Translocations are important tools in the field of conservation. Despite increased use over the last few decades, the appropriateness of translocations for amphibians and reptiles has been debated ...widely over the past 20 years. To provide a comprehensive evaluation of the suitability of amphibians and reptiles for translocation, we reviewed the results of amphibian and reptile translocation projects published between 1991 and 2006. The success rate of amphibian and reptile translocations reported over this period was twice that reported in an earlier review in 1991. Success and failure rates were independent of the taxonomic class (Amphibia or Reptilia) released. Reptile translocations driven by human-wildlife conflict mitigation had a higher failure rate than those motivated by conservation, and more recent projects of reptile translocations had unknown outcomes. The outcomes of amphibian translocations were significantly related to the number of animals released, with projects releasing over 1000 individuals being most successful. The most common reported causes of translocation failure were homing and migration of introduced individuals out of release sites and poor habitat. The increased success of amphibian and reptile translocations reviewed in this study compared with the 1991 review is encouraging for future conservation projects. Nevertheless, more preparation, monitoring, reporting of results, and experimental testing of techniques and reintroduction questions need to occur to improve translocations of amphibians and reptiles as a whole.
While most anurans lay their eggs in or near water, there is a wide diversity of species that lay their eggs on the ground, under rocks, or in burrows. For these terrestrial-breeding species, ...identifying the habitat requirements of oviposition sites is particularly useful for conservation and management planning, given that oviposition in anurans is strongly related to the environmental characteristics in which they live. Leiopelma archeyi is an endemic New Zealand frog that reproduces on moist substrates. Males brood eggs and carry larvae within retreats until metamorphosis is complete. Two previous observations (in November 2014) reported frogs attending eggs inside dead, hollow trunks of tree-ferns (ponga. Cyathea spp. or Dicksonia spp.). We examined whether these observations were random or whether ponga was a breeding resource consistently used by L. archeyi. We used a non-disturbance protocol and focussed on searching inside ponga systematically during three consecutive breeding seasons. This monitoring allowed us to corroborate the reproductive mode previously known for this species and confirm ponga as a recurring oviposition site for L. archeyi. Around 10% of the oviposition sites monitored during the parental-care period were observed with more than one adult inside. Furthermore, we selected three individual ponga known to be used as oviposition sites to mark the centre of a plot from which we measured all ponga trunks. We fitted a mixed-model logistic regression to examine whether the use of ponga as an oviposition site by L. archeyi was predicted by length and/or diameter at the opening of the trunk. However, neither of these trunk characteristics were useful predictors for the use of ponga as an oviposition site. Our observations raise questions about the reproductive mode of this species such as oviposition site fidelity, and interactions within a community level between two ancestral lineages (Leiopelmatidae and tree fems).
The use of translocations for conservation management has increased in frequency over recent decades. Though many early translocations were carried out as one-off management exercises, the need to ...test release strategies and gain knowledge in order to improve future reintroductions has been recognised. This study examined both the movements and survival of 101 Leiopelma hamiltoni (Anura: Leiopelmatidae) translocated to Long Island. New Zealand, and the response of the source population on Te Pākeka/Maud Island to the removal of a discrete subset of frogs. An experimental approach was taken to test whether familiarity would improve anchoring to the site and discomage homing and dispersal post translocation. Frogs translocated with their neighbours did not stay with those individuals and those that were released in a random pattern did not move towards their former Maud Island neighboms. While initial movements were significantly oriented to the bearing of Maud Island, after several months this had changed to indicate that the frogs moved in a downhill direction. Capture-recapture abundance estimates suggest a decline in the population of translocated frogs during the 46 months post-release and follow up surveys 10-13 years post-release confinn that this translocation failed. Capture-recapture abundance estimates suggest that the 240 nf grid emptied of frogs (i.e. the source population) took one year to return to pre-translocation densities. There is little doubt that translocations will continue to be an important tool for the conservation management of leiopelmatid frogs in New Zealand and for amphibians worldwide. However, a commitment to post-release monitoring, use of methods that allow for causes of failme to be assessed, and testing release strategies is imperative to informing methods and improving the success rates of future translocations.
