Table 1. Results of covariance analysis corresponding to the linear regressions drawn in Figure 1 plus Antarctic data.

InterceptSlope	NHWTSW	NHWT	SHWT	CT	A
NHWTSW		<0.0001*
NHWT	0.07			<0.0001*
SHWT	<0.0001 *	<0.0001 *			<0.0001*
CT	0.01 *	0.06	0.013 *		<0.0001*
A	0.01 *	0.004 *	0.27	0.37

P-values are indicated for the comparison between slopes and intercepts for each pair of environments. NHWTSH: Northern Hemisphere Warm Temperate environments in Shallow Water (<2 m), NHWT: Northern Hemisphere Warm Temperate environments in deeper water, SHWT: Southern Hemisphere Warm Temperate environment, CT: Cold Temperate environment and A: Antarctic environment.

^*: statistically significant.