Floral biology, breeding system, pollination and reproductive success of selected understory tree species in fragments of Atlantic rainforest in Pernambuco, Northeast Brazil
Auch gedruckt in der BibliothekZ: J-H 13.723; W: W-H 12.169
FakultätFakultät für Naturwissenschaften
Ressourcen- / MedientypDissertation, Text
Datum der Freischaltung2010-07-09
It has been little studied whether reproductive success of understory trees in tropical forests responds negatively to fragmentation. Pollination biology and reproductive success of four understory tree species in the Annonaceae and Violaceae families were studied in small and large fragments of Atlantic rainforest. All four species had limited seed dispersal ranges and aggregated (patchy) distributions. Anaxagorea dolichocarpa (Annonaceae) flowers were pollinated exclusively by small beetles (Colopterus spp.). The self-compatible plants reproduced well in small and large fragments. Pollen limitation was not detected, and pollinator abundance did not decline in small fragments. Flowers of Cymbopetalum brasiliense (Annonaceae), expected to be pollinated by large scarab beetles, received no visitors, but produced many seeds. Seed set was likely apomictic. Thermogenesis was detected in flowers of both Annonaceae species. Amphirrhox longifolia (Violaceae) and Paypayrola blanchetiana (Violaceae) flowers started anthesis at night, continuing during daytime. Both species were self-incompatible and showed signs of pollen limiation. A. longifolia flowers offered pollen and scent as rewards, and received few visits by orchid bees, halicticid bees (Megalopta sp.) and Heliconius butterflies. P. blanchetiana produced nectar as main reward and was visited by many diverse insects. However, plants had consistently low relative seed set (0.6 %). Relative seed set was a positive function of fragment size and a negative function of patch flowering intensity. Loss of incompatibility alleles and inbreeding depression are discussed as possible causes for the low reproductive success, especially in small fragments. Additionally, accumulating nectar reduces the viability of the pollen, which is presented in close proximity to the nectar in the spurless corolla tubes of Paypayrola flowers.
LizenzStandard (Fassung vom 01.10.2008)
Atlantic Forest: Brazil