We conducted an allozyme survey of genetic variation at 33 gene loci in smallmouth bass Micropterus dolomieu from 57 localities encompassing most of the range of the species, but with an emphasis (51 samples) on the Interior Highlands (Ozark and Ouachita uplands). Samples exhibited a moderate amount of total genic diversity (H T ϭ 0.068), but high genetic heterogenity (F ST ϭ 0.383). Phylogenetic analyses supported recognition of three clades from the Interior Highlands: (1) the previously recognized Neosho smallmouth bass in Ozark tributaries of the middle Arkansas River; (2) the Ouachita smallmouth bass in the Little and Ouachita river drainages of the Ouachita Highlands; and (3) a clade that included populations from the White, Black, Missouri, and other streams in the northern and eastern Ozarks. This third clade was very similar to populations from the Ohio and upper Mississippi river basins, and, on the basis of allele frequency parsimony, more closely related to them than to the Neosho and Ouachita smallmouth basses. To preserve genetic diversity and the options that divergent native stocks represent for future management, stock transfers of smallmouth bass should take into account potential effects on native forms of the species.

No abstract

Old World Bluestems (OWB), introduced from Europe and Asia in the 1920s, recently have begun to raise concerns in the Great Plains. Despite suggestion in the late 1950s that OWB were weedy and negatively impacted biological diversity, they were widely introduced throughout the Great Plains for agricultural purposes. Anecdotal evidence suggests that OWB exhibit invasive characteristics that promote competitive exclusion of native species. The objective of our study was to quantify the competitive abilities of two OWB species (Caucasian bluestem; Bothriochloa bladhii (Retz.) S.T. Blake (= Bothriochloa caucasica (Trin.) C.E. Hubb.) and yellow bluestem; Bothriochloa ischaemum (L.) Keng) with three native grass species (big bluestem (Andropogon gerardii Vitman), little bluestem (Schizachyrium scoparium (Michx.) Nash), and sideoats grama (Bouteloua curtipendula (Michx.) Torr.)). A greenhouse target-neighbor study was conducted to assess both interspecific and intraspecific competition. A total of 480 pots (4.4 l) filled with native soil was used with all pair-wise combinations of species and four density treatments (six replications). Vegetative tiller height, above-and belowground biomass were measured at the end of 16 weeks. Both of the OWB significantly inhibited at least one growth parameter of the three native grass species, while most of the native species did not inhibit growth of either OWB species. Growth of B. ischaemum was enhanced when grown in association with S. scoparium. Based upon the results of our study of OWB competitive superiority and previous research, many of the characteristics possessed by OWB are found to be in common with known invasive species. Hence, we propose that two OWB are competitively superior to three common native prairie species providing them with the ability to invade and threaten the native grasslands of the Central and Southern Great Plains.

No abstract

No abstract