title: A new technique for identifying sequence heterochrony.
abstract: Sequence heterochrony (changes in the order in which events occur) is a potentially important, but relatively poorly explored, mechanism for the evolution of development. In part, this is because of the inherent difficulties in inferring sequence heterochrony across species. The event-pairing method, developed independently by several workers in the mid-1990s, encodes sequences in a way that allows them to be examined in a phylogenetic framework, but the results can be difficult to interpret in terms of actual heterochronic changes. Here, we describe a new, parsimony-based method to interpret such results. For each branch of the tree, it identifies the least number of event movements (heterochronies) that will explain all the observed event-pair changes. It has the potential to find all alternative, equally parsimonious explanations, and generate a consensus, containing the movements that form part of every equally most parsimonious explanation. This new technique, which we call Parsimov, greatly increases the utility of the event-pair method for inferring instances of sequence heterochrony.
authors: Institute of Biology, Leiden University, Kaiserstraat 63, Leiden, 2311GP, The Netherlands.
authors: Jonathan E
authors: JE
authors: Jeffery
authors: Olaf R P
authors: OR
authors: Bininda-Emonds
authors: Michael I
authors: MI
authors: Coates
authors: Michael K
authors: MK
authors: Richardson
mesh_terms: D000465:Algorithms; D000818:Animals; D002965:Classification / Q000379:methods*; D003627:Data Interpretation, Statistical; D009024:Morphogenesis / Q000502:physiology*; D010802:Phylogeny; D013997:Time Factors