UC Davis

Egg weights and total eggs produced by nine Speyeria spp. (Nymphalidae) in California allowed estimates of per-egg and lifetime reproductive effort. Interpopulation reproductive effort in four species and intrapopulation reproductive effort of two species in different years were documented. Female body weight was uncorrelated with either individual egg weight or total lifetime egg weight. Smallest eggs (mean dry wt/egg = 0.05-0.06 ug), and the greatest number of eggs, were from S. coronis (Skinner) and S. zerene (Boisduval) whose females undergo summer reproductive diapause in dry habitats. Largest eggs (mean dry wt/egg = 0.10 ug) were from S. nokomis (Skinner), a wet habitat species. The greatest relative reproductive effort was made by dry habitat species lacking reproductive diapause. Reproductive effort and duration of first instar exposure to summer temperatures were positively correlated. Intrayear variation in total egg weight did not vary significantly among populations of S. callippe (Boisduval), S. hesperis (Boisduval), S. nokomis, or S. zerene but mean total egg weights were significantly different in females from the Donner Pass, CA population of S. mormonia (Boisduval) in two years. S. zerene from high elevations lacked the reproductive diapause characteristic of lower elevation populations. The reproductive strategies of Speyeria spp. are adaptive responses to the desiccation stress that their habitats impose on diapausing first instars.