Sources and consequences of seed mass variation in Banksia marginata (Proteaceae)

Abstract

Summary 0We examined the sources and consequences of seed mass variation in Banksia marginata occurring in _re!prone heath on nutrient!poor soils to determine factors in~uencing seed size and possible _tness bene_ts of large seeds[ 1 Individual seed mass varied _vefold[ Variation occurred among populations "18) of total#\ among years "09)# and among plants "plants\ 5)^year × plants\ 02)#\ but was most pronounced within plants "31)#[ Within plants\ seed mass variation was greater within infructescences "24)# than among infructescences "6)#[ 2 Seed mass variation within infructescences was not related to whether follicles contained one or two seeds[ Seed mass was also una}ected by ovule position within follicles and follicle position within infructescences[ 3 Seed mass variation among infructescences and plants was related to the limited availability of nutrient resources during seed provisioning[ Mean seed mass was negatively related to seed number per infructescence and per plant[ When resources decreased late in the~owering season and after defoliation\ seed mass declined by 6Ð 09) and seed number by 20Ð34)[ When resources increased after in~orescence removal\ seed mass increased by 7) but seed number was una}ected[ Plants thus had only a limited capacity to maintain seed mass by adjusting seed number when resources varied[ 4 The N and P contents of seeds "mg seed −0 # increased linearly with seed mass\ indicating costs of producing larger seeds in terms of limited environmental nutrients[ 5 Seedling size increased with seed mass\ implying _tness bene_ts of larger seeds in terms of increased seedling establishment on nutrient!poor soils[ Seed mass had little or no e}ect on seed germination\ relative growth rates and root]shoot ratios[ 6 Although stabilizing selection should eliminate seed mass variation occurring within plants\ such variation persists because resource constraints limit the ability of plants to control individual seed size[ Keywords] nutrient allocation patterns\ nutrient!poor soils\ seed nutrient content\ seed size and number\ seedlings Journal of Ecology "0887# 75\ 452Ð462

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).…”

Caracterização da germinação e morfologia de frutos, sementes e plântulas de Dalbergia cearensis Ducke (pau-violeta) - Fabaceae

“…2A-D Há uma tendência no sentido de assumir que sementes são estáveis em proporção de massa, comparadas a outros órgãos menos plásticos da planta (Clavijo 2002). Não obstante, variação na massa de sementes ocorre em muitas espécies de plantas e, com freqüência, na própria planta (Vaughton & Ramsey 1998). Sendo que essas variações de tamanho de sementes existentes na própria planta, não são provocadas por diferenças genéticas, mas são decorrentes dos efeitos do meio ambiente durante o seu desenvolvimento (Leishman et al 2000).…”

“…A massa de semente ideal é aquela que maximiza o retorno por investimento de unidade. Sementes abaixo do tamanho ótimo terão baixo fi tness, enquanto aquelas maiores que o ótimo desperdiçam recursos que poderiam ser usados para abastecer mais descendentes (Vaughton & Ramsey 1998).…”

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.…”