A comparative study of divergent embryonic and larval development in the Australian frog genus Geocrinia (Anura: Myobatrachidae)

Anstis, Marion

doi:10.18195/issn.0312-3162.25(4).2010.399-440

Cited by 13 publications

(29 citation statements)

References 39 publications

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“…Moler, 1985), Crinia, Geocrinia (Myobatrachidae; e.g. Doughty, Anstis & Price, 2009;Anstis, 2010), and Boophis (Mantellidae; e.g. Randrianiaina et al, 2009), requires detailed ontogenetic studies.…”

Section: Discussionmentioning

confidence: 99%

Different pathways are involved in the early development of the transient oral apparatus in anuran tadpoles (Anura: Leiuperidae)

Candioti

Haad

Baldo

et al. 2011

Biological Journal of the Linnean Society

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The oral apparatus of anuran tadpoles is a unique structure composed of soft and keratinized parts surrounding the mouth. Among the many variations, a common oral apparatus involves a dorsal gap in the marginal papillae, keratinized jaw sheaths, and two upper and three lower rows of labial teeth. In Leiuperidae, besides this generalized morphology, four configurations are distinguished by the arrangement of the lower marginal papillae and the number of lower tooth rows. Study of the early oral ontogeny in 12 species representing these five configurations shows variations in the development of the lower marginal papillae and the third lower labial tooth row. Similar configurations may result from similar pathways (e.g. Physalaemus cuvieri group and Pseudopaludicola falcipes) or different pathways (e.g. generalized oral discs of Pleurodema and Physalaemus). Different oral configurations may result from overlapping trajectories ending at different stages (e.g. Physalaemus riograndensis and Ph. biligonigerus) or different trajectories (e.g. Ph. henselii and Ph. gracilis). Further studies are needed to interpret the role that heterochrony has played in evolutionary change within this family. The unsuspected variation occurring in this transient structure highlights its evolutionary potential and might be insightful in studies of anuran phylogenies that are largely based on adult characters.

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Section: Discussionmentioning

confidence: 99%

Different pathways are involved in the early development of the transient oral apparatus in anuran tadpoles (Anura: Leiuperidae)

Candioti

Haad

Baldo

et al. 2011

Biological Journal of the Linnean Society

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“…This low dispersal is evident from genetic studies that showed almost no gene flow between populations (Driscoll 1998a). As the species are specialised terrestrial breeders with entirely endotrophic (non-feeding) development (Mitchell 2001;Anstis 2010), their lifecycle is completed in and immediately adjacent to breeding sites. Breeding sites are vulnerable to extremes of flooding and desiccation, as eggs develop in moist soils but cannot be submerged (Wardell-Johnson and Roberts 1993).…”

Section: Introductionmentioning

confidence: 99%

Drying microclimates threaten persistence of natural and translocated populations of threatened frogs

et al. 2020

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Defining species habitat requirements is essential for effective conservation management through revealing agents of population decline and identifying critical habitat for conservation actions, such as translocations. Here we studied the habitat-associations of two threatened terrestrial-breeding frog species from southwestern Australia, Geocrinia alba and Geocrinia vitellina, to investigate if fine-scale habitat variables explain why populations occur in discrete patches, why G. alba is declining, and why translocation attempts have had mixed outcomes. We compared habitat variables at sites where the species are present, to variables at immediately adjacent sites where frogs are absent, and at sites where G. alba is locally extinct. Dry season soil moisture was the most important predictor of frog abundance for both species, and explained why G. alba had become extinct from some areas. Sites where G. alba were present were also positively associated with moss cover, and negatively with bare ground and soil conductivity. Modelling frog abundance based exclusively on dry season soil moisture predicted recent translocation successes with high accuracy. Hence, considering dry season soil moisture when selecting future translocation sites should increase the probability of population establishment. We propose that a regional drying trend is the most likely cause for G. alba declines and that both species are at risk of further habitat and range contraction due to further projected regional declines in rainfall and groundwater levels. More broadly, our study highlights that conservation areas in drying climates may not provide adequate protection and may require interventions to preserve critical habitat.

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“…The breeding season commences in late winter/early spring (August/September) and continues into summer (December/January) ( Driscoll, 1998 ). Eggs are laid in a shallow depression in moist soil adjacent to ephemeral streams and develop endotrophically until metamorphosis is completed between November and January ( Anstis, 2010 ). Geocrinia vitellina is a closely related species with an allopatric distribution, occurring ~6 km to the east.…”

Section: Methodsmentioning

confidence: 99%

“…Development times were calculated as the average number of days from stage 19 to stage 39 according to developmental stages defined in Anstis (2010) for Geocrinia species. Stage 19 (hind limb buds just visible) was the earliest stage that all embryos were collected at, and stage 39 was just prior to metamorphosis (tail stub < 2 mm), when metamorphs are routinely transferred to different terraria, according to Perth Zoo husbandry practices.…”

Section: Methodsmentioning

confidence: 99%

Low desiccation and thermal tolerance constrains a terrestrial amphibian to a rare and disappearing microclimate niche

Hoffmann

Cavanough

Mitchell

2021

Conservation Physiology

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Drier and hotter conditions caused by climate change threaten species that exist close to their physiological limits, as well as those with limited ability to move. Habitat specialists may also be particularly vulnerable if they have specific abiotic requirements. Here we assess whether thermal and hydric constraints can explain the highly restricted and declining distributions of the critically endangered terrestrial-breeding frog, Geocrinia alba. We also evaluate the species’ vulnerability to climate change based on the similarity of current microclimatic conditions to their physiological limits. We found that G. alba had low thresholds of thermal and desiccation tolerance relative to other anuran species. The estimated thermal optimum (Topt) and critical thermal maxima (CTmax) were 23.3°C and 29.6°C, respectively, and adult frogs had an absorption threshold (AT, the lowest water potential at which water can be absorbed from a substrate) of −50 kPa, the lowest recorded for an amphibian. Comparing environmental conditions and water loss in the field using agar models showed that riparian habitats where frogs occur provide a unique microclimate in the landscape, offering significantly lower desiccation risk during extreme summer conditions compared to immediately adjacent riparian and terrestrial habitats. Monitoring of microclimate conditions within occupied frog habitats over 2 years showed that in extreme dry and hot years the AT was exceeded at six of eight sites, and Topt was exceeded at two of eight sites. Given their specific physiological limits, the apparent rarity of suitable microclimates and a regional drying–warming trend, we suggest that G. alba occupies a potentially disappearing niche and may be indicative of other habitat specialists that rely on ephemeral drainages. More broadly, this study highlights that desiccation thresholds may tightly constrain amphibian distributions and need to be considered along with thermal tolerance thresholds when predicting the impacts of climate change.

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A comparative study of divergent embryonic and larval development in the Australian frog genus Geocrinia (Anura: Myobatrachidae)

Cited by 13 publications

References 39 publications

Different pathways are involved in the early development of the transient oral apparatus in anuran tadpoles (Anura: Leiuperidae)

Different pathways are involved in the early development of the transient oral apparatus in anuran tadpoles (Anura: Leiuperidae)

Drying microclimates threaten persistence of natural and translocated populations of threatened frogs

Low desiccation and thermal tolerance constrains a terrestrial amphibian to a rare and disappearing microclimate niche

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