Spatial Distribution and Dispersal Patterns of Central North American Freshwater Crayfish (Decapoda: Cambaridae) with Emphasis on Implications of Glacial Refugia

Table 2

Species loadings on the four principle components (62% of variance) in the PCA analysis. PC I (20% of variance) a gradient of species associated with unglaciated sites (negative loading) and species associated with glaciated sites (positive loading). PC II (15% of variance) represents a gradient of Orconectes virilis to Orconectes immunis dominance.

Species	Principle component
	1	2	3	4
C. polychromatus
C. sp. A cf. diogenes
C. laevis
F. fodiens
P. acutus
O. immunis
O. propinquus
O. virilis