Current Graduate Students and Post-Docs

Originally from Japan, Tom Kashiwagi earned his Ph.D. from the University of Queensland in Australia.  Tom’s postdoctoral research involves a genomics study of the Manta Ray complex in collaboration with Gavin Naylor and Shannon Newman of the College of Charleston.  Mantas exhibit a variety of pigmentation morphs that may or may not conform to species boundaries.  By looking at thousands of single nucleotide polymorphism markers from specimens collected non-invasively worldwide, Tom hopes to resolve the number of species and identify the morphological characters that distinguish them.

Kevin Kingsland is working on Ph.D. studies to understand the physiological differences between Pallid Sturgeon, Shovelnose Sturgeon, and between Pallid Sturgeon from different latitudes and climate regimes.  Pallid and Shovelnose sturgeon are genetically, morphologically, and ecologically similar, although they are reproductively isolated throughout much of their historic range.  Pallid Sturgeon are less heat-tolerant than Shovelnose Sturgeon and presumably the two forms speciated when Pallid Sturgeon were isolated in a more northern refugium during the Pleistocene.  There are also significant genetic differences at neutral microsatellite markers between pallid sturgeon from the upper and lower Missouri River basins.  However, it is not known whether these differences are accompanied by physiological heat tolerance or merely indicate stock structure between ecologically interchangeable units.  Kevin is examining differences in gene expression in heat-shocked pallid and shovelnose sturgeon to characterize their physiological responses.  His work has implications for management and long term recovery of the federally endangered Pallid Sturgeon, especially in light of climate change.

One of the most significant ecological change to occur in the Mississippi River Drainage in the past few decades is the explosive growth of exotic and invasive Bighead and Silver Carp, which went from non-existent in the last quarter of the 20th century to the majority of fish biomass in some rivers today.  One way that invasive species spread to new habitats faster than they can adapt through natural selection on DNA sequences is by epigenetic alteration of gene expression.  For her MS thesis, Erica Krahl is examining differences in epigenetic patterns of bighead and silver carp collected from their native range in China and from recently established invasive populations in the Illinois River, where exotic Asian carp now comprise the majority of fish biomass.

Paddlefish are perhaps the only living species of the Polyodontidae, an ancient and charismatic lineage of fishes.  Paddlefish and are endemic to slower portions of large rivers of the mid-western US.  Their native range has been fractured through the construction of dams and reservoirs, and while they are numerous in the center of their range, they are largely extirpated from the periphery.  While paddlefish can grow in reservoirs, they need running water and a hard bottom to spawn.  Past management practices have included stocking of hatchery-reared paddlefish from distant locations and likely the use of stocked paddlefish from reservoirs to restock the same reservoir.  These practices can lead to outbreeding depression as Paddlefish are stocked into maladaptive environments and to inbreeding depression as when closely-related fish are crossed in a hatchery.  Allsion Asher (Ph.D. student of Drs. Heist and Garvery) is studying genetic diversity of Paddlefish among populations and genetic variation within populations, including those in stocked reservoirs.