Letteratura scientifica selezionata sul tema "Myobatrachidae"

AbstractTwo species of gastric-brooding frogs, Rheobatrachus silus and R. vitellinus, currently constitute the subfamily Rheobatrachinae of the Australian leptodactyloid family Myobatrachidae. The relationships of Rheobatrachus to other myobatrachids have remained obscure due to the specializations for aquatic life and unique gastric-brooding behavior of Rheobatrachus and to the rare and endangered status of R. silus, until recently the only known species. An antiserum to the serum albumin of R. vitellinus was used in micro-complement fixation analyses comparing R. vitellinus to R. silus, and to representatives of most of the myobatrachid genera as well as to select representatives of the South American and South African leptodactyloid fauna. The two species of Rheobatrachus are each others closest relative and no other lineage is distinctly associated with these two species. Albumin comparisons involving other leptodactyloids show that Rheobatrachus is part of the Australian fauna, but as all of the major lineages appear to have arisen in the late Cretaceous, no single sister lineage to Rheobatrachus can be unambiguously identified.

The hind-foot musculature of representatives of all myobatrachid frog genera was examined with a view to finding phylogenetic characters and characters correlated with the burrowing habit. Despite much intraspecific variation, evidence was found to support the monophyly of Mixophyes(possession of a fibrous section in the tendon of insertion of the m. lumbricalis longus digiti V, tendinous insertion of the m abductors brevis dorsalis digiti V), Rheobatrachus (threefold insertion of the m. extensor longus digiti IV), Neobatrachus +Heleioporus (possession of the m. lumbricalis longus digiti II), Pseudophryne + Metacrinia(loss or reduction of medial slip of the m. lumbricalis brevis digiti V), Adelotus + Heleioporus +Limnodynastes (minus L. ornatus-group) +Neobatrachus+Notaden (possession of a transversus-like muscle between the first metatarsus and the prehallux), and Rheobatrachus + Myobatrachinae (reduction of the m. plantaris brevis plantaris digiti V). Differences were found in the musculature associated with the metatarsal tubercles between (a) rear-foot-burrowing frogs of the genera Notaden, Neobatrachus,Heleioporus and Limnodynastes (minus L. ornatusandL. spenceri); (b)L. ornatus and L. spenceri; and (c)Uperoleia. The differences indicate separate evolution of burrowing in these taxa. A new muscle, the m. adductor praehallucis, is described. From its structure and distribution among species, this muscle appears to be associated with the burrowing habit.

The southern Australian endemic genus Geocrinia Blake 1973 (Anura: Myobatrachidae) currently contains seven species, with five restricted to Western Australia and two in the south-eastern states covering parts of New South Wales, Victoria, Tasmania and South Australia. All species have a modified life history with at least some or all of the larval stage being completed terrestrially. Four of the Western Australian species have terrestrial, non-feeding tadpoles nourished by yolk until metamorphosis. The remaining species have a biphasic development with embryos developing on land followed by an aquatic tadpole stage. The presence of species groups within the Geocrinia has been recognised since the 1970s, with all relevant subsequent studies supporting a model of two groups within the genus, recovered as reciprocally monophyletic in phylogenetic analyses. We examined character traits of the seven recognised Geocrinia species, concluding that distinction of the two monophyletic groups is supported by differences in life history strategy, larval morphology, adult morphology, call structure, breeding season and geographic distribution. The differences between the two groups correspond to phylogenetic structuring for all traits except distribution. Given reciprocal monophyly, and greater variation in traits than present within other myobatrachid genera, we conclude that the two groups should be given generic distinction. We therefore describe a new genus, Anstisia gen. nov., for four Western Australian Geocrinia species, retaining three species in Geocrinia. This increases the number of recognised myobatrachid genera to 14: five are endemic to south-western Australia.

