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Rodney Withall

MSc Candidate

Research: Molecular systematic investigations into the Rhodophyta with particular attention to the phylogeny of the Halymeniales.

Algae was first introduced to me while completing a Bachelor’s degree at the University of British Columbia. As my undergraduate career progressed, I expanded my knowledge beyond marine invertebrates, becoming interested in algal ecology such as diversity, reproduction, and symbiotic associations. While enrolled in a summer phycology course at the Bamfield Marine Sciences Centre, I was influence by two individual’s love for algae, Dr. Louis Druehl and Dr. Gary Saunders. It was here where I developed a keen interest in algal taxonomy, systematics, and population genetics.

Upon completion of my bachelors degree I gave into the lure of the Great Barrier Reef and set off to explore the marine habitats of Australia. This was facilitated by working as a marine educator and scuba diving instructor for Poseidon Outer Reef Cruises in Port Douglas (QLD) and then PRO DIVE in Sydney (NSW). These travels provided a great opportunity to familiarize myself with new, very different marine organisms and provided opportunity to develop and improve my underwater photography skills. some example photos.

Visas eventually expire, requiring me to take life seriously once again. I began research in September 2001 exploring issues in red algae taxonomy that are of interest to me. My research is driven by interest in the relationships between the approximately nine recognized orders within "Lineage 4" (Bonnemaisoniales, Ceramiales, Gelidiales, Gigartinales, Gracilariales, Halymeniales, Nemastomatales, Plocamiales, Rhodymeniales) of the class Floideophyceae. Molecular phylogenies based on the small-subunit (SSU) ribosomal DNA fail to resolve relationships for a number of key phylogenetic issues.

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Of the eight currently recognized orders in Lineage 4, SSU analysis only resolve an association between the Halymeniales and the Rhodymeniales. The situation is further confounded owing to a number of independent lines of the Gigartinales sensu lato (in the broad sense) also stemming from the polychotomy of Lineage 4, further eroding our understanding of ordinal relationships and boundaries.

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Gloiosaccion Harvey (photographed near Hobart on a recent trip to Tasmania)

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Stenogramme (photographed during the same dive at Arch rock, Ninepin point marine reserve)

 The primary objective of my research was to construct more comprehensive molecular phylogenies utilizing the more variable large-subunit (LSU) ribosomal DNA gene in addition to the SSU rDNA. The combined SSU+ LSU analyses indicate that the contradictory published gene phylogenies result from the presence of long branch attraction artifacts among numerous groups within the combined phylogenies of Lineage 4. Subsequent investigations remain in progress to elucidate the true affinities.