Variation in herbivory is often associated with plant density and light environment. The effect of these variables was studied on leaf production and herbivory of Manilkara bidentata in Puerto Rico. The major herbivore of M. bidentata is the leaf miner Acrocercops sp. To determine the effect of plant density, twenty-four 20-m × 20-m plots were established and the densities of saplings, juveniles and adults were determined. Leaf production, herbivory and growth were measured on saplings. Plant density was determined in eight 20-m × 20-m plots surrounding the focal plots. The effect of light was determined by comparing leaf phenology, leaf quality and herbivory in vertical and horizontal profiles. Sapling density in 60-m × 60-m plots was associated with herbivory. In the vertical profile, leaf production was continuous only for the canopy: herbivory increased from the canopy (1.3%) towards the understorey (35.6%). In the horizontal profile leaf production was related to light. Saplings in low light environments had narrow peaks in leaf production compared with saplings in high light environments. Differences in leaf phenology did not result in differences in herbivory possibly because of variation in herbivory among leaves. Although many saplings lost more than 80% of new leaf area, there was no detectable effect on growth. High levels of intra-specific variation in herbivory suggest that to better understand plant/herbivore interactions it is necessary to consider all size classes in a population. It is also important to document these pattern across different spatial scales.

The seasonal patterns of surface activity and behaviour were recorded for three species of juliform millipede in a savanna habitat in south-east Botswana. Initially, surface activity followed rainfall events but this association weakened as the season progressed and, although significant, the correlation between the magnitude of rainfall events and activity was weak. Activity also occurred on moist, relatively cool and cloudy days, particularly in Alloporus uncinatus which was much larger than the other species. The onset and duration of surface activity varied between species. Observations of feeding behaviour suggested that millipedes in semi-arid savannas did not subsist exclusively on tree leaf litter but appeared to select a range of food types. Mobility is necessary to obtain these patchy resources but differences between the sexes in patterns of behaviour are more likely related to the mating patterns of these species.

An evaluation of whether large arborescent palms depend on large treefall gaps for recruitment to the adult stage is reported. Specifically three hypotheses were tested: (1) The light requirement of juveniles of tall arborescent palms increases as they grow in size. (2) Tall arborescent palms depend on gaps over 0.10 ha for growth and survival to maturity, due to high light requirements during the stem height growth phase. (3) Stilt-rooted palms are not dependent on gaps for juvenile height growth. The hypotheses were evaluated using data on size and crown position of individuals of tall arborescent palm species as well as data on the forest-phase in which each individual grew. The study site was a 50-ha plot in old-growth rain forest in Amazonian Ecuador. The first hypothesis was accepted for the two most common species, Iriartea deltoidea and Oenocarpus bataua, but tentatively rejected for the arborescent palm community as a whole. The second hypothesis was rejected for Iriartea and the community as a whole. Only Oenocarpus had strongly gap-dependent recruitment. The results for Iriartea and Oenocarpus were consistent with the third hypothesis.

Almost 50% of the estimated 2500 species in the Bromeliaceae grow epiphytically in a remarkably wide range of habitats from inhospitable deserts to tropical rain forests (Benzing 2000). The degree of dependence on the host varies (Benzing 1990, Laube & Zotz 2006), and in some cases, epiphytic bromeliads may dispense completely with living hosts, and may thrive on artificial substrates such as electrical cables. This is not entirely surprising because this family provides examples of particularly remarkable adaptations to the epiphytic habitat like water-impounding leaf bases and water- and nutrient-absorbing scales (Benzing 2000). The so-called atmospheric forms in this family (e.g. Tillandsia recurvata) possess a dense covering of these scales, and use roots entirely as holdfasts, while leaves perform photosynthesis and take up water and nutrients. Although quite regularly mentioned in the literature (Benzing 1990, 2000; Brighigna et al. 1997, Lüttge 1989), we are not aware of any study investigating the vigour of plants growing on cables compared with plants growing on trees. The only functional aspects that have already been studied are related to nutrients, i.e. presence of nitrogen-fixing endophytes in Tillandsia recurvata plants from natural hosts and from electrical cables in Mexico (Puente & Bashan 1994) and differences in chemical composition of plant tissues and nutrient retention by leaves in Tillandsia capillaris growing on cables and trees in Argentina (Abril & Bucher 2009). Intermittent water supply, but also low nutrient supply, play an important role in epiphyte ecology (Zotz & Hietz 2001), which leads to the following alternative hypotheses: (1) Plants on electrical cables are usually close to roads.

