Investigating Sexual Dimorphisms in Amaranthus palmeri

Sexual dimorphisms are a unique observation between male and female organisms of the same species that can provide insight into their evolutionary life history strategies. Within angiosperms, this can be applied to trait selection for each sex that maximizes their respective fitness. The following study explores a variety of morphological and phenological traits between male and female individuals of Amaranthus palmeri. I subjected individuals to a fertilizer treatment gradient of varying concentrations to compare to an optimal nutrient environment to observe how each sex responded to nutrient limitations. I then performed an ANOVA for differences in the measured traits between males and females and used these observations to construct life history strategies that appeared to maximize fitness for both sexes. Our results showed that male individuals of Amaranthus palmeri appeared to follow a life history strategy that maximizes pollen dispersal through early investment in height growth. In contrast, females of Amaranthus palmeri appear to follow the life history strategy of gradual resource accumulation to maximize photosynthesis at the time of seed production through greater leaf and above-ground vegetative biomass resource allocation.