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

Table 1

Results of Mann-Whitney test for species abundance between glaciated ( = 141) and unglaciated ( = 35) regions (α = 0.05) and proportion of sites within each region that a species was collected for the six species occurring in both regions. Superscripts denote primary (1), secondary (2), or tertiary (3) species. Abundance is measured by catch-per-minute for tertiary and secondary species and number of individuals for primary species.

	Cambarus polychromatus	Fallicambarus fodiens	Cambarus laevis	Orconectes immunis	O. propinquus	O. virilis
Mean abundance; glaciated sites	1.43	0.46	0.024	0.64	0.38	0.19
Mean abundance; unglaciated sites	1.61	0.12	0.14	0.29	2.57	0.35
Mann-Whitney test	2452	2236	1515	1496	1496	2089
Significance	0.746	0.050	<0.001	0.001	0.001	0.247
Proportion of site; occurrence in; glaciated region	60.0	2.9	48.6	53.8	80.8	37.1
Proportion of site; occurrence in; unglaciated region	66.2	16.6	3.5	14.3	38.0	26.2