| In response to environmental variation, mixed reproductive strategies may have evolved to optimize reproductive response to local conditions. This study investigated the possible causes underlying the balance between chasmogamy and cleistogamy in a neotropical understory herb, Calathea micans (Marantaceae). In this species, CH (potentially outcrossed) and CL (selfed) flowers are produced all year long. Seeds are identical morphologically and are dispersed by ants. In natural populations as well as in experimental conditions, plants responded to an increase in light and nutrient availability by producing new shoots that had a higher probability of producing CH inflorescences while there was no effect of light or nutrient availability on the production of CL inflorescences. Because the seed coat remains attached at the base of the seedling for at least a few months after germination, this plant provided the opportunity to compare the fate of CH and CL seeds dispersed by ants. CH and CL seeds did not differ in removal rate or dispersal distances and this result contrasts with previous studies of dispersal in CH/CL species. There was no overall significant difference in seedling recruitment between CH and CL progeny. However, CL recruitment was uniform across light environment whereas CH recruitment varied according to light. In conclusion, in this species, CL ensures some seed set in conditions unfavorable to plant growth while CH progeny shows a more variable response to light environment than CL progeny. Even though reproduction is low in natural populations, a mixed reproductive such as chasmogamy/cleistogamy seems to allow this plant to optimize reproductive response to environmental conditions. |
