Study systems

Genetic structure of Greenland Sharks (Somniosus microcephalus)

Relatively little is known of the biology of Sleeper sharks. Partnering with researchers in Iceland, Norway, the Canadian Maritimes, and the USA, we are discovering a more complex evolutionary history among these long-lived elasmobranchs than previously thought. We have developed markers to characterize population structure from the Canadian Arctic and beyond (Swintek and Walter 2021 - BMC Research Notes). Previous work demonstrates the occurrence of Pacific Sleeper shark (Somniosus pacificus) genetic signatures among juvenile and adult Greenland sharks sampled in the Canadian Arctic (Hussey et al. 2014 - Polar Biology, Walter et al. 2017 - Ecology & Evolution), and further reports the admixed individuals well into the temperate and subtropical waters of the Atlantic. 

Genetic admixture in Manta Rays

Mantas are large mobile marine elasmobranchs exhibiting a variety of genetic, morphological, and ecological characteristics.  Recent taxonomic revision has reclassified Mantas into two species on the basis of morphology, although we are finding new and exciting data blurring these boundaries (Walter et al. 2014 - Marine Biodiversity; Hinojosa-Alvarez et al. 2016 - PeerJ).

O'opu - Hawaiian stream fishes

The Hawaiian archipelago is home to a number of amphidromous fish species, all of which exhibit a seemingly obligate marine larval phase. Their unique life history highlights vulnerabilities to changing global environmental conditions (Walter et al. 2012 - ESR). Four endemic species (Eleotris sandwicensis, Sicyopterus stimpsoni, Stenogobius hawaiiensis, Lentipes concolor) and one indigenous species (Awaous guamensis) are the focus of a broad phylogeographic study of genetic connectivity among watersheds and islands. Through a collaboration with researchers at Tulane University, NC State, and the University of Wisconsin-Madison, we have uncovered the existence of an endemic Awaous lineage among the Hawaiian islands (Lindstrom et al. 2012 - Copeia). 

Coral Reef Ecology

Diving and working on coral reefs is a passion I've held since my undergraduate years. As coral reefs are among the most speciose of aquatic environments, complex interactions exist among members of the coral reef community. Many fishes are associated with corals, algae and other reef-dwelling invertebrates at  some point in their lives. My MS with Jim Haynes (SUNY Brockport) examined comparative community structure among fishes and coral species on the shallow-water patch reefs of San Salvador, Bahamas (Walter & Haynes 2006 - Bull Mar Sci). I continue to work on a number of studies examining regional and local connectivity in coral reef fish species along the MesoAmerican Barrier Reef System in the Caribbean (Salas et al. 2010 - Mar Biol; Hogan et al. 2010 - Mol Ecol Notes).