• 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....
    • Conservation of amphibians and reptiles in the British Virgin Islands: status and patterns

      Perry, G.; Gerber, Glenn P.; Hailey, A.; Wilson, B.S.; Horrocks, J. (Brill Academic PublishersLeiden, The Netherlands, 2011)
      ...Invasive species are still arriving, establishing, and spreading. Thus, although the short-term conservation status of the BVI herpetofauna appears unlikely to change, we are more concerned about the mid-term outlook. We recommend some specific remedies intended to offset these pressures and provide long-term protection to the biota of the BVI
    • Do invasive rodents impact endangered insular iguana populations?

      Hayes, William K.; Iverson, John B.; Knapp, Charles R.; Carter, Ronald L. (2012)
      Ample evidence confirms that large invasive mammalian competitors and predators can devastate endangered insular iguana populations. However, the impact of invasive rodents, particularly rats (Rattus rattus), has remained elusive....
    • Grassland response to herbicides and seeding of native grasses 6 years posttreatment

      Endress, Bryan A.; Parks, Catherine G.; Naylor, Bridgett J.; Radosevich, Steven R.; Porter, Mark (2012)
      Herbicides are the primary method used to control exotic, invasive plants. This study evaluated restoration efforts applied to grasslands dominated by an invasive plant, sulfur cinquefoil, 6 yr after treatments....
    • Green iguanas (Iguana iguana) in the Dominican Republic

      Pasachnik, Stesha A.; Carreras De León, Rosanna; Reynoso, Víctor; Rupp, Ernst; León, Yolanda; Incháustegui, Sixto (2012)
      Iguana iguana has a natural distribution from México (Sinaloa and Veracruz) southward through Central America and into northeastern South America to the Tropic of Capricorn in Paraguay and southeastern Brazil. The species also occurs on numerous islands, including Cozumel, Utila, Roatán, Guanaja, the Corn Islands, Providencia, San Andrés, Aruba, Trinidad, Tobago, and others in the Lesser Antilles (Henderson and Powell 2009). It has been introduced to Anguilla, Antigua, Barbuda, British Virgin Islands, Canary Islands, Cayman Islands, Fiji, Guadeloupe, Grand Cayman, Les Îles de Saintes, Marie Galante, Martinique, Puerto Rico, Saint-Martin/Sint Maarten, St. Barthélemy, St. Croix, Turks and Caicos, U.S. Virgin Islands, and the United States (Florida, Hawaii) (Henderson and Powell 2009, Kraus 2009, Lindsay and Mussington 2009, Harlow and Thomas 2010, Powell et al. 2011)....
    • The soil seed bank in abandoned tropical pastures: source of regeneration or invasion?

      López-Toledo, Leonel; Martínez-Ramos, Miguel (2011)
      We assessed the availability of both pioneer and non-native species in the soil seed bank of old-growth forest and recently abandoned pasture, to evaluate whether the soil seed bank in these pastures represents a source of regeneration of species from adjacent old-growth forest or of invasion by non-native species. Our study was conducted at Selva Lacandona, Chiapas, Mexico. Soil samples were randomly collected from 6 sites in old-growth forest, and 6 sites in abandoned pastures. Seedlings from soil samples were identified and classified into pioneer, non-native (weeds/graminoids), and other forest species. Pioneer species seeds were virtually absent in pastures, but represented ~30% of seeds in the forest. Non-native species comprised ~99% of the soil seed bank in pastures. In the forest, soil seed bank density of weeds and graminoids decreased with increasing distance (up to 4 km) from agricultural fields, and comprised up to 25% (Mean ± 1SE= 16 ± 7) of the seed bank. Our results show a near total elimination of pioneer species from the soil seed bank in pastures, and considerable invasion of the borders of the Montes Azules reserve by seeds of non-native species. Thus, in the region studied, the soil seed bank in abandoned pastures represents a source of invasion by non-native species into old-growth forest rather than a potential source of forest regeneration.