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首页> 外文学位 >Environmental, landscape, and host-related factors associated with parasitism and its effects on larvae and metamorphic frogs of Rana pipiens.
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Environmental, landscape, and host-related factors associated with parasitism and its effects on larvae and metamorphic frogs of Rana pipiens.

机译：与寄生性有关的环境，景观和寄主相关因素及其对幼蛙和变态蛙的影响。

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摘要

The emergence of several diseases affecting amphibian populations worldwide has prompted investigations into factors that determine the distribution and abundance of parasites in frogs. Environmental and land use determinants of the structure of parasite communities of metamorphic frogs of Rana pipiens were examined in Minnesota. The parasite communities uncovered comprised of 25 taxa, and nearly every frog examined (∼98%) was infected with one or more helminth species. Larvae of trematodes, which have complex life cycles and use tadpoles as intermediate hosts, dominated the communities. The distributions and abundances of parasites across populations were related to the availability of forest within 2 km distances, and up to 10 km distances, from wetland perimeters. As more forest was available, mean parasite abundances and richness of parasite communities increased. In contrast, frogs that emerged from wetlands within landscapes dominated by agriculture, where forested habitats were much more limited, tended to be infected with fewer parasite species, at lower abundances. Loss of fragments of natural habitats as a result of intensified agricultural land practices probably accounts for fewer visits to wetlands by the definitive hosts of these parasites to wetlands remaining, and therefore, explains the lower abundances in metamorphic frogs. In addition to this field study, interactions between larvae of R. pipiens and two parasites that occurred in Minnesota, Echinostoma trivolvis (and related trematodes) and Ribeiroia ondatrae, were investigated in the laboratory. Individuals were exposed to cercariae at different stages of development and monitored for survival and, in the case of R. ondatrae, for abnormal limb development. For both parasite species, survival was dependent upon the developmental stage of tadpoles at the time of infection. Individuals infected with either of the parasites at early tadpole stages (Gosner [1960] 24–25) experienced higher mortality than later staged-tadpoles, and mortality at these early life stages often exceeded 90%. The ability of R. ondatrae to induce limb malformations was also stage-specific, with the majority of malformations observed in tadpoles infected during the limb bud phase (Gosner 27–28) of limb development. The importance of other hosts involved in parasite life cycles and temporal aspects of frog-parasite interactions are emphasized.
机译：影响全球两栖动物种群的几种疾病的出现，促使人们对决定青蛙中寄生虫的分布和数量的因素进行了调查。在明尼苏达州研究了环境和土地利用决定性变种 Pianaens 的青蛙的寄生虫群落结构。所发现的寄生虫群落由25个分类单元组成，几乎每只青蛙（〜98％）都感染了一种或多种蠕虫。吸虫的生命周期复杂，并以t作为中间宿主，它们占据了社区的主导地位。种群中寄生虫的分布和丰度与距湿地周界2公里以内（最长10公里）内的森林可用性有关。随着可用森林的增加，平均寄生虫数量和寄生虫群落的丰富度增加。相比之下，从以农业为主的景观中的湿地中出现的青蛙（森林栖息地更加有限）倾向于以较少的丰度感染较少的寄生虫物种。耕地集约化经营造成自然栖息地碎片的减少，可能是这些寄生虫的确定寄主对剩余湿地的湿地访问次数减少的原因，因此，可以解释变质蛙的丰度较低。除此实地研究外， R幼虫之间的相互作用。在实验室中调查了明尼苏达州的pipiens 和两种寄生虫，即 Echinostoma trivolvis （和相关的吸虫）和 Ribeiroia ondatrae 。个体在不同的发育阶段暴露于尾c，并监测其存活率，对于 R而言。 ondatrae ，用于异常肢体发育。对于这两种寄生虫，其存活都取决于感染时of的发育阶段。在t早期感染任何一种寄生虫的人（Gosner [1960] 24-25）的死亡率要比后期的-更高，并且在这些早期生命阶段的死亡率通常超过90％。 R的能力。 ondatrae 诱发肢体畸形也是特定于阶段的，在肢体发育的肢芽阶段（Gosner 27-28）感染的infected中观察到了大多数畸形。强调了其他宿主参与寄生虫生命周期以及青蛙与寄生虫相互作用的时间方面的重要性。

著录项

  • 作者

    Schotthoefer, Anna Marie.;

  • 作者单位

    University of Illinois at Urbana-Champaign.;

  • 授予单位 University of Illinois at Urbana-Champaign.;
  • 学科 Biology Ecology.; Biology Zoology.
  • 学位 Ph.D.
  • 年度 2003
  • 页码 p.1056
  • 总页数 225
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生态学（生物生态学）;
  • 关键词

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