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Faculty
Faculty

Mary McKenna (She/Her)

Associate Professor

  • Biology
  • College of Arts & Sciences

Biography

Mary McKenna is an ecologist with research interests in plant community ecology, climate change impacts on plants, plant/soil interactions and plant reproduction.  Dr. McKenna was awarded a Commitment to Human Diversity in Ecology Award from the Ecological Society of America in 2015 to recognize her efforts to support and encourage students of color entering the field of ecology. Dr. McKenna teaches courses in Ecology and in Climate Change Biology at Howard, where she received university-wide awards for excellence in mentoring (Faculty Senate Mentoring Award 2014, College of Arts & Sciences Honors Program Award 2007), and outstanding teaching (Biology Graduate Students Association 1997, Center for Excellence in Teaching & Learning 2005). From 1988-1996 she received grants from the US Forest Service to support research with Howard students in the Rocky Mountains, including three funded alpine ecology field courses for undergraduates. Dr. McKenna’s passion to immerse undergraduates in ecological research has been funded by NSF Biology Directorate (RIMI, UMEB, URM, REU) to create initiatives such as the Howard U Environmental Biology Scholars Program. Including graduate students trained in her lab, Dr. McKenna has mentored more than 30 students pursuing graduate research, primarily in ecology. Students in HU Environmental Biology Scholars won NSF Predoctoral and Postdoctoral Fellowships, an HHMI Gilliam Award, a Bouchet Honor Society Award, and a Brower Youth Leadership Award, as well as numerous awards for research presentations at national and international scientific meetings.  Dr. McKenna aided in development of the NSF-National Ecological Observatory Network (NEON) as a member of the national Science, Technology, and Education Advisory Committee for NEON (2013-2016) and the Mid-Atlantic Domain Executive Committee (2007-2009), as Chair of the Mid-Atlantic Domain Science and Education Committee (2009-2011), and as a member of the IBRCS Working Group that drafted the Rationale and Blueprint for  NEON  in 2003.  As a member of the Board of Directors for the American Institute of Biological Sciences (1999-2006), Dr. McKenna initiated a new program to highlight research from biology students of color (AIBS Diversity Scholars Program). As Chair of the Mid-Atlantic Chapter of the Ecological Society of America, she also organized seminars and activities to connect ecologists in the region.  From 2005 to the present, Dr. McKenna serves as co-PI of the UVA-Blandy NSF-REU summer research program where Howard undergraduates join students from across the country in ecological inquiry.    

Education & Expertise

Education

Biology

B.S.
Boston College
1976

Ecology and Evolution

Ph.D.
State University of New York, Stony Brook
1987

Expertise

Plant Community Ecology

Climate Change Biology

Evolutionary Ecology

Plant Reproductive Biology

Academics

Academics

Ecology (BIOL230)

Life on earth changes earth’s physical environment, and living organisms interact with each other in complex and exciting ways. Research in the fast-growing field of Ecology shows us how healthy ecosystems sustain all life on earth, including humans whose survival is linked to diverse biological systems that maintain robust food chains, moderate earth's climate, and naturally clean earth's oceans, freshwater, and atmosphere.  We will use an environmental justice perspective to examine inequities among people in access to environmental benefits, and the course will emphasize the critical role of indigenous cultures and traditional ecological knowledge in conservation of sustainable ecosystems. The interaction between an organism and its abiotic and biotic environment results in short-term ecological responses and long-term evolutionary adaptations. Ecologists seek to discover how these short and long-term responses to the environment influence the abundance and distribution of organisms on earth. The laboratory immerses students in original research to answer questions about the relationship between organisms and their environment. This course will provide students with experience in designing ecological experiments, carrying out statistical data analysis, and presenting scientific results. Students enrolled in this course are expected to have completed General Biology I and II, and Genetics.

