COAST RANGE CORRIDOR IN CALIFORNIA 



179 



1954, 1957). The pattern results from a southward movement of a 

 boreal species that split around the Great Valley barrier (Fig. 15). 

 The coastal arm is characterized by a solid color pattern, the Sierran 

 arm by a spotted color pattern. Aside from a trans-valley leak noted 

 earlier, the two arms maintain their identity at separate elevations 

 in southern California, but are found in true (if limited) sympatric 

 association at moderate elevations in the Peninsular Ranges. The 

 Sierran arm has undergone more differentiation and more fragmen- 

 tation, thus suggesting that it is older than the coastal arm. 



2. Two closely related species of the slender salamander, Batra- 

 choseps attenuatus and B. paci'ficiis, are associated in extensive 

 sympatry (Fig. 16) in southern California, along the coast (Stebbins 

 and Lowe, 1949; Savage and Brame, 1957). The species may live 

 together under the same rock or piece of wood. B. pacificus appears 

 to be an older species in southern California, if judged from the 

 degree of subspecific variation and particularly because of its oc- 



"■^ SLENDER 



/SALAMANDER 

 / BATRACHOSEPS 



--^ A, PLIOCENE ") . 



^-T-^ / ^FOSSIL }-t 



--^RACKWAYJ 



SYMPATRIC 



PACIFICUS' 



LEUCOPUS 



B. PACIFICUS / 



I 



-1 



^^^\CAr ^ 



Fig. 16. Distribution of slender salamanders, genus Batrachoseps. 

 Slender salamander, B. attenuatus, is found in sympatry with worm 

 salamander, B. pacificus, in numerous localities in Los Angeles and 

 Orange counties of California, and on Santa Cruz Island. 



