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Phylogenetic Relationships Among the Rangeomorpha: the Importance of Outgroup Selection and Implications for Their Diversification

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Phylogenetic Relationships Among the Rangeomorpha: the Importance of Outgroup Selection and Implications for Their Diversification Canadian Journal of Earth Sciences Phylogenetic relationships among the Rangeomorpha: The Importance of outgroup selection and implications for their diversification. Journal: Canadian Journal of Earth Sciences Manuscript ID cjes-2018-0022.R2 Manuscript Type: Article Date Submitted by the Author: 01-Jul-2018 Complete List of Authors: Dececchi, Thomas; University of Pittsburgh Johnstown, Biology Greentree, Carolyn; Monash University, School of Earth, Atmosphere and EnvironmentDraft Laflamme, Marc; University of Toronto - Mississauga, Chemical and Physical Sciences Narbonne, Guy; Queen's University, Geological Sciences and Geological Engineering Keyword: Ediacaran, Phylogenetics, Rangeomorpha, Evolution Is the invited manuscript for consideration in a Special Not applicable (regular submission) Issue? : https://mc06.manuscriptcentral.com/cjes-pubs Page 1 of 48 Canadian Journal of Earth Sciences Phylogenetic relationships among the Rangeomorpha: The importance of outgroup selection and implications for their diversification. Dececchi, T.A. 1*, Narbonne G.M.2, Greentree, C.3, and Laflamme, M.4 1- Queen's University, Department of Geological Sciences and Geological Engineering, Bruce Wing/Miller Hall, Kingston, ON, CAN * Current affiliation: Biology Department, Natural Sciences Division, University of Pittsburgh Johnstown, Johnstown, Pennsylvania, 15904, U.S.A. [email protected] Draft 2- Queen's University, Department of Geological Sciences and Geological Engineering, Bruce Wing/Miller Hall, Kingston, ON, CAN. [email protected] 3- Monash University, School of Earth, Atmosphere and Environment, Clayton, VIC, AUS. [email protected] 4- University of Toronto Mississauga, Department of Chemical & Physical Sciences, Mississauga, ON, CAN. [email protected] 1 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 2 of 48 1 Abstract 2 The Rangeomorpha are the oldest, most diverse, and most disparate clade of 3 Ediacaran macrofossils. Easily identifiable by their self-similar branching pattern, 4 they occupied epibenthic niche space ranging from the lowest tiered and recumbent 5 taxa up to meter-long upright fronds. A phylogenetic analysis using the largest and 6 most complete character set known for this group scored for 14 separate taxa was 7 undertaken to resolve their internal relationships and test previous hypotheses of 8 their evolutionary and ecological history. Owing to the lack of consensus on the 9 relationship amongst Ediacaran clades, several permutations with different 10 potential outgroup taxa were performed. Across these analyses, there is a strong 11 signal for an upright frondose ancestralDraft state for this clade, likely displaying 12 primary branches that were double sided, non-rotated, with the lower tiered and 13 recumbent forms being derived members of a single subclade. This has implications 14 on the life history reconstruction as well as taxonomic implications for this clade 15 and the origins of large multicellular life in the late Ediacaran. 16 17 KEYWORDS: Ediacaran, Phylogenetics, Rangeomorpha, Evolution 18 19 20 21 22 23 2 https://mc06.manuscriptcentral.com/cjes-pubs Page 3 of 48 Canadian Journal of Earth Sciences 24 Introduction 25 The Rangeomorpha represent the most diverse Ediacaran clade (Dececchi et al. 2017). 26 They are characterized by a modular and self-similar “fractal” branching pattern that 27 spans at least 4 orders of subdivisions, ranging from primary branches that are several 28 centimeters in size all the way down to fourth order, sub millimetre branching (Narbonne 29 2004; Liu et al. 2016; Kenchington and Wilby 2017). These modular elements are 30 combined into a diverse array of forms, from flat-lying mats to erect fronds, and range in 31 size from a few centimetres to well over a meter in length. Rangeomorpha occupied a 32 range of ecological niches (Clapham et al. 2003, Ghisalberti et al. 2014, Liu et al. 2015,) 33 time slices (Xiao and Laflamme 2008; Laflamme et al. 2013) and water depths (Boag et 34 al. 2016), suggesting they representedDraft a successful group prior to their demise in the 35 latest Ediacaran. They are particularly abundant and diverse in the post-Gaskiers 36 Conception and St. John’s groups in Newfoundland (Hofmann et al. 2008; Narbonne et 37 al. 2009; Liu and Matthews 2017), age-equivalent sections in Charnwood Forest in 38 England (Wilby et al. 2011), but are also found in northwestern Canada (Narbonne et al. 39 2014), and younger occurrences in the Flinders Ranges in South Australia (Gehling and 40 Droser 2013), Siberia (Grazhdankin et al. 