Sex-specific plant responses to two light levels in the liverwort Marchantia inflexa (Marchantiaceae)

In seed plants, the occurrence of spatial segregation of the sexes (SSS) along environmental gradients is well documented. SSS in bryophytes is usually more extreme than in seed plants, yet few bryophyte studies have explicitly linked SSS to environmental variables. For Marchantia inflexa, in which males are found beneath more tree-canopy openness than are females, we tested whether morphological, physiological and life history patterns are consistent with this sex-specific association to canopy openness. To accomplish this, we quantified morphology, physiology and life history differences between two light conditions for each sex. Responses to light levels were mostly analogous to sun and shade leaves of seed plants. However, we found that males had lower chlorophyll ab ratios (indicative of low-light plants) than females, contrary to our prediction.