- Animal Phylogeny
One of the primary lines
of research in the lab is to understand the evolutionary relationships
among major animal lineages. This work is drawing on information from
several different sources to build a comprehensive, consensus understanding
of animal phylogeny. In particular, we are focusing on the Lophotrochozoan
clade. This is a clade of bilaterian animals that is defined to be
all the descendants of, and including, the last common ancestor
of the annelids, mollusks, and the three lophophorate taxa (Brachiopoda,
Phoronida, and Bryozoa). The term Lophotrochozoa refers to the fact
that this lineage includes the traditional Lophophorate groups and
lineages with trochophore larvae (sensu lato).
- Icy Inverts: Evolution of Antarctic Invertebrates
The overarching goal of our studies in Antarctica is to develop an evolutionary understanding of how marine benthos have been influenced by the geological and evolutionary history in the Southern Ocean. Specifically, we are interested in how organisms can maintain genetic continuity (i.e., non-endemics) across the Drake passage, despite the presence of the strong anti-cyclonic current that forms the sub-Antarctic and Antarctic polar front. We are also interested in genetic connectivity or structure throughout Antarctic waters. To explore the genetic continuity among marine invertebrate taxa living on Antarctic and South America continental shelves, we are integrating observations of larval distribution with molecular information (mt DNA, microsatellites) on historical gene flow using samples collecting on research cruises. We are also interested in establishing a baseline of patterns along the Antarctic Peninsula, a place that is warmiing faster than anywhere else on earth.
- Hemichordate Phylogeny
Hemichordates are an enigmatic phylum of marine worms and their
relatives that are pivotal to hypotheses of deuterostome evolution and
chordate origins. Hemichordates and chordates share several important
morphological characters, but they are the sister group to
echinoderms, which places them in a unique position for assessing character
state evolution within deuterostomes. There are two currently
recognized groups within hemichordata; the solitary acorn worms, or
enteropneusts, and tiny colonial animals called pterobranchs. Both
groups have been implicated in hypotheses regarding the early
evolution of the deuterostomes, and have very different larval and
adult body plans. In collaboration with Dr. Billie Swalla at the
University of Washington, we are investigating phylogenetic
relationships within Hemichordata, using phylogenomic (expressed sequence tag) and
mitochondrial genome data. We are also investigating hemichordate
diversity using more traditional molecular markers.
- Siboglinids & chemosynthetic environments
Because hydrothermal vent systems are hypothesized
to be extreme environments that have been present since the early
history of the planet, understanding the ability of organismal lineages
to adapt and thrive in such environments is of interest to evolutionary
biologists. The lab has been focusing on the reconstructing the
phylogenetic history of key taxonomic groups to understand the origins
of vent fauna and how taxa in vent environments speciate and maintain
genetic communication. The primary taxon of interest has been the
siboglinid tube-worms. (Siboglids were formerly recognized as vestimentiferans
and pogonophorans.) These gutless worms are nourished by endosymbiotic
- Meiofaunal environmental genomics & hydrocarbon response
Many of the organisms in the sea are poorly known, especially meiofauna, organisms less then 1 millimeter that live between the sediment grains. We are coupling traditional techniques of meiofaunal study with next-generation molecular approaches that allow for the rapid evaluation of meiofaunal communities on much larger scale than previously possible. In particular, we are focuing on meiofaunal communities in the Gulf of Mexico. The lab's work in the this area has grown as a response to the Deepwater Horizon oil spill diaster. In additional to examining specific hydrocarbon related events, we are taking a broader approach to understanding meiofaunal diversity.
- Genomics & Bioinformatics
High throughput sequencing technologies have made it possible for researchers to quickly and easily collect large amounts of DNA sequence data from virtually any organism. However, in order to interpret these data, they must be properly processed, assembled, analyzed, and visualized. Our lab is currently employing numerous bioinformatics tools in order to study metazoan evolution. These include a bioinformatics pipeline to process genome and transcriptome data for use in phylogenomic studies of animal evolutionary relationships. Additionally, as part of our study of siboglind annelids and their chemosynthetic symbionts, we are surveying the transcriptomes of the annelid hosts and sequencing the genomes of several bacterial symbionis. Gene network analyses will improve our understanding of the functional genomic basis of this symbiosis.
- Early Evolution of Animals
Understanding the evolution of multicellular organisms is paramount in elucidating how advanced life can come to exist. On Earth, several multicellular groups arose independently, but only animals have evolved tissues that allow active, rapid movement and fast intercellular communication. In order to discern how these features arose, we must first unravel the evolutionary relationships among the earliest animal groups and identify the genetic mechanisms responsible for creating muscle and nervous tissue. Until recently, available data supported the hypothesis that sponges, which lack muscles and nerves, are basal to all other animals. However, recent data suggest that ctenophores are the most basal animal lineage, suggesting that such systems may have evolved twice within Metazoa, possibly including different molecular toolkits in different lineages. In order to test this hypothesis, we are employing cutting edge genomic approaches to study basal metazoan evolution.