Traits of recalcitrant seeds in a semi‐deciduous tropical forest in Panamá: some ecological implications

Abstract

Summary 1.We used cross-species and phylogenetic analyses to compare seed traits of 36 species with desiccation-sensitive and 189 with desiccation-tolerant seeds from a semi-deciduous forest in Panamá. 2. When correcting for phylogenetic dependence between taxa, the desiccation-sensitive seeds were significantly larger than desiccation-tolerant seeds (3383 vs 283 mg) and typically shed during the wet (as opposed to dry) season. Both traits presumably reduce the rate of seed drying and hence the risk of desiccation-induced mortality for the desiccation-sensitive species. 3. Growing-house germination trials in simulated understorey and canopy gap environments revealed that the desiccation-sensitive species germinated most rapidly. Additionally, on a proportion basis, the desiccation-sensitive seeds allocated significantly less resources to seed physical defences (endocarp and /or testa) which may partially facilitate rapid germination. Both relationships were significant when correcting for phylogenetic dependence and seed mass. 4. Our results suggest that, for large-seeded species which will dry slowly, desiccation sensitivity may be advantageous. Rapid germination may reduce the duration of seed exposure to predation, and the low investment in physical defence means that, per unit mass, desiccation-sensitive seeds are a more efficient use of resources in seed provisioning.

Limites térmicos para a germinação em função da origem de sementes de espécies de Eugenia (Myrtaceae) nativas do Brasil

“…Muitas espécies vegetais exibem diferentes respostas fi siológicas às adversidades impostas pelo seu habitat, que consistem num conjunto de características adaptativas decorrentes da constituição genética infl uenciada pelas condições ambientais (Daws et al 2005;Gebler et al 2005;Renaut et al 2005). O comportamento germinativo apresentado pelas sementes de Eugenia, no presente trabalho, mostrou-se muito próximo entre as espécies de Eugenia da mesma região (Fig.…”

Water potential and viability of seeds of Eugenia (Myrtaceae), a tropical tree species, based upon different levels of drying

“…Tropical rain forests are considered to have comparatively more species with desiccationsensitive seeds than other regions due to the high water availability throughout most of the year . In this case, the high water content of desiccation sensitive seeds, which allows rapid germination, may also reduce the duration of seed exposure to predation and for large-seeded species could increase the resourceuse efficiency Daws et al 2005). However, conservation of these species in seed banks is quite difficult and the alternative methods used to guarantee biodiversity are often expensive (Barbedo and Marcos Filho 1998).…”

Seed desiccation and salinity tolerance of palm species Carpentaria acuminata, Dypsis decaryi, Phoenix canariensis, and Ptychosperma elegans

“…Desiccation-sensitive seeds have been reported to be, on average, larger than desiccationtolerant seeds, so seed size would influence the rate of seed drying (Daws et al, 2005). In our study, D. decaryi seeds were larger than the others and were also susceptible to desiccation.…”

“…The ability to tolerate desiccation is clearly advantageous and enables seed persistence both through time and in relatively arid environments (Pammenter and Berjak, 2000). Nevertheless, according to Pritchard et al (2004) and Daws et al (2005), the sensitivity to desiccation, showed by seeds of D. decaryi and P. elegans, may also be advantageous because rapid seed germination may reduce the time that seed is exposed to predators. However, P. canariensis seeds, which is considered desiccation-tolerant, germinated after an average of 13 days, while seeds of P. elegans, D. decaryi, and C. acuminata germinated after 17, 40, and 92 days, respectively (Table 1).…”