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EFFECTS OF POLLEN QUANTITY ON PROGENY VIGOR: EVIDENCE FROM THE DESERT MUSTARD LESQUERELLA FENDLERI
Author(s) -
Mitchell Randall J.
Publication year - 1997
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1997.tb01490.x
Subject(s) - biology , pollen , botany , horticulture
Intense competition among pollen grains for access to ovules often increases progeny vigor (Mulcahy 1971, 1979; Mulcahy and Mulcahy 1975; Mulcahy et al. 1975; McKenna 1986; Winsor et al. 1987; Bertin 1990; Schlichting et al. 1990; Richardson and Stephenson 1992; Janse and Verhaegh 1993; Quesada et al. 1993, 1996a,b; Palmer and Zimmerman 1994; but see Smith et al. 1990; Snow 1990, 1991). The most common explanation for this is that selection on gametophytes is an efficient means for removing deleterious alleles at loci important for both gametophytic and sporophytic life stages (Charlesworth and Charlesworth 1992; Hormaza and Herrero 1992; Stephenson et al. 1992). Gametophytic selection therefore has been proposed as an important factor in the success of angiosperms (Mulcahy 1979). Studies of pollen competition and progeny vigor usually involve variation in the number of pollen grains applied to stigmas or of the distance pollen tubes must travel to reach ovules (utilizing natural or artificial variation style length). Studies of the latter type invariably show significant effects on progeny vigor (Mulcahy and Mulcahy 1975; Ter-Avanesian 1978; McKenna and Mulcahy 1983; Lee and Hartgerink 1986; McKenna 1986). However, effects of pollen load size are less consistent (e.g., Winsor et al. 1987; Bertin 1990; Smith et al. 1990; Snow 1990, 1991; Palmer and Zimmerman 1994). Furthermore, most studies to date involve cultivated plant species (but see Snow 1990, 1991; Richardson and Stephenson 1992), which may respond differently than wild plants because of their history of close inbreeding and hybridization. To better understand the effects of pollen competition on progeny vigor, and why results vary among different studies, more empirical data are needed. Here I report results from a study of the effects of pollen load size on progeny vigor for a native, desert mustard (Lesquerellafendleri; Brassicaceae). I then review published studies of the effects of pollen load size on progeny vigor, considering why results may vary among methods and species.