NegronOrtiz, Vivian .
Reproductive ecology of the threatened Miccosukee gooseberry (Ribes echinellum): Where have all the seedlings gone?
Germination and seedling establishment are critical stages in plant development and may determine the persistence of a species, particularly of rare species. One rare species with only two remaining wild populations is the federally threatened Miccosukee gooseberry, Ribes echinellum. This species is confined to two disjunct localities, one in private land along the north shoreline of Lake Miccosukee, Florida, and two public locations in McCormick County, South Carolina. Although this species reproduces both vegetatively (clonal growth) and sexually (seed production), seedling recruitment has not been observed. To understand why there is no seedling recruitment of this extremely rare species, a series of studies were carried out: 1) pollination treatments to test for asexual (apomixis) and sexual seed production, 2) pollen germination and pollen tube growth for each treatment to test for pre-zygotic barrier to reproduction (incompatibility), 3) seed set on monitored flowers, 4) seed viability to estimate germination potential, and 5) in-situ seed germination and seedling survival of monitored and control (open-pollinated) flowers. Hand-pollination treatments showed successful pollen tube germination after self- and outcrossing pollinations; but the protandrous flowers did not autogamously pollinate. These findings suggest that visitors are required for pollination. Fruits were produced after self- and outcross [both intra- (Florida x Florida crosses) and between (So. Carolina donor x FL recipients)] treatments; asexual seed production was not detected. Seed germination potential assessed with 1% tetrazolium solution in three treatments (testa scarification, puncture, and longitudinal section) indicated 60 % of the seeds were viable (n= 189 seeds); no differences were observed among the three treatments (pearson Χ2 =1.03, p > 0.59). No differences were detected in the proportion of in-situ seed germination or seedling establishment among cross, self and open treatments (df=2, F=0.90, p>0.91; df=2, F=0.08, p>0.92, respectively). This suggests no inbreeding depression. However, none of the seedlings survived a full year. Conservation implications of these findings will be discussed.
1 - U.S. Fish And Wildlfe Service, 1601 Balboa Avenue, Panama City, FL, 32405, USA
pollen tube growth
Presentation Type: Oral Paper:Papers for Topics
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