1. Waterbird-mediated endozoochory is an essential mechanism for the dispersal of sessile organisms in freshwater ecosystems. However, in the neotropics there are no previous studies of how different waterbird species vary in the dispersal functions they perform, and how seasonality influences endozoochory. In this study, we identified plant diaspores dispersed in faeces of five South American waterfowl (Brazilian teal Amazonetta brasiliensis, yellow-billed teal Anas flavirostris, ringed teal Callonetta leucophrys, coscoroba swan Coscoroba coscoroba, and whitefaced whistling-duck Dendrocygna viduata). 2. We collected 165 faecal samples from five wetlands in southern Brazil surrounded by pasture and rice fields, then separated and measured intact seeds and other diaspores. Using generalised linear models, we tested how diaspore abundance and taxonomic richness differed among bird species and between cold (April-September) and warm (October-March) periods. We also analysed bird-specific and seasonal variations in diaspore composition through principal coordinates analysis and permutational multivariate analysis of variance. We used indicator species analysis to determine which diaspore species discriminated between bird species and seasons. Finally, we measured diaspore length in order to analyse differences among waterfowl species in the size of diaspores dispersed. 3. We found 2,066 intact diaspores from 40 different plant taxa, including seeds of 37 angiosperms and diaspores of Lycophyta (Isoetes cf. maxima), Pteridophyta (Azolla filiculoides), and Charophyceae. There was at least one diaspore in 65% of all faecal samples. Diaspores of native amphibious and emergent plants were dominant. We found 1,835 diaspores (from 33 taxa) in the cold period but only 231 (23 taxa) in the warm period. Seeds of the grass Zizaniopsis bonariensis and of the sedge Rynchospora sp. were the most abundant taxa. A strong interaction between bird species and season was the most important predictor of variation in both taxonomic richness and abundance of diaspores. The taxonomic composition of diaspores differed among waterfowl species and season. Indicator species analysis identified 12 plant taxa associated with particular bird species and seasons. Coscoroba swan, the largest bodied species in our study dispersed a higher proportion (8.2%) of large (length >2 mm) seeds. | 79 SILVA et AL.
For the first time to our knowledge, we demonstrate that whole angiosperm individuals can survive gut passage through birds, and that this occurs in the field. Floating plants of the genus Wolffia are the smallest of all flowering plants. Fresh droppings of white-faced whistling duck Dendrocygna viduata (n ¼ 49) and coscoroba swan Coscoroba coscoroba (n ¼ 22) were collected from Brazilian wetlands. Intact Wolffia columbiana were recovered from 16% of D. viduata and 32% of Coscoroba samples (total ¼ 164 plantlets). The viability of plants was tested, and asexual reproduction was confirmed. Wolffia columbiana is an expanding alien in Europe. Avian endozoochory of asexual angiosperm propagules may be an important, overlooked dispersal means for aquatic plants, and may contribute to the invasive character of alien species.
Most zooplankton species inhabiting seasonal ponds produce dormant stages to overcome the dry seasons. Zooplankton specimens emerging from the sediment contribute to the ecological dynamics of these ecosystems, because they constitute important energy sources for higher trophic levels in aquatic food webs. In contrast to snapshot studies of the active communities, studying the ecological correlates of the distribution of the egg bank can help identify the potential drivers of zooplankton composition. We tested the association of local (habitat structure and water chemistry), climatic and spatial predictors with the alpha and beta diversity of zooplankton hatchling communities in subtropical seasonal ponds. Incubation experiments were conducted with sediment samples from 11 ponds distributed along an approximately 500‐km latitudinal gradient in southern Brazil. We assessed the patterns for the total community, Cladocera only and Rotifera only. The alpha diversity of the total community and Cladocera were primarily related to substrate heterogeneity. Annual rainfall and substrate heterogeneity jointly influenced the beta diversity of the total community. Annual rainfall solely influenced the beta diversity of Cladocera, while substrate heterogeneity influenced the overall beta diversity of Rotifera. Overall, the distinct relationships of the total hatchling community and Cladocera and Rotifera with the explanatory datasets suggest differing sensitivities of the zooplankton groups to impacts in habitat structure and climatic conditions in subtropical seasonal ponds.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.