Outcrossing increases infection success in the holoparasitic mistletoe <Emphasis Type="Italic">Tristerix aphyllus</Emphasis> (Loranthaceae) |
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Authors: | Wilfredo L Gonzáles Lorena H Suárez Rodrigo Medel |
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Institution: | (1) Departamento de Botánica, Universidad de Concepción, Casilla 160-C, Concepción, Chile;(2) Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile |
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Abstract: | Most studies on the fitness advantage of outbreeding in host–parasite systems have been assessed from the host rather than
the parasite perspective. Here, we performed experimental pollination treatments to evaluate the consequences of outbreeding
on fitness-related traits in the holoparasitic mistletoe Tristerix aphyllus in a 2-year field study. Results indicate that self-pollinated plants had a lower fruit production than outcrossed plants
(20.4% and 29.5% reduction in 2002 and 2003, respectively), and resulting inbred fruits were smaller than outcrossed fruits
in both years. No effect was detected for seed mass. The percentage of germination of inbred seeds was 15.1% and 6.0% lower
than outcrossed seeds in 2002 and 2003, respectively. Inbred seedlings had shorter radicles, which translated to a 71.6% and
60.0% reduction in infection success compared with outcrossed plants in 2002 and 2003, respectively. Overall, our results
revealed significant inbreeding depression on almost every trait that was examined. Although the mean value of traits varied
from a year to another, the magnitude of inbreeding depression did not change significantly between years. Our findings constitute
the first evidence that outcrossing increases infection success and probably virulence in parasitic plant populations. |
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Keywords: | Host– parasite interactions Inbreeding depression Radicle Selfing Outcrossing Chile Cacti |
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