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Krissa Skogen, Ph.D.

Krissa Skogen
Conservation Scientist
Manager, Conservation and Land Management Internship Program
(847) 835-6919
Curriculum Vitae: 
Teaching and Research Affiliations: 

Adjunct Professor, Biological Sciences, Northwestern University

Selected Professional Associations: 
  • Member, Botanical Society of America
  • Member, Society for Conservation Biology
  • Member, Ecological Society of America
Research Interests: 
  • Reproductive and pollination biology
  • Plant-insect interactions
  • Floral trait evolution
  • Demography
  • Population genetics
  • Large-scale anthropogenic threats to biodiversity
  • Understanding the causes and consequences of plant population and species decline
  • Onagraceae, Sphingidae, microlepidopterans

Because plants face a multitude of threats, using a combination of scientific methodologies is often necessary to understand the patterns of biodiversity we see today and to identify the causes and consequences of population and species decline. My research combines a variety of different scientific approaches to answer broad-scale questions to ultimately guide policy and management decisions. In particular, my research integrates data on reproductive biology, plant-insect interactions, population genetics, demography, and threats imposed by anthropogenic activities, including nitrogen deposition and habitat fragmentation.

Scent-mediated diversification of flowers and moths across western North America

We commonly think of floral scent for its role in attracting pollinators, but it can also be a cue for floral and seed predators. This project integrates chemical ecology and comparative genomics to explore the impact of past selective pressures on current patterns of diversity in non-model organisms: evening primroses, hawkmoths, bees, and micromoths. In particular, we are investigating how chemically-mediated interactions between flowering plants, pollinators, and enemies affect diversification at the population, species, and higher taxonomic levels. Onagraceae (evening primrose family) is one of the most species-rich families of night-blooming plants in North America. Many Onagraceae, particularly species in tribe Onagreae, produce floral scent that likely dictates the primary biotic drivers impacting plant fitness, including legitimate pollinators (hawkmoths, bees) and floral and seed predators (Mompha moths). The same floral characteristics (color, shape, scent) that attract pollinators are also suspected to attract floral antagonists to host plants. Mompha is one such moth genus that specializes on Onagraceae. A thorough survey of these micromoths associated with Onagreae in western North America will result in a more accurate assessment of diversity in this group. Three dimensions of biodiversity will be integrated through studies of (1) floral trait variation, (2) its genetic basis, and (3) their roles in driving patterns of diversity in Onagreae and Mompha. The identification of “hot” and “cold” spots of selection will provide a test of the role of scent in the creation and maintenance of biodiversity across landscapes and time.

This project is a collaborative National Science Foundation research project between myself, Jeremie Fant (Chicago Botanic Garden), Norm Wickett (Chicago Botanic Garden), Robert Raguso (Cornell University), Rachel Levin (Amherst College), Sylvia Kelso (Colorado College), Terry Harrison (University of Illinois at Urbana-Champaign), Jean-Francois Landry (Agriculture & Agri-Food Canada, Eastern Cereal and Oilseed Research Centre), Kathleen Kay (University of California, Santa Cruz), Mike Moore (Oberlin College), and Warren Wagner (Smithsonian Institution).

Long-Distance Pollinator Movement – Oenothera harringtonii
This project investigates pollination, reproduction, and gene flow in the Colorado Springs evening primrose (Oenothera harringtonii, Onagraceae), a species endemic to southeastern Colorado. The flowers of Oenothera harringtonii open soon after sunset and are pollinated primarily by hawkmoths. Hawkmoths can travel up to 20 miles in just one night, and may therefore contribute significantly to long-distance gene flow among populations. These moths feed on the nectar of Oenothera flowers, which they locate by the strong fragrance produced by the flowers. This species is found in an increasingly fragmented landscape; however, little is known of the impacts that fragmentation and light pollution may have on the community of pollinators upon which it relies for reproduction and long-term population persistence. Studying populations in both fragmented/developed and unfragmented areas will allow me to determine the extent to which habitat fragmentation and light pollution may be negatively impacting both hawkmoth populations as well as populations of Oenothera harringtonii. A combination of field, greenhouse, and molecular tools are being used to understand which pollinators visit flowers, to what they are attracted (floral scent, size, nectar sugar concentration, etc.), and whether plants are successfully reproducing (demographic data, hand pollinations), and to examine patterns of gene flow (microsatellite markers).

Conservation and Restoration in Changing Environments – Colorado Plateau
Together with Jeremie Fant, Ph.D., and Dan Larkin, Ph.D., I am investigating plant genetic, demographic, and community dynamics in intact and restored habitats designed to guide effective and efficient restoration in the western United States. This is a region with great need for research to help guide restoration practices and policies, as demonstrated by the Great Basin Native Plant Initiative and the Colorado Plateau Native Plant Initiative. These initiatives, comprising governmental, academic, and private agencies and institutions, focus on developing an adequate supply of appropriate native plant materials to facilitate the enhancement, recovery, and/or restoration of landscapes throughout the region, as well as on developing scientifically rigorous methodologies that ensure successful establishment and persistence of restored native plant habitats.

