Our study provides the first empirical evidence for a JM species. The resulting hybrid “ Jack-and-Master” strategy ( JM) broadened the geographic range and amplified average fitness in the range centre. Plasticity resulted in average fitness being positively maintained at the wet and dry range margins where extinction risks would otherwise have been high (“ Jack-of-all-Trades” strategy JT), and fitness being maximized at the species range centre where extinction risks were already low (“ Master-of-Some” strategy MS). The model confirms that the plastic response resulted in average fitness benefits across the life-cycle. The trade-off, the relation between seed mass, seed and seedling survival, and other fitness components of the plant life-cycle were integrated within a matrix population model. Bigger seeds were positively correlated with higher seed and seedling survival rates. Individual trees plastically and reversibly produced many small seeds at dry sites or years, and few big seeds at wet sites and years.
Using tree-level responses, we detected a trade-off between seed mass and seed number across the moisture gradient. We tested this possibility in Australia using a continental scale survey of the invasive tree Parkinsonia aculeata (Fabaceae) in twenty-three sites distributed across four climate regions and three habitat types. Phenotypic plasticity has long been suspected to allow invasive species to expand their geographic range across large-scale environmental gradients.
0 kommentar(er)
