Date of Award


Degree Type


Degree Name



Biological Sciences

First Advisor

Ciberowski, J. J. H.


Biology, Entomology.




There is tremendous size variation within both laboratory and field populations of the mayfly Hexagenia. I studied the size variation in adults (imagoes) of this mayfly collected in the summers of 1989 and 1990 from Lake St. Clair, Southwestern Ontario (42$\sp\circ$20$\sp\prime$N; 82$\sp\circ57\sp\prime$W). Additionally, I examined the influence of endogenous factors (egg hatching, egg diapause, maternal size) on size and survivorship of larval Hexagenia. Female imagoes collected early in the emergence period were significantly larger than females collected later in the summer. There was low incidence of parthenogenesis ($<$5%), egg diapause ($<$0.01%) and viability of eggs produced through interspecific mating (0%) in the laboratory. Egg size of H. limbata was negatively correlated with collection date. Although egg size did vary among female sizes, there was no clear relationship between egg size and maternal size. Maternal size was negatively correlated with larval size, after 40 d growth. Maternal size and (maternal size$\sp2$) were correlated with per cent larval survival. Maternal parents exhibiting mean body length produced larvae with the highest survivorship after 40 d growth. The length of incubation (days) required for egg hatch was negatively associated with per cent larval survival (40 d) but was positively correlated with larval size (80 d). Of sediments examined from six different waterbodies, Saginaw Bay sediment provided larvae with the best survivorship and the largest size, and when given a choice, larvae selected that sediment type. Subsequently, I developed a standard sediment (STND-3) that mimiced the particle size distribution and organic content of Saginaw Bay sediment. (Abstract shortened by UMI.)Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1993 .H354. Source: Masters Abstracts International, Volume: 32-02, page: 0540. Adviser: J. J. H. Ciborowski. Thesis (M.Sc.)--University of Windsor (Canada), 1993.