Douglas et al.: Geographic variation in cranial morphology of Stenella longiroscrls 



67 



Table 7 (continued) 



^Blanks indicate nonsignificant correlations. Individual symbols refer to significant positive or negative correlations (P<0.05; >0.396); 

 double symbols indicate highly significant correlations (P<0.01; >0.505); and triple symbols represent very highly significant correla- 

 tions (P<0.001; >0.620). 



'■Environmental variables: (1) Sea Current (N., Winter); (2) Sea Current (W., Winter); (3) Water Depth; (4) Solar Insolation (Jan.); 

 (5) Solar Insolation (Annual); (6) Sea Surface Temp. (Jan.); (7) Sea Surface Temp. (July); (8) Sea Surface Temp. (Ann. Var.); (9) Oxy- 

 gen Min. Layer (Depth); (10) Surface Salinity; (11) Thermocline Depth (Winter); (12) Thermocline Depth (Summer); and (13) Surface 

 Dissolved Oxygen. 





Environmental 



Principal 

 Component I 



I 



17 19 



Figure 10 



Geographic variation in environmental vari- 

 ables as summarized in (A) principal compo- 

 nent I and (B) principal component II. 

 Darkened part of bar indicates value for par- 

 ticular block. 



Water Depth (variable 3; Fig. 

 IIB) is positively correlated with 

 13 morphological measures, two 

 of which (L. Braincase and W. 

 Temporal Fossa) are very highly 

 significant (P< 0.001). The block 

 values for W. Temporal Fossa 

 (which have a 0.755 correlation 

 with Water Depth values) are 

 shown in Figure 11 A. For the 13 

 variables, relatively large values 

 typically were recorded in block 

 0117 and those in the vicinity of 

 the Hawaiian Islands (0702 and 

 0802), all of which have relative- 

 ly deep waters, while more shal- 

 low localities like 0516 and 0812 

 had individuals that were smaller 

 for these characters. 



The fourth environmental 

 measure, Solar Insolation (Jan.), 

 changes from high to low values 

 uniformly from north to south. It 

 is statistically associated with 

 only one character, W. Internal 

 Nares, which has small values for 

 0812; values tend to get higher 

 as one proceeds south, but there 

 are exceptions (such as 0802, 

 which is relatively high). Canon- 

 ical variable 2 has a pattern 

 statistically similar to this envi- 

 ronmental variable (bottom of 

 Table 7). 



