Fitness constraints on flower number, seed number and seed size in the dimorphic species Primula farinosa L. and Armeria maritima (Miller) Willd.

Abstract

SUMMARYUsing two dimorphic species with diallelic incompatibility. Primula farinosa \^. and Armeria maritima (Miller) Willd., we tested the hypothesis that an association of seedling performance with seed size, and an inverse association of seed size with seed numher, tnight, contrary to most fitness models, select for plants which set relatively few seeds.In P. farinosa we discovered positive relationships between seed number per eapsule and capsule nutiiber per inflorescence. As capsules are formed in most flowers, scapes with tew flowers set the fewest seeds per capsule. This suggests that conspieuousness to pollinators and/or plant resource play an important role in reproductive success in this species. Seed size and seedling performance were also positively associated.For P. farinosa, which has multi-seeded fruits, we discovered an inverse association between seed size and seed tiumher for capsules containing more than 65 seeds. We suggest that stabilizing selection may occur for flower number per inflorescence in this species, as inflorescences with 8-11 capsules tend to set many seeds which tnay be inefficiently small. This tends to confSrm our hypothesis.However, for A. maritima there is a positive association between seed size and seed number per inflorescence. For such plants with single-seeded fruits there should be directional selection for large flower number per inflorescence, a trend which may have led to the evolution of the capitulum.

Primula veris plants derived from in vitro cultures and from seeds: genetic stability, morphology, and seed characteristics

“…In the authors' opinion such dependence may indirectly influence the reproductive success of this species, as inflorescences with few flowers set the fewest seeds per capsule. In the present study no such correlation was found, but we agree with Baker et al (1994) on the fact that the positive correlation between the increase of number of seeds per fruit and number of fruits per inflorescence may result in competition for limited maternal resources among seeds, and reduction in seed size may be a consequence of such a relationship. Furthermore, according to Boyd et al (1990), In vitro derived specimens who examined the population ecology of heterostyle and homostyle Primula vulgaris in field populations, seeds compete for limited maternal resources, which results in a trade-off between seed size and seed number.…”

“…In turn, results from long-term observations in natural Primula veris populations showed much lower fruiting intensity, which ranged from 9.0% to 52.3%, depending on the population (Morozowska and Urbański, 2000). Fruiting efficiency and seed set are important parameters characterizing plant fecundity, which is an essential component of fitness (Baker et al, 1994). The very high fruiting efficiency observed in the present study suggests strong reproductive potential of cultivated cowslip plants either regenerated vegetatively from tissue cultures or propagated generatively from seeds.…”

“…Baker et al (1994) showed that P. farinosa tends to show a reduction in seed weight with increasing seed number per capsule; however, the authors found that it was clearly shown only for capsules containing more than 65 seeds. The same authors have also discovered a positive relationship between seed number per capsule and capsule number per inflorescence for P. farinosa.…”

“…Furthermore, according to Boyd et al (1990), In vitro derived specimens who examined the population ecology of heterostyle and homostyle Primula vulgaris in field populations, seeds compete for limited maternal resources, which results in a trade-off between seed size and seed number. Baker et al (1994) have shown that seed size and seedling performance were positively associated in P. farinosa. Such a relationship was also found for P. vulgaris and other Primula species for which the larger seeds might lead to more successful individuals than those arising from small seeds (Tremayne and Richrads, 2000;.…”

Seed mass versus seedling performance in Scots pine: a maternally dependent trait

“…In general, it is accepted that, relative to large seeds, small seeds usually have reduced emergence (Zimmerman & Weis, 1983 ;Weller, 1985 ;Winn, 1988 ;Tripathi & Khan, 1990 ;Hendrix & Trapp, 1992 ;Rice et al, 1993 ;Prinzie & Chmielewski, 1994), higher mortality (Schaal, 1980 ;Tripathi & Khan, 1990 ;Bonfil, 1998) and lower seedling growth (Wulff, 1986a ;Hendrix et al, 1991 ;Dawson & Ehleringer, 1991 ;Baker et al, 1994 ;Moegenburg, 1996 ;Weiner et al, 1997 ;Vaughton & Ramsey, 1998 ;Bonfil 1998). However, other studies show no relationship between seed size and seedling performance in some species, as described by Cipollini & Stiles (1991), Rice et al (1993) and Vaughton & Ramsey (1998) for seed germination ; Hendrix & Trapp (1992) for seedling survival ; Dolan (1984) and Marshall (1986) for seedling growth.…”