Climate Change Biology (BIOL 329)

Climate change biology is a research-intensive course that explores the interactions of biological systems with the earth’s climate system, with a focus on the dynamic responses of species, natural communities, and ecosystems. The course begins with an overview of the forces that regulate earth’s climate system and the natural and anthropogenic drivers of climate change. Ecosystem responses and feedbacks are examined, as well as mitigation strategies to reduce greenhouse gases in the atmosphere. The course explores responses of various species to climate change, and we discuss implications for policy, such as conservation and management strategies. We also examine human health implications of climate change, urban heat islands, and disproportionate impacts on BIPOC communities. The laboratory provides student with experience conducting hypothesis-driven research to study the biological impacts of changing climate, as well as an understanding of the human-influenced drivers of global change. Societal forces and impacts are explored from an environmental justice framework, and students gain proficiency in understanding how climate effects on population dynamics and distributions are modelled to make valid predictions for the future.

Plant Ecology (BIOL432)

Research

Research

Specialty

Evolutionary ecology, plant community ecology, climate change biology

Funding

NSF Biology Directorate- Research Experiences for Undergraduates (REU-Blandy) 2005-present (funded through 2022)NSF Biology Directorate - Undergraduate Research Mentoring (URM) - HU Environmental Biology Scholars Program 2010-2015NSF Biology Directorate - Undergraduate Mentoring in Environmental Biology -  HU Environmental Biology Scholars Program 2004-2009USDA Sabbatical Grant - Exploring Reproduction in Metal-Hyperaccumulator Plants 2001-2002NSF Education & Human Resources Directorate - Research Improvements in Minority Institutions - Plant Science Research 1996-2001 US Forest Service - Acid Rain Impacts on Forest Understory 1993-1995 US Forest Service -  Howard U/US Forest Service Partnership Program 1994-1995 US Forest Service - Rocky Mountain Alpine Ecology Field Courses for Howard U Students 1990, 1992, 1995 US Forest Service - Global Change in Alpine Plant Populations 1988-1995

