One 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.
