Journal of Tropical Ecology (2005) 21:109–112. Copyright © 2005 Cambridge University Press DOI: 10.1017/S0266467404001932 Printed in the United Kingdom SHORT COMMUNICATION Fleshy pulp enhances the location of Syagrus romanzoffiana (Arecaceae) fruits by seed-dispersing rodents in an Atlantic forest in south-eastern Brazil Paulo R. Guimar ˜ aes Jr. ∗1 , Priscila F. M. Lopes ∗ , Mariana L. Lyra† and Ana Paula Muriel‡ ∗ Programa de P ´ os-Graduac ¸˜ ao em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Caixa Postal 6109, 13083-970, Campinas, SP, Brazil † Programa de P ´ os-Graduac ¸˜ ao em Gen ´ etica e Biologia Molecular, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Caixa Postal 6010, 13083-970, Campinas, SP, Brazil ‡ Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil (Accepted 2 May 2004) Key Words: Caviomorpha, food hoarding, palm, seed dispersal, seed predation Rodents are the most diverse group of terrestrial mammals in neotropical forests (Emmons & Feer 1997). The in- teraction of rodents with plants is often pivotal for seed survival (Peres & Baider 1997, Vander Wall 1990). Many rodent species are seed predators (Brewer 2001, Galetti et al. 1992, Hoch & Adler 1997). However, some neotro- pical rodents, especially dasyproctids (such as Dasyprocta and Myoprocta) and echimyids (Proechimys), are im- portant secondary seed dispersers for large-seeded plants (Forget 1993, 1994; Hoch & Adler 1997, Wenny 1999). The seeds of some plants, such as the Brazil-nut tree Bertholletia excelsa and other Lecythidaceae species (including Lecythis spp.) have traits convergent with temperate rodent-dispersed nuts, e.g. large seeds with no fleshy tissue. However, several large-seeded genera dispersed by rodents have fleshy pulp, and include palms such as Acrocomia (Guimar˜ aes, pers. obs.) and Astrocaryum (Brewer 2001, Brewer & Rejm´ anek 1999, Hoch & Adler 1997), and legume trees such as Hymenaea (Asquith et al. 1999) and Dipteryx (Forget 1993). The presence of pulp in these large-seeded fruits may be an adaptation to promote predator satiation (Smith 1975, Smythe 1970), an anachronism ( Janzen & Martin 1982), a defence against insect predation (Silvius & Fragoso 2002), or simply a trait related to seed dispersal by mammals (van der Pijl 1982). Whatever the origin of fleshy pulp, its presence can have an impact on rodent behaviour and, consequently, plant recruitment. Although several studies have indicated that neotropical rodents such as agoutis and pacas consume fleshy pulp (Beck-King et al. 1999, Henry 1999, Nowak 1 Corresponding author. Email: paulomiudo@uol.com.br 1991), few studies have investigated how the presence of pulp affects the interaction between a plant species and the rodent community in the neotropics (Silvius & Fragoso 2002). In this study, we examined how rodent species in an Atlantic forest in Brazil interact with fruits and seeds of the jeriv´ a palm Syagrus romanzoffiana. We focused on the role of fleshy pulp on diaspore location, manipulation, removal and fate. In April 2001, fieldwork was conducted in a secondary- growth rain forest in the Parque Estadual Intervales (PEI) (24 ◦ 16 ′ S, 48 ◦ 25 ′ W), located in S˜ ao Paulo State, Brazil (Mantovani 2001). The altitude of the park varies between 40 and 1000 m and the climate is relatively cold and wet (Campos 2001). The annual rainfall is 1558 mm (mean for 1990–1993), with a relatively cold, dry season from April to August and a warm, wet season from September to March. The PEI, together with other three ecological reserves, form a large continuum of nearly 120 000 ha of Atlantic forest (Campos 2001). The PEI has 84 mammalian species, 28 of which are rodents, including scatterhoarding rodents such as species of Dasyprocta and Proechymis (De Vivo & Gregorin 2001). Syagrus romanzoffiana (Chamisso) Glassman is 10– 20-m tall palm that is widespread in semi-deciduous forests and rain forests of south-eastern Brazil, produces ripe fruit throughout year, especially from February to August (Lorenzi 1992). Syagrus romanzoffiana fruits are 3-cm long, elliptical, fibrous, orange drupes with a hard endocarp nearly 3 mm thick. The seed is deeply grooved and has only one embryo. The heavy consumption of palm fruit by rodents, and the evidence of scatterhoarding by squirrels (Galetti et al. 1992) and agoutis (P. R. Guimar ˜ aes, unpubl. data), made this palm an interesting system