Dissertation Research: The Importance of Tychoparthenogenetic Reproduction in Natural Populations of the Stenonema femoratum

Semlitsch 9801568生物学中一个最基本但基本上没有答案的问题是为什么大多数生物通过交配（双亲生殖）而不是通过自花受精或克隆（单亲生殖）进行繁殖。解决这一问题的理想研究体系是双亲和单亲繁殖在同一种群中共存的体系。第谷孤雌生殖（Tychoparthenogenesis）是一种孤雌生殖（由未受精卵产生后代），其特征是在正常有性生殖的种群中，雌性未受精卵的孵化成功率低;因此，双亲和孤雌生殖都发生在同一种群中。为了使用这样的研究系统来解决为什么大多数生物体表现出双亲生殖的问题，首先确定：1）孤雌生殖能力是否在种群之间变化; 2）雌性在自然条件下利用其孤雌生殖能力的程度; 3）第三孤雌生殖是否受遗传控制。这项研究解决了这三个标准，这将为进一步研究双亲繁殖所带来的优势以及为什么它发生在大多数生物体中提供必要的信息。这项研究是解决这些标准使用水生昆虫，蜉蝣，Stenonema femoratum。了解双亲和孤雌生殖对生物种群的影响很重要，因为生物繁殖的方式对种群长期生存的能力有重大影响。水生昆虫种群的长期生存对于许多依赖水生昆虫作为食物来源的重要猎用鱼类至关重要。

Semlitsch9801568One of the most fundamental yet largely unanswered questions in biology is why most organisms reproduce by mating (biparental reproduction) and not by self-fertilization or cloning (uniparental reproduction). The ideal study system with which to address this question is one in which both biparental and uniparental reproduction coexist within the same population. Tychoparthenogenesis is a type of parthenogenesis (production of offspring from unfertilized eggs) characterized by low hatching success of unfertilized eggs from females in normally sexually reproducing populations; therefore, both biparental and parthenogenetic reproduction occur within the same population. To use such a study system to address questions about why most organisms exhibit biparental reproduction, it is important to first determine: 1) whether parthenogenetic capacity varies among populations; 2) the extent to which females utilize their parthenogenetic capacity under natural conditions; 3) whether tychoparthenogenesis is genetically controlled. This research addresses these three criteria that will provide necessary information for further studies investigating the advantages conferred by biparental reproduction and therefore, why it occurs in most organisms. This research is addressing these criteria using an aquatic insect, the mayfly, Stenonema femoratum. Understanding the influence of biparental and parthenogenetic reproduction on populations of organisms is important because the way in which organisms reproduce can have significant impacts on the ability for populations to persist in the long-term. Long-term survival of aquatic insect populations is critical for many important game fish that rely on aquatic insects as a food source.