Collaborative Research: Understanding the Roles of Natural Selection and Evolutionary Constraints in the Maintenance of Invariant Floral Traits.

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9903880ConnerA remarkable property of biological diversity is the patterning that is observed when characteristics of organisms are compared. While some features show considerable variation and can uniquely identify individuals within a population, other traits are less variable and are shared by large groups of related species. Although biologists have long recognized the importance of variation as the raw material for future evolution, the reasons why variation may sometimes be lacking are less often studied. This lack of variation could be due to constraints on evolution, caused by a lack of genetic variation or by genetic correlations with other traits. Alternatively, the lack of variation could result from natural selection eliminating unfit variants and maintaining a narrow range of traits that are well-adapted to the environment. In this research, a novel combination of artificial selection in the greenhouse and studies of natural selection in the field will be used to determine whether constraints or selection cause the low levels of variation found in two sets of floral traits. The research will be done using the wild radish (Raphanus raphanistrum Brassicaeae) and two aspects of anther morphology, the ratio of long- and short-filament lengths and the extent of long-filament exertion beyond the corolla. The basic understanding of constraints and selection generated by this research may be applicable to understanding a variety of applied evolutionary problems, such as whether crops and wild species can adapt rapidly to global climate change, conservation of endangered species (which often lack genetic variation), and the evolution of resistance to antibiotics, pesticides, and herbicides by pathogens and pests.