Mark Rebeiz

One of the greatest puzzles in evolutionary biology is to understand how the spectacular array of organismal forms on our planet arose. Research in evolutionary developmental biology (evo-devo) aims to molecularly characterize evolutionary changes in the developmental mechanisms that control morphology. Pioneering work in evo-devo uncovered the remarkable discovery that an ancient "toolkit" of regulatory pathways and transcription factors shared between flies and humans shape the development of vastly different animals. Sequencing of multiple genomes (including our own) has shown that even the most complex creatures lack originality in their repertoire of genes, suggesting that changes in gene regulation are important for generating complexity. Our research is focused on learning how these evolutionarily resilient building blocks are molecularly rearranged and modified to generate diversity, particularly differences in morphology. Specific topics include:

Figure 1. The light pigmentation of D. santomea has recently evolved from the dark coloration typical of its close relatives

How do new expression patterns evolve?

Every location where a gene is expressed (gene expression pattern) arose at some point in the past, yet the evolutionary origins of these patterns remain murky. In a hunt for newly evolved expression patterns, we are investigating the molecular mechanisms that generate new patterns, and the origins of regulatory sequences that control gene expression.

How do networks of genes evolve to generate complex phenotypes?

We are studying highly divergent pigmentation patterns of closely related Drosophila species (Figure 1) as a model to understand the intricate web of genes and mutations that underlie complex traits.

Fig.2 The posterior lobe is a male genital structure that recently evolved in the melanogaster clade.

How do new structures originate?

The evolutionary beginnings of morphological novelties, structures that bear no obvious antecedent, represent a major mystery of biology. Using the wildly divergent morphology of Drosophila genitalia (Figure 2), we are investigating genes and mutations that generate elaborate novel structures.