Seed dispersal and seed predation in Neotropical palms Organized by: Patrick A. Jansen, Community and Conservation Ecology University of Groningen, the Netherlands Kirsten M. Silvius, Gordon and Betty Moore Foundation, San Francisco Palms are a dominant life form in many Neotropical forests. Their fruits often represent an important food resource for frugivores and granivores, which act as dispersers and/or predators of palm seeds. This symposium aims to present recent work on interactions between palms, frugivores and granivores. We will invite people studying aspects of palm seed dispersal, seed predation and seedling recruitment. We aim for a 10-12 talk state-of-the-art symposium with strong coherence and a logical thread, starting with talks on specific interactions and finishing with talks on palm-centered food webs. A second aim is to stimulate co-operation among the participants and their research groups. Bruchids as predators on palm seeds (Coleoptera: Bruchidae) Jesús Romero Napoles Instituto de Fitosanidad, Colegio de Postgraduados Email:jnapoles@colpos.mx Bruchids comprise approximately 66 genera and 1,700 species worldwide. Of these, more than half are known from the New World and the remainder spread on the rest of the world. Actually the family Bruchidae is divided into the subfamilies Amblycerinae, Bruchinae, Eubaptinae, Kytorhininae, Pachymerinae, and Rhaebinae. About 80% of bruchid species are in the Bruchinae, 10% in the Amblycerinae, 9% in the Pachymerinae, with the other 1% assigned to the other three subfamilies. All bruchid larvae feed in seeds and about 84¬% of bruchid species feed in the seeds of the Fabaceae. The others feed in the families Arecaceae (4.5), Convolvulaceae (4.5), and Malvaceae (2%). The remaining 5% feed in seeds of 35 other plant families. No all species of Pachymerinae are predators of seed palms; the tribes Caryopemini and Caryedontini are restricted to the Old World and feed mainly on seeds of Fabaceae and Combretaceae. All species commonly called palm bruchids are in the tribe Pachymerini, which is restricted to the New World. Some species of Pachymerinae are now cosmopolitan in their distribution. The Pachymerini is formed by the genera Caryoborus (3 species), Caryobruchus (6 species), Pachymerus (7 species), and Speciomerus (4 species). Some studies state that Pachymerini females lay eggs only in seeds where the exocarp and mesocarp have been removed, and larval predation may be up to 100%. Using the BRUCOL data base (Romero & Johnson, 2004) it is known that Pachymerini may feed on seeds of 32 genera and about 110 species of Arecaceae family, with the single exception of Pachymerus abruptestriatus, which feeds on Dyospiros sp. seeds (Ebenaceae). keywords: Palm bruchids, hosts, predation Phenology and seed predation in three species of palms Evan Notman 1 and Ana Villegas 2 1 National Science Foundation 2 Gordon and Betty Moore Foundation Email:enotman@nsf.gov The timing of fruit and seed production may influence seed survival via differences in abiotic and biotic conditions. Levels of seed predation may differ with time of dispersal for various reasons, including seasonal changes in predator abundance, and changes in the number of conspecific seeds produced. We examined how the timing of seed production influenced seed survival and germination of three species of lowland rainforest palms, Welfia regia, Socratea exorrhiza, and Iriartea deltoide in Costa Rica. We also compared timing of seed production and seed germination and survival of S. exorrhiza between a site in Panama with highly seasonal rainfall, and a site in Costa Rica with a relatively weak dry season. We expected that levels of seed predation would be influenced more strongly by time of seed production for the species that had more pronounced fruiting peaks (S. exorrhiza, and I. deltoide) than for W. regia which fruits throughout the year. We also expected larger differences in seed survival for S. exorrhiza between placement dates in the more seasonal site in Panama than in Costa Rica. Seeds of each species in Costa Rica were placed in the field during 24 different time periods that represented a low and high period of conspecific fruit production and survival and germination was monitored. In Panama seeds of S. exorrhiza were placed in the field during 2 periods corresponding to the start and the peak of S. exorrhiza fruiting. Although seed survival rates differed between placement dates, survival patterns were not consistent between predator type or palm species, and contrary to expectations, the greatest differences in seed survival time between placement dates were found for W. regia. Despite the seasonal differences between Costa Rica and Panama the rate of seed predation between placement dates was fairly