Abstract Detail

Reproductive biology

Stammer, Theodore J. [1], Donoghue, Michael [2], Clement, Wendy [3].

Evolution of Endocarp Morphology and Implications for Seed Dispersal in Viburnum (Adoxaceae).

Viburnum is a group of ~165 shrubs and small trees whose fleshy fruits are typically dispersed by birds. Throughout Viburnum the fruit is a drupe, which is fleshy, indehiscent, and contains a single seed. The endocarp (hard inner wall of the ovary) varies considerably in shape and size, and endocarp characteristics have long been used to identify major subgroups within Viburnum. We have quantified variation in endocarps and have traced the evolution of endocarp morphology using a robust Viburnum phylogeny. By comparing endocarp shape and size relative to the volume of the entire fruit, we can identify evolutionary strategies of resource allocation in relation to potential dispersers. Endocarps from 129 species of Viburnum were sampled from herbarium (A, YU) and field collections. Whole endocarps and cross sections were scanned from camera lucida drawings or obtained using digital microscopy. Digital measurements, including endocarp length, width, height, and cross-sectional area were calculated using ImageJ. Scanned images were then binarized using Photoshop CS5.1 and volumes were calculated by multiplying average cross-sectional area by length. Additionally, we used Elliptical Fourier analysis as implemented in SHAPE and Momocs to study variation in Viburnum endocarp shape. Cases of parallel evolution were identified using our quantitative shape data and ancestral state reconstructions. Many Viburnum clades have endocarps with multiple grooves/undulations, and this appears to represent the ancestral condition for the majority of Viburnum. We recovered two clear instances of parallel evolution. The Tinus and Oreinotinus subclades have converged on spherical endocarps, while the Lentago and Opulus subclades have converged on flattened endocarps with little grooving. Correlations with fruit color and mesocarp texture highlight the existence of several dispersal strategies. For example, Tinus and Oreinotinus fruits are purple in color with a thin layer of mealy flesh. Lentago and Opulus fruits are notably enlarged, with a thick layer of flesh, but they are purple and mealy in Lentago versus red and juicy at maturity in Opulus. Ruminate endosperm has evolved several times independently in fruits with more rounded endocarps. These findings are used to elucidate and characterize seed dispersal strategies in Viburnum.

1 - The College of New Jersey, Biology, 2000 Pennington Road, Ewing, NJ, 08628, USA
2 - Yale University, Department Of Ecology And Evolutionary Biology, 21 Sachem Street, PO Box 208105, New Haven, CT, 06511, USA
3 - The College Of New Jersey, Biology, 2000 Pennington Road, Department Of Biology, Ewing, NJ, 08638, USA

Keywords:
endocarp
Viburnum
Phylogeny
seed dispersal
Morphometrics.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PRP008
Abstract ID:912
Candidate for Awards:None