In the summer of 2010, two teams of students assessed plant and pollinator communities and phenological changes over a six-week flowering period in and around Springdale, Utah, and Montrose, Colorado, working with the Bureau of Land Management and the National Park Service (Zion National Park) to provide a baseline data for use in future projects.

Understanding Causes and Consequences of Species Decline – Desmodium cuspidatum
My previous research on the perennial legume, Desmodium cuspidatum (large-bracted tick-trefoil, Fabaceae), explored whether nitrogen deposition (acid rain) may contribute to the decline of a nitrogen-fixing plant species. This species has experienced a dramatic decline in the northeastern portion of its range in the last 30 years, from approximately 28 populations in the mid-1970s to just nine populations as of 2007. However, populations elsewhere in the species range have not declined. Interestingly, the pattern of decline in Desmodium cuspidatum is consistent with the pattern of nitrogen deposition in the United States: the highest, for the longest period of time, in the northeast. Studies of demography and reproductive biology revealed that extremely low reproductive success and recruitment (birth) rates might be limiting population growth. Furthermore, patterns of genetic diversity suggest that current populations harbor high levels of genetic diversity but might be threatened in the future if gene flow is restricted among existing populations.

Selected Publications: 

Fant, J., H. Weinberg-Wolf, D. Tank and K. Skogen. Characterization of 12 microsatellite markers in Castilleja sessiliflora and transferability to other Castilleja species. Applications in Plant Sciences. 1(6):1200564.

Ksiazek†, K., J. Fant and K. Skogen. 2012. An assessment of pollen limitation on Chicago green roofs. Landscape and Urban Planning. 107(4):401-408.

Skogen, K., E. Hilpman†, S. Todd†, and J. Fant. 2012. Microsatellite primers in Oenothera haringtonii (Onagraceae), and annual endemic to the shortgrass prairie of Colorado. American Journal of Botany Primer Notes and Protocols in the Plant Sciences. 99(8):e313-6.

Skogen, K., K. H. Holsinger, and Z. G. Cardon. 2011. Nitrogen deposition and the decline of a regionally threatened legume, Desmodium cuspidatum. Oecologia.165(1):261-269.

Skogen, K., L. Senack†, and K. Holsinger. 2010. Dormancy, small seed size and low germination rates contribute to low recruitment in Desmodium cuspidatum(Fabaceae). Journal of the Torrey Botanical Society. 137(4):355-365.

Tienes, M., K. Skogen, P. Vitt and K. Havens. 2010. Optimal monitoring of rare plant populations - Report for the USDA Forest Service.

Johnson-Groh, C., C.Riedel, L. Schoessler and K. Skogen. 2002. Below-ground distribution and abundance of Botrychium gametophytes and juvenile sporophytes. American Fern Journal 92(2):80-92.

(† indicates student author)

Graduate Students: 
Kelly Ksiazek (Northwestern University, Ph.D. expected 2016)
Matthew Rhodes (Northwestern University, master's degree, 2013)
Rebecca Barak (Northwestern University, master's degree, 2012)
Ricardo Rivera (Northwestern University, master's degree, 2012)
Emily Booth (Northwestern University, master's degree, 2011)
Melissa Gray (Northwestern University, master's degree, 2011)

Skogen Lab
Research in the Skogen Lab combines a variety of different scientific approaches to answer broad-scale conservation and biodiversity questions to ultimately guide policy and management decisions. In particular, the research that my students and I conduct integrates data on pollination biology, reproductive biology, population genetics, and threats imposed by anthropogenic activities, including nitrogen deposition, habitat fragmentation, and climate change. This website provides information on research conducted by myself and my students, as well as news, photos, and videos of current and previous research.

CARICE – Conservation and Restoration in Changing Environments
In the arid environments of the western states, more than one-third of the habitat in the region has been degraded by invasive species and changes in fire regimes. There is a great need to learn more about how to effectively restore these ecosystems. Some of the questions our research comprises include 1) What are the ecosystems services most at risk from climate change and/or invasive species? 2) What are “appropriate” sources of plant material to use in restoration, i.e., how far can seed be moved without having negative effects on restoration outcomes? 3) What are the best management practices to meet restoration goals? and 4) How can ecosystem functions in these degraded areas be restored in the face of a changing environment? This website provides information about ongoing projects that I am working on together with Jeremie Fant, Dan Larkin, Emily Yates, Andrea Kramer, and Northwestern University graduate students.

Conservation and Land Management Internship Program
The Conservation and Land Management Internship Program provides a unique internship experience to college graduates. Interns learn new skills, experience real-world land management and conservation, and develop connections that can lead to future employment. Each year, between 70 and 85 interns are hired to work closely with federal biologists in the Bureau of Land Management, National Park Service, USDA Forest Service, and other federal agencies. The CLM program invests in young people and builds on their enthusiasm and capacity to make a substantial contribution to protecting the environment. The majority of internships focus on projects in botany or wildlife-related fields, or combinations that have involved monitoring or assessing threatened and endangered species. Interns have also worked in fire ecology, fisheries, livestock utilization, and native plant materials. Most recently, internships have involved native seed collecting that will contribute to seed banks or restoration activities. For more information and to apply for an internship, please visit the CLM website. To learn about projects that current and previous interns have participated in, please visit the CLM Blog at