similar at both sites. Keywords: phenology, palms, seed predation, Costa Rica, Panama Fruit handling by frugivorous vertebrates enables niche partitioning by granivorous beetles: small scale pattern detected by a landscape scale experiment Mariana Silvius Kirsten Gordon and Betty Moore Foundation Email: kirsten.silvius@moore.org Preliminary data from Barro Colorado Island, Panama, suggested that co-occurrence and relative population abundance of two sympatric bruchid beetles restricted to the same host palm species is mediated by vertebrate frugivore use of the palm fruits. A large scale field experiment at Maraca Island Ecological Reserve, Brazil, confirms that the two bruchid species use the palm resource differently--Speciomerus giganteus is almost completely restricted to endocarps derived from fruits whose husk has been removed by vertebrates, while Pachymerus cardo occurs in those derived from both handled and intact fruits. Early in the fruiting season, paired vertebrate exclosures containing 30 intact and 30 handled fruits were placed at 4 replicate fruiting trees at each of 6 sites along a 10 kilometer ecosystem-and-palm-density gradient ranging from interior terra firme through edge forest, savanna forest islands and riverine forest. Endocarps were collected after 1 year and the exit holes left by emerging beetles measured. Speciomerus produces significantly larger exit holes than Pachymerus; exit hole size is not related to endocarp size. Exit holes were significantly larger for handled fruits than for intact fruits, indicating predominant use by the larger Speciomerus. Although there were significant site effects and site-by-fruit type interactions, niche separation was consistent across all habitats. Lab based experiments are needed to determine the mechanism for separation. If Speciomerus cannot use intact fruits in the absence of Pachymerus, then it would be excluded by Pachymerus at sites of low mammal abundance. Pachymerus is the dominant competitor, being able to use both forms of fruits. Speciomerus is more abundant than Pachymerus at BCI, while the opposite is true at Maraca, suggesting an over-abundance of small frugivorous mammals at BCI relative to Maraca. Keywords: Bruchid beetle, niche-separation, competition, Attalea, frugivory Seed density, dispersal and predation in an understory palm Tarek Milleron Utah State University Email: tarekmill@gmail.com Rodents cache and consume seeds of Astrocaryum gynacanthum, an abundant understory palm, in lowland rain forests of the Caura River Basin, in southern Venezuela. I did several experiments with marked and unmarked seeds to examine the effect of seed density on seed caching and removal. Hunting in the study area may have very slightly reduced populations of agoutis, but did not impact acouchy, spiny rat or large felid populations during a period of at least a decade before this study. Seed caching was intensive toward the tail-end of a fruiting peak and then fell off sharply. Initial seed density in 1-m x 1-m plots did not affect rates of seed removal, but there was a trend toward lower proportions being removed from higher density plots. On plots of a range of sizes, from 0.5-m x 0.5-m to 12-m x 12-m, there was an inverse trend of disproportionately long caching distance with initial density. More unmarked seeds were taken from open sites than from paired sites accessible only to small rodents (p = 0.01), but time to discovery did not differ between access treatments. These results comport with caching models derived from other field sites. Manipulative experiments of much greater sophistication will be required in order to elucidate mechanisms behind seed caching and consumption. Keywords: rodents,palms, seeds Differential handling of palm seeds by Central American agoutis (Dasyprocta punctata; Rodentia) and collared peccaries (Tayassu tajacu; Artiodactyla) has contrasting effects on seed fates Erin K. Kuprewicz University of Miami, Department of Biology Email: erin@bio.miami.edu In neotropical forests, terrestrial mammals are important palm seed dispersers and predators. The positive (dispersal) and negative (predation) effects that mammals have on seeds influence tree propagation and forest regeneration yet little is known about how seed dispersers with different seed-handling strategies affect seed fates. Central American agoutis (Dasyprocta punctata) disperse seeds via scatter-hoarding whereas collared peccaries (Tayassu tajacu) consume and kill most of the seeds they find. The main goal of this study was to determine the effects that agoutis and peccaries each have on the survival of palm seeds at Estacion Biologica La Selva, Costa Rica and how scatterhoarding by agoutis affects seed survival. I tracked individual threadmarked seeds of Socratea exorrhiza