We analysed the effect of a hurricane on a plant–ant network and on vegetation cover. Plant cover was sampled using linear sampling in several vegetation types: deciduous forest, a dry forest, sand dune pioneers, sand dune scrub, ecotone of freshwater marsh, deciduous forest and dune scrub, and mangrove forest. We sampled ant–plant interactions and vegetation cover before and after Hurricane Karl hitting (September 2010) the central coast of the state of Veracruz, Mexico. The pre-hurricane network consisted of 16 plant and 25 ant species in 52 associations. The post-hurricane network consisted of 17 plant and 20 ant species in 56 associations. We found a significant decrease in the total linear cover of EFN-bearing plants between October 2009 (646 m, no hurricane effect) and October 2010 (393 m, after hurricane Karl) (total sample length 2025 m). Both networks were significantly nested (0.999 and 0.973, P < 0.001), suggesting that network topology remained similar. Our results show changes in several network characteristics and species proportions. The number of plant species that contributed to nestedness vs. idiosyncratic species did not differ significantly in the pre-hurricane network, while the number of plant species that contributed to nestedness vs. idiosyncratic species did differ significantly in the post-hurricane network. The number of ant species that contributed to nestedness vs. idiosyncratic species differed significantly in the pre-hurricane network, and also in the post-hurricane network. Differences in nestedness contributions of species before and after the hurricane reflect an alteration from a generalized, highly nested, more stable pre-disturbance network, to a more low-degree or specialized network (i.e. fewer interactions among generalist species, those species with the most associations). The maintenance of important core components of the network after a huge disturbance, suggests a short-term resilience typical of mutualistic networks.

Soluble carbohydrates are the major nutritional reward in the pulp of most vertebrate dispersed fruits (Corlett 1996, Herrera 1987, Johnson et al. 1985, Jordano 1995). However, although detailed analyses have been made of the carbohydrate content of many cumtivated fruits (e.g. Nagy et al. 1990, Widdowson & McCance 1935), most studies of wild fruits have only quantified total soluble carbohydrates (e.g. Conklin & Wrangham 1994, Corlett 1996, Foster & McDiarmid 1983, Herrera 1987, Izhaki 1992). This is unfortunate because relatively minor differences in the chemical structure of nutrients can have profound implications for frugivorous animals (Martinez del Rio & Restrepo 1993), and the fruit choices of these animals in turn, may have major implications for the abundance and distribution of the plant species.

Nanophyes shoreae is a pre-dispersal fruit-predator of several species of Dipterocarpaceae. The timing of oviposition of this weevil was monitored in six trees in Pasoh Forest Reserve, West Malaysia from September 1986 to February 1987. A flowering event occurred during this period. Oviposition started within 12 days after peak anthesis, and continued within any one tree for 11–39 days. Host trees of N. shoreae flowered over a 75 day period. Intra-specific flowering synchrony was high but different species flowered sequentially. The behaviour of N. shoreae and the period of the oviposition ‘window’ strongly suggest that this pre-dispersal fruit-predator ‘tracks’ the sequence of flowering shown by its host species. The implications for predator satiation through mass-flowering of the Dipterocarpaceae are discussed.

Fragment-size determination by workers of the grass-cutting ant Atta vollenweideri and the extent of size-matching between ant size and fragment size were investigated as a function of the distance from the nest. Foragers and their loads were sampled in four different sectors along a 30-m foraging trail in the field: directly on the harvested source, in the patch, on the trail and close to the nest. Ants sampled on the source immediately after cutting were significantly larger than carrying ants on any trail sector, whereas body mass did not differ among other samples. Thus, foraging was partitioned into at least two stages, with large ants cutting the source and smaller ants carrying the fragments to the nest. Fragments collected directly after cutting were significantly larger than those carried on the trail, indicating that the fragments were cut once again on their way to the nest. Size-matching depended on the trail sector considered. It was stronger in ants sampled closer to the nest, suggesting that carriers either collect dropped fragments according to their body mass, or cut fragments out of the dropped fragments in sizes corresponding to their body mass prior to transport.

