Complex implications around a simple trait: ecological context determines the fecundity effects of corolla marcescence

Abstract

Post-anthesis functionality of persistent perianth parts has rarely been investigated, but available evidence suggests that perianth persistence may not always have an adaptive value. Given the high occurrence of the trait, that it may sometimes be maladaptive is an intriguing possibility and deserves exploration. This paper tests the hypothesis that the fitness value of corolla persistence after anthesis depends on ecological context, specifically the abundance of fruit predators and pollinators. The study was conducted on Narcissus longispathus, a species in which corolla marcescence is apparently maladaptive because withered corollas provide a shelter for fruit-predatory lepidopteran larvae. By experimentally manipulating corolla persistence, presence of fruit predators, and pollination, I tested whether variation in ecological scenario led to concomitant variation in the sign and magnitude of the effects of corolla marcescence on fecundity. Persistent corollas were detrimental to fecundity when plants were exposed to larvae, but not when larvae were excluded. Pollination and herbivory had nonadditive effects on the fecundity consequences of corolla marcescence, the strongest detrimental effects of corolla persistence occurring for the "exposed to larvae + supplementary pollination" treatment combination. The hypothesis that ecological context is a major determinant of the fitness value of corolla marcescence was supported. In N. longispathus, corolla marcescence will be a maladaptive trait in situations in which pollinators and fruit predators are simultaneously abundant, but will be a neutral character in the absence of fruit predators, irrespective of pollinator service.