Intraspecific differences in seed dispersal caused by differences in social rank and mediated by food availability

We use individual-based information on the behavior of wild female Japanese macaques in two consecutive years with different food availability (nut-rich vs. nut-poor) to test effects of dominance rank and nut fruiting on seed dispersal parameters. We predicted that social rank would affect dispersal (1) quantity, (2) quality, (3) species richness, and (4) percentage of berries in the diet in the nut-poor year, while these differences would disappear in the nut-rich year. We found seeds of nine fleshy-fruited plant species in the feces of the monkeys. The frequency of seed occurrence for two plant species (Viburnum dilatatum and Rosa multiflora) showed an interaction between dominance ranks and years; in the nut-poor year V. dilatatum seeds were more abundant among dominant females and R. multiflora among subordinates, while such inter-rank differences disappeared in the nut-rich year. Similarly, the intact ratio of V. dilatatum seeds was lower for dominants in the nut-poor year, while inter-rank variations disappeared in the nut-rich year. Finally, percentage of berries in diet and seed richness showed no inter-annual nor inter-rank variations. Our study highlights that differences in individuals’ social rank lead to within-group variation in seed dispersal services and that these differences are dependent on nut availability

Katsuhara_et_al_data_for_FuncEcol

All data archived here were used for GLMM analyses in Katsuhara et al. "Functional significance of petals as landing site in fungus-gnats pollinated flowers of Mitella pauciflora (Saxifragaceae). Data is in six worksheets

Data from: Functional significance of petals as landing sites in fungus-gnat pollinated flowers of Mitella pauciflora (Saxifragaceae)

Despite the well-known visual attraction function of angiosperm petals, additional roles of these floral organs (e.g. the provision of landing-site platforms for pollinators) have rarely been examined. This is likely because most petals perform multiple functions, making it difficult to isolate the importance of landing sites in pollination success. We investigated the landing-site function of dull-coloured pinnately branched petals in Mitella pauciflora flowers, which are predominantly pollinated by fungus gnats. We conducted a field experiment, in which the effects of experimental petal removal on pollinators’ approach, landing and visit duration and floral reproductive success were examined in naturally pollinated flowers. According to direct and time-lapse camera observations, petal removal did not influence pollinators’ approach frequency or visit duration, but did significantly decrease their landings. Fruit set and pollen dispatch both significantly decreased with petal removal, indicating that petals promote female and male reproductive success in M. pauciflora by facilitating pollinator landing. This demonstrates that inconspicuous petals primarily have a landing-site function rather than a visual attraction function in M. pauciflora. Discriminating between diverse petal functions is a challenging problem, and new approaches are required to elucidate the functional features of angiosperm flowers

Data from: Neglected seed dispersers: endozoochory by Javan lutungs (Trachypithecus auratus) in Indonesia

Leaf monkeys are known to be leaf eaters, and thus, their potential role as seed dispersers has been neglected. However, they do also feed on fruits. To examine the role of leaf monkeys as endozoochorous seed dispersers, we studied the Javan lutung (Trachypithecus auratus) in Indonesia. We compared multiple aspects of seed dispersal processes (amount and diversity of seeds ingested, dispersal distance, and germination rate) of lutungs with that of the sympatric long-tailed macaque (Macaca fascicularis). Over the study period, 54 percent of the lutung feces contained intact seeds, which was equivalent to the macaque feces contained seeds (62%). Seeds of at least six plant species were detected in the lutung feces, which was less than those found in the macaque feces (>19 plant species). The main species of seeds defecated by both lutungs and macaques was Ficus spp. (seed size: 0.7 mm). Seed shadow, estimated from travel distance (range: 1–299 m) and gut passage rate (24–96 h), had a unimodal-distribution with a peak at 51–100 m, and was shorter than that reported in published accounts of macaques and other similar and smaller sized frugivores. Finally, germination rates of Ficus spp. seeds ingested by both lutungs and macaques were lower than that of the control seeds. These results imply that the dispersal effectiveness of lutungs would be lower than that of the sympatric primate frugivores. However, at a population level, lutungs could play a significant role as seed dispersers for the small-seeded species, and therefore, more research into their frugivorous habits is warranted

Factors affecting forest area change in Southeast Asia during 1980-2010

<div><p>While many tropical countries are experiencing rapid deforestation, some have experienced forest transition (FT) from net deforestation to net reforestation. Numerous studies have identified causative factors of FT, among which forest scarcity has been considered as a prerequisite for FT. In fact, in SE Asia, the Philippines, Thailand and Viet Nam, which experienced FT since 1990, exhibited a lower remaining forest area (30±8%) than the other five countries (68±6%, Cambodia, Indonesia, Laos, Malaysia, and Myanmar) where forest loss continues. In this study, we examined 1) the factors associated with forest scarcity, 2) the proximate and/or underlying factors that have driven forest area change, and 3) whether causative factors changed across FT phases (from deforestation to net forest gain) during 1980–2010 in the eight SE Asian countries. We used production of wood, food, and export-oriented food commodities as proximate causes and demographic, social, economic and environmental factors, as well as land-use efficiency, and wood and food trade as underlying causes that affect forest area change. Remaining forest area in 1990 was negatively correlated with population density and potential land area of lowland forests, while positively correlated with per capita wood production. This implies that countries rich in accessible and productive forests, and higher population pressures are the ones that have experienced forest scarcity, and eventually FT. Food production and agricultural input were negatively and positively correlated, respectively, with forest area change during 1980–2009. This indicates that more food production drives deforestation, but higher efficiency of agriculture is correlated with forest gain. We also found a U-shaped response of forest area change to social openness, suggesting that forest gain can be achieved in both open and closed countries, but deforestation might be accelerated in countries undergoing societal transition. These results indicate the importance of environmental, agricultural and social variables on forest area dynamics, and have important implications for predicting future tropical forest change.</p></div

Changes in percentage forest area of the eight SE Asian countries during 1980–2010.

<p>Changes in percentage forest area of the eight SE Asian countries during 1980–2010.</p

Relationship between remaining forest area as of 1990 and the three variables in which significant correlation at <i>P</i> < 0.05 was observed.

<p>Relationship between remaining forest area as of 1990 and the three variables in which significant correlation at <i>P</i> < 0.05 was observed.</p