What makes an animal? The molecular quest for the origin of the Animal Kingdom Jordi Paps 1,2 1. School of Biological Sciences, University of Essex, Colchester CO4 3SQ, Essex, UK 2. Department of Zoology, University of Oxford, Oxford OX1 3PS, UK https://orcid.org/0000-0003-2636-6636
[email protected] From the symposium “From small and squishy to big and armored: Genomic, ecological and paleontological insights into the early evolution of animals”, presented at the annual meeting of the Society for Integrative and Comparative Biology, January 3–8, 2018, San Francisco, CA. Running title: The origin of the Animal Kingdom The total number of words (excluding references, tables, and figure legends): 4.668 Synopsis What makes an animal? To find the answer we need to integrate data from disciplines such as phylogenetics, palaeontology, ecology, development, anatomy and physiology, as well as molecular biology and genomics. Knowledge of which groups branched before and after the origin of animals is essential. Recent advances in molecular phylogenetics, together with the discovery of new eukaryotic lineages, have drawn a new picture of the ancestry of animals. The nature of the early diverging animal lineages and the timing of the transition are in a state of flux. Various factors have been linked to this striking transition to multicellularity, including changes in environmental conditions and the ecological interactions between unicellular eukaryotes. The current wealth of genomic data has also shed new light on this question. The analysis of the genome of various close relatives of animals has revealed the importance that recycling of ancient genes into metazoan biological functions played into animal origins.