AoB Plants. 2016 Dec 30; doi: 10.1093/aobpla/plw089. Epub 2016 Dec 30.

Size-dependent sex allocation and reproductive investment in a gynodioecious shrub.

AoB PLANTS

Akari Shibata, Gaku Kudo

PMID: 28039117 PMCID: PMC5497021 DOI: 10.1093/aobpla/plw089

Abstract

In sexually dimorphic plants, resource allocation to reproduction often differs between sex morphs. In gynodioecious species, i.e. coexisting hermaphrodite and female plants within a population, females often produce more fruits than hermaphrodites. Since fruit production is costlier than flower production, hermaphrodites and females may regulate flower and fruit production differently in response to resource availability. To clarify the gender-specific strategies of reproductive allocation, we assessed sexual dimorphism in reproductive traits, size-dependent resource allocation, morphological traits, and photosynthetic capacity in a natural population of a gynodioecious shrub, Daphne jezoensis Hermaphrodites had larger flowers and increased flower number with plant size at a rate greater than females, but showed consistently smaller fruit production. Although females did not increase flower production as much as hermaphrodites did as their size increased, they produced 3.7 times more fruits than did hermaphrodites. Despite a large sexual difference in fruiting ability based on hand-pollination, total resource investment in reproduction (the sum of flower and fruit mass) was similar between sex morphs across plant sizes, and there was little sexual difference in the cost of reproduction, i.e. the negative effect of current reproduction on future reproductive effort, in the natural population. In addition, there were no sexual differences in the resource allocation to vegetative organs (leaf and root mass) and photosynthetic capacity (light response photosynthetic rates). Under natural conditions, pollen limitation strongly restricted the fruit production of females, resulting in similar cost of reproduction between hermaphrodites and females.

Published by Oxford University Press on behalf of the Annals of Botany Company.

Keywords: Cost of reproduction; flower production; fruit set; gynodioecy; pollen limitation; resource allocation; sexual dimorphism; size-dependency.

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• Journal Article