• A reservoir species for the emerging amphibian pathogen Batrachochytrium dendrobatidis thrives in a landscape decimated by disease.

      Reeder, N.M.M.; Pessier, Allan P.; Vredenburg, V.T. (2012)
      Chytridiomycosis, a disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is driving amphibian declines and extinctions in protected areas globally. The introduction of invasive reservoir species has been implicated in the spread of Bd but does not explain the appearance of the pathogen in remote protected areas. In the high elevation (>1500 m) Sierra Nevada of California, the native Pacific chorus frog, Pseudacris regilla, appears unaffected by chytridiomycosis while sympatric species experience catastrophic declines. We investigated whether P. regilla is a reservoir of Bd by comparing habitat occupancy before and after a major Bd outbreak and measuring infection in P. regilla in the field, monitoring susceptibility of P. regilla to Bd in the laboratory, examining tissues with histology to determine patterns of infection, and using an innovative soak technique to determine individual output of Bd zoospores in water. Pseudacris regilla persists at 100% of sites where a sympatric species has been extirpated from 72% in synchrony with a wave of Bd. In the laboratory, P. regilla carried loads of Bd as much as an order of magnitude higher than loads found lethal to sympatric species. Histology shows heavy Bd infection in patchy areas next to normal skin, a possible mechanism for tolerance. The soak technique was 77.8% effective at detecting Bd in water and showed an average output of 68 zoospores per minute per individual. The results of this study suggest P. regilla should act as a Bd reservoir and provide evidence of a tolerance mechanism in a reservoir species....
    • Change: Risks and predictability

      Hobohm, Carsten; Vanderplank, Sula E.; Hobohm, Carsten; Cabin, Robert J. (Springer International PublishingCham, Switzerland, 2021)
      ...This study deals with the question of how stochastic effects, changing ecological conditions, the introduction of alien species, and dramatic events in general, can be characterized and quantified. We propose some initial ideas for the establishment of an indicator system for constancy and change through time, with respect to the effect size....
    • Efforts to restore the California condor to the wild

      Wallace, Michael P. (2012)
      By the early 1980s new studies using radio telemetry and moult patterns to identify individuals indicated that only 21 California condors (Gymnogyps californianus) existed, with five pairs sporadically breeding. With continuous and poorly understood mortality, the decision was made to capture the remaining animals and in 1987 all 27 birds were placed in the protective custody of the San Diego and Los Angeles zoos, at which time the species was considered Extinct in the Wild....
    • Reducing the extinction risk of populations threatened by infectious diseases

      Glassock, Gael L.; Grueber, Catherine E.; Belov, Katherine; Hogg, Carolyn J. (2021)
      Extinction risk is increasing for a range of species due to a variety of threats, including disease. Emerging infectious diseases can cause severe declines in wild animal populations, increasing population fragmentation and reducing gene flow. Small, isolated, host populations may lose adaptive potential and become more susceptible to extinction due to other threats. Management of the genetic consequences of disease-induced population decline is often necessary. Whilst disease threats need to be addressed, they can be difficult to mitigate. Actions implemented to conserve the Tasmanian devil (Sarcophilus harrisii), which has suffered decline to the deadly devil facial tumour disease (DFTD), exemplify how genetic management can be used to reduce extinction risk in populations threatened by disease. Supplementation is an emerging conservation technique that may benefit populations threatened by disease by enabling gene flow and conserving their adaptive potential through genetic restoration. Other candidate species may benefit from genetic management via supplementation but concerns regarding outbreeding depression may prevent widespread incorporation of this technique into wildlife disease management. However, existing knowledge can be used to identify populations that would benefit from supplementation where risk of outbreeding depression is low. For populations threatened by disease and, in situations where disease eradication is not an option, wildlife managers should consider genetic management to buffer the host species against inbreeding and loss of genetic diversity.
    • Rewinding extinction in the northern white rhinoceros: Genetically diverse induced pluripotent stem cell bank for genetic rescue

      Korody, Marisa L.; Ford, Sarah M.; Nguyen, Thomas D.; Pivaroff, Cullen G.; Valiente-Alandi, Iñigo; Peterson, Suzanne E.; Ryder, Oliver A.; Loring, Jeanne F. (2021)
      Extinction rates are rising, and current conservation technologies may not be adequate for reducing species losses. Future conservation efforts may be aided by the generation of induced pluripotent stem cells (iPSCs) from highly endangered species. Generation of a set of iPSCs from multiple members of a species can capture some of the dwindling genetic diversity of a disappearing species. We generated iPSCs from fibroblasts cryopreserved in the Frozen Zoo: nine genetically diverse individuals of the functionally extinct northern white rhinoceros (Ceratotherium simum cottoni) and two from the closely related southern white rhinoceros (Ceratotherium simum simum). We used a non-integrating Sendai virus reprogramming method and developed analyses to confirm the cells’ pluripotency and differentiation potential. This work is the first step of a long-term interdisciplinary plan to apply assisted reproduction techniques to the conservation of this highly endangered species. Advances in iPSC differentiation may enable generation of gametes in vitro from deceased and non-reproductive individuals that could be used to repopulate the species.
    • The Frozen Zoo

      Ryder, Oliver A. (2012)
      Wildlife gene banks provide a tool for studying species and monitoring conservation efforts