Root climbers constitute a distinctive group within climbing plants and some evidence suggests that they are associated with high precipitation and low light availability at local scales, which is in contrast with general patterns of liana distribution in the tropics. The influence of precipitation and seasonality on the occurrence of root climbers was evaluated both globally and in the tropics. The presence/absence of root climbers was recorded in 174 sites of Alwyn H. Gentry Forest Transect Data Set. The effects of mean annual precipitation and dry-season length (and temperature) on their occurrence were analysed using logistic regressions. Root climbers were significantly more frequent in sites with greater precipitation and reduced seasonality. Increasing temperature reduced root-climber occurrence in tropical sites, but this effect was marginally significant at a global scale. Dry and open habitats appear unsuitable for root climbers. This can be explained by the susceptibility to desiccation of adventitious roots and/or the low acclimation ability of these climbers to high irradiance.

The aim of this work was to analyse the phenological variation of a residual invasive semi-evergreen shrub in Sahelian fallows in Niger. This species, Guiera senegalensis (Combretaceae), has benefited from the elimination of other species thanks to its high resistance to the increasing cutting pressure for cultivation. We sought to identify traits of its life cycle that could contribute to its persistence and widespread dominance under such a disturbance regime. Leafing, flowering and fruiting were monitored on seven fallows differing in topographic location, age, shrub density and degradation state, during two rainy seasons and one dry season. Phenological spectra showed similar timing of the three phenophases of the seven populations. Differences were observed mainly in magnitude of the phases. However, there were both a high intra-fallow variability (64.6% of the whole variability) and a statistically significant inter-fallow variability, despite only 35.4% of the total variability being due to differences between fallows. A statistical classification of the fallows was proposed based on shrub phenological course over the two cycles monitored. This classification corresponds to a gradient of life-cycle achievement primarily linked to the topographic situation of the stations, and then to a combination of other factors. The flexibility of the phenology at the individual, population and metapopulation scales, inherent to its specific semi-evergreenness property, appeared as an essential phenological attribute contributing to successful widespread persistence of G. senegalensis in the study area.

Evaluation of proximate mechanisms (e.g. dispersal, immigration, competition, facilitation) that determine patterns of assemblage or community structure is an important step in the development of paradigms in ecology. Host–parasite systems are useful for such studies because host-parasite assemblages are easily defined units of study, each host individual harbours a sample from a community or assemblage, and many host species are common, providing replicate samples. I used ectoparasite assemblages from Noctilio leporinus collected from Paraguay to evaluate effects of host sex and body size on ectoparasite abundance and to determine if these assemblages exhibit a nested pattern of species co-occurrence. A total of 533 ectoparasites representing seven species and four families were collected from 28 hosts. Abundances of Paradyschiria fusca and Noctiliostrebla aitkeni responded positively to host body size. Host sex had no affect on ectoparasite abundances. Streblid bat fly assemblages from Noctilio leporinus were strongly and significantly nested. Abundances of all species of streblid were positively correlated with one another with Pearson product moment correlation coefficients between 0.424 and 0.646. Competition does not appear to affect community structure of streblids from Paraguayan Noctilio leporinus. Independent responses of species of streblid to host characteristics appear to mould assemblage structure in this system.

Frugivorous bats are important seed dispersers for many plant species (Cox et al. 1991, Fleming & Heithaus 1981, Hodgkison et al. 2003a, McConkey & Drake 2006, Nyhagen et al. 2005, Utzurrum 1995). They regularly consume figs in the wild (Fujita & Tuttle 1991, Kalko et al. 1996, Shilton et al. 1999). Various species of pteropodid bats have been reported foraging on the fruits of more than 30 fig species in tropical and subtropical Asia, Africa and Australia (Bhat 1994, Fujita & Tuttle 1991, Marshall & McWilliam 1982, Thomas 1984). Food transit times in frugivorous bats are relatively rapid; generally less than 30 min (Laska 1990, Tedman & Hall 1985). Several studies have demonstrated that seed germination was either enhanced or unaffected after passage through the digestive tract of bats (Figueiredo & Perin 1995, Fleming & Heithaus 1981, Lieberman & Lieberman 1986).

Pollinator visitation to, and the reproductive success of, Sonneratia caseolaris (Sonneratiaceae) and Aegiceras corniculatum (Myrsinaceae) was investigated in a mangrove forest in India. S. caseolaris was shown to be primarily outcrossed and A. corniculatum was shown to be a selfing species. The flowers of both plant species attracted several diurnal and nocturnal visitors. Earlier reports had indicated that S. caseolaris flowered for one night and was exclusively night-pollinated. But flowers of this species were found to be in bloom both at night and during the day, and diurnal visitors to the flowers were more diverse and frequent than nocturnal ones. This was related to the higher volume and energy value of nectar in the morning. The effects of time of day and temperature on visitation rates were quantified. The importance of visitors to plant reproductive success was investigated via controlled visitor-exclusion experiments. Pollinators were expected to be more important for the outcrossing species than for the selfing species, and this was confirmed by the results of the exclusion experiments. In S. caseolaris reproductive success was determined both by pollinator availability and the intensity of flower and fruit predation, while in A. corniculatum it is likely to be resource limited.

