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Aim: The efficiency of animal-mediated seed dispersal is threatened by declines of animal populations, especially in tropical forests. We hypothesise that large-seeded plants with animal-mediated dispersal tend to have limited geographic ranges and face an increased risk of extinction due to the potential decline in seed dispersal by large-bodied fruit-eating and seed-dispersing animals (frugivores) Location: Atlantic Forest, Brazil, South America Taxon: Angiosperms Methods: First, we collected dispersal-related trait (dispersal syndrome, fruit size, seed size), growth form (tree, climber, other) and preferred vegetation type (open, closed) data for 1,052 Atlantic Forest plant species. Next, we integrated these with occurrence records, extinction risk assessments, and phylogenetic trees. Finally, we performed phylogenetic generalized least squares (PGLS) regressions to test the direct and interactive effects of dispersal-related traits and vegetation type on geographical range size. Results: Large-seeded species had smaller range sizes than small-seeded species, but only for species with animal-mediated dispersal, not for those dispersed by abiotic mechanisms. However, plants with abiotic dispersal had overall smaller range sizes than plants with animal-mediated dispersal. Furthermore, we found that species restricted to forests had smaller ranges than those occurring in open or mixed vegetation. Finally, at least 29% of the Atlantic Forest flora is threatened by extinction, but this was not related to plant dispersal syndromes. Main Conclusions: Large-seeded plants with animal-mediated dispersal may be suffering from dispersal limitation, potentially due to past and ongoing defaunation of large-bodied frugivores, leading to small range sizes. Other factors, such as deforestation and fragmentation, will probably modulate such effects of dispersal on range size, and ultimately extinction. Our study sheds light on the relationship between plant traits, mutualistic int, Aim: The efficiency of animal-mediated seed dispersal is threatened by declines of animal populations, especially in tropical forests. We hypothesise that large-seeded plants with animal-mediated dispersal tend to have limited geographic ranges and face an increased risk of extinction due to the potential decline in seed dispersal by large-bodied fruit-eating and seed-dispersing animals (frugivores) Location: Atlantic Forest, Brazil, South America Taxon: Angiosperms Methods: First, we collected dispersal-related trait (dispersal syndrome, fruit size, seed size), growth form (tree, climber, other) and preferred vegetation type (open, closed) data for 1,052 Atlantic Forest plant species. Next, we integrated these with occurrence records, extinction risk assessments, and phylogenetic trees. Finally, we performed phylogenetic generalized least squares (PGLS) regressions to test the direct and interactive effects of dispersal-related traits and vegetation type on geographical range size. Results: Large-seeded species had smaller range sizes than small-seeded species, but only for species with animal-mediated dispersal, not for those dispersed by abiotic mechanisms. However, plants with abiotic dispersal had overall smaller range sizes than plants with animal-mediated dispersal. Furthermore, we found that species restricted to forests had smaller ranges than those occurring in open or mixed vegetation. Finally, at least 29% of the Atlantic Forest flora is threatened by extinction, but this was not related to plant dispersal syndromes. Main Conclusions: Large-seeded plants with animal-mediated dispersal may be suffering from dispersal limitation, potentially due to past and ongoing defaunation of large-bodied frugivores, leading to small range sizes. Other factors, such as deforestation and fragmentation, will probably modulate such effects of dispersal on range size, and ultimately extinction. Our study sheds light on the relationship between plant traits, mutualistic int

Why some species occupy almost all of the Earth’s terrestrial (e.g. barn owl) or marine (e.g. moon fishes) systems, whereas others are only found in single freshwater springs (like the devils hole pupfish) or on small, isolated islands?. What is impeding species to occupy all of the Earth?. Is it that species cannot reach all places because of reduced dispersal abilities? Or is it that geometric constraints and habitat availability plays an important role on how far species can go? Is it that species are adapted to certain abiotic conditions (e.g. salinity, temperature, etc) and they are unable to adapt to habitats where conditions are different? Or is it that they cannot successfully colonize habitats in which competitor species are already present? Is it that just given enough time all species will be able to occupy all places, thus older species are more widespread than younger ones? Ultimately, only a few ecological processes should be important in determining a species’ range size: speciation (creation/division of ranges) dispersal to a new habitat (expansion of the range), successful colonization of that habitat (successful dispersal) and (avoidance of) local extinctions. Among these processes, dispersal has a central role as it is important for population’ persistence in suboptimal habitats, by providing demographic rescue to populations that otherwise would go extinct. Furthermore, dispersal also promotes gene flow, bringing the genetic variability necessary for adaptation, which is important for successful colonization and ultimately range expansion. In this thesis, using a wide variety of approaches and model systems to study how these various mechanisms can act together to eventually determine range sizes.

Why some species occupy almost all of the Earth’s terrestrial (e.g. barn owl) or marine (e.g. moon fishes) systems, whereas others are only found in single freshwater springs (like the devils hole pupfish) or on small, isolated islands?. What is impeding species to occupy all of the Earth?. Is it that species cannot reach all places because of reduced dispersal abilities? Or is it that geometric constraints and habitat availability plays an important role on how far species can go? Is it that species are adapted to certain abiotic conditions (e.g. salinity, temperature, etc) and they are unable to adapt to habitats where conditions are different? Or is it that they cannot successfully colonize habitats in which competitor species are already present? Is it that just given enough time all species will be able to occupy all places, thus older species are more widespread than younger ones? Ultimately, only a few ecological processes should be important in determining a species’ range size: speciation (creation/division of ranges) dispersal to a new habitat (expansion of the range), successful colonization of that habitat (successful dispersal) and (avoidance of) local extinctions. Among these processes, dispersal has a central role as it is important for population’ persistence in suboptimal habitats, by providing demographic rescue to populations that otherwise would go extinct. Furthermore, dispersal also promotes gene flow, bringing the genetic variability necessary for adaptation, which is important for successful colonization and ultimately range expansion. In this thesis, using a wide variety of approaches and model systems to study how these various mechanisms can act together to eventually determine range sizes.