2008), southern Namibia (Vickers-Rich et al. 41 2013), and central China (Chen et al 2014) . This ubiquity has led to the Rangeomorpha 42 being one of the most well studied members of the Ediacaran paleocommunity, with 43 research focusing on aspects of their architecture (Narbonne 2004; Narbonne et al. 2009: 44 Brasier and Antcliffe 2009; Brasier et al. 2012), growth (Gehling and Narbonne 2007; 45 Antcliffe and Brasier 2007, 2008; Flude and Narbonne 2008; Bamforth et al. 2008; Hoyal 46 Cuthill and Conway Morris 2014; Dunn et al. 2017), ecology (Clapham et al. 2003; Liu et 3 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 4 of 48 47 al. 2015; Boag et al. 2016), population structure (Darroch et al. 2013) and even potential 48 reproductive mode (Mitchell et al. 2015). Despite these studies, evolutionary 49 relationships amongst the Rangeomorpha remain contentious (Brasier et al. 2012; Liu et 50 al. 2016; Dececchi et al. 2017). 51 Phlylogenetic approaches have previously been employed to explore the natural history 52 of the Rangeomorpha (Brasier and Antcliffe 2009; Dececchi et al. 2017). The present 53 paper expands on these studies to explore the effects that character definition, selection, 54 and variation have on Rangeomorpha alpha taxonomy, including testing previous 55 proposals for defining higher-order rankings (i.e. genus and above). Furthermore, a series 56 of standards for character construction and taxonomic classification within this clade is 57 proposed and applied to investigate Draftthe relationships among the Rangeomorpha. 58 Establishing a cladistic-based hypothesis for the internal relationships among 59 Rangeomorpha will help guide the understanding of the diversity of life prior to the 60 Cambrian explosion of complex metazoans (Erwin et al. 2011; Schiffbauer et al. 2016). 61 62 Methods 63 In order to create a well-supported phylogenetic hypothesis with a well-resolved 64 topology, it is recommended to incorporate characters derived from multiple axes of 65 information (development, growth, branch architecture, gross structural morphology, 66 etc.). In accordance with this proposal, and following the methodology of Dececchi et al. 67 (2017) in constructing a matrix of 19 distinct characters (Tables S1, S2) that fully 68 describe all morphological regions of known Rangeomorpha, and includes previously 69 proposed criteria for taxonomic differentiation (Brasier and Antcliffe 2009; Narbonne et 4 https://mc06.manuscriptcentral.com/cjes-pubs Page 5 of 48 Canadian Journal of Earth Sciences 70 al. 2009; Brasier et al. 2012).While this dataset is small compared to analysis of non- 71 Ediacaran taxa, it represents the most granular possible character resolution for these taxa 72 based on the available morphology. One major difference between this analysis and the 73 source data (Dececchi et al. 2017), beyond the addition of new taxa, is the modification 74 of several characters including changes in how growth polarity was previously defined by 75 Brasier et al. (2012) and expanding how growth is characterized and scored to reflect the 76 growth dynamics within the range of Rangeomorpha. The present paper uses the term 77 “polarity” as opposed to “terminal” from Dunn et al. (2017) due to the formers greater 78 prevalence in the literature, ease of use and the fact that the two do not differ in terms of 79 how one classifies the morphology of the taxa examined here. All characters were 80 unordered and unweighted in order toDraft reduce potential user bias. All phylogenetic 81 investigations were done in PAUP v. 4.0 (Swafford 2003) using the heuristic search 82 under default settings. Both the strict and majority rules consensus trees are presented to 83 illustrate both the most conservative topological reconstruction as well as one that are 84 found in the majority of trees, but due to the nature of the dataset with some taxa missing 85 data and the small number of OTU’s, may not be in 100% of reconstructions. This paper 86 uses parsimony over Bayesian approaches it may more accurately reflect how 87 morphological, as opposed to molecular data, functions (Goloboff et al. 2017, 2018). 88 All named taxa known from multiple specimens (5 or more) as well as several rare taxa 89 whose morphology may be informative for increasing topological resolution were 90 investigated and included in the analysis (Table S2). An expansive view of operational 91 taxonomic units (OTUs), including 14 named and 2 referred species as ingroup OTUs, 92 were included in the phylogenetic analysis in order to investigate recent proposals for 5 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 6 of 48 93 synonymy/splitting in alpha taxonomy. The genus Fractofusus into F. misrai and F. 94 andersoni were differentiated based on the criteria identified by Gehling and Narbonne 95 (2007) as they show distinct branching architecture
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