Presentation Title

A Mistletoe of the Highest Honour: Evolution of the Optimized Body Form of Dwarf Mistletoes

Format of Presentation

Poster to be presented Friday March 31, 2017

Abstract

Mistletoes are, broadly speaking, hemiparasitic flowering plants that parasitize various plants and occupy numerous geographic regions, with representative species across a nigh-cosmopolitan range. Parasitic relationships of the epiphytic mistletoes establish them as important species ecologically, where the growth deformities they induce in their hosts provide crucial shelter to small animals. Additionally, many mistletoes fruit with edible berries and are an important resource for birds and rodents. Despite these keystone ecological functions, much of mistletoe phylogeny remains unresolved. Current angiosperm phylogenetic organization divides all mistletoe species between two families, the Loranthaceae and Santalaceae, based almost entirely on molecular data. Interestingly, the accepted sister taxa (Nuytsia, Gaiadendron, and Atkinsonia) have highly developed body forms, possessing conspicuous flowers, leaves, true roots, and adopt a terrestrial growth habit with low host-specificity. In contrast, modern mistletoes are epiphytic with high host specificity, and possess modified root systems (haustoria) specialized for invading the host’s vasculature. Using environmental scanning electron microscopy, I investigate the anatomical features of the genus Arceuthobium (the dwarf mistletoes), the most diminutive mistletoe genera, and compare anatomical and developmental trends in other mistletoes. Arceuthobium represents the most substantive evolutionary reduction of the mistletoes, and thus is an important indicative genus of the modification the body form the group has undergone. In comparing floral structure, branching, and resource allocation, I will describe the complex history of mistletoes. Arceuthobium, given its reduced features and optimized body form for parasitism, appears to be the latest diverging genus, reaffirming its position as the most specialized mistletoe.

Department

Biological Sciences

Faculty Advisor

Cynthia Ross Friedman

This document is currently not available here.

Share

COinS
 

A Mistletoe of the Highest Honour: Evolution of the Optimized Body Form of Dwarf Mistletoes

Mistletoes are, broadly speaking, hemiparasitic flowering plants that parasitize various plants and occupy numerous geographic regions, with representative species across a nigh-cosmopolitan range. Parasitic relationships of the epiphytic mistletoes establish them as important species ecologically, where the growth deformities they induce in their hosts provide crucial shelter to small animals. Additionally, many mistletoes fruit with edible berries and are an important resource for birds and rodents. Despite these keystone ecological functions, much of mistletoe phylogeny remains unresolved. Current angiosperm phylogenetic organization divides all mistletoe species between two families, the Loranthaceae and Santalaceae, based almost entirely on molecular data. Interestingly, the accepted sister taxa (Nuytsia, Gaiadendron, and Atkinsonia) have highly developed body forms, possessing conspicuous flowers, leaves, true roots, and adopt a terrestrial growth habit with low host-specificity. In contrast, modern mistletoes are epiphytic with high host specificity, and possess modified root systems (haustoria) specialized for invading the host’s vasculature. Using environmental scanning electron microscopy, I investigate the anatomical features of the genus Arceuthobium (the dwarf mistletoes), the most diminutive mistletoe genera, and compare anatomical and developmental trends in other mistletoes. Arceuthobium represents the most substantive evolutionary reduction of the mistletoes, and thus is an important indicative genus of the modification the body form the group has undergone. In comparing floral structure, branching, and resource allocation, I will describe the complex history of mistletoes. Arceuthobium, given its reduced features and optimized body form for parasitism, appears to be the latest diverging genus, reaffirming its position as the most specialized mistletoe.