• Benefits of overwintering in the conservation breeding and translocation of a critically endangered amphibian

      Calatayud, Natalie E.; Hammond, Talisin T.; Gardner, Nicole R.; Curtis, Michelle J.; Swaisgood, Ronald R.; Shier, Debra M. (2020)
      At high altitudes, amphibians brumate (over winter) during the winter months, an adaptation that provides protection from harsh weather and minimizes metabolic demand when food resources are scarce. However, brumation in ex situ populations is often avoided due to concerns regarding slow growth rates, compromised immunity, and increased morbidity, and to accelerate growth and sexual maturation. Running counter to these ideas is the hypothesis that husbandry that mimics the environmental conditions under which a species evolved may benefit animal health and reproduction. This may be particularly critical for animals slated for release into the wild. Here, we evaluated the effects of brumation on juvenile southern mountain yellow-legged frogs (Rana muscosa) in a conservation breeding and release program. Growth measurements, (weight and snout-urostyle length [SUL]), were examined in three experimental groups: Nonbrumated, 1 or 3-month brumation. Postrelease survival was also analyzed and compared between nonbrumated and 3-month brumated frogs. This study indicates that brumated R. muscosa juveniles grow to sizes and weights similar to controls within 3 to 4 months following brumation. Mark-recapture models suggested that short-term postrelease survival was not lower and in fact, may be higher in brumated compared to nonbrumated frogs. Results of this study indicate that although brumation entails short-term costs to growth, this species possesses compensatory growth mechanisms following brumation which allow them to attain similar body size to nonbrumated conspecifics in time for the next winter and that for frogs destined for translocation to the wild, brumation could improve survival outcomes.
    • Differential success in obtaining gametes between male and female Australian temperate frogs by hormonal induction: A review

      Clulow, John; Pomering, Melissa; Herbert, Danielle; Upton, Rose; Calatayud, Natalie E.; Clulow, Simon; Mahony, Michael J.; Trudeau, Vance L. (2018)
      Most Australian frogs fall into two deeply split lineages, conveniently referred to as ground frogs (Myobatrachidae and Limnodynastidae) and tree frogs (Pelodryadidae). Species of both lineages are endangered because of the global chytrid pandemic, and there is increasing interest and research on the endocrine manipulation of reproduction to support the use of assisted reproductive technologies in conservation....
    • Emerging trends for biobanking amphibian genetic resources: The hope, reality and challenges for the next decade

      Kouba, Andrew J.; Lloyd, Rhiannon E.; Houck, Marlys L.; Silla, Aimee J.; Calatayud, Natalie E.; Trudeau, Vance L.; Clulow, John; Molinia, Frank; Langhorne, Cecilia; Vance, Carrie; et al. (2013)
      …Although many institutions have responded by establishing captive assurance colonies for several critically endangered amphibians, the resources provided by these conservation organizations will not be enough to save all species ‘at risk’ without a multi-pronged approach… Several international workshops on amphibian gene banking and assisted reproductive technologies have been held between 2010 and 2012, bringing together leading experts in the fields of amphibian ecology, physiology, and cryobiology to synthesize emerging trends for biobanking amphibian genetic resources, provide opportunities for collaboration, and discuss future research directions.…
    • Ovarian control and monitoring in amphibians

      Calatayud, Natalie E.; Stoops, M.; Durrant, Barbara S. (2018)
      Amphibian evolution spans over 350 million years ago, consequently this taxonomic group displays a wide, complex array of physiological adaptations and their diverse modes of reproduction are a prime example. Reproduction can be affected by taxonomy, geographic and altitudinal distribution, and environmental factors....
    • Reproductive techniques for ovarian monitoring and control in amphibians

      Calatayud, Natalie E.; Chai, Norin; Gardner, Nicole R.; Curtis, Michelle J.; Stoops, Monica A. (2019)
      Ovarian control and monitoring in amphibians require a multi-faceted approach. There are several applications that can successfully induce reproductive behaviors and the acquisition of gametes and embryos for physiological or molecular research. Amphibians contribute to one-quarter to one-third of vertebrate research, and of interest in this context is their contribution to the scientific community's knowledge of reproductive processes and embryological development. However, most of this knowledge is derived from a small number of species. In recent times, the decimation of amphibians across the globe has required increasing intervention by conservationists. The captive recovery and assurance colonies that continue to emerge in response to the extinction risk make existing research and clinical applications invaluable to the survival and reproduction of amphibians held under human care. The success of any captive population is founded on its health and reproduction and the ability to develop viable offspring that carry forward the most diverse genetic representation of their species. For researchers and veterinarians, the ability to monitor and control ovarian development and health is, therefore, imperative. The focus of this article is to highlight the different assisted reproductive techniques that can be used to monitor and, where appropriate or necessary, control ovarian function in amphibians. Ideally, any reproductive and health issues should be reduced through proper captive husbandry, but, as with any animal, issues of health and reproductive pathologies are inevitable. Non-invasive techniques include behavioral assessments, visual inspection and palpation and morphometric measurements for the calculation of body condition indices and ultrasound. Invasive techniques include hormonal injections, blood sampling, and surgery. Ovarian control can be exercised in a number of ways depending on the application required and species of interest.