Figure A, Graphic illustration of hypothetic two traits which are perfectly heritable in their relative signal expression but show no heritability in their absolute level of expression.

A) The expression of two uncorrelated traits (signals) by fathers (blue) and their sons (red). Father-son pairs are denoted by the same symbol and have the same distance from the diagonal line of equal relative expression, so that relative expression is perfectly heritable (see figure D). Nevertheless, despite identical relative expression strategies, the absolute magnitude of signals’ expression vary across generations (possibly due to environmental conditions) resulted in no apparent heritability of each trait (figures B and C). Table A, Hypothetic two traits which are perfectly heritable in their relative signal expression but show no heritability in their absolute level of expression. Table B, The relationship between the expression of tail streamers, ventral coloration, and their relative expression index in fathers and their one year old sons. Table C, Two competing models testing one year old sons relative expression index (of tail streamers length TSL and ventral coloration VC) in relation to 1) their fathers relative expression index and 2) their fathers TSL and VC separately. (PDF)