Group Information

Overview of the McKenna Research LabThe McKenna Lab explores the evolutionary ecology of plant populations and communities with a particular focus on how plants respond to changing abiotic conditions (climate, soil nutrients, allelochemicals) and changing biotic conditions (competition, herbivory, pathogens).  Understanding how plants interact with the geosphere, and how the interactions between plants and other species influence the stability and healthy functioning of our global ecosystem (including human health) is critical for protecting and sustaining life on earth. Members of the McKenna Research Lab (past and present): Shalom Entner 2021 BS Biology Howard U -Honors Thesis: Ecological and evolutionary influences on butterfly wing morphology *further training in ecology -current PhD student at Boston University (John Finnerty)Amoi Campbell 2020 BS Biology Howard U -Research Topic: Exposure to Ni during germination creates persistent effects on above and below-ground growth in serpentine plants *further training in ecology -U Pittsburgh Post-bacc Research Program (Sara Kuebbing), current PhD student at Rice University (Matthew McCary)Kristian Harris 2019 BS Biology Howard U -Honors Thesis: Functional root traits differ in congeneric serpentine specialist and generalist plants *further training in ecology -current PhD student at Ohio State U (Alison Bennett)Jelani Lyda 2019 BS Biology Howard U -Honors Thesis: Exploration and exploitation during root foraging by serpentine plants *further training -current PhD student at UC San Diego (Kit Pogliano)Arquel Miller 2019 BS Biology Howard U -Research Topic: Influence of Ni and Ca/Mg ratios on root foraging in serpentine plants * further training in ecology -current Research Lab Manager, Evolution & Ecology, UC Davis (Jenny Gremer)Whitney White 2018 BS Biology Howard U -Honors Thesis: Rooting for Heavy Metal: Alyssum roots seek Ni in their soil environments *further training in ecology – MS at U Michigan (Regina Baucom)Kortland Casselberry 2018 BS Biology Howard U -Honors Thesis: Let’s not get physical: evidence for a defense tradeoff in a Ni-hyperaccumulator plant *further training – current student at Ohio U College Osteopathic Medicine.  Paige Stephens 2017 NSF REU -Research Topic: Routes for roots: Nutrient foraging patterns in serpentine plants *further training in ecology -current MS student at Oregon State U (Lisa Ellsworth)Morgen Owens 2017 BS Biology Howard U -Honors Thesis: Edaphic factors influence stomatal development and physical defense in a Ni-hyperaccumulator. *further training- MD, U Alabama at Birmingham School of MedicineFrederick Nelson 2017 BS Biology Howard U -Research Topic: The effects of ontogeny, soil environment, and endemism on the production of trichomes in Ni-hyperaccumulators *won Best Research Award at Ecological Society of America Mid-Atlantic Meeting *received NSF Predoctoral Fellowship * further training in ecology -current PhD student at UC Davis (Ann Todgham)Madalyn Slook (Meyers) 2016 NSF REU -Research Topic: Bringing metal to a slugfest: How Ni alters plant defenses against herbivory *won Best Research Award at Ecological Society of America Mid-Atlantic Meeting *further training in ecology -MS at Penn State (Paul Bartell)Tayanna Rivers 2016 BS Biology Howard U -Honors Thesis: Effects of Ni-hyperaccumulation and previous exposure on the specialist herbivore, Murgantia histrionica *won Best Research Award at 2016 Howard University Research Week SymposiumErin Manaigo 2016 BS Biology Howard U -Honors Thesis: Effects of thymol on microbial symbioses     in two species of annual lespedeza (Kummerowia striata & Kummerowia stipulacea) *further training in ecology -current PhD candidate at UC Davis (Ben Houlton)Robert Neblett 2016 BS Biology Howard U -Research Topic: Determination of nitrogen content in alfalfa (Medicago sativa) by spectral analysis  Amanda De la Rosa 2016 NSF REU -Research Topic: Edaphic effects on constitutive and induced plant defenses in a Ni-hyperaccumulator *further training in ecology -current MS student at Ghent U, BelgiumJalyse Cuff 2016 BS Biology Howard U -Honors Thesis: Chinks in the armor: Is heavy metal uptake an effective defense for plants? *further training in ecology -current PhD student at U Miami (Katherine