Quinnipiac University College of Arts and Sciences

CAS Discovery

In Research, Students on December 1, 2011 at 6:39 pm

QU Graduate Students Discover New Species

When Joanne Jankowski and Kristan Heverin began their master’s thesis work in the Molecular and Cell Biology graduate program, they never expected a seemingly very simple aquatic invertebrate to be so complex and engaging, both physically and intellectually. For their research, Jankowski and Heverin collected and analyzed hundreds of H. azteca from Moodus Reservoir and Upper Bolton Lake in East Haddam and Bolton, Connecticut respectively. Through careful molecular and morphological analysis, they completed the most comprehensive study of H. azteca to date, and provided strong evidence that H. azteca is a cryptic species complex, or in other words, a group of species which look very similar, but are unable to breed with one another.

Hyalella azteca is a species of freshwater amphipod crustacean found living widely throughout aquatic environments in North and South America. The species was first discovered in a cistern in Vera Cruz, Mexico, by Henri Louis Frédéric de Saussure in 1858. Since its discovery, researchers have reported divergent species of H. azteca across North America. However, Jankowski and Heverin’s studies were among the first and the most comprehensive to compare specific morphological measurements of divergent populations to the originally described H. azteca specimen. Their work marks the most substantial evidence that H. azteca is a species complex.

While Jankowski and Heverin can accurately distinguish between H. azteca isolated from Upper Bolton Lake and Moodus Reservoir, they both agree that these amphipods likely belong to the same species. “Although there are slight morphological distinctions between the two populations, the molecular analysis indicated they are very closely related,” stated Jankowski and Heverin. “These molecular differences are population specific differences, not species specific.”

“What I found to be most astounding was the molecular results. The divergence seen in the sequence alignments was incredible. There were four different molecular “groups” based on sequences similarities for both populations, and we only collected from a limited site. I can’t even imagine what a larger sampling would give” exclaimed Heverin.

The discovery of a new species of H. azteca in Connecticut has far-reaching implications nationwide and internationally. “Hyalella azteca is one of the most heavily studied amphipod species, with a long history of use in toxicological investigations,” stated Eric Lazo-Wasem, senior collections manager at the Peabody Museum of Natural History at Yale University. “The genetic and morphological variability revealed here implies there are multiple species that must be broken out of the H. azteca complex. This will ultimately have far reaching consequences that may force us to question long-held environmental and pharmaceutical conclusions reached using H. azteca as a model system.”

Jankowski and Heverin worked under the close guidance of their thesis advisor, Dr. Dennis Richardson. “This work is very important because it further elucidates the taxonomic confusion surrounding an important group of aquatic invertebrates. It also provides a conceptual and methodological foundation needed to clarify the true taxonomic status of populations of H. azteca throughout North America,” stated Dr. Richardson. “Based largely on methods and concepts elaborated in these two theses, we are currently undertaking formal descriptions of newly recognized species of H. azteca throughout the United States.”

“I believe that our research provides future investigators with a great stepping-stone in describing many other species that are considered to be H. azteca but are in fact a different undescribed species,” stated Jankowski.

Looking forward, Jankowski plans to continue assisting Dr. Richardson with future H. azteca investigations as she pursues a research job that will allow her to use the skills she has learned during her thesis research. Heverin is in the process of becoming a nursing assistant, and ultimately hopes to apply to medical school and become a pediatrician.

H. azteca image by E. A Lazo-Wasem, Copyright 2010 Yale Peabody Museum


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