Comparative ecology of seed mass in Psychotria (Rubiaceae): within- and between-species effects of seed mass on early performance
Article first published online: 19 AUG 2005
Volume 19, Issue 4, pages 707–718, August 2005
How to Cite
PAZ, H., MAZER, S. J. and MARTINEZ-RAMOS, M. (2005), Comparative ecology of seed mass in Psychotria (Rubiaceae): within- and between-species effects of seed mass on early performance. Functional Ecology, 19: 707–718. doi: 10.1111/j.1365-2435.2005.00984.x
- Issue published online: 19 AUG 2005
- Article first published online: 19 AUG 2005
- Received 21 December 2004; accepted 23 December 2004
- neotropical forest;
- phylogenetic independent contrasts;
- seedling emergence;
- seedling growth;
- seedling recruitment;
- seedling survival
- 1Experimental field data and interspecific comparative analyses were used to detect effects of seed mass on seedling performance within and among seven species of Psychotria sown in gaps and shaded rainforest sites. In addition we compared the effects of seed mass within and among species to detect concordance between the two ecological scales. We used two comparative methods: phylogenetically independent contrasts and cross-species correlations.
- 2Among species, we detected weak evidence of a positive correlation between seed mass and the probability of emergence in the shaded forest, and no effects of seed mass in gaps.
- 3Among species, no significant correlations between seed mass and either seedling survival or seedling recruitment were found in any habitat. Other variables specific to each subgenus appear to be more important than seed mass in determining survival in the shaded forest.
- 4There was a negative correlation between seed mass and relative growth rate (RGR) in both habitats. In gaps, small-seeded taxa exhibited particularly high RGR, compensating for the initial advantages of higher seed mass.
- 5All species studied exhibited recruitment in gaps equal to or higher than that in the shaded forest. However, recruitment success in shaded forest relative to gaps increased with seed mass, indicating a higher affinity for shaded forest among larger-seeded taxa, but this relationship was only detected using PICS analysis.
6. Correlations between seed mass and seedling mass are similar within and among species, indicating a simple principle of mass transference. In contrast, correlations between seed mass and seedling emergence, seedling survival, seedling recruitment and RGR depend on the scale at which they are observed.