题目选项分析

Scientist: Evolutionary biology has long held that the most attractive males of a species, defined as those with the highest quality physical traits that have no Darwinian survival value, will draw the most female mates. The resulting male offspring will inherit that attractiveness and themselves have more children as a result, thus ensuring widespread dissemination of the grandparents' genes. Recently, however, scientists have found that the sons of "high quality" male flycatchers failed to inherit the father's mating status. Further, the most attractive males were so busy mating that they neglected their offspring; as a result, the sons of homelier birds, who took better care of their offspring, had more success at propagating the species. The two portions in boldface play which of the following roles in the scientist's argument?

【选项】The first is an explanation of how a biological theory is thought to work; the second is an example of research results that do not support this theory