confused flour beetle larvae have a tendency to cannibalize nearby eggs (’cause they’re confused? (~_^) ). wade wanted to find out if there were any differences in the cannibalization rates between more closely related versus not so closely related hatches. so, he outbred some groups of beetles and inbred other groups to see what would happen.
“In experimental studies of kin selection, using laboratory populations of the flour beetle, Tribolium confusum, Wade (1980a) investigated the effects of discontinuities in population breeding structure on the predictions of kin selection theory. The experiment consisted of synthesizing a strain of T. confusum with genetic variability for the tendency of larvae to cannibalize eggs. Beetles randomly chosen from this strain were then placed in six different treatments, each representing a different population structure, and the evolution of the cannibalism behavior was followed for several generations….
“The population structure was varied by varying both the degree of genetic relatedness between the larval cannibals and their egg victims and the degree of random mating. Depending on the treatment, the genetic relationship between the larvae and eggs was .50 (full-sibs), .25 (half-sibs), or .00 (no relationship). These ‘interaction treatments’ were factorially combined with two different breeding structures, representing the extremes of (1) random mating and (2) within-group mating. Wade (1980a) observed that the egg cannibalism rates, which were initially equal, diverged significantly from one another only in the within-group mating treatments. Specifically, in that treatment where the larvae and eggs were full-sibs, cannibalism rates declined relative to the treatment where the larvae and eggs were unrelated. Cannibalism rates in the half-sib treatment were intermediate. In those treatments with random mating, however, no differences in cannibalism rates were observed regardless of the larval-egg relationship….
“On the basis of this comparison of two extreme mating systems, Wade (1980a) concluded that inbreeding should accelerate the rate of evolution of social behaviors.”
so, inbreeding makes the evolution of altruism (and other social behaviors) easier.
digression. this research with bugs reminded of an amusing story from bill hamilton about doing research at the univ. of michigan and some other bugs [pg. 51]:
“I mathematized them [some models] as far as I could and then used simulation on the Michigan main computer, accessing it either from a huge cave-like room called NUBS in the basement of the herbarium (our nearest-neighbour building) or, later, from a smaller terminal room in my own floor of the Museum of Zoology. NUBS had firebrats plus a spectrum of dazed, earnest, and sometimes frighteningly expert freshmen. Freshmen are first-year university students; firebrats, not arsonists but primitive insects. Smartly striped like football players, the latter dashed swiftly about on the floor under the piles of unwanted output paper, especially favouring that mounded against walls. I think their name’s origin lies in their being commonly found near bakery ovens. The nature of their food there is obvious; but what it was under the paper in NUBS is hard to imagine unless perhaps there were mummified students, dead of their sorrow at their unco-operating programs.”
(note: comments do not require an email. the beetles!)