Mach)Katherine Beigel 2015 NSF REU -Research Topic: Chemical and elemental defenses of Ni-hyperaccumulators, and their effects on the specialist herbivore Murgantia histrionica. *further training in ecology -current PhD student at U Texas (Jon Seal)Chandler Puritty 2015 BS Biology Howard U -Honors Thesis: Exploring plant defenses against herbivory in the Brassicaceae: trade-off or joint defense? * Best Research Award at Annual Meeting Botanical Society of America *received NSF Predoctoral Fellowship *further training in ecology -PhD at UC San Diego (Elsa Cleland)Nia Johnson 2015 BS Biology Howard U -Honors Thesis: Herbivory and oviposition response of specialist herbivores on Alyssum murale and Alyssum corsicum *Best Research Award at Annual Meeting Botanical Society of America *further training in ecology -current PhD candidate at U Michigan (Regina Baucom)Lauren Summers 2015 BS Biology Howard U -Honors Thesis: Growth responses of the N-fixing bacterium Rhizobium leguminosarum to plant-derived terpenes. *further training -current student at UNC School of MedicineLaura Aponte Diaz 2014 NSF REU -The role of terpenes in mediating above-and below-ground interactions in cowpea (Vigna unguiculata) *further training in ecology -current Field Research Technician (Floral Surveys) for National Ecological Observatory Network (NEON) in Puerto Rico.Adrian Pekarcik 2013 NSF REU- Fitness consequences of thymol’s impact on nodulation in Medicago sativa L. (Fabaceae) and Vigna unguiculata (L.) Walp. (Fabaceae) *further training in ecology- MS at Auburn U (Alana Jacobson), current PhD student at Ohio State U (Kelly Tilmon)Calyn Harrigan 2013 BS Biology Howard U -Honors Thesis: Thymol impacts on germination, nodulation, and growth of Medicago sativa *further training – MD at St James School of Medicine, AnguillaAlexandria Igwe- BS 2012 Biology Howard U -Honors Thesis: Elemental defense in Alyssum murale: effects on plant-herbivore interactions *received NSF Postdoctoral Fellowship *further training in ecology - MS Texas Tech (Paul Schwab), PhD at UC Davis (Rachel Vanette), -current postdoctoral researcher at U Miami (Michelle Afkhami)  Brittany Stallworth 2012 BS Biology Howard U- Honor Thesis: Elemental defense in Alyssum murale: effects on plant-pathogen interactions *further training -MD at Wayne State U School of MedicineDawn Ruiz Diaz - 2012 NSF REU - Climate change and the 'hungry season'- nodulation, growth, and reproduction in black-eyed pea (Vigna unguiculata). Ebony Hampton- BS 2012 Biology Howard U -Honors Thesis: Soil nickel effects on root growth patterns in a hyperaccumulator, Alyssum murale Waldst and Kit. (Brassicaceae). *further training -MSW at Tulane University Veronica Rodriguez Rosas 2011 NSF REU - The effects of thymol on microbial symbioses in alfalfa, Medicago sativa (Fabaceae) *further training in botany -MS in Landscape Architecture, current Research Associate, USDA ARS, Mayaguez, Puerto Rico. Iman Sylvain 2010 BS Biology Howard U - Honors Thesis: Soil Ni enhances seedling vigor of the serpentine Ni-hyperaccumulator, Alyssum murale Waldst and Kit. (Brassicaceae) *Best Research Award, Annual Meeting Botanical Society of America, * Ecological Society of America SEEDS Fellowship *further training in ecology -MS U Michigan (Timothy James), PhD UC Berkeley (John Taylor)Sara Negash 2010 NSF REU -Research Topic: Ni Effects on growth and physical defense in Alyssum hyperaccumulators * further training - MD degreeKatherine Mincey 2010 NSF REU -Research Topic: Physical and elemental defenses of nickel hyperaccumulators and their effects on herbivory. *further training in ecology -PhD at Auburn U (Robert Boyd) Kiona Ervin -BS 2010 Howard U -Honors Thesis: Edaphic and density effects on the competitive ability of the Ni-hyperaccumulator Alyssum murale Elyse Holz -BS 2009 Biology Howard U -Honors Thesis: Edaphic effects on seed weight in Ni-hyperaccumulators  *further training -MS in Public Health ManagementTyra Pendergrass- BS 2008 Biology Howard U - Honors Thesis: Survivorship, competitive ability, and reproduction of Alyssum hyperaccumulators *Best Research Award -HBCU UP Annual Conference      *further training in ecology -MS at Yale University Michelle Nicholson -BS 2008 Biology Howard U - Honors Thesis: Ecological effects of terpenoids