Morphological, electrophoretic, and ecological analysis of Quercus macrocarpa populations in the Black Hills of South Dakota and Wyoming

Morphological data support the hypothesis that oak populations in the Black Hills of South Dakota and Wyoming reflect the effect of introgressive hybridization between Quercus macrocarpa and Q. gambelii; these populations cannot be electro-phoretically differentiated from Q. macrocarpa. Thirteen populations of oaks were sampled in the Black Hills of South Dakota and Wyoming, and a single population each of Q. macrocarpa and Q. gambelii were sampled outside of the Black Hills. Morphological data suggest significant similarities of populations located in northwestern Black Hills with Q. gambelii and populations located in the eastern Black Hills with Q. macrocarpa. Disparity between morphological and electrophoretic data suggests that natural selection is operating differently on the morphological and isozymic characters.