and Astrocaryum alatum over 34-day periods to determine their fates. Seeds were either exposed to only agoutis and small mammals (excluding peccaries) or to all terrestrial mammals. I also simulated agouti hoards and exposed seeds to invertebrate or vertebrate seed predators for 34 days. Seed removal was faster at depots open to all mammals but most Socratea seeds suffered predation by peccaries, whereas seeds in semi-permeable mammal exclosures survived longer and were more likely to be hoarded and dispersed by agoutis. Artificially-hoarded seeds escaped predation by invertebrates and vertebrates while exposed seeds suffered high beetle infestation or almost complete removal by mammals. Peccaries consumed most Socratea seeds present on the forest floor, however hoarding by agoutis may counteract the overall damage that peccaries and insects have on seed survival to germination. Keywords: Dasyprocta, Tayassu, seed dispersal, seed predation, scatter-hoarding Production and fate of Astrocaryum mexicanum seeds before and after hurricane Iris in southern Belize Marcel Rejmanek1 and Rob Klinger2 1 University of California, Davis 2 US Geological Survey Email: mrejmanek@ucdavis.edu Astrocaryum mexicanum is an understory dominant palm species that is an important constant food resource for many mammals of all sizes. Before hurricane Iris (October 8, 2001), mean fruit production was 45.4 fruits per tree per year. After the hurricane, mean annual production exceeded 130 fruits per tree. This was due to a substantial increase in mean canopy openness (from <7% to 32% between July 2001 and March 2002) that is currently only slowly declining. Fruit production approached the pre-hurricane level in 2005. However, in 2007 fruit production appeared to be declining to about 60% of the pre-hurricane level. As canopy openness is still significantly higher than in the prehurricane years, this decline must be attributed to a physiological exhaustion of the reproductive trees. In general, while >95% of seeds falling into exclosures below mature Astrocaryum trees either did not germinate or failed to produce viable seedlings because of desiccation or decomposition, seeds dispersed and buried under the surface by mammals, namely by Heteromys desmarestianus, had significantly higher survival rates. Removal rates and fate of A. mexicanum seeds were strongly related to abundance of H. desmarestianus. Because all other fruit production ceased for two years after the hurricane, density of H. desmarestianus decreased from 46 per ha in September 2001 to 23 per ha between January 2002 and January 2004. While this resulted in a 60% decline in removal rates of A. mexicanum seeds, the proportion that was eaten increased by 50% because no alternative foods were available. Seed removal rates and the proportion eaten returned to pre-hurricane levels as density of H. desmarestianus increased after fruiting non-Astrocaryum woody plants resumed in January 2004. Keywords: Astrocaryum mexicanum, hurricane, seed production, seed fate, Heteromys desmarestianus Seed predation and the Arecaceae: a valid model for tropical systems? Steven Brewer University of North Carolina Wilmington Email: brewers@uncw.edu What can be learned from single-taxon studies of seed predation, and how suitable is the Arecaceae as a model for seed predation in general? In order to be an appropriate model for the effects of seed predation on tropical forest structure and dynamics, the Arecaceae should be ecologically representative of plant taxa in general. This study examines what is known about (1) how palm taxa respond to environmental variation compared to arborescent species in general, using studies from Central and South America and (2) population dynamics of palms and their associated guilds of seed predators. In the studies examined, patterns of variation in the composition of palm species is similar to those of arborescent taxa in general, suggesting that palms and other taxa respond similarly to community-organizing forces. Physiological and morphological constraints imposed by Arecaceae phylogeny on palm reproduction offer unique opportunities for detailed quantification of plant population dynamics, however they impose considerable limitations to the applicability of long-term studies of palm seed predation and dispersal. Keywords: seed predation, seed dispersal, palms Seed dispersal and predation in two Atlantic Forest palms with different responses to habitat loss Alexandra dos Santos Pires1, Cecilia Siliansky de Andreazzi2, Clarissa Scofield Pimenta2, Fernando Antonio dos Santos Fernandez2 and Mauro Galetti 2 1 Departamento de Ciencias Ambientais, Universidade Federal Rural do Rio de Janeiro 2 Departamento de Ecologia, Universidade Federal do Rio de Janeiro Email: aspires@biologia.ufrj.br