Effects of evolutionary history on adaptation in bean beetles, a model system for inquiry-based laboratories

Abstract

Current reforms in undergraduate biology education are advancing research experiences in laboratory courses. Such experiences in evolutionary biology have largely been limited to microbial systems. We designed a guided-inquiry experiment in which students examine the effect of evolutionary history on the potential for adaptation in the bean beetle (Callosobruchus maculatus), an insect model system widely used in evolutionary biology research. Bean beetles lay their eggs on a variety of species of dried beans (seeds of species in the Fabaceae) and the larvae develop within the bean. They are an ideal model system for studies of experimental evolution in teaching laboratories as they are easy to rear, handle and manipulate. In this study, students design an experiment to determine if adaptation to a particular bean host pre-adapts their offspring to be more successful on a new bean host. Preliminary experiments by our students suggest that beetles adapted to a lower quality host (adzuki beans, Vigna angularis) are more successful on a new higher quality host (black-eyed peas, Vigna unguiculata) than beetles adapted to a higher quality host (mung beans, Vigna radiata). However, beetles adapted to black-eyed peas are more successful on mung beans than adzuki beans. Taken together, their results show that an evolutionary history on a low quality host might allow bean beetles to be more successful at invading new hosts.