Evolution of pattern formation in insects

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Polyembryony refers to a unique form of reproduction in which a single egg results in multiple progeny, maximizing the reproductive capacity of the species. Study of the phenomenon of polyembryony in insects has the potential for addressing one of crucial questions in the evolution of development: How do developmental novelties arise? Polyembryony in insects represents a developmental novelty whereby both precursor structure and evolutionary processes are basically unknown. Copidosoma floridanum is a polyembryonic parasitic wasp that undergoes total cleavage and despite its relative close relatedness to Drosophila exhibits a major deviation from the canonical insect early developmental program. Copidosoma development consists of three phases: early cleavages, which leads to formation of a single proliferative morula; the novel proliferative phase, that generates thousands of embryos; and the morphogenetic phase, where the patterning of individual embryos takes place. Previously, we have shown by laser ablation that caste fate and embryo proliferation in Copidosoma are regulated by a single cell at the four-cell-stage embryo, which also specifies the germ line. This differential allocation of determinants to a specific cell serves as a starting point for the functional dissection of individual genes in the process of embryo proliferation and patterning.