Throughout the latter part of the dry season (January-April) of 1985 and 1986, we studied the demography of mature adults in a small population of Argia chelata along a stream at Monteverde, Costa Rica. Males defended sunlit spots along the stream between 1030 h and 1400 h central standard time each day and females visiting these sunlit spots were soon mated. By individually marking all mature adults in the population we found that there was no significant difference between the sexes in daily survival rates (0.85 for males and 0.86 for females). Lifetime mating success was positively correlated with longevitiy in both males and females but the ability of males to obtain a mate appeared to be independent of age.

Although the sex ratio at emergence was 1:1, that of mature adults at the stream was strongly male-biased (87% male), perhaps as a result of a longer or more risky prereproductive period in females related to the costs of egg formation. We argue that the strongly male-biased sex ratio has important effects on the mating system of this species in that the male contact-guards the female for the entire oviposition period each day. Although this limits each male to mating with one female per day, it probably ensures that the male will fertilize most of the eggs laid by the female that day.

Different C4 photosynthesis pathways may influence plant response to shade and/or moisture stress. In the savanna of south-eastern Botswana, seedlings of PCK C4 type grass species were frequently observed to emerge in shaded habitats. The species Digitaria eriantha subsp. pentzii, which shows the NADP-ME pathway, was also found to be associated with the tree canopy. Species emerging in habitats exposed to full sun often showed the NAD-ME C4 pathway. Seedlings or Aristida congesla, Eragrostis rigidior and Tragus berteronianus which normally emerge in full light, showed higher relative growth rates and/or unit leaf rates compared with seedlings of Panicum maximum and Urochloa panicoides which are associated with shaded habitats. Seedlings of the latter species, however, survived low light conditions. Relative growth rate of the seedlings appeared to be negatively related to caryopsis weight. Light response analysis of leaves of Digitaria eriantha subsp. pentzii, grown under low light intensities, showed similar trends in light saturation to those reported for the PCK type in Panicum maximum. Mesophyll rather than stomatal limitations appeared to induce light saturation at higher light intensities in leaves grown under shade conditions.

As the destruction and severe disturbance of primary tropical forest continues, it is important to understand how these forests may recover from perturbations. Considerable work has been done on above-ground recovery but below-ground processes are less well understood. To determine changes in root mass during tropical secondary succession in lowland forests of Central Borneo, samples were taken from stands of increasing ages since abandonment of agriculture (1, 3, 14 and 31 y) with a primary forest control (six plots from 1-y-old stands and three from all other ages). Root mass and elemental concentrations were determined and soils were chemically analysed. There was no increase in root mass with stand age for fine-root (< 2 mm diameter) or small-root (< 5 mm diameter) mass but there was a trend for coarse-root mass (5–10 mm diameter) to increase with stand age. Negative correlations were shown between root mass and soil nutrient status. Fine-root C concentrations increased with stand age but there was no clear effect of stand age on fine-root N or P. Fine-root mass did not increase significantly with stand age suggesting a rapid recovery; instead, soil nutrient status appeared to be the most important factor controlling root mass. Of the soil nutrients measured in this study, N had a stronger control over root mass than P suggesting that this element may be limiting during secondary succession in tropical lowland forests of Borneo.

The present study examined the effect of a catastrophic cyclone (Aila) on ichthyofaunal assemblages in a tidal river of the Sundarban Delta. Sampling in six stations with a gill-net of 20-m length and 1-cm mesh size resulted in the collection of 63 species in a pre-Aila survey. Among them, 16 species were not available in the year after the cyclone. However, 12 new species were added to the assemblages in the post-Aila year during which 59 species were recorded. Analysis of Similarity (ANOSIM) confirmed significant changes in fish assemblages after the cyclone with a corresponding reduction of the species diversity and variation in the seasonal pattern of abundance. Hydrological parameters also differed with a significant surge in nutrient concentrations. Tolerance to low dissolved oxygen seemed to be a determinant factor as evident from the higher abundance of certain fishes viz. Harpadon nehereus, Liza parsia, Pampus argentius, Tenualosa ilisha and Toxotes chatareus during post-Aila year. Despite the recovery of the ichthyofaunal assemblages at the later stage of the study, a strong seasonal variation was persistent. The study therefore suggests that environmental variation in terms of increasing temperature and salinity elicit greater response in an estuarine community than temporary natural disturbances even as severe as cyclones.

