title: Toward a study of gene regulatory constraints to morphological evolution of the Drosophila ocellar region.
abstract: The morphology and function of organs depend on coordinated changes in gene expression during development. These changes are controlled by transcription factors, signaling pathways, and their regulatory interactions, which are represented by gene regulatory networks (GRNs). Therefore, the structure of an organ GRN restricts the morphological and functional variations that the organ can experience-its potential morphospace. Therefore, two important questions arise when studying any GRN: what is the predicted available morphospace and what are the regulatory linkages that contribute the most to control morphological variation within this space. Here, we explore these questions by analyzing a small "three-node" GRN model that captures the Hh-driven regulatory interactions controlling a simple visual structure: the ocellar region of Drosophila. Analysis of the model predicts that random variation of model parameters results in a specific non-random distribution of morphological variants. Study of a limited sample of drosophilids and other dipterans finds a correspondence between the predicted phenotypic range and that found in nature. As an alternative to simulations, we apply Bayesian networks methods in order to identify the set of parameters with the largest contribution to morphological variation. Our results predict the potential morphological space of the ocellar complex and identify likely candidate processes to be responsible for ocellar morphological evolution using Bayesian networks. We further discuss the assumptions that the approach we have taken entails and their validity.
authors.affiliation: CABD (Andalusian Centre for Developmental Biology), CSIC-UPO-JA, Campus Universidad Pablo de Olavide, 41013, Seville, Spain. daguilar@pks.mpg.de.|Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187, Dresden, Germany. daguilar@pks.mpg.de.
authors.forename: Daniel
authors.initials: D
authors.lastname: Aguilar-Hidalgo
authors.affiliation: Universidad Loyola Andalucía (AYRNA), 41014, Seville, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Becerra-Alonso
authors.affiliation: CABD (Andalusian Centre for Developmental Biology), CSIC-UPO-JA, Campus Universidad Pablo de Olavide, 41013, Seville, Spain.
authors.forename: Diana
authors.initials: D
authors.lastname: García-Morales
authors.affiliation: CABD (Andalusian Centre for Developmental Biology), CSIC-UPO-JA, Campus Universidad Pablo de Olavide, 41013, Seville, Spain. fcasfer@upo.es.
authors.forename: Fernando
authors.initials: F
authors.lastname: Casares
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D004330:Drosophila / Q000033:anatomy & histology* / Q000145:classification / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics; D019143:Evolution, Molecular; D053263:Gene Regulatory Networks; D014644:Genetic Variation; D053823:Hedgehog Proteins / Q000235:genetics; D000069550:Machine Learning
chemical_list: D029721:Drosophila Proteins; D053823:Hedgehog Proteins; C077245:hh protein, Drosophila
keywords: Bayesian network; Evolution; Gene network; Hedgehog; Mathematical model; Ocellus; Patterning