Abstract Detail

Developmental and Structural Section

Leslie, Andrew [1], Beaulieu, Jeremy [2], Crane, Peter [3], Donoghue, Michael [4].

Corner’s rules, cone size, and branching architecture in conifers.

Scaling relationships between branch diameter and leaf size have been widely used to understand how resources are allocated within the plant canopy. These relationships, known as Corner’s rules, state that plants with thick branches tend to bear large appendages such as leaves, but these thick branches are widely spaced in the canopy. Branching architecture also influences the size and canopy distribution of reproductive appendages, although fewer studies have explored this relationship at broad phylogenetic and ecological scales. Here, we test whether the size of pollen-producing and seed-producing cones scales with branch diameter across a wide sample of conifers, a diverse and globally distributed lineage of non-flowering seed plants. We also test whether scale-shaped leaves, which are correlated with a specific branching habit in conifers, and fleshy seed cones, which are associated with small cone size, influence these scaling relationships. After analyzing branch diameter and cone size from 293 extant species using phylogenetic multiple regression models and models of trait evolution, we find that branch diameter is a strong predictor of cone size across conifer species in general, particularly for pollen cones and woody seed cones where it explains between 50 to 80 percent of the variation in cone size. These relationships are not simple, however, and the evolution of key features alters their expression. The evolution of scale-shaped leaves is associated with shifts towards small branch diameter and small cones, regardless of ecology or reproductive biology. Additionally, the evolution of seed cones with fleshy tissues for animal dispersal decouples cone size from branch diameter; fleshy seed cones are small regardless of branching architecture. Nevertheless, the general strength of the scaling relationships between cone size and branch diameter in conifers suggests that their reproductive and vegetative morphology are tightly coupled. It is therefore difficult to disentangle the evolution of cone size from the evolution of branching architecture.

1 - Brown University, Box G-W, 80 Waterman Street, Providence, RI, 02912, USA
2 - University of Tennessee, National Institute for Mathematical & Biological Synthesis, Claxton Building 1122 Volunteer Boulevard, Knoxville, TN, USA
3 - Yale University, School of Forestry and Environmental Studies, 195 Prospect Street, New Haven, CT, USA
4 - Yale University, Department Of Ecology And Evolutionary Biology, 21 Sachem Street, PO BOX 208105, New Haven, CT, 06511, USA

Keywords:
allometry
conifers
seed cone
pollen cone
reproductive allocation.

Presentation Type: Oral Paper:Papers for Sections
Session: 25
Location: Pines North/Boise Centre
Date: Tuesday, July 29th, 2014
Time: 10:15 AM
Number: 25001
Abstract ID:156
Candidate for Awards:None