Lab Alumni


Weider Lab Fall 2017: Back Row: L-R: Larry Weider, Jake Scott, Emily Kiehnau, Michael Onwuchuruba, Ronak Tapiavala; Front Row: L-R: Ritu Kulkarni, Rachel Hartnett


Weider Lab Fall 2016: L-R Larry Weider, Weston Speer, Rachel Hartnett, Emily Kiehnau, Michael Onwuchuruba, Christian Brewer


Weider Lab Spring 2015: L-R, L.J. Weider, R. Hartnett, D. Frisch, W. Speer, A. Yousey, B. Culver

Postdoctoral Associates

 2012-15   Dr. Joaquin Muńoz, U. of Oklahoma Biological Station/Sevilla, Spain

2010-13   Dr. Philip Morton, U. of Oklahoma Biological Station (currently an Assistant Professor and Dept Chair, Murray State College, OK)

2007-15   Dr. Dagmar Frisch, U. of Oklahoma Biological Station (currently a Marie Sklodowska-Curie Research Fellow, School of Biosciences, U. of Birmingham, U.K.)

2006-07   Dr. James Larson, U. of Oklahoma Biological Station (currently a Research Scientist, USGS Upper Midwest Environmental Science Center, La Crosse, Wisconsin)

2005-06   Dr. Chad Hargrave, U. of Oklahoma Biological Station (currently an Associate Professor, Dept. of Biological Sciences, Sam Houston State U., Texas)

2000-01   Dr. Richard Broughton, Dept. of Zoology/Biological Station, U. of Oklahoma (currently Professor and Chair, OU Dept. of Biology)

1997       Dr. Martin Cerny, Dept. of Hydrobiology, Charles University, Prague, Czech Rep.

1994-96   Dr. Piet Spaak, Centre for Limnology, Netherlands Inst. of Ecology, Nieuwersluis, NL(currently Head of the Dept. of Aquatic Ecology, EAWAG, Dubdendorf, Switzerland)

1995       Dr. France Dufresne, Dept. of Zoology, U. of Guelph, Ontario, Canada. (currently an Associate Professor, Dept. of Biology, U. of Quebec at Rimouski)

1994-95   Dr. Luc De Meester, Laboratory of Animal Ecology, U. of Ghent, Belgium. (currently a Professor, Dept. of Biology, KU-Leuven, Belgium)

1991-93   Dr. Joanna Pijanowska, Department of Hydrobiology, U. of Warsaw, Poland.

Weider Lab Spring 2012: L-R, L. Weider, Quini Munoz, B. Culver, D. Frisch, Philip Morton


Previous Graduate Students:

2012-2017   Rachel Harnett (Ph.D., former NSF Graduate  Research Fellow)

Dr. Hartnett’s work has focused on how population dynamics influence community properties using Daphnia as a model organism.  She has been interested in potential mechanisms of size-distribution variation along an increasing experimental scale of size and ecological complexity (from life-history to mesocosm experiments).  From this work, she has focused on two main arms: 1) mechanisms and patterns of size distributions, and 2) the role of species evenness in community theory and application.  Rachel successfully defended her Ph.D. dissertation in November 2017, and was awarded her doctorate in December 2017.   She was awarded and has accepted one of the inaugural Diversity Postdoctoral Fellowships in the College of Arts & Sciences (CAS) at Oklahoma State University.  She took up her new position effective 1 July 2018.  Please visit her website for more information.

2010-16   Billy Culver (Ph.D. student, U. of Oklahoma) (currently an Assistant Professor, Dept. of Natural Sciences, Centenary Univ., N.J.)

2013-15   Aime’e Yousey (M.S. student, U. of Oklahoma) (currently Assistant-to-the-Chair, OU Dept. of Educational Psychology)

2008-10   Mingyan Lin (M.S., U. of Oklahoma)

2002-07   Punidan Jeyasingh (Ph.D., U. of Oklahoma) (currently an Associate Professor, Dept. of Integrative Biology, Oklahoma State Univ.)

2000-01   Wenjun Wang (Ph.D. student, U. of Oklahoma)

1997-00   Petra Limburg (Ph.D., U. of Kiel, Germany) (currently in the private sector in Germany)

1996-99   Thomas Berendonk (Ph.D., U. of Kiel, Germany) (currently Professor of Limnology, Technical University-Dresden, Germany)

1997-98   Angelika Denk (M.Sc. student, U. of Regensburg, Germany)

1994-97   Suzanne E. Mitchell (Ph.D. – NERC-CASE, U. of Hull, England) (currently Director, Aeona Limited, Edinburgh, Scotland)

 1997       Lilla Pokutta (M.Sc. – U. of Hamburg, Germany)

1989-90   Mary H. Murdoch (M.Sc. – U. of Windsor, Canada) (currently Principal, Stantec Environmental Services, Fredericton, New Brunswick, Canada)


Previous Undergraduate Students:

2017-2018  Ronak Tapiavala (B.S., U. of Oklahoma)

