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Sheep gut passage and survival of Mediterranean shrub seeds

Published online by Cambridge University Press:  22 February 2007

Pablo Manzano*
Affiliation:
Departamento Interuniversitario de Ecología, Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049, Madrid, Spain
Juan E. Malo
Affiliation:
Departamento Interuniversitario de Ecología, Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049, Madrid, Spain
Begoña Peco
Affiliation:
Departamento Interuniversitario de Ecología, Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049, Madrid, Spain
*
*Correspondence: Fax: +34 91 497 8001, Email: pablo.manzano@uam.es

Abstract

Although viable seeds of Mediterranean dry-fruited shrubs are found in herbivore dung, the ecological importance of this observation is still not well understood. We analysed seed retrieval percentages, defecation time and germinability after sheep gut passage for the five most common shrub species of an area in central Spain (Retama sphaerocarpa, Cytisus scoparius, Halimium umbellatum subsp. viscosum, Cistus ladanifer and Lavandula stoechas subsp. pedunculata). Five ewes were fed seeds, and their dung was collected regularly during the following week. Seeds were hand-sorted from dung subsamples and tested for germinability. The defecated seeds were clustered in time, with a majority retrieved in the 24–40 h period, although over 1% of the seeds were retained in the gut for more than 72 h. Data suggested a possible link between seed size and retrieval, with medium-sized seeds less damaged (16–23%) than larger and smaller seeds (10–12%), although only a small number of species were studied. Germination results showed an increased percentage of germination after gut passage for H. umbellatum (x2 test, P<0.05) and a marginally significant difference for C. scoparius (P<0.1). Soft-seeded L. stoechas did not germinate after gut passage. The results indicate a potential role of herbivore endozoochory for the long-distance dispersal of dry-fruited shrubs and their potential colonization of distant sites.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2005

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