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Primary Seed Dispersal (primary + seed_dispersal)
Selected AbstractsInterspecific variation in primary seed dispersal in a tropical forestJOURNAL OF ECOLOGY, Issue 4 2008Helene C. Muller-Landau Summary 1We investigated the relationships of seed size, dispersal mode and other species characteristics to interspecific variation in mean primary seed dispersal distances, mean annual seed production per unit basal area, and clumping of seed deposition among 41 tropical tree species on Barro Colorado Island, Panama. 2A hierarchical Bayesian model incorporating interannual variation in seed production was used to estimate seed dispersal, seed production, and clumping of seed rain for each species from 19 years of data for 188 seed traps on a 50-ha plot in which all adult trees were censused every 5 years. 3Seed dispersal was modelled as a two-dimensional Student's T distribution with the degrees of freedom parameter fixed at 3, interannual variation in seed production per basal area was modelled as a lognormal, and the clumping of seed rain around its expected value was modelled as a negative binomial distribution. 4There was wide variation in seed dispersal distances among species sharing the same mode of seed dispersal. Seed dispersal mode did not explain significant variation in seed dispersal distances, but did explain significant variation in clumping: animal-dispersed species showed higher clumping of seed deposition. 5Among nine wind-dispersed species, the combination of diaspore terminal velocity, tree height and wind speed in the season of peak dispersal explained 40% of variation in dispersal distances. Among 31 animal-dispersed species, 20% of interspecific variation in dispersal distances was explained by seed mass (a negative effect) and tree height (a positive effect). 6Among all species, seed mass, tree height and dispersal syndrome explained 28% of the variation in mean dispersal distance and seed mass alone explained 45% of the variation in estimated seed production per basal area. 7Synthesis. There is wide variation in patterns of primary seed rain among tropical tree species. Substantial proportions of interspecific variation in seed production, seed dispersal distances, and clumping of seed deposition are explained by relatively easily measured plant traits, especially dispersal mode, seed mass, and tree height. This provides hope for trait-based generalization and modelling of seed dispersal in tropical forests. [source] Effects of gut passage, feces, and seed handling on latency and rate of germination in seeds consumed by capuchins (Cebus capucinus)AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Kim Valenta Abstract One of the key measures of the effectiveness of primary seed dispersal by animals is the quality of seed dispersal (Schupp: Plant Ecol 107/108 [1993] 15,29). We present data on quality of seed dispersal by two groups of white-faced capuchins (Cebus capucinus) in Costa Rica to test the hypothesis that capuchin seed handling results in effective primary dispersal for some fruit species they consume. We examined seed handling for 27 plant species, and germination rates of 18 species consumed by capuchins. For five of the most commonly swallowed seed species, we determined germination rates and average time to germination (latency) for seeds ingested and defecated by capuchins and compared these to seeds removed directly from fruit and planted. For the same five species, we compared germination rates and latency for passed seeds planted in capuchin feces to those cleaned of feces and planted in soil. For three of five species, differences in proportion of germinated seeds were significantly higher for gut passed seeds than for controls. For four of five species, germination latency was significantly faster for gut passed seeds than for controls. Feces had either no effect on seed germination rate or precluded germination. Data presented here support the hypothesis that white-faced capuchins are effective primary dispersers. