Small vertebrates are key elements in the frugivory networks of a hyperdiverse tropical forest

Abstract

The local, global or functional extinction of species or populations of animals, known as defaunation, can erode important ecological services in tropical forests. Many mutualistic interactions, such as seed dispersal of large seeded plants, can be lost in large continuous forests due to the rarity of large-bodied mammalian frugivores. Most of studies that try to elucidate the effects of defaunation on seed dispersal focused on primates or birds, and we lack a detailed understanding on the interactions between ground-dwelling fauna and fleshy fruits. Using camera traps in forest areas with different degrees of defaunation, we described the organization of frugivory networks involving birds, mammals and plants. We recorded 375 frugivory interactions between 21 frugivores and 150 fruiting trees of 30 species of fleshy fruit plants in six sites in continuous Atlantic forest of Brazil. We found that small frugivores—particularly small rodents and birds—were responsible for 72% of the events of frugivory. Large frugivores, such as tapirs and peccaries, were responsible for less than 21% of frugivory events. Our results indicate that the interactions between flesh fruiting plants and frugivores are dominated by small frugivores, an indication of a functional loss of large frugivores in this endangered biome.

Sensitivity of Tropical Insectivorous Birds to the Anthropocene: A Review of Multiple Mechanisms and Conservation Implications

“…Diverse tropical organisms other than insectivorous birds are evolutionarily specialized in their species interactions, which likely increases their vulnerability to many of the same threats that impact insectivorous birds. For example, tropical mutualisms involving plant pollinators and fruit dispersers can involve few interacting animal or plant species, making these species interactions highly vulnerable to forest fragmentation (e.g., Laurance, 2005;Marjakangas et al, 2019;Carreira et al, 2020). Addressing all these, and many other tropical species interactions is beyond the scope of this review, but many lessons from this review may extend beyond just insectivorous tropical birds.…”

Plant species with the trait of continuous flowering do not hold core roles in a Neotropical lowland plant‐pollinating insect network

“…Land use types within the Tropical Wet Life Zone, with a diverse assemblage of plant species that provide floral resources continuously may foster plant–pollinator interactions with higher levels of specialization and more modular structure compared to other global regions (Spiesman & Gratton, 2016). Highly modular networks have also been found in protected systems where the loss of specialized interactions has not yet occurred, and it is assumed that modularity protects communities within anthropogenic landscapes from species loss (Carreira et al., 2020; Ramos‐Robles et al., 2018). The widespread use of several different species of native, continuous flowering shrubs as ornamentals throughout the tropics may contribute to favoring modularity even in the anthropogenic landscape that we sampled.…”

“…The conservation of pollinators in smallholder farms can also increase food security for subsistence farmers who have a higher dependence on free pollination services (Ashworth et al., 2009). Undoubtedly, because highly modular networks have also been reported for networks with non‐native species included (Vizentin‐Bugoni et al., 2019) and species roles within the network are expected to change with disturbance level (Carreira et al., 2020), there is still an urgent need to study pollinating insect–plant networks in protected tropical forests and in the absence of introduced species in an effort to develop best management practices for complete ecological restoration of tropical forest community structure and function (Harvey et al., 2017; Raimundo et al., 2018).…”

“…This approach can often result in substantially different rankings of species, and little information is available to guide practitioners on the “best” measure for conservation decision‐making. The second approach, modularity analysis, identifies core species directly by assigning topological roles to species that indicate the degree to which the species supports other species in the network via both direct and indirect interactions (Biella et al., 2016; Carreira et al., 2020; Guimerà et al., 2007). This approach, however, assumes (a) that the most important species in the network will be assigned into core roles and (b) that species with core roles are those responsible for promoting stability in the network (Kaiser‐Bunbury & Blüthgen, 2015).…”

“…Despite this, tropical plant–pollinator networks remain limited in number and overrepresented by vertebrate pollinators (e.g., hummingbirds and bats) (Vizentin‐Bugoni et al., 2018). The development of pollinating insect–plant network studies in the megadiverse tropics is an urgent task given the current data‐deficiency coupled with the unprecedented rates of habitat modification and functional extinctions of interactions in the tropics (Barlow, 2018; Carreira et al., 2020). Here, we construct a pollinating insect–plant network from countryside habitat in the Tropical Wet forest Life Zone (Holdridge, 1967; Sanchez‐Azofeifa et al., 2002).…”