When condition trumps location: seed consumption by fruit‐eating birds removes pathogens and predator attractants

Abstract

Seed ingestion by frugivorous vertebrates commonly benefits plants by moving seeds to locations with fewer predators and pathogens than under the parent. For plants with high local population densities, however, movement from the parent plant is unlikely to result in ‘escape’ from predators and pathogens. Changes to seed condition caused by gut passage may also provide benefits, yet are rarely evaluated as an alternative. Here, we use a common bird-dispersed chilli pepper (Capsicum chacoense) to conduct the first experimental comparison of escape-related benefits to condition-related benefits of animal-mediated seed dispersal. Within chilli populations, seeds dispersed far from parent plants gained no advantage from escape alone, but seed consumption by birds increased seed survival by 370% – regardless of dispersal distance – due to removal during gut passage of fungal pathogens and chemical attractants to granivores. These results call into question the pre-eminence of escape as the primary advantage of dispersal within populations and document two overlooked mechanisms by which frugivores can benefit fruiting plants.

Ingestion by an invasive parakeet species reduces germination success of invasive alien plants relative to ingestion by indigenous turaco species in South Africa

“…The removal of pulp may prevent microbial attacks to seeds and thus enhance germination (Figueroa and Castro 2002). Pulp-removal is also essential for shorter germination times which would reduce the likelihood of seed predation (Fricke et al 2013). …”

“…The process of seed dispersal by avian frugivores usually involves the consumption of pulp and regurgitation or excretion of intact seeds (D'Avila et al 2010;Fedriani et al 2011;Czarnecka et al 2012). This process is mutually beneficial as plants benefit from seed dispersal away from the parent plant to locations with fewer pathogens (Wenny 2001;Aslan 2011;Fricke et al 2013) while frugivores benefit from important food resources and energy rewards (Jordaan et al 2011b; Mokotjomela et al 2013a). Avian frugivores consume both native and invasive fruit and therefore can facilitate the rapid spread of fruiting invasive species (Davis 2011;Mokotjomela et al 2013b).…”

Dispersión de semillas de Mauritia flexuosa (Arecaceae) por frugívoros terrestres en Laguna Azul, Beni, Bolivia

“…Las distancias de dispersión de semillas por D. punctata en la Laguna Azul son también similares a las reportadas para Attalea maripa (Fragoso 1994), B. excelsa (Peres et al 1997) Astrocaryum aculeatissimum a distancias máximas de 48.7 m, con una media de 6.8 m y Prada-Villalobos y Araújo-Bagno (2012) reportan la exitosa dispersión de palma real por aves, especialmente Psittacidae, lo cual muestra que la dispersión de Mauritia podría no depender tanto de mamíferos como se había pensado originalmente, y que la dispersión por aves podría llevar las semillas mucho más lejos; pero esto no fue cuantificado en nuestro sitio de estudio. Dado que la palma real es la especie dominante en Laguna Azul, el alejamiento de las semillas desde los parentales no serviría como estrategia para evitar depredación, pues la mayoría de las semillas caen muy cerca a otra planta de la misma especie y la depredación probablemente no va a ser dependiente de la distancia a los parentales (Fricke et al 2013).…”

The Plight of Reptiles as Ecological Actors in the Tropics

“…Organism movement by reptiles is likely to have several benefits for the associating species: (a) seed survival is greater away from the parent plant (Fricke et al, 2013); (b) pollination enhances the volume, speed, and synchrony of fertilization (Kormann et al, 2016); (c) epibiosis allows species that attach to reach specific sites that are favorable for survival, such as nutrient-or prey-rich microhabitats (Hayashi and Tsuji, 2007). Finally, at larger scale, these movements may allow associated organisms to colonize vacant habitats and, or, new regions.…”