The present study optimised artificial fertilisation and oocyte storage conditions in Limnodynastes tasmaniensis (Myobatrachidae). Data on general reproductive biology, the effect of sperm motility and concentration, medium osmolality and oocyte storage on artificial fertilisation success are presented. Egg number was most strongly correlated with bodyweight (r = 0.819). Sperm yield was correlated with testes weight (r = 0.827), which was strongly correlated with snout–vent length (r = 0.772). Optimal artificial fertilisation occurred in 0–7 mOsm kg–1 amphibian Ringer, similar to ranid, bufonid and hylid species. High fertilisation rates were achieved using spermatozoa with little forwards progressive motility at comparatively low concentrations (3 × 104 sperm cells mL–1) and with no relationship between percentage sperm motility and fertilisation success (correlation of fertilisation rate with sperm motility after activation: r = –0.145). Oocytes stored in 5 mOsm kg–1 solutions showed no significant decline in fertilisability after 2 h, showing that swelling of the jelly surrounding the eggs does not prevent sperm from fusing with the oocyte in this species. Fertilisability of oocytes was extended to > 4 h in medium to high osmolality solutions (124–271 mOsm kg–1). These data allow for the future use of L. tasmaniensis in developing assisted reproductive technology protocols for foam-nesting myobatrachid species, many of which are now threatened with extinction in the wild.

Seven species of frog are currently considered to be missing from the eastern seaboard of Queensland, Australia. Two species of these missing frogs were rediscovered in streams in the wet tropics of north Queensland in November 1996. One individual of Taudactylus acutirostris was observed calling in a small tributary of the South Johnstone River, five individuals of T. rheophilus were heard calling in a small, high altitude tributary of the Mulgrave River, and a further seven individuals of T. rheophilus were heard calling and one captured, in a small, high altitude tributary of the Mitchell River. Implications for the declining frog phenomenon are raised and the need for continued monitoring is emphasized.

Thesis (M.S.)--East Tennessee State University, 2004.
Title from electronic submission form. ETSU ETD database URN: etd-1115104-100927 Includes bibliographical references. Also available via Internet at the UMI web site.

Life history exist as a set of co-adapted traits designed to solve ecological problems, and theory predicts that in unpredictable environments, these are geared towards relatively slow growth and a long reproductive lifespan with relatively few offspring per reproductive event. However, recently the response of anurans to such conditions has been controversial and little empirical data are published on the response of Australian anurans living under such conditions. Limnodynastes Tasmaniensis is a medium sized endemic frog of the family Myobatrachidae that has an extensive range that encompasses every Australian state. Limited published data indicates that intra-population variation in reproductive parameters exist in this species and therefore it is an ideal model to test life history theory under Australian conditions. A population of the species was studied within remnant woodlands of North West Sydney, Australia. Many observations were made and the results shown in some detail. The data found does not completely conform with current theory developed largely for data collected in the northern hemisphere and highlights the need for further research into life history strategies of Australian anurans.
Doctor of Philosphy (PhD)

Thesis (PhD.) -- University of Western Sydney, 2002.
"A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Western Sydney, Centre for Integrated Catchment Management". References : leaves 133 - 162.

