Laserfiche WebLink
<br />w <br />~~ <br />. In the Amargosa <br />E results from the <br />s. Rapid evolution <br />ations, the warm <br />roduced, and the <br />g (Miller, 1961b). <br />-n, attempts have <br />nations have been <br />s, the Devil's Hole <br />been isolated for <br />pfish in the same <br />b). Under severe <br />in (1972) indicate <br />ar, the Cottonball <br />period of time, its <br />stem and to the <br />ably entered the <br />Pliocene, and the <br />:r date, after the <br />antan connection <br />Wing Mono Lake <br />:rain by volcanic <br />ay comparatively <br />~f cutthroat trout <br />re, since suitable <br />Mrens River and <br />~ to the coastal <br />the Santa Ana <br />3 in four streams <br />and Santa Ana <br />e intermittently <br />that. needs to be <br />phically (Miller, <br />stal area shortly <br />entry was either <br />the ocean in the <br />knt capture of a <br />L. Hubbs, pers. <br />DISTRIBUTION AND ZOOGEOGRAPHY 23 <br />True freshwater fishes were absent from coastal streams north and south of the four <br />rivers of the Los Angeles Plain prior to introductions by man, with the exception of <br />the unannored threespine stickleback in the Santa Clara River system and probably <br />the arroyo chub in the Santa Margarita and San Luis Rey rivers. The population of <br />speckled dace in San Luis Obispo Creek is a bit of an enigma. It is difficult to see from <br />physiographic evidence how they could have become established there naturally yet, if <br />they were brought there by man (presumably as bait), they must have been introduced <br />prior to 1880, when D. S. Jordan first collected them from the creek (C. L. Hubbs, <br />pers. comm.). <br />COLORADO RNER SYSTEM <br />The Colorado River is of major interest to students of fish evolution and zoogeography <br />~ in western North America because it drains much of the soythwestern United States. It <br />has served both as a highway to distribute fish species throughout the southwest and as <br />a major center of fish evolution. The latter role has been possible because the system <br />as. we know it today consists of a number of separate drainage basins that were isolated <br />from each other for long periods of time (Miller, 1958). In California, the lower <br />Colorado River was the ultimate source of the ancestors of a number of species <br />endemic to the Death Valley system and to southern California. It was home to only <br />four native freshwater fishes (aside from the mullet and other marine visitors), the <br />humpback sucker,. the Colorado squawfish, the bonytail, and the desert pupfish, <br />i although many other native fishes normally found elsewhere in the lower Colorado <br />drainage system, especially the Gila River in Arizona, undoubtedly washed into the <br />California portion on occasion. It is most likely, that the minnows and suckers of the <br />lower Colorado evolved in upstream regions where other related species are also found. <br />