Secondary sexual dimorphism in Gleditsia triacanthos , honey locust, at local and regional levels.

摘要

The general objective was to identify sexually dimorphic traits in a wide-ranging, native North American dioecious tree, Gleditsia triacanthos (Honey Locust), and to estimate the extent to which landscape-level factors influence dimorphism. Males and females from fourteen populations, between southern Ontario, Canada, and northern Tennessee, USA, were sampled for 37 measures of plant performance representing reproductive and vegetative characteristics. Plant traits were analyzed in relation to certain regionally-varying environmental parameters as well as several population parameters.;Results of a three-factor analysis of variance (site, sex, and size) indicated that greatest dimorphism occurred in reproductive traits. These traits along with some vegetative traits all varied significantly between the sexes, across the populations.;Differential responses between the sexes to environmental properties are discussed in terms of resource costs, and are explained in terms of differential reproductive effort in males and females, as females produce many large, energetically costly carbohydrate-rich pods. The greater reproductive costs incurred by females may make them more responsive to changes in resource availability, and this sensitivity is in turn more markedly affected by regional soil and climatic conditions and by population structure. (Abstract shortened by UMI.)