Variation in fruit and seed dimensions is better explained by dispersal system than by leaf size in a tropical rainforest

• Published in: American journal of botany 2023-08, Vol.110 (8), p.1-n/a
• Main Authors: Stevenson, Pablo R., Acosta‐Rojas, Diana C., Cárdenas, Sasha, Francisco Henao‐Díaz, L.
• Format: Article
• Language: English
• Subjects: Allometry; Byproducts; Dispersal; Dispersion; Frugivores; fruit and seed allometry; fruit size; Fruits; functional traits; Hypotheses; leaf area; leaf length; Leaves; Phylogeny; Plant species; plant trait evolution; Rainforests; Seed dispersal; Seeds; Species
• ISSN: 0002-9122; 1537-2197
• DOI: 10.1002/ajb2.16211

Premise Variation in fruit and seed traits could originate from selection pressures exerted by frugivores or other ecological factors (adaptive hypotheses) and developmental constraints (by‐product hypotheses) or chance. Methods We evaluated fruit and leaf traits for nearly 850 plant species from a rainforest in Tinigua Park, Colombia. Through a series of linear regressions controlling for the phylogenetic signal of the traits (minimum N = 542), we tested (1) whether the allometry between seed width and length depends on seed dispersal system (Mazer and Wheelwright's adaptive hypothesis of allometry for species dispersed in the guts of animals = endozoochory) and (2) whether fruit length is associated with leaf length (i.e., Herrera's by‐product hypothesis derived from the assumption that both organs develop from homologous structures). Results We found a strong negative allometric association between seed width and length for seeds of endozoochorous species, as expected; but also, for anemochorous species. We found a positive relationship between fruit and leaf length, but this relationship was not evident for zoochorous species. Fruit size was highly correlated with seed size. Conclusions The allometry between seed length and width varied among dispersal systems, supporting that fruit and seed morphology has been modified by interactions with frugivores and by the possibility to rotate for some wind dispersed species. We found some support for the hypothesis on developmental constraints because fruit and leaf size were positively correlated, but the predictive power of the relationship was low (10–15%). Resumen Premisa La variación en los rasgos de frutos y semillas de las plantas podría tener su origen en las presiones de selección ejercidas por los frugívoros u otros factores ecológicos (hipótesis adaptativas), así como en limitaciones del desarrollo (hipótesis de subproductos) o en el azar. Métodos Nosotros evaluamos rasgos de frutos y hojas en cerca de 850 especies de plantas de un bosque húmedo tropical en el Parque Nacional Natural Tinigua, Colombia. Usando una serie de regresiones lineales que controlan por la señal filogenética de dichos rasgos (mínimo N = 542), nosotros probamos (1) si la alometría entre el ancho y largo de la semilla depende del sistema de dispersión de la semilla (i.e., hipótesis adaptativa de Mazer y Wheelwright; en la que se espera una alometría negativa para especies dispersadas por endozoocoria) y (2) si el largo del fruto