Rooting the Animal Tree of Life. (7th June 2021)

• Record Type: Journal Article
• Authors: Li, Yuanning; Shen, Xing-Xing; Evans, Benjamin; Dunn, Casey W; Rokas, Antonis
• Editors: Tamura, Koichiro
• Is Part Of: Molecular biology and evolution. Volume 38:Number 10(2021)
• Page Start: 4322
• Page End: 4333
• Publication Date: 2021-06-07
• Subjects: phylogenomics -- Ctenophora-sister -- Porifera-sister -- substitutional models -- substitutional categories -- outgroup sampling -- sensitivity analyses; Molecular biology -- Periodicals; Molecular evolution -- Periodicals; Evolution, Molecular -- Periodicals; Molecular Biology -- Periodicals; 572.8
• DOI: 10.1093/molbev/msab170
• Languages: English
• ISSNs: 0737-4038

Abstract

Abstract: Identifying our most distant animal relatives has emerged as one of the most challenging problems in phylogenetics. This debate has major implications for our understanding of the origin of multicellular animals and of the earliest events in animal evolution, including the origin of the nervous system. Some analyses identify sponges as our most distant animal relatives (Porifera-sister hypothesis), and others identify comb jellies (Ctenophora-sister hypothesis). These analyses vary in many respects, making it difficult to interpret previous tests of these hypotheses. To gain insight into why different studies yield different results, an important next step in the ongoing debate, we systematically test these hypotheses by synthesizing 15 previous phylogenomic studies and performing new standardized analyses under consistent conditions with additional models. We find that Ctenophora-sister is recovered across the full range of examined conditions, and Porifera-sister is recovered in some analyses under narrow conditions when most outgroups are excluded and site-heterogeneous CAT models are used. We additionally find that the number of categories in site-heterogeneous models is sufficient to explain the Porifera-sister results. Furthermore, our cross-validation analyses show CAT models that recover Porifera-sister have hundreds of additional categories and fail to fit significantly better than site-heterogenuous models with far fewer categories. Systematic and standardized testing of diverse phylogenetic models suggests that we should be skeptical of Porifera-sister results both because they are recovered under such narrow conditions and because the models in these conditions fit the data no better than other models that recover Ctenophora-sister.