Figure 2

Analysis of co-variance showing regression slopes of log endocranial volume versus log skull length for highland (red) and lowland (blue) (a) Peromyscus mice (Cricetidae), (b) Muridae (Otomyini), (c) Muridae (Praomyini). Since length is proportional to the cube of mass (body size), the allometric exponents for body size the slopes in the above regression coefficients are equivalent to one third of the regression coefficients shown. Thus, the allometric exponents for Peromyscus (0.7 for high and low populations) are higher than those for Otomys (0.4 for high and low species), and Praomyini have different slopes for high (0.5) and low (0.2) species.