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Pollen competition reduces inbreeding depression in Collinsia heterophylla (Plantaginaceae)
Author(s) -
LANKINEN Å.,
ARMBRUSTER W. S.
Publication year - 2007
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2006.01233.x
Subject(s) - inbreeding depression , biology , pollen , genetic load , plantaginaceae , outcrossing , competition (biology) , inbreeding , pollen tube , outbreeding depression , pollen source , offspring , plantago , botany , ecology , pollination , pollinator , demography , genetics , population , pregnancy , sociology
We tested two predictions of the hypothesis that competition between self‐pollen may mitigate negative genetic effects of inbreeding in plants: (1) intense competition among self‐pollen increases offspring fitness; and (2) pollen competition reduces the measured strength of inbreeding depression. We used Collinsia heterophylla (Plantaginaceae), an annual with a mixed mating system, to perform controlled crosses in which we varied both the size of the pollen load and the source of pollen (self vs. outcross). Fitness of selfed offspring was higher in the high pollen‐load treatment. Our second prediction was also upheld: inbreeding depression was, on average, lower when large pollen loads were applied (11%) relative to the low pollen‐load treatment (28%). The reduction was significant for two fitness components relatively late in the life‐cycle: number of surviving seedlings and pollen‐tube growth rate in vitro . These findings suggest that intermittent inbreeding, which leads to self‐fertilization in plants with genetic loads, may select for traits that enhance pollen competition.