Since I provide a link to the web site my wife and I have authored on this topic, I won't develop this interest to the same extent I devlop the following interests. Suffice it to say that our lake is a remarkable resource, about which much remains to be learned. It is a natural laboratory for exploring a wide range of ideas, from migration to community structure. We are fortunate to have such a resource close at hand, and Peg and I are working to make the value of this resource more widely acknowleged with our web site.
Olympia Marbles are a sand-prairie species in Illinois. At one time, they were considered as candidates for the state endangered and threatened species list because of the scarcity of their habitat.
There is a colony of these butterflies not far from Eureka, at Sand Ridge State Forest. I initially began exploring their nectaring behavior in the hopes of eventually doing some optimal foraging work. However, while reading Foundations of Ecology, edited by Leslie Real and James Brown, I came across the following passage from the introduction to the section entitled "Theses, Antitheses, and Syntheses: Conservation Biology and Ecological Debate" (by Joel Kingsolver and Robert Paine): "Finally, we cannot ignore the role of individual variation. While evolutionary and natural history studies continue to document ubiquitous variations among individuals in ecologically important traits, population and community ecology deal only with `average' individuals... the basic question remains: is individual variation merely `noise', or does it qualitatively alter the outcomes of ecological interactions? Here the points of debate have not yet been clearly articulated, much less synthesized."
What our natural history work with the Olympia Marble showed was marked differences in individuals in how they spent their time each day. Such variation is the raw material for evolutionary change, and deserves to be characterized rather than hidden by statistical methods that lump all individuals together as if they were all the same.
Hackberry butterflies (Asterocampa celtis [Boisduval & LeConte]) are abundant during the summer here on campus. One often sees them perching on buildings in a typical "head-down" position. If you've ever had a butterfly land on you during the summer, and sit quietly slurping up your sweat, it's probably this species.
Perching behavior seems to be a mate-locating strategy, and convential wisdom said that only the males perch, because females are a valuable resource for males and they therefore compete for optimal perch sites. I began observing this behavior on campus, and very quickly noted that females perch, too.
Statistical analyses of male and female perching behavior showed no significant differences between them, and so they must be perching for the same reasons. Since they perch regardless of ambient temperature or insolation, it seemed likely that they were both perching as a mate-locating strategy. Therefore, males are a valuable resource for females, too.
One reason for this is that males pass a large nutrient-rich spermatophore to females during mating, and research on other species of Asterocampa has shown that females mate more than once. One mating is sufficient to give the female all the sperm she needs to fertilize all the eggs she'll produce in her adult life, so she must be mating more often to obtain nutirients in the spermatophores.
In Darwin's Descent of Man... sexual selection is defined as differential success in acquiring mates. The two types of sexual selection, intrasexual selection and intersexual selection, lead to the evolution of different traits. In intrasexual selection, member of one sex compete with one another for access to members of the opposite sex. Things such as large body size are favored by this type of selection. In intersexual selection, members of one sex advertise to members of the opposite sex; indicating that the advertising individual is a good mate.
Both types of sexual selection seem to be operating in Hackberry butterflies, but what is interesting is that intrasexual selection seems to occur between females as well as between males. That is an unusual circumstance in the animal world, because males are usually "a dime a dozen" and therefore not a particularly valuable resource for females.