The Distribution of Genetic Variation Among Relictual Populations of Missouri Tallgrass Prairie Plants

Date of Graduation

Fall 1994


Master of Science in Biology



Committee Chair

John Heywood


The amount of genetic variability that is lost from a species when an ecosystem is fragmented will be proportional to the magnitude of genetic differentiation among its individual populations. To assess the genetic effect of habitat destruction on tallgrass prairie plant species, Wright's F-statistics were used to describe the distribution of allozyme variation among five prairie preserves in Missouri for three plant species: Schizachyrium scoparius (little bluestem), which presumably reproduces in the prairie ecosystem predominantly via vegetative propagation, Ruellia humilis, which has a mixed mating system, and Liatris pycnostachya, which is an obligate outcrosser. The Fst estimates were 0.0318 for S. scoparius (two polymorphic loci), 0.0385 for R. humilis (six polymorphic loci), and 0.0242 for L. pycnostachya (seven polymorphic loci). thus, over 96% of the allozyme variation present within each of these species in Missouri is found with individual populations. The very low level of differentiation indicates that gene flow among prairie plant populations has been sufficient to counteract genetic drift in these populations, so that the present day system of prairie preserves should contain the majority of allozyme variability which was present in the unfragmented prairie ecosystem. This homogeneous pattern may not be present for genetic loci which are affected by selection.

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