[Truncated abstract] Southwestern Australia is a global biodiversity hotspot. The region contains a high number of endemic species, ranging from Gondwanan relicts to more recently evolved plant and animal species. Biogeographic models developed primarily for plants suggest a prominent role of Quaternary climatic fluctuations in the rampant speciation of endemic plants. Those models were not based on explicit spatial analysis of genetic structure, did not estimate divergence dates and may be a poor predictor of patterns in endemic vertebrates. Myobatrachid frogs have featured heavily in the limited investigations of the biogeography of the regions fauna. Myobatrachid frogs are diverse in southwestern Australia, and while we know they have speciated in situ, we know little about the temporal and spatial patterning of speciation events. In order to gain insight into the biogeographic history and potential speciation patterns of Myobatrachid frogs in the southwest I conducted a comparative phylogeography of four frog species spanning three life history strategies. I aimed to: 1) assess the biogeographic history of individual species, 2) determine where patterns of regional diversity exist using a comparative framework, 3) determine whether congruent patterns across species enable the development of explicit biogeographic hypotheses for frogs, and 4) compare patterns of diversity in plants with the models I developed for frogs. I conducted fine-scale intraspecific phylogeographies on four species. ... Geocrinia leai: deep divergences, coincident with late Miocene arid onset, divide this species into western and southeast coastal lineages, with a third only found within the Shannon-Gardner River catchments. Phylogeographic history within each lineage has been shaped by climatic fluctuations from the Pliocene through to the present. Arenophryne shows the first evidence of geological activity in speciation of a Shark Bay endemic. Divergence patterns between the High Rainfall and Southeast Coastal Provinces within C. georgiana are consistent with patterns between Litoria moorei and L. cyclorhynchus and plant biogeographic regions. Subdivision between drainage systems along the southern coast (in M. nichollsi, G. leai and the G. rosea species complex) reflect the relative importance of distinct catchments as refuges during arid maxima, similarly the northern Darling Escarpment is identified as a potential refugium (C. georgiana and G. leai). Divergences in Myobatrachid frogs are far older than those inferred for plants with the late Miocene apparently an important time for speciation of southwestern frogs. Speciation of Myobatrachids broadly relates to the onset of aridity in Australia in the late Miocene, with the exception of earlier/contemporaneous geological activity in Arenophryne. The origins of subsequent intraspecific phylogeographic structure are coincident with subsequent climatic fluctuations and correlated landscape evolution. Divergence within frogs in the forest system may be far older than the Pleistocene models developed for plants because of the heavy reliance on wet systems by relictual frog species persisting in the southwestern corner of Australia.