from Thymus serpyllum on nodulation and growth of clover (Trifolium spp.) *Best Research Award, Annual Meeting -American Institute of Biological Sciences *further training -Clinical Research Analyst/Coordinator  Alisha Kissel (Schleining) -2008 NSF REU- Research Topic: Seedling herbivory in the Ni-hyperaccumulator, Alyssum murale *further training in ecology -U Washington, VT Youth Conservation Corps, Ohio Ecological Food & Farm Association  Ayesha Smith -BS 2007 Biology Howard U -Honors Thesis: Soil nutrient effects on growth and competitive ability of Alyssum murale from Bulgaria *further training -MPH at Emory U, ; JD at Howard ULatoya Archibald- BS 2007 Biology Howard U - Honors Thesis: Competitive ability of a Ni-hyperaccumulator (Alyssum murale) under varying soil nutrient conditions. *Best Research Award at International Serpentine Meeting, Bar Harbor, Me *further training in ecology – Environmental Integrity Project, Washington DCHoward Hamilton- BS 2006 Biology Howard U - Honors Thesis: Competitive interactions between white clover (Trifolium repens) and three species of mint (Lamiaceae) *Best Research Award - Annual Meeting American Institute of Biological Sciences *further training - MD at Howard U Medical SchoolShelby Burks (Ward) -BS 2006 Biology Howard U - Honors Thesis: Ecological factors influencing leaf litter decomposition by stream insects. *futher training -MS in ecology at U Tennessee (Paul Armsworth), JD at U TennesseeRachel Ahern (Streit)- 2006 NSF REU -Research Topic: Floral development in Ni-hyperaccumulators in high-Ni and low-Ni edaphic environments *further training in botany - MS in Landscape Architecture at U Penn, current Environmental Consultant for City of Philadelphia- Green City, Clean Waters program, lecturer at Thomas Jefferson UDaniel Serrano Volpe - 2005 NSF REU -Research Topic: Competitive ability of Ni-hyperaccumulator Alyssum corsicum in a low-Ni medium: implications for invasiveness. *further training in biology -PhD at U Maryland, current Research Associate at U Maryland.Juliette Scantlebury - BS 2005 Howard U Biology - Honors Thesis: Competitive ability of Alyssum murale (Brassicaceae) under low-Ni soil conditions *further training -MD at Howard U School of MedicineKaren Gordon - MS 2005 (Mary McKenna) Howard U Biology – MS Thesis  Jeneen Stewart -MS 2002 (Mary McKenna) Howard U Biology – MS Thesis topic: Secondary compounds from Thymus serpyllum stimulate nodulation in Trifolium repens *further training in biology -K-12 science teacher, current Principal, Ballenger Creek Middle School  Corey Palmer - MS 2002 (Mary McKenna) Howard U Biology – MS Thesis Topic: Acid rain effects on reproductive success in alpine plantsJoel Abraham - BS 2000 Howard U Biology - Honors Thesis: Allelopathic effects of Bidens polylepis in early successional plant communities. *further training in ecology - PhD at UC Berkeley (Wayne Sousa), current Assoc Prof-Plant Ecology at CSU-Fullerton, Dept of Biology, Fullerton, CATara Collins -BS 2000 Howard U Biology -Honors Thesis: *further training -MD & MPH at Emory University, current Asst Professor of Psychiatry at UC San Francisco School of Medicine, 2018 Watson Scholar at UCSF  https://www.youtube.com/watch?v=EUb8gZTe25cTonia Bennett (Quintero) - MS 1997 (Mary McKenna) Howard U Biology – MS Thesis: Acid rain effects on pollen performance in understory species in Monagahela National Forest. *further training in botany -PhD at University of Hawaii, Manoa. Gerod Hall -BS 1995 Howard U Biology – Research topic: pH effects on pollen performance *further training in ecology -PhD in Ecology at Cornell University (Alison Power).Kerry Brown -BS 1991 Howard U Biology -Research topic: Alpine plant community interactions in Snowy Range, WY. *further training in ecology -PhD at SUNY Stony Brook (Patricia Wright), postdoctoral research at Columbia U (Shahid Naeem), current Assoc Professor -Plant Ecology at Kingston U, Dept Geography, Geology & Environment, London, UKMaria Hille-Salgueiro -MS 1991 (Mary McKenna) Howard U Biology -MS Thesis topic: Ecotypic differentiation in reproductive characteristics of serpentine plants Donna Eversley -MS 1990 (Mary McKenna) Howard U Biology -MS Thesis topic: Pollen competition in Dianthus armeria *further training - MD at Howard U School of Medicine