ABSTRACT. Seeds with ‘imitation arils’ appear wholly or partially covered by pulp or aril but actually carry no fleshy material. The mimetic seed hypothesis to explain this phenomenon proposes a parasitic relationship in which birds are deceived into dispersing seeds that resemble bird-dispersed fruits, without receiving a nutrient reward. The hard-seed for grit hypothesis proposes a mutualistic relationship in which large, terrestrial birds swallow the exceptionally hard mimetic seeds as grit for grinding the softer seeds on which they feed. They defecate, dispersing the seeds, and abrade the seed surface, enhancing germination. Any fruit mimicry is incidental. Fruiting trees of Ormosia spp. (Leguminosae: Papilionoideae) were observed to ascertain mechanisms of seed dispersal and the role of seemingly mimetic characteristics of the seeds in that dispersal. Seed predation and seed germination were also examined. Ormosia isthamensis and O. macrocalyx (but not O. bopiensis) deceived arboreally-foraging frugivorous birds into taking their mimetic seeds, although rates of seed dispersal were low. These results are consistent with the mimetic seed hypothesis. On the other hand, the rates of disappearance of seeds from the ground under the Ormosia trees, hardness of the seeds, and enhancement of germination with the abrasion of the seed coat are all consistent with the hard-seed for grit hypothesis.

RESUMEN. Semillas con arilos falsos aparecen estar cubiertas en parte o completamente por pulpa o arilo, pero en realidad no llevan ninguna materia carnosa. El hipótesis semilla mímica propone que las semillas parecen frutos carnosos cuyas semillas están dispersadas por aves y que engañan las aves a dispersar sus semillas sin recibir una recompensa nutritiva — una relación parasítica. El hipótesis semilla dura para arenisca propone que aves grandes y terrestres tragan las semillas mímicas y excepcionalmente duras como arenisca para moler las semillas más suaves en que se alimentan; las aves defecan y dispersan las semillas, y las rascan, lo cual mejora la germinación — una relación mutua. Cualquier mimetismo es incidente. Se observaron árboles de Ormosia espp. (Leguminosae: Papilionoideae) con frutos para averiguar los mecanismos de dispersión de semillas y el papel que hacen las características aparentemente mímicas de sus semillas en esa dispersión. Se examinaron también la depredación y germinación de semillas. Las semillas mímicas de Ormosia isthamensis y O. macrocalyx (pero no O. bopiensis), engañaron aves frugivoras y arbóreas en comerlas, aunque las tasas de dispersión eran bajas. Estos resultados son consistente con el hipótesis semilla mímica. En cambio, las tasas de desaparición de semillas caídas de Ormosia, dureza de las semillas, y mejoramiento de germinación con la raedura de las capas de las semillas son consistente con el hipótesis semilla dura para arenisca.

The plant vigour hypothesis proposes that herbivores should favour feeding on more vigorously growing plants or plant modules. Similarly, we would expect herbivores to favour plants that regrow vigorously after herbivory. Larger animals, like elephants, may also select plant species relative to their availability and prefer species with larger growth forms in order to meet their intake requirements. The food preferences of the Bornean elephant (Elephas maximus borneensis) in the Lower Kinabatangan Wildlife Sanctuary, Sabah, Malaysia, were investigated along 12 transects in areas where elephants were recently sighted feeding. One hundred and eighty-two plants were eaten and 185 plants were measured for species availability along transects. Species vigour was determined by the monthly regrowth in new shoot length after elephant feeding and the number of new shoots produced on each plant. Measurements were carried out on each plant for 9 mo or until the new shoot was eaten. Plant sizes were determined from their basal diameter. The Bornean elephant did not prefer more vigorous species or species with larger growth forms. New shoots did not grow longer on preferred than avoided species. Additionally, unlike other elephants that live in a forest environment, the Bornean elephant preferred species from the Poaceae (specifically Phragmites karka and Dinochloa scabrida) over other plant types including gingers, palms, lianas and woody trees.