Reassessment of Species Boundaries and Phylogenetic Relationships in the Desmodium ciliare complex (Fabaceae) Using Morphological and DNA Data

<p><em>Desmodium</em> (Beggar's ticks) is a generally weedy genus of approximately 280 species in the angiosperm family Fabaceae (Subfamily Papilionoideae, Tribe Desmodieae) characterized by indehiscent loments constricted into segments. Within the Southeastern U.S., the <em>Desmodium</em> <em>ciliare</em> group is one of two <em>Desmodium</em> species complexes that have been historically difficult, with much argument about the limits of species and the role of hybridization. There are three commonly recognized species within the <em>D</em>. <em>ciliare</em> group, <em>D</em>. <em>ciliare</em> (Muhl. ex Willd.) DC., <em>Desmodium</em> <em>marilandicum</em> (L.) DC., and <em>D</em>. <em>obtusum</em> (Muhl. ex Willd.) DC., with two supposed hybrids in addition to the three main species involving <em>D</em>. <em>ciliare</em> with <em>D. strictum </em>(Pursh) DC. and <em>D. paniculatum</em> (L.) DC. To test the species boundaries, focused principally on material collected in Mississippi where all of the three putative species occur, principal component analysis (PCA) of morphological characteristics and analyses of both plastid <em>trnL</em>–<em>trnL</em>-<em>F</em> and nuclear ITS DNA were utilized. Based on phylogenetic analysis using 73 ITS and 12 <em>trnL</em>–<em>trnL</em>-<em>F</em> sequences, there was not enough resolution to circumscribe the <em>Desmodium </em>species of Mississippi, including the <em>D</em>. <em>ciliare</em> complex itself. However, a PCA and subsequent MANOVA of relevant vegetative/floral characters (49 used) among 33 individuals of the <em>D</em>. <em>ciliare</em> complex significantly distinguished all three species and two hybrid individuals (<em>D</em>. <em>ciliare</em> × <em>D</em>. <em>obtusum</em>) from each other. The three species in this complex differ morphologically by terminal leaflet length:width ratio, amount of stem/leaf pubescence, and petiole length.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Year dc:date.available

2022

Author dc:creator

• Wilkinson, Joshua

Contributors dc:contributor

• Mac Alford
• Donald Yee
• Micheal Davis

• Plant systematics
• Desmodium
• Fabaceae
• Leguminosae
• papilionoideae
• phylogenetics
• Botany
• Molecular Genetics
• Other Plant Sciences
• Plant Breeding and Genetics

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/896

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1959