Seed dispersal by marsupials shaped the scale of mistletoe recruitment in two ways. Nothofagus trees show genotype difference that influence infection by mistletoes, Misodendraceae. We sought to explain the spatial patterns of seed dispersal as a function of the fruit‐resource tracking by the marsupials. Insights from spatial analyses of bird foraging in a tropical forest, Spatial patterns of seed dispersal and the unification of plant population ecology, Dissemination limitation and the origin and maintenance of species‐rich tropical forests, Seed Dispersal and Frugivory: Ecology, Evolution and Conservation, Local dispersal can facilitate coexistence in the presence of permanente spatial heterogeneity, Effect of seed passage through vertebrate frugivores’ gut on germination: a review. Presumimos que la ecologia de dispersión de este muérdago está relacionada directamente con la abundancia de las aves frugívoras; y nos preguntamos si esta especie sigue la estrategia de alta inversión en nutrimentos sugerida por Godschalk (1983). the distance along the transect; the first plot referring to 0, the second plot to 20 m, ... , and the last plot to 1480 m). Psittacanthus schiedeanus madura sus frutos nutritivos de no‐viembre a abril, con un pico de abundancia en enero y febrero. Step 4: Calculating the predicted values of a given response variable (i.e. In a single fruiting season, we evaluated the abundance of mistletoe fruits, adult plants, dispersed seeds and recruits (seedlings and saplings), as well as the abundance of marsupials, along a 1500‐m linear transect. Similarly, Aukema (2004) explained the patchiness of the mistletoe Phoradendron californicum as a consequence of the spatial structure of seed dispersal by birds. Dromiciops gliroides PCNM analysis for detecting the Node-by-node disassembly of a mutualistic interaction web driven by species introductions. Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA. One approach to this question has been to explore the occurrence of a positive spatial feedback between adults and their offspring, that is, a spatial matching between fruiting adults and recruitment resulting from disproportionate dispersal close to adults, coupled with disproportionate establishment in high‐density seed clumps (Aukema & Martínez del Río 2002; Carlo & Aukema 2005). Our study suggests that seed dispersal by the marsupial D. gliroides plays a crucial role in shaping the spatial structure of the populations of the mistletoe T. corymbosus. The predominant tree species are the evergreen southern beech Nothofagus dombeyi, and the cedar Austrocedrus chilensis. We considered the variation in seed dispersal accounted for by the abundance of fruits to represent the effect of the marsupial when tracking mistletoe fruits. The distribution of the spatial variability across scales, and the shape of the patches were, however, different between the mistletoe and the marsupial. The seeds inside are coated in a sticky substance which sticks to the beaks of birds feeding on the fruit. 2002). The role of differential host mortality. If you do not receive an email within 10 minutes, your email address may not be registered, Spatial feedback between mistletoe adults and recruits. Please check your email for instructions on resetting your password. : Effects of Host Provenance, Gut Passage, and Host Fate on Mistletoe Seedling Survival Almost all dispersed seeds germinate, independently of the substrate in which they are deposited, but only seeds germinating on host plants are able to establish as seedlings (Amico 2000). (iii) If so, does the scale‐dependent spatial structure of mistletoe recruitment relate to the patterns of seed dispersal generated by the marsupial when tracking fruits? Increased resource availability prevents the disruption of key ecological interactions in disturbed habitats. Previous studies have found that the spatial structure of mistletoe populations may result from long‐term responses to large‐scale environmental gradients related to the availability of host plants and light in the immediate surroundings of the host plant (Hoffman et al. We assumed that these predicted values represented the variability in a response variable at a given spatial scale, with a degree of fit indicated by the coefficient of determination of the corresponding spatial submodel. the abundances of mistletoes and marsupials) into several additive submodels, which account for the spatial variability at different spatial scales within the extent of the sampling scheme. I have never been able to get such a good view
and you may need to create a new Wiley Online Library account. We thus considered the sum of captures to represent the abundance of marsupials in the transect area. These PCNM vectors are positive eigenvectors obtained from applying an ordination procedure to the truncated matrix of Euclidean distances between all sampling points. Efectos de la fragmentación del hábitat sobre un mutualismo de dispersión del bosque templado de Sudamérica Austral, Habitat fragmentation disrupts a plant‐disperser mutualism in the temperate forest of South America, Aggregated seed dispersal by spider monkeys limits recruitment to clumped patterns in, How do frugivores track resources? In any case, our multi‐scaled approach was still a valuable and robust tool for evaluating how different ecological factors may explain the spatial patchiness in mistletoe and marsupial abundances at different spatial scales. Dromiciops gliroides moulded the spatial scale of T. corymbosus recruitment by generating patchiness at a scale larger than that occupied by mistletoe adults, but more strongly, by creating a positive spatial feedback between mistletoe adults and their offspring. When plotted against the distance along the transect, these predicted PCNM values may be used to interpret the shape of patches, in terms of both magnitude (height of the peak) and spatial dimension (extent on the x‐axis) of the response variable at different spatial scales. The number of PCNM spatial predictors (from the 50 vectors generated by the PCNM analysis in the 75‐plot linear transect) that accounted significantly for spatial variation ranged from 19 (in the case of the abundance of mistletoe adults) to 6 (in the case of the abundance of marsupials, see Table S1 in Supporting Information). 