Hybridization between native and introduced species is an increasingly important topic in conservation biology. Two studies addressing similar questions with different systems were conducted. Chapter 1 investigates the potential for hybridization between between Typha angustifolia and Typha latifolia (Typhaceae) in a constructed Ohio wetland. Chapter 2 compares genetic diversity and flowering phenology of Andropogon gerardii between native Ohio prairies and Conservation Reserve Program (CRP) grasslands.
Three taxa of cattail are recognized in the central USA: native Typha latifolia, the invasive Typha angustifolia, and a hybrid between the two species, Typha x glauca. I investigated cattail establishment and the potential for hybridization in a constructed wetland. Typha angustifolia shoots were more abundant and densely packed than those of T. latifolia in the six-year-old wetland. Typha angustifolia flowered two weeks earlier than T. latifolia. RAPDs were used to screen for hybrids. These DNA markers corresponded well to pollen type and the presence or absence of a gap in the floral spike. I found no putative hybrids based on surveys involving molecular and/or morphological traits. Thus, I did not detect gene flow between cattail species, despite opportunities for cross-pollination and F 1 seedling establishment.
In Ohio and elsewhere, grassland plantings in the federal Conservation Reserve Program (CRP) have become much more extensive than native prairie remnants. Non-local seed is often planted for CRP grasslands, which may be undesirable from the standpoint of conservation genetics. The goal of this study was to evaluate the genetic diversity of local vs. non-local big bluestem (Andropogon gerardii) populations and examine the potential for genetic assimilation of native populations with non-local genotypes. Flowering times overlapped extensively, indicating that cross-pollination is possible where native and introduced genotypes co-occur. Using RAPD markers, no significant differences were detected in genetic diversity composition between the two groups (CRP vs. native); 84% of the genetic variation occurred within populations, and 16% occurred among populations. Native and CRP populations did not cluster together strongly in a neighbor joining tree, and genetic diversity values were similar and relatively high for both population types. Taken together, these analyses suggest that genetic differentiation between the two types of Andropogon populations may be minor.