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The goal of lab exercise described in this paper is to provide biology undergraduate students with research experience comparable to graduate studies but performed during regular lab sessions. Working on regular weekly 3 hour lab projects, students dedicate a portion of time to do continuous experiments on butterfly wing pattern formation. In that way students are capable to generate experimental results superior in comparison to regular lab projects. Procedure which is stretched across several weeks includes observation of butterfly growth and metamorphosis, cold shock experiments and pupae injections with sodium tungstate, chemical which alters wild type colour patterning through the modification of cell signals. Furthermore students learn how to spread specimens, photograph them, and do comparative analysis of wild type and altered colour morphs of Painted Lady with other butterfly species from the same genus. In that way students compare induced polyphenism with the actual evolution of colour patterns, getting familiar with evodevo paradigm.

Polyembryonic development is a unique mode of metazoan development in which a single zygote generates multiple embryos by clonal proliferation1. The polyembryonic parasitic insect Copidosoma floridanum shows one of the most extreme cases of polyembryony, producing up to 2,000 embryos from a single egg. In addition, this wasp exhibits an unusual polyphenism, producing two morphologically distinct larval castes, termed precocious and reproductive, that develop clonally from the same zygote2. This form of development seems incompatible with a model of insect development in which maternal pre-patterning of the egg specifies embryonic axial polarity3. Here we show that maternal pre-patterning in the form of germ plasm creates cellular asymmetry at the four-cell stage embryo of Copidosoma that is perpetuated throughout development. Laser ablations of cells show that the cell inheriting the germ plasm regulates both the fate and proliferation of the reproductive caste. Thus, we have uncovered a new mechanism of caste specification, mediated by the regulatory capacity of a single cell. This study shows that the evolution of mammalian-like regulative development of an insect embryo relies on a novel cellular context that might ultimately enhance developmental plasticity.