Kg. Murray et al., FRUIT LAXATIVES AND SEED PASSAGE RATES IN FRUGIVORES - CONSEQUENCES FOR PLANT REPRODUCTIVE SUCCESS, Ecology, 75(4), 1994, pp. 989-994
To explore how plants may influence dispersal of their own seeds by ma
nipulating the behavior and physiology of their dispersers, we studied
the effect of a soluble chemical (or chemicals) in the fruits of With
eringia solanacea (Solanaceae), a Costa Rican cloud forest shrub, on p
assage of its seeds through the guts of one of its major dispersers, t
he Black-faced Solitaire, Myadestes melanops (Muscicapidae: Turdinae).
Using artificial fruits containing natural seeds, we found that the p
resence of a crude pulp extract reduced the median seed retention time
by nearly 50%. Estimation of seed dispersal distance as a function of
retention time suggested that more rapid seed passage results in shor
ter average dispersal distances, especially for seeds retained <20 min
. At the same time, germination trials revealed that seeds voided rapi
dly were far more likely to germinate than those remaining longer in M
yadestes guts. We propose that ''laxative'' chemical(s) in Witheringia
fruits balance these positive and negative consequences of ingestion
by Myadestes.