Vivian Negrón-Ortiz
Rhodora 120 (982), 99-116, (18 June 2018) https://doi.org/10.3119/17-25
KEYWORDS: Ribes echinellum, threatened species, breeding systems, germination and recruitment, Florida
Reproductive ecology studies of rare species can provide information pertinent to population growth and persistence. One rare species confined to two disjunct localities, one on private land located in Florida and the other one that is composed of two subpopulations on public land in South Carolina, is the federally threatened Miccosukee gooseberry, Ribes echinellum. Studies were carried out in the Florida population to determine change in abundance between 1992 and 2012 and to understand the lack of seedling recruitment in the wild. In Florida, the number of patches increased in the northern part of the study area but decreased in the southern part. Hand pollination experiments indicate Ribes echinellum exhibits a mixed mating system. Although autogamous pollination occurred, it did not result in fruit production. Reduced seed set of selfed flowers and seedling size provided some support for inbreeding depression, yet small sample sizes precluded full evaluation. No asexual seed production was detected. Seeds persisted in the field less than one year, suggesting a transient seed bank. Although germination potential, estimated by staining seeds with tetrazolium, was 60%, in situ seed germination from fruits of manipulated and control flowers was only 25%. Seedling survival was zero, indicating high risk of extirpation. Either low spring precipitation during the years of this study or scarcity of compatible mates could explain the lack of seedling survival. These results are important for developing a conservation strategy for this species.