TY - JOUR
T1 - Incorporating dispersal distance into the disperser effectiveness framework
T2 - Frugivorous birds provide complementary dispersal to plants in a patchy environment
AU - Spiegel, Orr
AU - Nathan, Ran
PY - 2007/8
Y1 - 2007/8
N2 - Fleshy-fruited plants are usually dispersed by an array of frugivores, differing in the effectiveness of the dispersal service they provide to the plant. Body size differences among frugivores are hypothesized to affect seed dispersal distances and consequently their effectiveness as dispersers. We tested this hypothesis by comparing the effectiveness of two passerine birds, grackles (Onychognathus tristramii) and bulbuls (Pycnonotus xanthopygos), dispersing the desert shrub Ochradenus baccatus. Laboratory experiments, quantifying gut retention time and the effect on germination, were combined with field observations quantifying bird movements and fruit consumption rates. An empirically parameterized mechanistic model showed that the two dispersers switch roles as a function of spatial-scale: while most seeds within the local habitat were dispersed by bulbuls, the larger grackles were exclusively responsible for between-patches, long-distance dispersal. We suggest that distance-related differences are common and important to plant fitness, and thus should explicitly be considered in studies of disperser effectiveness.
AB - Fleshy-fruited plants are usually dispersed by an array of frugivores, differing in the effectiveness of the dispersal service they provide to the plant. Body size differences among frugivores are hypothesized to affect seed dispersal distances and consequently their effectiveness as dispersers. We tested this hypothesis by comparing the effectiveness of two passerine birds, grackles (Onychognathus tristramii) and bulbuls (Pycnonotus xanthopygos), dispersing the desert shrub Ochradenus baccatus. Laboratory experiments, quantifying gut retention time and the effect on germination, were combined with field observations quantifying bird movements and fruit consumption rates. An empirically parameterized mechanistic model showed that the two dispersers switch roles as a function of spatial-scale: while most seeds within the local habitat were dispersed by bulbuls, the larger grackles were exclusively responsible for between-patches, long-distance dispersal. We suggest that distance-related differences are common and important to plant fitness, and thus should explicitly be considered in studies of disperser effectiveness.
KW - Arid ecosystems
KW - Dispersal curve
KW - Fragmentation
KW - Frugivory
KW - Long-distance dispersal
KW - Ochradenus baccatus
KW - Onychognathus tristramii
KW - Pycnonotus xanthopygos
KW - Radio telemetry
UR - http://www.scopus.com/inward/record.url?scp=34347239693&partnerID=8YFLogxK
U2 - 10.1111/j.1461-0248.2007.01062.x
DO - 10.1111/j.1461-0248.2007.01062.x
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C2 - 17594427
AN - SCOPUS:34347239693
SN - 1461-023X
VL - 10
SP - 718
EP - 728
JO - Ecology Letters
JF - Ecology Letters
IS - 8
ER -