Are our phylomorphospace plots so terribly tangled?An investigation of disorder in data simulated under adaptive and nonadaptive models

• 来源期刊: 动物学报（英文版）
• 年，卷（期）: 2020,（5）
• 所属期刊栏目: Articles
• 页码范围: 565-574
• 页数: 10页
• 语种: 英文
• DOI: 10.1093/cz/zoaa045

摘要

Contemporary methods for visualizing phenotypic evolution,such as phylomorphospaces,often reveal patterns which depart strongly from a na?ve expectation of consistently divergent branching and expansion.Instead,branches regularly crisscross as convergence,reversals,or other forms of homoplasy occur,forming patterns described as"birds'nests","flies in vials",or less elegantly,"a mess".In other words,the phenotypic tree of life often appears highly tangled.Various explana-tions are given for this,such as differential degrees of developmental constraint,adaptation,or lack of adaptation.However,null expectations for the magnitude of disorder or"tangling"have never been established,so it is unclear which or even whether various evolutionary factors are required to explain messy patterns of evolution.I simulated evolution along phylogenies under a number of varying parameters(number of taxa and number of traits)and models(Brownian mo-tion,Ornstein-Uhlenbeck(OU)-based,early burst,and character displacement(CD)]and quantified disorder using 2 measures.All models produce substantial amounts of disorder.Disorder increases with tree size and the number of phenotypic traits.OU models produced the largest amounts of disorder—adaptive peaks influence lineages to evolve within restricted areas,with con-comitant increases in crossing of branches and density of evolution.Large early changes in trait values can be important in minimizing disorder.CD consistently produced trees with low(but not absent)disorder.Overall,neither constraints nor a lack of adaptation is required to explain messy phylomorphospaces—both stochastic and deterministic processes can act to produce the tantaliz-ingly tangled phenotypic tree of life.