Fragmentation impacts biodiversity through several mechanisms, including the disruption of plant-animal interactions. We investigated the processes of seed dispersal and predation in two palms dispersed by scatterhoarding rodents but with distinct responses to fragmentation: Astrocaryum aculeatissimum, which is negatively affected, and Attalea humilis, which increase their abundance in small remnants. Attalea has more pulp, a harder endocarp and 1-3 seeds per fruit, while Astrocaryum has thinner endocarp and only one seed per fruit. We compared seed predation beneath parents and seed dispersal rates among large (2400 and 3500ha) and small (19, 26 and 57ha) Atlantic Forest fragments in southeastern Brazil. The number of endocarps remaining beneath palms was significantly higher in small fragments, both for Astrocaryum (U=98, p<0.01) and Attalea (U=168, p<0.01), indicating low seed removal in these remnants. For Attalea, this result was also due to increased fruit production in small areas (U=115.5, p<0.01). Predation rates by rodents beneath palms were low (below 20%) in most cases for both palms. Beetle predation seemed to be more important, as rates were high (always above 60%). For Astrocaryum beetle predation was higher in small remnants (U=512.5, p<0.05) whereas for Attalea predation rates tended to be higher at the larger ones (U=138, p=0.08). For both palms, the number of dispersed seeds was lower in smaller fragments (Astrocaryum: U=1619.5, p<0.01; Attalea: U=1258.5, p<0.01), where viable populations of dispersers (such as Dasyprocta spp.) probably cannot be maintained in long term. In synthesis, in small fragments Astrocaryum is strongly affected by the intense predation pressure from beetles combined with the loss of its dispersers, whereas Attalea, even with reduced dispersal rates as well, is more resilient because it suffers less predation by beetles and because its higher productivity allows high local recruitment. Support: FAPESP, CNPq, CYTED, Idea Wild. Keywords: fragmentation, palms, seed dispersal, seed predation, Atlantic Forest Hunting indirectly alters the abundances of insect seed predators S. Joseph Wright1, Dumas Galvez and Patrick A. Jansen2 1 Smithsonian Tropical Research Institute 2 University of Groningen Email: wrightj@si.edu Hunters are removing game species from most tropical forests, giving rise to the pantropical bush meat crisis. Game species interact with plants as seed dispersal agents and seed predators, and through these interactions hunting also affects plants. Game species also interact with insects, and we will explore how hunter-game species interactions affect insect seed predators and their palm hosts. Seeds of the palm, Attalea butyraceae, are eaten and killed by larvae of the bruchid beetle, Speciomerus giganteus. The female bruchid is only able to lay eggs on the stony endocarp after the tough exocarp has been removed. The hard, white eggs are nearly 2 mm long and are easily counted. A single larva develops inside a seed, and the emerging adults leave large circular exit holes. These traits make it possible to manipulate seed availability to bruchids and to determine how many eggs are produced and how many adults recruit to the bruchid population. We compare bruchid population dynamics at protected and hunted sites. The agouti, Dasyprocta punctata, is both a prized game species and a voracious predator of Attalea seeds and the bruchid larvae they contain. An order of magnitude more adults recruit to the bruchid population at hunted sites, where predation by agoutis on bruchid larvae is greatly reduced. The phenology of oviposition differs with eggs produced yearround at hunted sites and just during the six months of peak seed production at protected sites. Nonetheless, the number of eggs produced is only twice as large at hunted sites as at protected sites. This suggests compensatory mortality among adult bruchids at hunted sites. Bruchids only kill 70% of the available seeds at hunted sites, and many more seeds survive to produce seedlings at hunted sites than at protected sites. Similar huntergameplant-insect interactions are to be expected elsewhere. Keywords: bruchid beetle, hunting, seed predation, larval predation, beetle recruitment Hunting relieves recruitment limitation in a Neotropical palm Patrick A. Jansen1, Pieter Van Eijk1, S. Joseph Wright 2 and Helene Muller-Landau2 1 University of Groningen 2 Smithsonian Tropical Research Institute 3 University of Minnesota Email:p.a.jansen@rug.nl Recruitment limitation contributes to the coexistence of many tree species in tropical forest. We studied how various components of recruitment limitation are affected by hunting, which alters the mammal fauna, changing the abundances of seed dispersers and natural enemies. We