174 Branley A. Branson 



The Teays and the Old Ohio rivers greatly influenced the distribu- 

 tion of fishes and other aquatic organisms in the Low Plateau. Accord- 

 ing to Hocutt (1979), the Old Ohio River headed near the present con- 

 fluences of the Salt River (Kentucky) and the Blue River (Indiana), a 

 major tributary being the Green River from Tennessee and Kentucky. 

 The Teays headed in North Carolina and flowed through Ohio, Indiana, 

 and Illinois, then southward into the Mississippi Embayment; its major 

 southern tributaries were the Old Kentucky and Old Licking rivers 

 (Hocutt et al. 1978). Pleistocene glaciation destroyed most of the Lower 

 Teays, creating the vast Upper Ohio River by westward diversion of the 

 Big Sandy, Little Sandy, Licking, Kentucky, and Kanawha rivers and, 

 during Kansan times (Wayne 1952), by diverting a large segment of the 

 Teays system into the Wabash River. Such drainage modifications 

 allowed eastern fishes, such as Percina macrocephala (Cope) and 

 Etheostoma blennioides blennioides Rafinesque, to disperse westward 

 into Low Plateau streams. This may account for the strong resemblan- 

 ces between the fish faunas of the Green and Licking rivers (Retzer et al. 

 1983) and the distribution of Percina cymatotaenia (Gilbert and Meek) 

 and its undescribed sibling species (Branson and Batch 1974). 



Lachner and Jenkins (1971) considered the Teays River to have 

 functioned as a generation center, a reservoir of species, and a dispersal 

 pathway. According to them, for example, the ancestral stock of Noco- 

 mis micropogon (Cope) evolved in the Upper Teays (Kanawha-New) 

 system, and dispersed from there into the Lower Teays and into the 

 southwestern Ohio basin. Since the Wabash was nearly completely 

 overwhelmed by Pleistocene ice, the population in that stream has to be 

 the result of later re-invasion from refugia to the south. Lachner and 

 Jenkins (1971) presented evidence that N. micropogon entered the Ten- 

 nessee River via stream capture, probably by headwater piracies between 

 the Tennessee, Chattahoochee and Savannah rivers (Ross 1971). Ross 

 (1971) also documented transfers of the Duck and Elk rivers from the 

 Cumberland to the Tennessee and stream captures between the Coosa- 

 Hiwassee and Tennessee rivers in northern Alabama. A Cumberland- 

 Kentucky river drainage exchange of Etheostoma sagitta (Jordan and 

 Swain), and doubtless other fishes as well, including N. micropogon (the 

 only Nocomis in most of the Kentucky River), was documented by 

 Kuehne and Baily (1961). If true, these exchanges would explain many 

 of the mollusk and fish distributional patterns mentioned previously 

 and below, and would strengthen the idea that the Tennessee, Coosa- 

 Alabama , and Cumberland rivers have been potent differentiation and 

 dispersal centers for various piscine, molluscan, and other groups of 



aquatic organisms. 



There appears to have been considerable faunal exchange between 



the Alabama River system and the Mobile basin and the Tennessee 

 River. The Tennessee and Alabama river systems share many species of 



