

Traditional methods for identifying individual amphibians in capture¿mark¿recapture (CMR) studies have been primarily confined to post-metamorphic stages, using artificial markers that come with a variety of limitations. An alternative that may open CMR studies to earlier life stages involves the use of a species' natural external markers in photo-based identification. In this study, we investigated whether it was possible to distinguish tadpoles of the threatened green and golden bell frog (Litoria aurea) at the individual level based on tail venation patterns. We collected photographs of the tails of captive-raised tadpoles using a smartphone over a 4-week period. This photo-library was used to create an electronic survey where participants were asked to detect matches for query tadpoles from small image pools. We found that most participants agreed on a match for each query, with perfect consensus achieved for most queries (83%). We detected a 14% decline in perfect consensus when participants were asked to match images of tadpoles separated by longer time intervals, suggesting that it is more difficult to visually identify recapture events of L.¿aurea tadpoles over extended periods due to changes to tail appearance. However, consensus was obtained by participants for all queries, with all matches verified as being correct by the primary researcher. The strength of agreement among participants with no prior experience in matching tadpole tails suggests that there is sufficient inter-individual variation in this feature for individuals to be manually identified. We thus propose that photo-identification is likely to be a valid, non-invasive technique that can be used for short-term studies on tadpole populations that display tail venation. This offers an alternative to artificial markers that may not allow for individual identification, while also opening up tadpole monitoring programmes to citizen scientists who can be recruited online to process image data from home.

Few spiders are known to construct silk webs that physically contact water, despite it being both a surface and medium that can be exploited for web construction. Herein, we report on an Australian long-jawed spider from the Tetragnatha genus (Tetragnatha cf. nitens) that frequently produces aerial webs that touch the surface of ephemeral waterbodies. Field observations revealed webs that were built by these spiders at varying heights above water in emergent vegetation stands around the edge of ephemeral waterbodies. Approximately, 15 of the 100 webs recorded were constructed immediately above the water with their lower sections making physical contact with the water's surface. We observed water striders becoming stuck within these low-lying webs, suggesting that associating webs with surface water allows the spiders to exploit prey types that cannot be passively filtered from the environment in purely aerial webs. This could suggest that some species of long-jawed spider select the positioning of their webs above water, which would be adaptive if it allows them to target different and possibly multiple prey communities.

Introduced rodents, particularly the black rat (Rattus rattus), have caused serious ecological impacts due to their ability to interact with native species as both predators, and by eliciting competitive pressure. However, impacts of black rats upon many Australian mammals have yet to be determined, particularly when those mammals are arboreal. Here, we present novel observations in the form of camera trap footage and photographs of interspecific competition between the introduced black rat and two species of arboreal gliding marsupial (sugar gliders (Petaurus breviceps) and squirrel gliders (Petaurus norfolcensis)) in urban bushland reserves in New South Wales, Australia. Gliders were found to flee or were prevented from exploiting food resources due to antagonistic posturing and physical attacks by black rats. While interspecific aggression and interference competition between black rats and native mammal species has been demonstrated previously, this appears to be the first observation of such interactions for Australian gliders. Our findings may have implications for the future management of glider populations in urban bushland where they co-occur with rats; however, further research needs to be undertaken to determine the extent of this potential threat.

The most well-known use of silk among spiders is the formation of webs to capture flying prey. However, spiders have evolved many different foraging strategies involving silk, including the capture and subsequent manipulate of prey prior to consumption. Herein, I report on the use of silk lines by a long-jawed spider from the Tetragnatha genus to move a large prey item vertically through the air. Field observations revealed a long-jawed spider attaching multiple silk lines across the body of an adult dragonfly that had recently emerged from its final moult and attaching these threads to overlying vegetation to incrementally haul the prey item from the surface of a waterbody. My observations suggest that some Tetragnatha spiders are able to move large prey items that are much heavier then themselves using a series of silk lines that allow lift to be accomplished in a gradual and controlled manner. This is an interesting finding, given that other individuals from the same population were using web structures to passively catch much smaller, flying prey. This indicates that some Tetragnatha spiders not only participate in the mobile pursuit of prey but that they possess multiple foraging strategies that may allow them to exploit a larger number of prey types.

For amphibians that oviposit in temporary aquatic systems, there is a high risk of desiccation-induced offspring mortality when water evaporates prior to the completion of embryo or tadpole development. Such a strong selective pressure has led to the evolution of a variety of traits in reproducing females and their offspring to improve the odds of reproductive success when free-standing water is temporarily available. Herein, we describe an adaptive function of froth nesting in the Sandpaper Frog, Lechriodus fletcheri, as a possible maternal strategy for protecting embryos from the immediate risk of desiccating in highly ephemeral pools that frequently dry prior to hatching. Field observations revealed that embryos located near the core of nests remained alive and continued to develop for several days after becoming stranded out of water due to declining water levels, with embryo viability maintained long enough for additional rainfall to recharge pools and support hatching of tadpoles into water in some cases. In laboratory trials, the proportion of embryos surviving in nests exposed to desiccating conditions was positively correlated with nest volume, while the rate of water loss relative to nest mass declined, both of which are likely a function of reduced surface area relative to volume in larger nests. We suggest that the encapsulation of embryos within an aerated mucus shields them from desiccation by trapping moisture around their external surfaces. As embryos of L. fletcheri complete development rapidly, the ability for the froth nest to protect against desiccation for several days may allow embryogenesis to be completed largely out of water despite the larval phase not being terrestrial. These results suggest froth nesting has played an important role in facilitating this species' use of ephemeral habitats that most other amphibians with aquatic reproductive modes are incapable of exploiting.

