Damage tolerance and cotyledonary resource use in the tropical tree Gustavia superba

Explanations for the extremely large seed size of some tropical forest plants are currently lacking. In this study we examine cotyledonary resource use of the tropical tree Gustavia superba, and test whether tolerance to damage of either seeds or establishing seedlings might be an important function leading to, or maintaining, its large (> 5 g) seed reserves. We found that seeds of Gustavia were both tolerant of insect infestation and were also capable of successful germination after removal of half of their cotyledonary reserves. Simulated complete above-ground herbivory resulted in repeated resprouting (up to 8 times). Resprout shoots were constructed of a small, but fixed proportion of remaining cotyledonary mass regardless of seed size. In the absence of damage, cotyledon reserves were used for onward seedling growth; however, conversion of cotyledon resources was slow, lasting several months. Given high rates of damage to Gustavia seeds and seedlings in the field, and the apparent use of cotyledonary reserves to tolerate or recover from it in growing house experiments, we conclude that cotyledonary seed size and morphology in this species is adaptive in surviving pre- and early post-germination hazards.