Prof. Chema Martin, Queen Mary University of London, UK
Prof. Chema Martin, from the Department of Biology at the Queen Mary University of London, will present: "The evolution and development of animal larvae"
Main content
Larvae are intermediate, often free-living life stages that occur in nearly all animal phyla and define whether animals have direct (no larval phase) or indirect (with a larva) development. With a fascinating degree of morphological and ecological diversity, larvae have played central roles in most hypotheses of animal evolution. Yet, how larvae evolved is contentious because the mechanisms controlling their development and diversification remain elusive. Recently, we have shown that temporal shifts (i.e., heterochrony) in trunk development might explain the evolution of larvae and life cycles in animals with bilateral symmetry. Yet, how these heterochronic changes occur remains unclear. Here, I will show that the establishment of a topologically associated domain (TAD) spanning the Hox cluster mirrors the timing of activation of these genes during larval development in two annelid worms with distinct timings of trunk development and larval types. This is reminiscent of vertebrate Hox regulation, where high-order chromatin structures ensure spatial and temporal collinear expression. Therefore, ancestral epigenomic and developmental principles underpin Hox gene regulation in bilaterian animals, providing a novel mechanistic framework to investigate trunk development and the evolution of animal life cycles.