Accomplishments

Accomplishments

2014 Exemplary Mentoring Award

Ecological Society of America Representative on AIBS Council (1998-present)

Faculty Sponsor, HU SEEDS Chapter, Ecological Society of America (2006-present)

Board of Directors, American Institute of Biological Sciences (AIBS) 1999-2006

IBRCS Working Group, Blueprint and Rationale for NSF NEON (2002-2004)

CETLA Featured Teacher Award (2005)

Faculty of the Year Award, HU Biology Graduate Students Association (1997)

2015 HU ADVANCE-IT Follow the Leader Award

Related Articles

Optimizing; Nitrogen Management in Food and Energy Production and Environmental Protection

Stewart, JC and MA McKenna. 2002. Nodulation and growth of white clover is enhanced by a monoterpene from wild thyme. In Galloway, J. N., Cowling, E. B., Erisman, J. W., Wisniewski, J., and Jordan, C. (eds). 2002. Optimizing; Nitrogen Management in Food and Energy Production and Environmental Protection: Contributed papers of the Second International Nitrogen Conference, Potomac, MD, 14-18 October 2001. Publisher: A.A. Balkema The Scientific World. ISBN: 90 265 1927 3. 1033pp.

Endemism vs invasiblility in nickel hyperaccumulators. 9th New Phytologist Symposium

McKenna, MA., R.L. Chaney and E. Brewer. 2002. Endemism vs invasiblility in nickel hyperaccumulators. 9th New Phytologist Symposium.,U. Pennsylvania, Philadelphia, PA.

Pollen response to environmental stress in natural populations

McKenna, M.A. 1998. Pollen response to environmental stress in natural populations. p. 38.  In  Pollen and Spores 1998: Proceedings of an International Conference. The Royal Botanic Gardens, Kew and The Natural History Museum, London.

Effects of pH on pollen germination, reproduction and growth in alpine plants

McKenna, M.A., N.V. Summers and M. Bond. 1994. Effects of pH on pollen germination, reproduction and growth in alpine plants. In: Stephenson, A.G. and T.H. Kao (eds.), Pollen-Pistil Interactions and Pollen Tube Growth.  American Society of Plant Physiologists, Rockville, MD.

Genotypic and phenotypic components of alpine plant response to acid rain

McKenna, M.A. 1994. Genotypic and phenotypic components of alpine plant response to acid rain.  Report to Forest Service Rocky Mountain Station, Fort Collins, Colorado.

Atmospheric effects on plant reproduction.

McKenna, M.A. 1993. Atmospheric effects on plant reproduction.  Final Report to Forest Service Rocky Mountain Station, Fort Collins, Colorado.

Effects of pH on pollen germination, reproduction and growth in alpine plants

McKenna, M.A., N.V. Summers and M. Bond. 1994. Effects of pH on pollen germination, reproduction and growth in alpine plants. In: Stephenson, A.G. and T.H. Kao (eds.), Pollen-Pistil Interactions and Pollen Tube Growth. American Society of Plant Physiologists, Rockville, MD.

Pollen competition and heterostyly.

McKenna, M.A. 1992. Pollen competition and heterostyly. pp. 225-246 in S. Barrett (ed) Evolution and Function of Heterostyly, Monographs in Theoretical and Applied Genetics. Springer-Verlag, Zurich.

Temporal patterns of nectar and pollen production in Aralia hispida: Implications for reproductive success

Thomson, J.D., M.A. McKenna, and M. Cruzan. 1989. Temporal patterns of nectar and pollen production in Aralia hispida: Implications for reproductive success. Ecology 70:1061-1068. 

A technique for sampling and measuring sugar content of small amounts of floral nectar

McKenna, M.A. and J.D. Thomson. 1988. A technique for sampling and measuring sugar content of small amounts of floral nectar. Ecology 69: 1306-1307.

Heterostyly and microgametophytic selection: The effect of pollen competition on sporophytic vigor

McKenna, M.A. 1986.  Heterostyly and microgametophytic selection: The effect of pollen competition on sporophytic vigor in two distylous species. pp. 443-448 in D.L. Mulcahy, G.B. Mulcahy and E. Ottaviano eds. Biotechnology and Ecology of Pollen, Springer-Verlag, New York.