Bythotrephes longimanus
the spiny water flea



PhD Research
Dissertation: What gives the spiny water flea its name? Natural selection, genetic variation, and phenotypic plasticity in spine length of the invasive species, Bythotrephes longimanus
Invasive species are one of the leading threats to global biodiversity. A considerable amount of research has addressed how the ecology of invasive species contributes to their persistence and negative effects on ecosystems, but until recently, little attention has been paid to how evolution affects invasive species persistence and effects. The spiny water flea, Bythotrephes longimanus, is a predatory zooplankton with a conspicuous tail spine that invaded the Great Lakes during the 1980s. Bythotrephes have reached high densities throughout the Great Lakes and may be having large negative effects on fisheries. Previous field studies show that the morphology and life history of Bythotrephes strongly vary spatially and temporally, but the cause of this variation is not known. My dissertation research investigates ecological and evolutionary factors that influence morphological and life history variation in Bythotrephes and addresses how these factors affect potential for future evolutionary change. I found significant genetic and maternal variation for Bythotrephes spine length and body size and moderate-to-high heritabilities and maternal effects in both traits. Natural selection favored shorter spine length early in the growing season, but longer spine length late in the season, a trend that matches predictions based on changes in predation pressure from fish. Further, experiments revealed that spine length, body size, and clutch size responded plastically to temperature, with longer spine length, larger body size, and smaller clutch size at higher temperature. Although Bythotrephes use temperature as the proximate cue of plasticity, it is likely that the trait changes represent adaptations to varying fish predation risk which correlates with water temperature. The results of this study suggest the phenotype of Bythotrephes can respond evolutionarily to fish selection on genetically based traits across multiple generations as well as through short-term, phenotypically plastic responses. This combination likely promotes Bythotrephes success as an invasive species in the Great Lakes.
Bythotrephes and alewife (a non-native
fish species in Lake Michigan)
Bythotrephes on fishing line in Lake Erie
Bythotrephes on fishing line in
Lake Erie (with jet diver)

Master's Research
Yellow perch (Perca flavescens) swimming over a bed of zebra mussels (Dreissena polymorpha) with SCUBA diver (Scott Miehls) in background.
Thesis: Invasive species impacts on ecosystem structure and function
Exotic species invasion is a worldwide threat to the integrity of aquatic ecosystems.  To understand ecosystem level response to the introduction of exotic species, I compared food web characteristics of two eutrophic Great Lakes ecosystems - the Bay of Quinte, Lake Ontario, Canada, and Oneida Lake, New York, USA - before and after zebra mussel (Dreissena polymorpha) invasion using ecological network analysis (ENA) and a social network analysis method, cohesion analysis (CA).  ENA quantifies ecosystem function through an analysis of food web transfers, while CA assesses ecosystem structure by organizing food web members into subgroups of strongly interacting predators and prey.  In Oneida Lake and the Bay of Quinte, zebra mussel invasion increased food web organization and the potential for system development.  Additionally, zebra mussel invasion stimulated benthic production in both systems.  Effects on food web structure were strongest in the Bay of Quinte where zebra mussel invasion removed subgroup structure entirely.  In Oneida Lake, over 33% of taxa changed subgroup association after invasion, with benthically associated subgroups gaining the most members.  This analysis suggested that the effects of zebra mussel introduction are similar in ecosystems of comparable trophic status and that future invasions of eutrophic systems could have similar impacts on ecosystem structure and function.

Miehls, A.L.J., S.D. Peacor, and A.G. McAdam. 2012. Genetic and maternal effects on tail spine and body length in the invasive spiny water flea (Bythotrephes longimanus). Evolutionary Applications 5: 306-316. Open Access Link
Miehls, A.L.J., D.M. Mason, K.A. Frank, A.E. Krause, S.D. Peacor, and W.W. Taylor. 2009. Invasive species impacts on ecosystem structure and function: A comparison of the Bay of Quinte, Canada, and Oneida Lake, USA, before and after zebra mussel invasion. Ecological Modelling 220: 3182-3193.
  Link to publication on ScienceDirect
  Great Lakes Fishery Commission Press Release
Miehls, A.L.J., D.M. Mason, K.A. Frank, A.E. Krause, S.D. Peacor, and W.W. Taylor. 2009. Invasive species impacts on ecosystem structure and function: A comparison of Oneida Lake, New York, USA, before and after zebra mussel invasion. Ecological Modelling 220: 3194-3209.
  Link to publication on ScienceDirect

Academic CV current as of July 2012


My research would not be possible without the tremendous support of advisors, assistants, and research volunteers. Click here to view pictures and information about the people that have helped with my research.
Assistants in 2007
Assistants and others in 2009
Lab Assistants in 2011
Lab Assistants in 2010

And now for something completely different...

As an undergraduate student, I completed my first internship at the Illinois Natural History Survey's Lake Michigan Biological Station. I assisted graduate student Brian Graeb (advised by Dr. John Dettmers) with experiments investigating ontogenetic niche shifts in yellow perch. As part of my daily responsibilities, I cultured phytoplankton, zooplankton, and larval perch. One day creative inspiration hit and the result was a poem about my experiences called...

Research Links

Department of Fisheries and Wildlife at Michigan State University
Ecology, Evolutionary Biology, and Behavior Program at Michigan State University
NOAA Great Lakes Environmental Research Laboratory

PhD Lab Webpages:
Andrew McAdam Lab Webpage - University of Guelph
Scott Peacor Lab Webpage - Michigan State University

Last Updated 7-12-12 | Michigan State University - Department of Fisheries and Wildlife