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Howler monkeys (Alouatta palliata), dung beetles (Scarabaeidae) and seed dispersal: ecological interactions in the tropical rain forest of Los Tuxtlas, Mexico
Published online by Cambridge University Press: 10 July 2009
Abstract
The dispersal of seeds by howler monkeys (Alouatta palliata) and the activity of dung beetles in modulating the fate of the dispersed seed were studied at Los Tuxtlas, Mexico. Howlers consumed the fruits of 35 species of plants. The seeds of 28 of these were dispersed by the monkeys. The majority (≥90%) of the seeds dispersed by monkeys were destroyed by rodents. Rapid relocation and burial of dung by dung beetles resulted in accidental relocation and burial of large numbers of seeds shortly after deposition. Faecal clumps (20 mg) remained on the ground for an average of only 2.5 h (range 1–3 h). Ball rolling beetles transported balls up to 5.0 m from the site of deposition (range 1–5 m). Burrowing and ball-rolling dung beetles buried seeds at depths ranging from 2.5 to > 12.0cm. The deeper a seed is buried, the less likely it is to be found and eaten by rodents. Eighty percent of the species used by Alouatta as sources of fruit at Los Tuxtlas benefited by the dispersal and post dispersal service provided by howlers and dung beetles respectively. Seasonality in dung beetles abundance in the forest may influence the number of seeds per species escaping post-dispersal predation during the year. Dung beetles play not only an important ecological role in the recycling of matter and energy in the ecosystem, but also in the process of rain forest regeneration.
Resumen
La dispersión de semillas por monos aulladorcs (Alouatla palliata) y el impacto de la aclividad de forrajeo y nidificación de escarabajos coprófagos sobre cl destino de las semillas dispersadas fucron cstudiados en la selva de Los Tuxtlas, México. La mayoría (≥90%) de las semillas (28 cspecies de plantas) dispersadas por los monos son deprcdadas por rocdores. El aprovechamicnto de matcria faecal por escarabajos en el suelo dc la selva resulta en la relocalización y cntcrramiento accidental de tin gran número dc semillas poco después de ser expulsadas por los monos a traves de sus heces. Los escarabajos enticrran las semillas a profundidades que van desde 2.5 a < 12.0cm disminuyendo asi la eficiencia con la qiie los rcodores pueden localizarlas. Ochenta porciento de las especies de planlas usadas por lo monos como fuentcs de frutos en Los Tuxtlas reciben los beneficios de dispersion y postdispersion aportados por aulladorcs y escarabajos coprofagos respectivamente. La estacionalidad en la abundancia relativa de escarabajos coprofagos en la selva de Los Tuxtlas podria detcrminar el numcro de semillas que escapan a la fuerte depredacion postdispersion en el ańo. Los escarabajos coprofagos son componcntcs imporlantcs no solo en rcciclajc de matcria y energia en el ccosistcma pcro tambicn en el proceso natural dc regencracion dc la selva.
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- Research Article
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- Copyright © Cambridge University Press 1991
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