Morphological Variation in Pseudemys 



117 



STATISTICAL RESULTS 

 The first factor (PC I) extracted by principal components analysis 

 was size-related, as expected (Wiley 1981). It accounted for more than 

 50% of the total variance in male and female turtles and all loading 

 coefficients (eigenvectors) were high and positive (except angle of anal 

 scute, AA). PC II accounted for 24 and 26% of the remaining variance, 

 respectively, by sex. Among the 30 components extracted, only PC II 

 showed evidence of clustering by species. When individuals were plotted 

 according to their PC II scores (Fig. 8 and 9), P. rubriventris showed 

 distinct separation from P. concinna and P. floridana, which clustered 

 together and did not appear morphologically distinct. The most 

 influential mensural characters loaded on PC II are identified in Table 

 2. Two male specimens (NCSM 11365 and 13812) from extreme 

 northeastern North Carolina (Gates Co.) had been tentatively identified 

 as P. rubriventris. Because these two individuals plotted well outside the 



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PC II 



Fig. 9. Plot of individual adult female Pseudemys based on principal components 

 analysis (PC II) and discriminant function analysis (DF 1) of morphometric 

 characters. Open circles represent P. rubriventris, closed circles represent P. 

 concinna, and triangles represent P. floridana. 