Smooth muscle cells contribute to extracellular matrix remodeling during atherogenesis. De-differentiated, synthetic smooth muscle cells are involved in processes of migration, proliferation and ...changes in expression of extracellular matrix components, all of which contribute to loss of homeostasis accompanying atherogenesis. Elevated levels of acute phase proteins, including serum amyloid A (SAA), are associated with an increased risk for atherosclerosis. Although infection with periodontal and respiratory pathogens via activation of inflammatory cell Toll-like receptor (TLR)2 has been linked to vascular disease, little is known about smooth muscle cell TLR2 in atherosclerosis. This study addresses the role of SAA and TLR2 activation on smooth muscle cell matrix gene expression and insoluble elastin accumulation. Cultured rat aortic smooth muscle cells were treated with SAA or TLR2 agonists and the effect on expression of matrix metallopeptidase 9 (MMP9) and tropoelastin studied. SAA up-regulated MMP9 expression. Tropoelastin is an MMP9 substrate and decreased tropoelastin levels in SAA-treated cells supported the concept of extracellular matrix remodeling. Interestingly, SAA-induced down-regulation of tropoelastin was not only evident at the protein level but at the level of gene transcription as well. Contributions of proteasomes, nuclear factor κ B and CCAAT/enhancer binding protein β on regulation of MMP9 vs. tropoleastin expression were revealed. Effects on Mmp9 and Eln mRNA expression persisted with long-term SAA treatment, resulting in decreased insoluble elastin accumulation. Interestingly, the SAA effects were TLR2-dependent and TLR2 activation by bacterial ligands also induced MMP9 expression and decreased tropoelastin expression. These data reveal a novel mechanism whereby SAA and/or infection induce changes in vascular elastin consistent with atherosclerosis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Amphibians are currently the most threatened group of vertebrates worldwide, and introduced fauna play a major role in their decline. The control of introduced predators to protect endangered species ...is often based on predation rates derived from diet studies of predators, but prey detection probabilities using different techniques are variable. We measured the detectability of frogs as prey, using morphological and DNA‐based diet analyses, in the stomachs and faeces of four mammal species that have been introduced to many areas of the world. Frogs (Litoria raniformis) were fed to rats (Rattus norvegicus and R. rattus), mice (Mus musculus) and hedgehogs (Erinaceus europaeus). DNA‐based analysis outperformed morphological analysis, increasing the prey detection rate from 2% to 70% in stomachs and from 0% to 53% in faeces. In most cases, utilizing either stomachs or faeces did not affect the success of prey DNA detection; however, using faeces extended the detectability half‐life from 7 to 21 h. This study is the first to measure prey DNA detection periods in mammalian stomachs, and the first to compare prey DNA detection periods in the stomachs and faeces of vertebrates. The results indicate that DNA‐based diet analysis provides a more reliable approach for detecting amphibians as prey and has the potential to be used to estimate the rate of predation by introduced mammals on endangered amphibians.
Amidst a global amphibian decline, captive breeding has become an important component of many conservation management programs. Some species fail to readily reproduce in captivity, including ...leiopelmatid frogs, an archaic lineage endemic to New Zealand. Assisted reproductive technologies can improve the reproductive potential and genetic management of captive programs. Herein we describe efforts to induce spermiation and mating in the threatened Hamilton's frog Leiopelma hamiltoni using a gonadotrophin-releasing hormone agonist and human chorionic gonadotrophin. The spermiation response was poor, with few individuals releasing spermatozoa and a low sperm concentration (mean (±s.e.) 27.4±8.5×103 spermatozoa mL-1 ) when spermiation was stimulated. The sperm concentration peaked 12-24h after hormone administration, suggesting this species may be slower to react than other anurans. Spermic urine was present in five males before hormone treatment. The sperm concentration was higher in this group (128.7±54.9×103 spermatozoa mL-1 ) than in the hormone-induced males. All spermatozoa observed exhibited no motility or, at most, a limited swaying movement with no forward progression. In separate hormone induction trials with 60 individuals (two males to one female per trial), no mating was exhibited during the 12h after treatment. Further studies to hormonally stimulate gamete release and mating are needed in leiopelmatids.
Methods in amphibian biotelemetry: Two decades in review Altobelli, Joseph T.; Dickinson, Katharine J. M.; Godfrey, Stephanie S. ...
Austral ecology,
November 2022, 2022-11-00, 20221101, Letnik:
47, Številka:
7
Journal Article
Recenzirano
Odprti dostop
The use of biotelemetry in amphibian behaviour, migration, dispersal and homing research has increased with the miniaturisation and improved reliability of telemetry equipment. Here we synthesise ...biotelemetry methods and outcomes from the past two decades of published studies (n = 128; 1 January 2000–31 December 2020). We discuss trends in amphibian study duration, transmitter weight and transmitter attachment methods. The most commonly used harness designs for external transmitter attachment and surgical methods for internal implantation are described, and the benefits and potential problems of these methods are discussed. We recommend improved practices for future studies and address gaps within the current amphibian telemetry literature in regard to accurately reporting study endpoints and study subject survival. Finally, we highlight emerging technologies that could influence the next 20 years of telemetry research on amphibians.