My thesis concerns the evolutionary history of the endemic Austro-Papuan frog genus Uperoleia (Family Myobatrachidae). I use a molecular phylogenetic approach, in conjunction with ecological and palaeoclimate modelling, to evaluate and describe true Uperoleia diversity, and to understand how this diversity relates to historic and contemporary landscape history. As the majority of Uperoleia species are distributed in the Australian Monsoonal tropics, much of this thesis focuses on Northern Australia. Studies of Australian monsoonal tropics biogeography are in their infancy. For species active in the wet season, including frogs, the remoteness and inaccessibility of this massive region has made studies inherently difficult. Researchers are still working to understand patterns of species distributions and the barriers and mechanisms that have shaped them. Due in part to its vast size, huge variation exists in sub-region climate patterns in the monsoonal tropics, which is driven in part by strong topological complexity, especially compared to the adjacent desert regions. Do species within biomes form monophyletic groups? What factors have driven between-biome diversification? What are the patterns of within-biome phylogeography? What role has the aridification of the Australian continent played in shaping the evolutionary histories of mesic-adapted taxa? These were the questions that I sought to address in my thesis. In doing so, I uncover patterns of mitochondrial introgression, and explore the possible influence of hybridization on diversification in this group of frogs. The first chapter of my thesis investigates the diversity and distribution of Uperoleia species in the arid zone of Australia. The dunefield deserts of Australia are particularly poorly explored for frogs. In order to understand patterns of diversification between the monsoonal tropics and the arid zone, systematics of arid zone Uperoleia needed to be resolved. Using a combination of molecular genetics, morphological data, and acoustic data, I found that five species were present in the arid zone, rather than the previously described three. In this chapter I redescribe four of these species, as well as a new species only found in the Pilbara. The high level of arid zone diversity and distinct distribution patterns indicated that the topographic complexity creates strong patterns of sub-region endemism. Chapter II explores monsoonal tropics biogeography using a widespread clade of Uperoleia that span the entire region. Using multiple mitochondrial and nuclear loci, I generated a well-resolved phylogeny. Despite numerous instances of mitochondrial introgression, morphological and acoustic data allowed me to resolve the species distributions of four parapatric species. Using distribution and environmental data, combined with climate modelling, I generated species distribution models to explore the biogeographic barriers influencing the patterns of present day species. These data allowed me to revise the biogeographic terminology related to the Australian monsoonal tropics and propose new barriers within the region. In addition, I project the current niche space back to the Last Glacial Maximum (21 kya) in order to identifY putative refugia. These refugia largely match the population structure we see today. In Chapter III, I resolve the systematics of U. trachyderma using the molecular genetic, morphological, and acoustic data from Chapter II. The previous chapter concluded that there is sufficient evidence to conclude that individuals from the western half of the Northern Deserts are reproductively isolated from U. trachyderma, and in this chapter I resolve the systematics with the description U. stridera sp. nov., and the re-description of U. trachyderma. Due to increasing evidence that the Northern Deserts region of Australia harbours a unique fauna, I also discuss the status of protected areas within the Northern Deserts. In Chapter IV, I generate a multi-locus molecular data set for almost 600 specimens to provide a comprehensive assessment of Uperoleia phylogeny and clarify the distributions of 25 of the 28 Uperoleia species. I then investigate phylogeographic structure within each of the arid, monsoonal tropic, and mesic biomes, and the timing and patterns of between-biome diversification. I provide a detailed review of the geology, landscape and climate patterns that may have influenced current species distributions and contrast these with previous studies. For the eastern mesic zone, species distribution patterns are largely congruent with previous phylogeographic studies. Examination of molecular dates revealed the divergence between an eastern mesic clade and a largely monsoonal tropics clade was associated with the peak of the wann, wet Miocene epoch. It also appears that species have diverged into the arid zone from the monsoonal tropics multiple times. The majority of these divergence events coincide with the peak of the Pliocene, which saw warmer wetter conditions in central Australia. The divergence between the most arid-adapted taxa and its monsoonal sister species was associated with the beginning of the Pleistocene and beginning of the intense aridification of central Australia. Chapter V addresses the topological differences between the mitochondrial and nuclear phylogenies of Uperoleia. Here I make the case that due to chromosomal conservatism, and evidence of recent and regular hybridization, it is possible that homoploid hybrid speciation played a role in the generation of diversity. Although patterns such as deep coalescence and mitochondrial gene capture may also explain some topological differences, ecological changes associated with potential hybrid species mean further investigations are necessary. Consideration of heterozygosity in the nuclear markers, and next-gen sequencing are the way forward for understanding tree discordance in Uperoleia.

