Douglas et aL: Geographic variation in cranial morphology of Stenella longirostns 



69 



pattern with similarities to those 

 for sea surface temperatures. 



Table 7 indicates that the pat- 

 tern of correlations of environ- 

 mental principal component I 

 with cranial measures is similar 

 to that of Sea Surface Temp. 

 (July) (variable 7), which is ex- 

 pected given the strong loadings 

 of this environmental variable on 

 this component (see Table 6). En- 

 vironmental principal component 

 11 has positive correlations with 

 most skull-width measures (Table 

 7). The third environmental com- 

 ponent has relatively few signifi- 

 cant correlations with morpho- 

 logical characters; its strongest 

 association is with one of the 

 summary morphological vari- 

 ables, canonical variable 2. 



In Table 8, we have summar- 

 ized Mantel i -values and matrix 

 correlations between selected 



Table 8 



Results of Mantel tests (t ) and matrix correlations (r ) for Stenella kmffirostris. Comparison of interiocality differences for 13 environmental 

 variables and 3 environmental components against those for 5 morphological variables selected in canonical variates analysis. 



Environmental variable 



Postorbital W. 



( 



10 

 11 



12 



13 



Sea Current (N., Winter) 

 Sea Current (W., Winter) 

 Water Depth 

 Solar Insolation (Jan.) 

 Solar Insolation (Ann.) 

 Sea Surface Temp. (Jan.) 

 Sea Surface Temp. (July) 

 Sea Surface Temp. 



(Ann.Var.) 

 Oxygen Minimum Layer 



(Depth) 

 Surface Salinity 

 Thermocline Depth 



(Winter) 

 Thermocline Depth 



(Summer) 

 Surface Dissolved Oxygen 



Environmental Component I 

 Environmental Component II 

 Environmental Component III 



-0.56 

 -1.38 

 3.23* 

 4.46* 

 2.14* 

 5.47* 

 4.82* 



1.64 



1.22 

 4.57* 



2.92* 



2.52* 

 2.52* 



3.63* 

 2.75* 

 1.39 



L. Rostrum 

 (frm.Pterygoid) 



t r 



W Internal 

 Nares 



t r 



W Premax. 

 (at 1/2 L.) 



t r 



W Rostrum 

 (at Base) 



t r 



-0.050 

 -0.092 

 0.235 

 0.339 

 0.176 

 0.371 

 0.353 



0.114 



0.077 

 0.323 



0.241 



0.172 

 0.204 



0.268 

 0.212 

 0.120 



-0.59 

 0.12 

 1.27 

 2.60" 

 1.95 

 3.71** 

 1.73 



1.22 



2.12* 

 0.37 



4.42*' 



1.63 

 1.43 



1.68 



3.85*' 

 1.19 



-0.083 

 0.010 

 0.128 

 0.283 

 0.241 

 0.327 

 0.176 



0.113 



0.158 

 0.035 



0.548 



0.146 

 0.172 



0.174 

 0.429 

 0.160 



1.99* 

 -0.72 

 2.25* 

 4.49*** 

 1.86 

 3.63*** 

 4.65*** 



3.80*** 



3.54*** 

 1.03 



-0.96 



-0.15 

 1.88 



4.09*** 

 -1.11 

 1.99* 



0.215 

 -0.053 

 0.186 

 0.393 

 0.180 

 0.271 

 0.387 



0.236 

 0.082 



-0.56 

 0.59 



-0.76 

 0.77 



-0.54 

 0.53 

 2..55* 



-0.073 

 0.048 



-0.073 

 0.079 



-0.062 

 0.045 

 0.244 



-0.79 

 -0.44 

 2.22* 

 1.81 

 1.43 

 1.63 

 0.64 



0.294 1.40 



0.123 -0.40 



1.62 

 0.06 



0.116 

 0.005 



-0.61 

 0.62 



-0.093 -0.55 -0.063 3.87*** 



-0.001 

 0.179 



0.345 



-0.099 



0.207 



-0.35 

 0.93 



2.02* 

 -0.75 

 -0.97 



-0.030 

 0.105 



0.197 

 -0.078 

 -0.121 



3.41*** 

 -0.18 



0.11 



3.70*** 



0.32 



-0.141 

 -0.044 

 0.271 

 0.241 

 0.219 

 0.170 

 0.079 



-0.044 



-0.051 

 0.072 



0.598 



0.362 

 -0.027 



0.014 

 0.508 

 0.054 



*P<0.05; •*P<0.01; •**F<0.001. 



