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| Author(s): |
Carolina da Silva Carvalho
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Rio Claro. 2018-02-26. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro |
| Defense date: | 2018-01-12 |
| Advisor: | Mauro Galetti; Marina Corrêa Côrtes; Pedro Diego Jordano Barbudo |
| Abstract | |
Seed dispersal is the first template upon which plant recruitment takes place, and it is crucial to regeneration, spatial distribution, colonization of new environments, and connectivity of forest fragments, being critical for the long-term viability of populations. Human impacts, however, impose pressures that alter recruitment. For example, the extinction of large seed dispersers may impair seed dispersal services if extant medium- to small-bodied vertebrates only provide suboptimal dispersal services because: (i) they often mobilize a reduced fraction of propagules per visit; (ii) they do not ingest large-sized seeds, and therefore, only mediumto small-sized seeds get dispersed; and (iii) they fail to reach distant sites, which reduces connectivity at the landscape level. Yet, we still do not know if defaunation also leads to dispersal limitation by changing the spatial distribution of maternal progenies in the seed rain, which might imperil local plant recruitment. Moreover, the lasting effects of frugivore defaunation on microevolutionary processes of plants they disperse remain understudied. Here, we characterized the spatial distribution of the maternal progenies in a bird-generated seed rain of a tropical palm (Euterpe edulis) that produces medium-sized seeds. Moreover, we tested if the loss of large seed dispersers can lead to microevolutionary changes of this tropical palm. Finally, we evaluate the potential of phenotypic rescue of this bird-dispersed palm that present seed size reduction due to defaunation of large frugivores. Overall, our study highlights that medium- and large-sized frugivores provide complementary services. We found that extant medium-sized frugivorous birds can maintain the seed dispersal services in plants of medium-sized seeds, contributing the maintenance of high local genetic diversity. Nevertheless, the loss of large-sized seed dispersers impacted the quality of seed dispersal service, mainly in terms of long distance dispersal and maintenance of large seed sizes. Moreover, our results indicate that the defaunation of large seed dispersers has a distinct signal on large-scale genetic variability, potentially arising from microevolutionary changes in the palm populations. Therefore, the lack of seed dispersers leads to both phenotypic and genetic changes, with unknown effects on the long-term persistence of plant species and entire communities. Finally, to rescue large seeds in palm populations it is necessary to restore the seed dispersal processes by large frugivores. The most effective strategy to restore seed size variation is to rewild defaunated forests with large frugivores, either by connecting remnants to faunated areas or by frugivores' reintroduction. The restoration of the seed dispersal processes by large frugivores will benefit several bird-dispersed species and may be crucial to face ongoing global change scenarios. (AU) | |
| FAPESP's process: | 14/01029-5 - Ecological and genetics effects of seed size variation in a defaunated landscape |
| Grantee: | Carolina da Silva Carvalho |
| Support Opportunities: | Scholarships in Brazil - Doctorate |