Examines the habitat, microhabitat and the calling behaviour of the Krombit tinkerfrog, which is a critically endangered myobatrachid frog endemic to the rainforest gullies of Kroombit Tops in south-east Queensland.. Taudactylus pleione (the Kroombit tinkerfrog) is a critically endangered myobatrachid frog endemic to the rainforest gullies of Kroombit Tops, an elevated plateau in southeast Queensland, Australia. Its numbers have declined in recent times, particularly at the higher altitude plateau streams. Efforts to conserve the species, including a proposal to commence captive breeding, are hampered by inadequate knowledge of the species' habitat requirements and conditions required for reproduction. This project investigated the characteristics of occupied rainforest patches and streams, microhabitat and structure of male call sites and influence of climatic variables on male calling activity. Habitat characteristics of rainforestlwet sclerophyll patches and streams used by T. pleione were compared to randomly selected unoccupied patches and streams. Callsites and call-perches used by male T. pleione were compared to available potential callsites and perches. Daily calling activity of male T. pleione was analysed in relation to climatic and other variables. Patches of notophyll rainforest and adjacent wet sclerophyll forest were mapped from aerial photography. The habitat and spatial patterns of ten patches occupied by T pleione and ten randomly selected unoccupied patches were compared. Within these, habitat and microhabitat data were compared for seven occupied and eight unoccupied streams. The habitat of T.pleione can be described as first-order streams at Kroombit Tops originating above 825 m within patches of simple notophyll gully vine forest (Regional Ecosystem 12.12.1) spanning more than 168 m of elevation, that are generally greater than 20 ha in area with an area-perimeter ratio of 73 or higher and a catchment of over 56 ha, no more than 207 m from the nearest occupied patch. Patches of less than 20 ha may be occupied provided they have patch roundness index values of 0.68 or higher. Streams have generally less than 7.9% crevice cover and 'large pebbles' (2.1- 6.0 cm) occurred at a frequency of 30% or more. Data were collected from call-sites used by male T. pleione for advertisement calling and from randomly selected paired locations within the same gully. Occupied call-sites had significantly higher rock and crevice cover, but significantly lower slope and direct summer radiation values. Males were significantly more likely to be found using rockpiles than other call-perch structures available at the site. Preliminary analysis of the acoustic reflectivity of the call-perches used by T. pleione males, based on the density of their component materials, showed they were significantly more reflective than potential call-perches. Daily male T. pleione calling activity was recorded at one escarpment stream over 1,836 days. Associated daily temperature and rainfall data were collected at Kroombit Tops and long-term rainfall and temperature data obtained from Bureau of Meteorology stations within 50 km of the study site. Logistic regression was used to explore the relationship between male calling behaviour at this site and meteorological and astronomical variables. The resultant modelling identified two distinct periods within the calling season: the calling onset and sustained calling periods. The calling onset period model explained 85.9% of cases using five variables describing atmospheric moisture, temperature, rainfall and moon phase. The sustained calling period model explained 77 .8% of cases using three variables describing atmospheric moisture and rainfall. This study has provided the first quantitative data on habitat and microhabitat use by T. pleione and the methodology developed has application for further research on the habitat requirements of the species. Further, this study has greatly increased knowledge of when male T. pleione call and the factors influencing calling. These results can improve the effectiveness of future surveys and monitoring as well as providing a application to any future attempts at translocation or captive breeding of this critically endangered species.

Throughout much of the world, frog populations are declining and some species are disappearing totally. In Australia, several species have become extinct in the past 25 years. This fully illustrated guide to all the known frogs of Australia provides concise accounts of 227 species within the five main frog families: Hylidae, Limnodynastidae, Microhylidae, Myobatrachidae and Ranidae. It also includes the introduced Cane Toad and provides notes on other ‘stowaway’ species that have arrived in Australia. The text for each species includes details of size, status, distribution, habitat, behaviour and advertisement call. Each species is accompanied by a map of Australia showing its known distribution, and a full-colour painted illustration. Closely related frogs are shown in identical poses so that comparisons can be made readily. The introductory section of the book covers frog biology and habitats and includes notes on families and genera.

Throughout much of the world, frog populations are declining and some species are disappearing totally. In Australia, several species have become extinct in the past 25 years. This revised and updated guide provides concise accounts of all the known frogs of Australia. There are 230 species within the five native frog families: Hylidae, Limnodynastidae, Microhylidae, Myobatrachidae and Ranidae. Also included are the introduced Cane Toad and nine ‘stowaway’ species that have arrived in Australia. The text for each species includes details of size, status, distribution, habitat, behaviour and advertisement call. Each species is accompanied by a map of Australia showing its known distribution, and a full-colour painted illustration. Closely related frogs are shown in identical poses so that comparisons can be made readily. The introductory section of the book covers frog biology and habitats and includes notes on families and genera.

Throughout much of the world, frog populations are declining, with the survival of many species under threat. In Australia, several species have become extinct in the past 35 years. This second edition of Field Guide to the Frogs of Australia provides fully updated accounts of all the known frogs of Australia. There are 248 species within the five native frog families: Hylidae, Limnodynastidae, Microhylidae, Myobatrachidae and Ranidae. Also included are the introduced Cane Toad and nine ‘stowaway’ species that have arrived in Australia. Each species account includes details of size, status, distribution, habitat, behaviour and advertisement call. Species are beautifully illustrated with full-colour paintings and distribution maps are also included. Closely related frogs are shown in identical poses so that comparisons can be made readily. The introductory section of the book covers frog biology and habitats and includes notes on families and genera.