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] Genetic structure of the endangered perennial plant Eryngium alpinum (Apiaceae) in an alpine valleyBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2008MYRIAM GAUDEUL We investigated the genetic structure of Eryngium alpinum (Apiaceae) in an Alpine valley where the plant occurs in patches of various sizes. In a conservation perspective, our goal was to determine whether the valley consists of one or several genetic units. Habitat fragmentation and previous observations of restricted pollen/seed dispersal suggested pronounced genetic structure, but gene dispersal often follows a leptokurtic distribution, which may lead to weak genetic structure. We used nine microsatellite loci and two nested sampling designs (50 × 50 m grid throughout the valley and 2 × 2 m grid in two 50 × 10 m quadrats). Within the overall valley, F -statistics and Bayesian approaches indicated high genetic homogeneity. This result might be explained by: (1) underestimation of long-distance pollen/seed dispersal by in situ experiments and (2) too recent fragmentation events to build up genetic structure. Spatial autocorrelation revealed isolation by distance on the overall valley but this pattern was much more pronounced in the 50 × 10 m quadrats sampled with a 2-m mesh. This was probably associated with limited primary seed dispersal, leading to the spatial clustering of half-sibs around maternal plants. We emphasize the interest of nested sampling designs and of combining several statistical tools. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 667,677. [source] Vertebrate Fruit Removal and Ant Seed Dispersal in the Neotropical Ginger Renealmia alpinia (Zingiberaceae),BIOTROPICA, Issue 2 2009Carlos García-Robledo ABSTRACT Plants frequently display fruit characteristics that support multiple seed-dispersal syndromes. These ambiguous characteristics may reflect the fact that seed dispersal is usually a complex process involving multiple dispersers. This is the case for the Neotropical ginger Renealmia alpinia (Zingiberaceae). It was originally suggested that the aromatic fruits of R. alpinia located at the base of the plant are adapted for terrestrial mammal seed dispersal. However, the dark-purple coloration of the fruits and bright orange aril surrounding the seeds suggest that birds may play a role in R. alpinia seed dispersal. At La Selva Biological Station, Costa Rica, we used camera traps to record vertebrate visits to infructescences of R. alpinia. Most visitors were toucans and aracaris (Ramphastidae). However fruits were also removed by terrestrial mammals (coatis and armadillos). In addition to vertebrate fruit removal, some of the fruits dehisce and the seeds that fall on the ground are dispersed by ants. Fruitfall traps showed that 77 percent of fruits are removed by vertebrates. However, 15 percent of fruits fall to the base of parent plants to be potentially dispersed by ants. Experiments using a laboratory ant colony showed that ants are effective seed dispersers of R. alpinia. Ant seed manipulation increased germination success and reduced time to germination. In conclusion, primary seed dispersal in the Neotropical ginger R. alpinia is mostly performed by birds, additionally ants are effective dispersers at short distances. Seed dispersal in R. alpinia is a complex process involving a diverse array of dispersal agents. RESUMEN Los frutos de algunas plantas presentan características que se ajustan a más de un síndrome de dispersión. Es posible que estas características ambiguas reflejen el hecho de que la dispersión de semillas es usualmente un proceso complejo que involucra múltiples organismos dispersores. Ese es el caso de la Zingiberaceae Neotropical Renealmia alpinia. Originalmente se sugirió que los frutos aromáticos y la posición basal de las infrutescencias de R. alpinia son adaptaciones para la dispersión por mamíferos terrestres. Sin embargo, el color morado oscuro del exocarpo y el color anaranjado de los arilos en los frutos maduros sugieren que las aves pueden jugar un papel importante en la dispersión de semillas de R. alpinia. En la estación Biológica La Selva, Costa Rica, usamos cámaras trampa para registrar las visitas por invertebrados a las infrutescencias de R. alpinia. La mayoría de las visitas fueron por tucanes y arasaríes (Ramphastidae). La dispersión de semillas en R. alpinia puede ser aún más compleja pues parte de los frutos maduros liberan semillas en la base de la planta, las cuales son dispersadas por hormigas. Trampas de frutos registraron 77% de los frutos removidos por vertebrados. Sin embargo las semillas de 15% de los frutos cayeron en el suelo para ser potencialmente dispersadas por hormigas. Experimentos en laboratorio demostraron que las hormigas son dispersores efectivos de R. alpinia. Semillas manipuladas por hormigas germinaron en mayor proporción y presentaron una reducción en el tiempo de germinación. En conclusión, los frutos de R. alpinia son principalmente dispersados por aves. Adicionalmente, las hormigas son eficaces dispersoras de semillas a cortas distancias. La dispersión de semillas en R. alpinia es un proceso complejo que involucra un diverso gremio de agentes dispersores. [source] | ||||||||||