Effects of seed size on seedling size in Virola surinamensis; a within and between tree analysis

Abstract

We conducted a greenhouse study of the effects of initial seed mass on seedling characteristics in a Panamanian population of Virola surinamensis, a canopy tree in which mean seed mass of different individuals ranges from 1.34 to 4.04g. The system is of particular interest because birds preferentially eat fruits of small-seeded plants, leaving seedlings of large-seeded individuals under conditions of potentially severe sibling competition (Howe and Vande Kerckhove 1980).Effects of differences of mean seed mass between trees are explored using an analysis of variance, while effects of seed-mass variation within crops are demonstrated with a regression analysis. A two-way analysis of variance decisively shows effects of parental source and light condition on seedling height, leaf length, and dry shoot mass (all P<0.0001). A posteriori tests show that differences in seedling characteristics reflect differences in initial seed mass, with especially strong differences apparent in shoot mass. Regression of seedling characteristics on initial seed mass shows that variation of seed size within a crop is sufficient to influence shoot mass at 15 weeks (P<0.0001).Effects of size differences of seeds that land adjacent to each other, either under the parent or in monkey droppings, are documented with growth of pairs of seedlings in pots. Differences in shoot height and mass at 15 weeks are evident when seeds of average size differ by only 0.2 g, and dramatic differences are evident when paired seeds differ by an average of 1.5 g. Seedlings grow more when isolated than when planted with conspecifics.These experimental results offer indirect support for the hypothesis that small-seeded Virola parents secure an advantage in reproduction through differential dispersal, while large-seeded plants produce more competitive seedlings under their own crowns - an advantage most likely to be of importance when frugivores are scarce.

Propagule size and predispersal damage by insects affect establishment and early growth of mangrove seedlings

“…In the cases of Avicennia and Rhizophora, these larger seedlings also had more leaves than those that developed from smaller propagules. The latter result, that larger seedlings develop from larger propagules, appears quite general (Howe and Richter 1982;Stanton 1984;Wulff 1986b;Moegenburg 1996;Vaughton and Ramsey 1998;Eriksson 1999). However, the effect of propagule size on seedling establishment is more variable; in some cases there is little or no effect, as in our study (Wulff 1986b;Vaughton and Ramsey 1998;Eriksson 1999), but in others, seedling emergence rates are higher for larger propagules (Stanton 1984;Winn 1988).…”

“…Despite Harper et al's (1970) prediction that seed size should be a canalized trait that varies little within a species, intraspecific variation in seed size, of similar or greater magnitude to that which we observed, has been demonstrated in numerous subsequent studies. Such variation occurs over a wide range of spatial scales: within plants, among plants, and among populations (Wulff 1973(Wulff , 1986aSchaal 1980;Howe and Richter 1982;Stanton 1984;Winn 1988;Moegenburg 1996;Ramsey 1997, 1998;Eriksson 1999).…”

Consequences of cutting off distal ends of cotyledons of Quercus robur acorns before sowing

“…In many tree species, initial seedling growth is positively correlated with seed mass (Howe and Richter 1982;Vaughton and Ramsey 1998;Sousa et al 2003;Kennedy et al 2004), and this is also true in oak species (Merouani et al 2001;Grossman et al 2003). Furthermore, larger oak acorns have a higher germination rate (Gomez 2004;Tilki 2010).…”

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

“…In natural vegetation, seedlings from larger single-seeded fruits outcompete those from smaller fruits (Wulff, 1986;Roach, 1986;Counts & Lee, 1991), but we have found no comparable studies of multi-seeded fruits. However while small seeds may disperse further from the parent, thus escaping parental competition (Baker, 1972 ;Howe & Richter, 1982), large seeds, and their fast growing seedlings, may become more 'conspicuous', resulting in more predation (Smith & Fretwell, 1974). There is also some suggestion that seed size effects on subsequent adult fitness may be swamped by siterelated phenotypic variation in some short-lived species (Solbrig, 1981;Gross & Kromer, 1986).…”