Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA.
The influence of cactus size and previous infection on bird deposition of mistletoe seeds
Article first published online: 28 JUL 2006
Australian Journal of Ecology
Volume 20, Issue 4, pages 571–576, December 1995
How to Cite
DEL RIO, C. M., HOURDEQUIN, M., SILVA, A. and MEDEL, R. (1995), The influence of cactus size and previous infection on bird deposition of mistletoe seeds. Australian Journal of Ecology, 20: 571–576. doi: 10.1111/j.1442-9993.1995.tb00577.x
- Issue published online: 28 JUL 2006
- Article first published online: 28 JUL 2006
- Accepted for publication April 1995
- seed dispersal
Abstract Tristerix aphyllus (Loranthaceae) is a bird-dispersed mistletoe that infects several cactus species in central and north-central Chile. At Las Chinchillas National Reserve it parasitizes two species of columnar cacti (Echinopsis chilensis and Eulychnia acida) and its seeds are dispersed exclusively by the Chilean mockingbird Mimus thenca. The prevalence of T. aphyllus on cacti depended on host species and size. Echinopsis chilensis was parasitized at a higher, and E. acida at a lower, frequency than expected from their relative abundances. In both species, the incidence of T. aphyllus parasitism increased with cactus height. Birds perched and deposited seeds primarily on parasitized cacti, which resulted in an aggregated distribution of seeds. By preventing bird perching and thus reducing seed deposition, the long spines of E. chilensis and E. acida may help protect cacti against T. aphyllus infestation. However, the seeds of T. aphyllus produced a slow-growing radicle that reached up to 91 mm long in 43 days. Radicles of this length are unique among mistletoe species and may have evolved to overcome the barrier posed by cactus spines.