Sexual dimorphism and pattern of resource allocation under variable abiotic factors

Dioecious taxa partition resources between sexes to fulfil maternal and paternal functions. The biased partitioning of resources results in differences in morphological, physiological, and life-history traits between sexes, thereby giving rise to sexual dimorphism. Such a pattern enables the evolution and maintenance of dioecy. The interaction between abiotic factors and sex-specific allocation strongly influences the extent of sexual dimorphism and shapes sex-specific adaptive strategies. These strategies enable the survival of the species in given ecological contexts. The key life-history traits associated with dioecy are also strongly influenced by abiotic factors and are intrinsically connected to evolutionary pathways. In dioecious taxa, both sexes exhibit plasticity in resource allocation, enabling them to survive. Under optimal light and water conditions, sex-specific responses may not appear, but at various stress levels male and female plants often differ in photosynthetic efficiency, stress tolerance, and growth patterns. Research indicates that the extent of this specialization is limited and far from a unifying generalization. Nonetheless, it could be argued that the higher reproductive cost may lead to a reduction in stress tolerance in females. Moreover, higher water use efficiency allows males to better survive in xeric conditions. Thus, the poor reproductive, vegetative, and physiological performance of females has been observed under stress conditions. The combined effect of multiple stresses may be much more pronounced than of each acting independently. This may also change the magnitude of physiological specialization between sexes. These factors modulate life history traits such as the spatial segregation of sexes, clonality etc. among dioecious taxa and, as a result, may enhance the extent of sexual dimorphism. Intriguingly, generalizations made at present may not hold true for the future due to plasticity responses exhibited by dioecious plants that have been investigated, so the generalization remains context-dependent.