The miniaturisation of very high frequency transmitters over the last 20 years has allowed researchers to use radio telemetry to study the movements and behaviours of increasingly smaller animals. ...However, the sensitive skin of many amphibians has continued to make fitting telemetry packages difficult. Here we describe the applicationof a waist-harness style radio telemetry package foruse on two of New Zealand's native terrestrial frogs (Leiopelma archeyi and L. hamiltoni). To determine if the harness design was suitable for field use. we conducted a laboratory trial on four captive L. hamiltoni. Individuals carried harnesses for up to 22 consecutive day s without abrasions or changes inbehaviour. After confinningthe harness would not negatively impact captive individuals, we fitted harnesses to 20 L. hamiltoni in Te Pākeka/Maud Island Scientific Reserve, northern South Island. We tracked individuals for a maximum of 8 days and recaptured L. hamiltoni showed no signs of skin irritation or skin damage at the time of harness removal. We also tested harnesses on four L. archeyi within the Wharekirauponga area of the Coromandel Forest Park, northeastern North Island. We were able to track one L. archeyi for 7 days before locating the transmitter loose in leaf litter. The harness detached from two additional individuals, one within 24 hours of frog release and another 12 hours after release. We were unable to relocate one individual. Although the use of radio telemetry on leiopelmatids is not without difficulties, the observations collected during our field trials provide strong support that a waist-harness design is a suitable and effective method to conduct short-tenn radio telemetry on leiopelmatid frogs.
1. Altered global climates in the 21st century pose serious threats for biological systems and practical actions are needed to mount a response for species at risk. 2. We identify management actions ...from across the world and from diverse disciplines that are applicable to minimizing loss of amphibian biodiversity under climate change. Actions were grouped under three thematic areas of intervention: (i) installation of microclimate and microhabitat refuges; (ii) enhancement and restoration of breeding sites; and (iii) manipulation of hydroperiod or water levels at breeding sites. 3. Synthesis and applications. There are currently few meaningful management actions that will tangibly impact the pervasive threat of climate change on amphibians. A host of potentially useful but poorly tested actions could be incorporated into local or regional management plans, programmes and activities for amphibians. Examples include: installation of irrigation sprayers to manipulate water potentials at breeding sites; retention or supplementation of natural and artificial shelters (e.g. logs, cover boards) to reduce desiccation and thermal stress; manipulation of canopy cover over ponds to reduce water temperature; and, creation of hydrologoically diverse wetland habitats capable of supporting larval development under variable rainfall regimes. We encourage researchers and managers to design, test and scale up new initiatives to respond to this emerging crisis.
Translocations are becoming increasingly common although the effectiveness of this conservation tool for amphibians is highly variable. We reviewed ten translocations of Leiopelma frogs occurring ...between 1924 and 2016. Data were gathered on factors which may have influenced translocation outcomes. Results at each location were measured against an established four-step framework for stages of success: survival of individuals, reproduction, population growth, and population viability. Three conservation translocations and two mitigation translocations were considered to have failed, indicated by no or low survival of founders or lack of evidence of reproduction within a reasonable timeframe. Causes of failure include invasive predators at the release site, small founder numbers, homing, and poor habitat quality. The remaining five translocations were considered either successful (meeting all four stages of success), or on the road to success (meeting at least the first two stages of success). Successful translocations included predator control, total release of more than 70 founders, and in some cases adaptive management to address management decisions over time. Our findings emphasise the need for long-term post-release monitoring (> 25 years) to determine translocation success for K-selected species. Better, cost-effective, methods for monitoring population growth and population viability are required for Leiopelma frogs. Improvements could be made in open access reporting of methods and decision-making, disease risk analysis and stakeholder engagement. Further, improving our knowledge of what makes high quality Leiopelma habitat would help to objectively assess potential future translocation sites. Future translocations should consider the impacts of predicted global climate change; assisted migration may be required in the future. Translocations are a risky conservation strategy, so should only be undertaken with good cause, quality planning, and sufficient long-term resources for monitoring and management. Any future translocations for Leiopelma, whether motivated by conservation or mitigation, should follow best practice guidelines and use evidence-based decision-making to maximise outcomes.
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