Rooting morphologically divergent taxa – slow-evolving sequence data might help (original) (raw)
2020
When fossils are sparse and the lineages studied are very divergent morphologically, analyses based exclusively on morphology may lead to conflicting and unexpected hypotheses. Through integration of data from conservative genes/gene regions the terminals including these data can anchor or constrain the search, thereby practically circumscribing the search space of the combined analyses. In this study, we revisit the phylogeny of a highly divergent group of mosses, class Polytrichopsida. We supplemented the morphological matrix by adding sequence data of the nuclear gene 18S, chloroplast genesrbcL andrps4, plus the mitochondrial genenad5. For the phylogenetic analyses we used parsimony as the optimality criterion. Analyses that included all the terminals resulted in one most parsimonious tree with a clade comprised ofAlophosia azoricaand the fossilMeantoinea alophosioidesrepresenting the basal-most lineage. Analyses with different outgroup sampling produced the same topology for mos...
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The class Polytrichopsida are a diverse but phylogenetically isolated lineage of mosses, and hence putative homologues of many molecular characters that are informative within the group cannot be confidently identified in outgroup taxa. Here we use a small dataset of predominantly slowly evolving nuclear and chloroplast DNA characters to identify the earliest dichotomy within the class and provide an internal root for our ongoing larger scale analyses including more rapidly evolving regions. The peristomate Atrichopsis compressa, previously hypothesised to form the sister group to the rest of the class together with the eperistomate Alophosia azorica, is shown to be derived from within Notoligotrichum. Alophosia alone is sister to all other polytrichopsid taxa while the next dichotomy within the class involves a second lineage of eperistomate taxa and the peristomate clade, strongly supporting the hypothesis that the structurally unique polytrichopsid peristome is a parallel evoluti...
The diversity of the Polytrichopsida—a review
Bryophyte Diversity and Evolution, 2021
The class Polytrichopsida are a phylogenetically isolated moss lineage of around 200 species. The nematodontous peristome found in most species has a fundamentally different structure from the arthrodontous peristome of the Bryopsida and may be independently evolved from an ancestral type of spore dehiscence apparatus. Within the class generic circumscriptions and relationships are now fairly confidently resolved and more or less congruent with the most developed pre-molecular taxonomy. Drawing on previously published datasets, we conducted a phylogenetic analysis of a novel matrix of terminals representing diversity across the Polytrichopsida. The class comprises 17 extant genera and two known only from fossils. Most of these are numerically small, the most notable exception being Pogonatum with over 50 species. Considering current phylogenetic hypotheses in the light of morphology and global distributions, Alophosia, Bartramiopsis and Lyellia, the earliest diverging lineages accor...
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