Ronak Tapiavala

Ronak’s research project involved the study of the artificial sweetener sucralose, and its potential impact on physiological and metabolic aspects of Daphnia. Sucralose is one of the main ingredients found in the artificial sweetener, Splenda, which is found in a wide variety of low-calorie beverages.  Given that sucralose is quite “metabolically stable”, much of it ends up into aquatic ecosystems via waste-water run-off.  Its role as a man-made eco-toxicant remains to be fully examined. One of the major assays that Ronak  performed involved testing the effects of sucralose on the heart rate of various clones of Daphnia, including both modern-day clones, as well as “ancient” (centuries-old) clones to determine if modern Daphnia clones have adapted to this artificial sweetener.  Here is a video clip of a Daphnia pulicaria female (carrying eggs/embryos) that has been exposed to sucralose.  You can see the beating heart just above the brood chamber (containing developing embryos).  Ronak graduated from OU in May 2018.  He is in the process of applying to Dental School for fall 2019.


2017 – 2018 Jake Scott (B.S., U. of Oklahoma)

Jake Scott

Jake joined our lab in fall 2017.  He completed his independent study project in spring 2018, which was a comparative study on the “nutritional ecology” of several different algal food types and their impact on growth and reproduction among several species of Daphnia, including D. pulicaria, and D. mendotaeHe plans on graduating from OU in May 2019.


2016-17   Michael Onwuchuruba (B.S., National Merit Scholar, U. of Oklahoma).  Michael graduated from OU in May 2018 and is applying to medical/DO schools for fall 2019.

Michael Onwuchuruba examined various cues (i.e., hormonal, food-level, photoperiod) that have been implicated in affecting the sex ratio of Daphnia offspring. He found no clear-cut effects of these cues on sex-ratio of offspring, but did find a significant effect of suppression of fecundity (i.e., egg production) in the presence of the juvenile hormone analog, methyl farnesoate (MF).


2016-17   Christian Brewer (B.S., U. of Oklahoma, National Merit Scholar, OU Honors College)(Christian started medical school in August 2017 at UT-Southwestern in Dallas).

Christian Brewer conducting a predator cue experiment and examining phototactic response in Daphnia prey


2015-16   Hayley Severson (B.S., U. of Oklahoma, National Merit Scholar, UROP award winner) (Hayley completed her Masters of Public Health, U. of Wisconsin-Madison, and began medical school at UWM in fall 2017).

OU Graduation May 2016 Hayley Severson with Dept of Biology Faculty Marshal L.J. Weider


2012-2016    Frank “Weston” Speer (B.S. Biology, 2016, U. of Oklahoma; UROP award winner)

Weston’s research project involved the study of the aquatic crustacean (brine shrimp) Artemia franciscana, a prominent model organism. With the aid of international colleagues, he obtained A. franciscana populations from several different countries. His project aimed to determine the optimal hatching cues for these populations. Additionally, he engineered a novel hatchery system that could be applied to an array of aquatic organisms.  The results of his independent study research were recently published in the journal Hydrobiologia. Currently, he is conducting nuclear imaging research in the Oklahoma City area.   In August 2018, he will begin medical school at Oklahoma State University (OSU)-Tulsa.

Frank “Weston” Speer (L) receives an Undergraduate Research (UROP) Award from OU (pictured here with L.J. Weider)

2015        Arianne Rick (B.S., U. of Oklahoma, OU Honors College) (will begin dental school at the U. of Florida in fall 2017)

2011-13   Jeff Medders (B.S., U. of Oklahoma)

2012-13   Alex Mutz (B.S., U. of Oklahoma)

2011        Rosa Yorks (B.S. , Oklahoma State Univ.)

2011       Tiffany Glover (B.S., Langston Univ., Oklahoma)

2011       Garrett Schulze (Kingston High, Oklahoma)

2011       Kelsie Montgomery (high-school student, Red River Technology Center, Oklahoma)

2010       Michael Leitch (B.S., U. of Oklahoma)

2005-06   Laura Harolds (B.S. Honors, U. of Oklahoma, UROP award winner)

2003       Andrea Bean (B.S., U. of Oklahoma)

2003       Jaime Ramos (B.S., U. of Oklahoma)

2002       Robyn Moran (B.S., S.W. Okla. State)

2002       Lynette Matthews (B.S., Arizona State U.)

2002       Amy Ramsey (B.S., Botany, U. of Oklahoma)

2001       Jeremiah Smith (B.S., U. of Oklahoma)

2001       Kim Land (B.S., U. of Oklahoma)

2000       Amanda Warren (B.S., U. of Oklahoma)

1992       Gerhard Griebe (B.Sc. honors – U. of Oldenburg, Germany)

1992       Andreas Heinken (B.Sc. – Free University – Berlin, Germany)

1992       Adrian Howe (B.Sc. – EC Comet Program, U. of Swansea, Wales)

1989-90   Catherine Delvanminck (B.Sc. honors – U. of Windsor, Canada)