Plasticity facilitates Anthemis cotula to invade diverse habitats

In view of the significant contribution of phenotypic plasticity in survival and spread of invasive species in heterogeneous adventive environments, present study was carried out on natural populations of Anthemis cotula L. (Stinking mayweed) growing in habitats that differ in disturbance. The vegetative (stem height, number of lateral branches, root mass, and shoot mass) and reproductive (number of disc florets per plant and per capitulum and number of capitula per plant) traits exhibited significant phenotypic plasticity across such habitats. Number of disc florets per plant (used as the measure of fitness) was highest in riparian populations and lowest in populations growing in habitats with relatively low disturbance. Fitness in populations supported by habitats with high disturbance was 5183.85 disc florets per plant. Although the number of disc florets per capitulum did not vary significantly across populations supported by different habitats, the number of capitula per plant ranged from 148.10 in riparian populations to 20.74 in populations growing in low disturbance habitats. Among the vegetative attributes, stem mass and number of lateral branches per plant varied significantly across populations supported by habitats with different disturbance regimes. Quantification of the phenotypic selection acting on these vegetative and reproductive traits estimated through use of selection differentials and gradients varied in sign and strength across the sites which indicate that different traits are favoured under different habitat conditions. Comparison of the phenotypic plasticity of A. cotula with a con-familial alien but less invasive species-Galinsoga parviflora - allows us to conclude that phenotypic plasticity not only enables the former to maintain fitness across a broad range of environments but also contributes significantly to its invasiveness in the Kashmir Himalaya.