For oviparous animals such as amphibians, the presence or absence of conspecifics can influence site selection, with each life history stage potentially influencing the decision-making process in a different manner. In the present study, we tested the effect of conspecific life history stage on oviposition site selection in the sandpaper frog, Lechriodus fletcheri. We quantified preferences for spawning in pools that were unused by conspecifics, as well as pools with conspecific spawn or tadpoles present, or both. The study included two ecological contexts: a system of naturally occurring breeding pools and a field experiment with 40 artificial pools that controlled for habitat variation. Mothers preferred to oviposit in pools that already contained conspecific spawn, despite the likelihood of intense resource competition upon offspring hatching. This could be due to the potential benefits obtained by providing offspring access to a significant nutrient supply upon hatching via cannibalism of conspecific tadpoles and might be an important adaptation for completing tadpole development in highly ephemeral and resource-limited pools prior to desiccation. In contrast, mothers avoided ovipositing in pools with conspecific tadpoles, a probable adaptation to avoid their own offspring from becoming victims of cannibalism themselves prior to hatching. Such nuances in the effect of conspecific presence on offspring survival highlight the often complex decision-making process that amphibians need to make when selecting oviposition sites, as well as the influence cannibalism can have on the evolution of reproductive behaviour.

Human modification of natural landscapes is a key threatening process contributing to the decline of global biodiversity. Amphibians are particularly vulnerable to this threat, with over a third of species threatened as a direct result. However, some habitat modifications may be less detrimental than others, with some species known to successfully thrive in certain artificial habitats while others undergo further declines. Yet, recognizing how amphibians respond to different habitat modifications remains limited, particularly on a global scale. Herein, we examine the known artificial habitat associations of amphibian species globally, demonstrating artificial habitat use is dependent on their conservation status, life history, taxonomic order, and geographical location. Approximately one-third of all amphibians were found to use artificial habitats, including nearly half of all non-threatened and one-sixth of threatened species, with usage decreasing as conservation status increased. Terrestrial, generalist, and caecilian species were much more likely to use artificial habitats. Non-threatened species were more likely to utilize artificial habitats such as aquaculture ponds, pastureland, canals, excavations, urban areas, and rural gardens. Plantations, heavily degraded former forests, and wastewater treatment areas contained a greater proportion of threatened species, particularly in Afrotropical, Indomalayan, and Oceanian regions. Countries with the most amphibians utilizing artificial habitats were Brazil, Colombia, Peru, Madagascar, and Ecuador. However, the greatest number of threatened species using artificial habitats were found in Mexico, Madagascar, India, Sri Lanka, and China. We highlight the potential value or threat of each artificial habitat type, which may be used to better focus valuable conservation efforts.

Individuals within amphibian populations are commonly identified using artificial marking techniques, such as toe clipping and microchipping. However, many species in this group may be strong candidates for visual identification from photographs given intraspecific variability in skin features. We investigated the potential for dorsal skin patterns to be used as natural markers for the photo-identification of both juveniles and adults of the green and golden bell frog (Litoria aurea). This is a threatened species that has come under intense population monitoring using capture-mark-recapture procedures primarily involving the use of artificial markers, with no apparent investigation of the potential for natural markers to be used instead. We collected photographs of marked individuals to determine the level of intraspecific variability in dorsal patterning within a population. This photo-database was subsequently used to create an online survey in which participants were asked to match separate images of query frogs from small image pools by comparing dorsal patterns. Photographs were taken on a smartphone device under field conditions to test whether this technique could be applied to the study of wild populations with little cost or expertise required. We showed that dorsal patterns are clear and distinct among L.¿aurea individuals and easily visualised from field-acquired images to detect recapture events by eye with a low error rate. While an overwhelming majority of adults possessed dorsal patterning that can be easily distinguished by eye, juveniles often showed a complete absence of patterning, suggesting that photo-identification may be more effective for adult stages. Nevertheless, we highlight the feasibility of collecting visual information on the natural markings of a threatened anuran, providing evidence that it may be used as a supplementary form of identification alongside more traditional techniques, highlighting a potential direction for the future monitoring of this species.

The functions of secreted animal mucuses are remarkably diverse and include lubricants, wet adhesives, protective barriers, and mineralizing agents. Although present in all animals, many open questions related to the hierarchical architectures, material properties, and genetics of mucus remain. Here, we summarize what is known about secreted mucus structure, describe the work of research groups throughout the world who are investigating various animal mucuses, and relate how these studies are revealing new mucus properties and the relationships between mucus hierarchical structure and hydrogel function. Finally, we call for a more systematic approach to studying animal mucuses so that data sets can be compared, omics-style, to address unanswered questions in the emerging field of mucomics. One major result that we anticipate from these efforts is design rules for creating new materials that are inspired by the structures and functions of animal mucuses.