Summary: ECOGRAPHY 25: 139144, 2002
Variation in mistletoe seed deposition: effects of intra- and
interspecific host characteristics
Juliann Eve Aukema and Carlos MartiŽnez del Rio
Aukema, J. E. and MartiŽnez del Rio, C. 2002. Variation in mistletoe seed deposition:
effects of intra- and interspecific host characteristics. Ecography 25: 139144.
We investigated differences in host infection by a desert mistletoe, Phoradendron
californicum, and examined one of the processes that contributes to these differences:
variation in seed deposition among host individuals and species. In the Sonoran
Desert, P. californicum parasitizes the sympatric leguminous trees Olneya tesota,
Cercidium microphyllum, Prosopis 6elutina, Acacia constricta, and Acacia greggii. We
hypothesized that seed deposition depends on host height and crown architecture. At
a site in Arizona, frequency of infection did not reflect host relative abundance.
Olneya tesota was parasitized at a higher frequency than expected from its abundance
and maintained the highest mistletoe loads per individual host. In contrast, P.
6elutina was infected less frequently than expected. Infection frequency increased with
host tree height for all hosts. Mistletoe seed deposition by avian dispersers differed
among host species and was disproportionately high in O. tesota and P. 6elutina. Seed
deposition was higher in infected than in non-infected host trees, and increased with
tree height in O. tesota but not in C. microphyllum. We suspect that increased seed