324 



INTRODUCTION TO EVOLUTION 



Subspecies and Microgeographic Races 



Another difficulty in identifying subspecies or geographic races is the 

 fact that they possess no clear-cut lower limit. They grade insensibly into 

 microgeographic races, local races inhabiting small areas, e.g., one pond or 

 one wood lot (Wilson and Brown, 1953). For example, Dice (1937) in- 

 vestigated populations of Peromysciis inhabiting wood lots only 3 or 4 miles 

 apart but separated by cultivated land. He found statistically significant dif- 



too 



DALLES 



100 



100 



BHi BH2 DHi DH3 DHs BDi BD2 



FIG. 14.4. "Profiles" representing the distribution of 

 seven red-blood-cell antigens in three stocks of Pero- 

 m-iscvis. Ordinate scale represents percentages of indi- 

 viduals possessing the respective antigens designated 

 on the abscissa. (From Moody, "Cellular antigens in 

 three stocks of Peromyscus maniculafus from the Colum- 

 bia River valley," Confributions from fbe Laboratory of 

 Vertebrate Biology, University of Michigan, No. 39, 

 1948, p. 13.) 



ferences between these various subpopulations in a variety of bodily and 

 skeletal measurements and in hair color. The present author made a sero- 

 logical study of three populations of Peromyscus maniciilatus living a few 

 miles apart in the Columbia River valley (Moody, 1948). He identified 

 seven antigens in the red blood cells somewhat comparable to the A and B 



