Leaf herbivory and branch autonomy in Psychotria carthagenensis Jacq. (Rubiaceae)

Abstract

Valoy, Mariana; Mariano Ordano; Analía Benavídez. 2012. “Leaf herbivory and branch autonomy in Psychotria carthagenensis Jacq. (Rubiaceae)”. Lilloa 49 (1). The principle of allocation establishes that resources assigned to defense against herbivores compromises resource allocation to reproduction. This trade-off will differ under different circumstances of autonomy in the use of resources at intra-plant level. Assuming autonomy, we might expect to find greater levels of herbivory in branchs with fruits. Assuming partial or null autonomy, the plants might resolve the conflict transporting assimilates among branchs. Also in perennial plants, the allocation trade-off will depend on the prevalence in fruit bearing by a branch in consecutive years. We evaluated these predictions in a population of Psychotria carthagenensis, a shrub that produces fleshy fruits arranged in single infrutescences in apical branchs. The results indicated that the proportion of leaf area removed (pAFR) did not differ among branchs with fruits (average = 3.4% ± standard deviation = 3.5) and without fruits (3.4 ± 3,7). The prevalence was on average 14%, and independent of the pAFR by plant. These results suggest that: (1) the levels of herbivory observed did not compromise allocation to reproduction and/or the use and transportation of assimilates, (2) the autonomy is partial or null at the apical branch level. This might permit resolve the trade-off among allocate resources to defense without compromises allocation to fructification.