Tests of Competing Hypotheses for the Maintenance of Sex and Parthenogenesis in Campeloma limum, a SE United States Snail

美国东南部蜗牛 Campeloma limum 维持性和孤雌生殖的竞争假设检验

• 批准号: 0075967
• 负责人: Steven Johnson
• 金额: $ 10.31万
• 依托单位: University of New Orleans
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-15 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0075967&HistoricalAwards=false
• 关键词: Tests; Competing; Hypotheses; Maintenance; Sex

Why organisms reproduce sexually instead of asexually is one of the outstanding problems in biology. Recent models suggest that, under higher dispersal rates of asexuals relative to sexuals, asexual organisms may persist for three reasons: escape from parasites (Red Queen hypothesis); relaxed selection against deleterious mutations; or local adaptation of asexuals to marginal environments. Using diploid sexual and asexual Campeloma limum, a freshwater snail from the southeastern US, this proposal outlines molecular and experimental field tests of these hypotheses. Using sequence variation in a mitochondrial gene (cytochrome b) and a nuclear intron (calmodulin), we will assess whether asexuals have higher dispersal rates than sexuals. We will also test unique predictions of the three models by field experiments. Because plant pathologists, epidemiologists, and conservation biologists realize that host genetic diversity plays an important role in the spread of diseases, the results from this study will be of considerable to these scientists. These results will also be of considerable interest to evolutionary biologists, because the study will provide critical tests of ecological and evolutionary causes of the spatial distribution of sexual and asexual organisms.

为什么生物是有性繁殖而不是无性繁殖是生物学中的一个突出问题。 最近的模型表明，在较高的传播率的无性相对于有性，无性生物可能会持续存在的原因有三个：逃离寄生虫（红皇后假说）;放松选择对有害的突变;或本地适应的无性边缘环境。使用二倍体有性和无性Campeloma limum，来自美国东南部的淡水蜗牛，这项建议概述了这些假设的分子和实验现场测试。 利用线粒体基因（细胞色素B）和核内含子（钙调素）的序列变异，我们将评估无性生殖者是否比有性生殖者具有更高的扩散率。 我们还将通过现场实验来测试这三个模型的独特预测。 由于植物病理学家、流行病学家和保护生物学家认识到宿主遗传多样性在疾病传播中起着重要作用，因此本研究的结果对这些科学家来说将是相当重要的。 这些结果也会引起进化生物学家的极大兴趣，因为这项研究将为有性和无性生物的空间分布的生态和进化原因提供关键的测试。