2005), the total area occupied by a plant population or metapopulation (Freckleton & Watkinson 2002; Purves & Dushoff 2005), and the geographical range of a species (Nathan 2006). The broad‐scale submodels always explained a larger percentage of variance than intermediate‐ and fine‐scale submodels, the latter never accounting for more than 6% of spatial variance (Fig. 2002; Aukema 2004). Ecology of neotropical mistletoes: an important canopy-dwelling component of Brazilian ecosystems. Even so, the bird digests a significant amount of glucose from the sticky layer, which is still intact when the seed is defecated. Mistletoebirds and Xylose: Australian Frugivores Differ in Their Handling of Dietary Sugars. in rural Chiloé Island, Chile Additionally, we consider that our findings may also be generalized to other plant‐frugivore systems in which there is sharp spatial matching between fruit resources and frugivorous seed dispersers and, consequently, large aggregations of dispersed seeds occur near fruiting adults (e.g. The two forest layers are well differentiated, with tree canopy reaching up to 40 m in height and understorey reaching up to 7 m in height. Extinction debt in a biodiversity hotspot: the case of the Chilean Winter Rainfall-Valdivian Forests. 2005) and the lack of infection in most host plants present in the study site suggest that the mistletoe recruitment was limited more by seed availability than by the availability of microsites suitable for establishment. We also considered the links between canopy cover and bamboo cover, and between forest cover and mistletoe fruit abundance. Vectors were generated using SpaceMaker 2 software (Borcard & Legendre 2004). Dispersal process performed as a strong demographic filter capable of changing the mistletoe spatial structure from adults to recruits, despite a low frequency of far‐from‐adult dispersal events. Dispersión de semillas por aves en un bosque templado de Sudamérica austral: ¿quién dispersa a quién? Seed dispersal may affect the distribution of recruitment within populations (Schupp & Fuentes 1995; García et al. For example, lowly mobile vertebrates, such as territorial birds or small rodents, disperse the majority of seeds of certain plants under the canopies of adult individuals, determining that the spatial extent occupied by recruits would seldom exceed that of adults (Wenny 2000; García & Houle 2005). Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Instituto Cantábrico de Biodiversidad (CSIC‐Universidad de Oviedo‐Principado de Asturias), C/ Rodrigo Uría s/n, Oviedo 33071, Asturias, Spain, Laboratorio Ecotono, CRUB, Universidad Nacional del Comahue, Bariloche, Río Negro, Argentina. Establishment success is c. 30% for seeds on host plants, postdispersal losses of germinating seeds being mostly caused by fungal attack, light‐resource limitation and host mortality (Amico 2000; Rodríguez‐Cabal 2003; see also Yan & Reid 1995; Norton & Reid 1997). 4a). The mistletoe bird performs a number of twisting movements when defecating, wiping the seeds on to the branch on which the bird is perched, rather than dropping them to the ground. The PCNM is based on four main steps (Fig. abundance) and environmental factors (e.g. The mistletoe plant and the mistletoe bird thus show complementary adaptations for mutual benefit, the plant attaining efficient dispersal and the bird ensuring a continuing food supply. 4c) predicted by the linear trend model, with a positive correlation to the abundance of marsupials, and, to a lesser extent, a negative correlation to the abundance of fruits. We estimated the abundance of dispersed mistletoe seeds and recruits in the second week of March 2005, by selecting, for logistical reasons (see Sampling of marsupials), the two central subplots in each plot. For this, we built a path model that considered the forest canopy cover (an inverse measure of light availability in the understorey) and the cover of host species as explanatory variables, the potential link between them, and the abundance of mistletoe adults as response variable. Thus, we considered an adult to be a flowering or fruiting mistletoe of any size, or any individual of diameter larger than 0.2 m. The abundance of mistletoe adults per plot was calculated as the cumulative number of adult plants in all four subplots. We also need spatially explicit approaches (Overton 1996; Aukema 2004; Russo & Augspurger 2004) to dissect and correlate the spatial variability of both plant and seed disperser populations along gradients of scale. Effects of the overabundance of wild ungulates on natural grassland in Southern Spain. Mistletoe Bird photographed by LPJC via Flickr "Not an easy bird to photograph. The Relative Contribution of Specialists and Generalists to Mistletoe Dispersal: Insights from a Neotropical Rain Forest. Like many fruit-eating birds, these species have a relatively simple digestive tract, so that the seed passes through the bird rather quickly. 5% of their spatial variance (Fig. This research was funded by BBVA Foundation (Project BIOCON03‐162 to D.G. Our study lacks of an explicit treatment of the phase between seed dispersal and establishment, as we do not have data about the microhabitat of deposition and the long‐term fate of dispersed seeds and seedlings.