Graduation Date
Fall 2021
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Alexandru M. F. Tomescu
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Allison Bronson
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Christopher Berry
Third Committee Member Affiliation
Community Member or Outside Professional
Fourth Committee Member Name
Gar Rothwell
Fourth Committee Member Affiliation
Community Member or Outside Professional
Keywords
Botany, Paleobiology, Paleobotany, Zosterophyll, Systematics, Evolution
Subject Categories
Botany
Abstract
Important constituents of Siluro-Devonian floras, zosterophylls gave rise to the lycophytes. I explore the relationships of 18 zosterophyll species from 16 genera, maximizing sampling of anatomy. Using phylogenetic and phenetic methods, I (1) assess the influence of tree rooting, taxon sampling, and morphological vs anatomical characters on the stability of relationships; and (2) compare phylogenetic and phenetic methods in terms of relationships recovered. Phenetic analyses show sensitivity to taxon sampling and support placement of Renalia among zosterophylls, but do not provide results that are strongly congruent with those of phylogenetic analyses. Phylogenetic analyses demonstrate that taxon and character sampling significantly influence patterns of relationships. I consistently recovered two major clades: one, which lacks internal resolution and comprises the bulk of the zosterophyll taxa included in the analyses; the other clade includes the zosterophyll Ventarura and the lycopsid Sengelia, often accompanied by Discalis and Trichopherophyton (depending on taxon and character sampling). The placement of Sengelia in phylogenetic analyses supports earlier ideas that the zosterophyll ancestor of lycopsids had nonterminate fertile axes. Morphology- and anatomy-only analyses recover trees that differ from those obtained using morphology+anatomy, highlighting the importance of broader sampling of the morphological character space. Breadth of character sampling and not the amount of phylogenetic resolution should be the primary criterion for selecting between alternative hypotheses of relationships.
Citation Style
International Journal of Plant Sciences
Recommended Citation
Nibbelink, Megan, "Exploring zosterophyll relationships within a more broadly sampled character space: a focus on anatomy" (2021). Cal Poly Humboldt theses and projects. 534.
https://digitalcommons.humboldt.edu/etd/534