Table 3.

General linear model analysis (GLMs) of morphological differences in terms of size and shape, as well as shape accounting for the influence of size (CS)

GLMs
	df	SS	Z	p
Centroid Size
Littorina fabalis versus Littorina obtusata
Species	1	20.636	1.511	.009*
Location	7	2.182	6.460	.001*
Residuals	273	2.354
Total	281	25.171
L. fabalis ecotypes
Ecotype	2	0.747	0.139	.447
Location	3	0.952	3.736	.001*
Residuals	168	1.814
Total	173	3.513
Shape
L. fabalis versus L. obtusata
Species	1	0.757	2.700	.003*
Location	7	0.544	6.608	.001*
Residuals	273	2.414
Total	281	3.715
L. fabalis ecotypes
Ecotype	2	0.339	1.877	.030*
Location	3	0.105	2.863	.002*
Residuals	168	1.563
Total	173	2.007
Shape accounting for size
L. fabalis versus L. obtusata
CS	1	0.7830	6.054	.001*
Species	1	0.0334	−0.782	.789
Location	7	0.5478	6.683	.001*
Residuals	272	2.3507
Total	281	3.7148
L. fabalis ecotypes
CS	1	0.0379	2.200	.014*
Ecotype	2	0.3968	2.604	.006*
Location	3	0.0673	2.039	.016*
Residuals	167	1.5052
Total	173	2.0072

Only individuals from allopatric sites were included in this analysis.

Abbreviations: df, degrees of freedom; SS, sums of squares; Z, Z‐scores; p, p‐value (*indicates significant values).