Publication Date


Advisor(s) - Committee Chair

Dr. Albert J. Meier (Director), Dr. Lawrence A. Alice, Dr. Doug McElroy

Degree Program

Department of Biology

Degree Type

Master of Science


Helianthus eggertii (Asteraceae) is a federally threatened sunflower species that typically grows between open woods and barrens. This species has both sexual and asexual modes of reproduction, which can influence the amount of genetic diversity present within and among populations. Maintaining genetic diversity is one of the primary objectives in managing threatened species or populations. Fire and population size may influence genetic diversity. Two Inter-Simple Sequence Repeat Markers (873 and MAO) were used to characterize many important genetic parameters of 17 populations in 2003 and four populations in 2004. This information was used to assess the effectiveness of different conservation management strategies.

The main objectives of this project were to determine whether:

1) larger populations of Helianthus eggertii have a higher genetic diversity within populations than smaller populations

2) fire or other management strategies influence genetic diversity of populations

3) sexually derived progeny of H. eggertii have greater genetic diversity than mixed reproduction in parent populations assuming some degree of clonal reproduction.

This study found that there is higher mean genetic diversity in larger populations, though not significant. Genetic diversity showed no difference in populations that are frequently burned than in populations that are not burned. However, there tends to be an increase in genetic diversity in some populations immediately after a fire event. The seed population studied had a higher genetic diversity. Genetic diversity is high at both Mammoth Cave National Park (.5246) and Arnold Engineering and Development Center(.4555). The high genetic diversity observed suggests that while clones may exist in a population, seedling establishment is actively putting new genetically diverse individuals in a population. These results show that the current management strategies being used are suitable for protecting this species.


Botany | Plant Sciences

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Botany Commons