studied the palm Astrocaryum standleyanum, the agoutis that disperse palm seeds through scatter-hoarding, and various mammals and insects that depredate the seeds, in Central Panama. We selected 60 individuals across 12 plots with contrasting levels of hunting and palm abundance, and compared rates of pre- and post dispersal seed predation, seed removal, seed dispersal, seed survival, seedling establishment, and seedling survival. We found that two components of recruitment limitation, source limitation and dispersal limitation, were stronger under hunting. But, the third component of recruitment limitation, establishment limitation, was dramatically weaker under hunting. The net effect of hunting was to relieve intense recruitment limitation. Our results suggest that hunting can indirectly affect mechanisms of species coexistence. This effect may partially explain why palms attain dominance in disturbed forests, which usually have high levels of hunting, at the cost of other tree species and hence biodiversity. Keywords: Astrocaryum standleyanum, Panama, seed dispersal, seed predation, seedling recruitment Impact of vertebrate defaunation on seed predation and dispersal of palms: implications for rain forest conservation Eduardo Mendoza and D Camila onatti Department of Biological Sciences, Stanford University Email: eduardom@stanford.edu Palms are an emblematic component of tropical forests that exemplifies the complex network of trophic interactions occurring in these ecosystems. A diverse array of vertebrates preys upon palm seeds, impacting the seed/seedling transition. At the same time, a large proportion of palm species rely on vertebrates to disperse their seeds and escape from the attack of other vertebrates and insects. Both ensembles of animals (predators/dispersers) include a common set of species, predominantly medium and large-bodied mammals and birds. Defaunation is strongly decimating populations of medium and large mammals, a situation contrasting with that observed in populations of small rodents and birds, which seem to be coping better with anthropogenic perturbation. This situation opens the possibility to find divergent effects of defaunation on palm recruitment brought about by the simultaneous breakdown of predation and dispersal interactions. This study is aimed at: i) providing an overview of the levels of palm seed predation by vertebrates and palm dependence on vertebrate dispersal as inferred from the literature, ii) presenting case studies from rain forests sites in Brazil and Southeast Mexico illustrating the mechanisms that may lead to palm decline in the absence of their dispersers (recruitment limitation) or palm escape in the absence of their seed predators (differential size related predation), iii) presenting a conceptual framework to guide the study of the factors that need to be taken into account to evaluate the overall impact of vertebrate predator/dispersal defaunation on palm performance. Our study indicates that there is a spectrum of responses to defaunation among palms and that these responses are scale dependent. However, whether palm populations respond positively or negatively to defaunation there is a strong potential for rain forest functioning to be affected as a consequence of the disruption of vertebrate-palm interactions. Keywords: Defaunation, palms, seed dispersal, seed predation, rain forest conservation A plague of palms: why large-seeded Attalea form monodominant stands in anthropogenic landscapes Jose Manuel Vieira Fragoso 1 and Kirsten M. Silvius2 1 University of Hawaii 2 Gordon & Betty Moore Foundation Email: fragoso@hawaii.edu Researchers have long commented on the predilection of Attalea palms to form large monodominant stands on pasture and farmland. A number of hypotheses have been proposed to explain this phenomenon, including fire resistance and removal of potential competitors. We compared seed mortality around adult trees in pasture and old growth forest and found significantly higher survivorship in pasture. Bruchid beetles and fungi were the only mortality agents in pasture, while these plus white-lipped peccaries and rodents added significantly to mortality in forest. We found no difference in beetle generated mortality between the two vegetation types. However, in pasture survivorship was higher due to a lack of seed depredation by white-lipped peccaries and rodents. Mortality by beetles in forest may be higher than measured, as white-lipped peccaries open seeds to eat beetle larvae. Early stage seed survivorship patterns sets the regeneration trajectory and in pasture this contributes to the formation of high-density monodominant stands of Attalea palms. Keywords: Attalea, Bruchid beetles, recruitment limitation, Janzen-Connell, pasture succession