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SILVIA PINEDA-MUNOZ ET AL.


requires storing energy by consuming highly energetic food resources and increasing body fat (Humphries et al. 2003). In early spring, when more energetic and protein-rich foods are less abundant, U. arctos feeds on vegeta- tion. However, it switches to amore nutritious diet in late summer. This mixed diet would be beneficial for supporting a seasonal higher demand of nutrients before periods of hiberna- tion (Beeman and Pelton 1980;McLellan 2011). Thus, U. arctos and other generalist hibernating ursids feed on a diverse, unspecialized diet despite their high body mass. A few of the generalist species in the data


the largest ones foraged on an increasingly higher amount of foliage, a pattern also observed in previous studies (Kay 1984). Frugivore species in our data set are


set show a less diverse diet than some classified as specialists, which could be explained as a mathematical artifact arising in unusual circumstances. For example, an animal feeding on 60% vegetation, 10% insects, 10% fruit, 10% fungi, and 10% seeds would be classified as an herbivore, but its diet will be more diverse (inverse Simpson index = 1.23) than that of an animal eating 45% vegetation, 45% fruit, and 10% fungi (inverse Simpson index = 0.95).


Frugivory and Body Mass


Mostdietary specializations have an optimum body-mass range, and few dietary specializa- tions occur in the medium-size range; the only common ones are herbivory, frugivory, and carnivory. Most frugivorous mammal species in our data set have a bodymass between 500g and 30kg. Previous studies found similar patterns, suggesting a peak in frugivory in the medium-size range for Neotropical primates (Kay 1984; Robinson and Redford 1986; Hawes and Peres 2014). A diet with a very high proportion of fruit has been proposed to constrain body size due to mechanical, locomo- tional, ecological, and metabolic factors (Milton and May 1976; Robinson and Redford 1986; Hawes and Peres 2014). Hawes and Peres (2014) performed an


exhaustive study on the frugivory of Neotropi- cal primates with special attention paid to the relationship with body mass. They observed higher rates of frugivory in medium-sized primate species (2–3kg). The proportion of fruit in the diet of smaller species was much lower, with a higher intake of seeds and insects, while


distributed around tropical and subtropical moist broadleaf forests. Thus, species with a higher percentage of fruit in their diet have a more restricted geographical distribution. They can also be found in forested patches in the surrounding areas, where they have to complement their diets with other food resources such as vegetation or insects, as shown in our resource utilization data set (see Supplementary Table 1). We recorded frugivore species in tropical


environments in South America and Africa but not in Southeast Asia and the Indo-Pacific (Fig. 4). This fact could be related to the nature of our dietary data. Pineda-Munoz and Alroy (2014) limited their study to the stomach content literature in order to standardize data and avoid sampling bias. Unfortunately, very little stomach content research has been performed in the latter two regions. However, there are some examples of medium-sized tropical frugivores in these regions, such as the Indian giant squirrel Ratufa indica, with an average adult size of 1.5–2kg; the liontail macaque Macaca silenus, with an average size of 3–10kg (Ganesh and Davidar 1999); and the binturong Arctictis binturong,withanaverage size of 9–20kg (Colon and Campos-Arceiz 2013). Similarly, the more restricted geographical


distribution of South American frugivore species as compared with African ones could be related to sampling biases and a higher level of endemism in the South American region. Stomach content studies have been mainly carried out near the Amazon River. However, South America seems to have a high diversity of frugivore species such as primates, which ultimately results in allopatric, closely related species having more restricted geo- graphic distributions (Wilson et al. 1988). Pure frugivores such as the black uacari (Cacajao melanocephalus) or the Colombian woolly mon- key (Lagothrix lugens) can be found in areas surrounding those that provided most of the South American stomach content data. We hypothesize that a wholly frugivorous diet is only suitable in tropical rain forests or


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