Abstract Detail

Macroevolution

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

The evolution of endocarp shape in relation to seed dispersal strategies in Viburnum (Adoxaceae).

Viburnum is a group of ~165 species of woody angiosperms that are distributed throughout temperate forests of the northern hemisphere as well as in the mountains of Central and South America and subtropical montane forests of Southeast Asia. Over the past decade, increased sampling and resolution of the Viburnum phylogeny has resulted in a tree that accounts for nearly every species, thus providing a robust framework for evolutionary studies. Key to the geographical movement of Viburnum throughout its evolutionary history has been the attraction of seed dispersers. Viburnum are largely bird dispersed and are characterized by having drupe fruits that are fleshy, single-seeded, and indehiscent. The fruits of Viburnum have a hardened inner ovary wall, or endocarp, that vary in size and shape across the clade. Taxonomists have long used endocarp shape as a way to differentiate major Viburnum lineages, but the function of this trait and its implications for seed dispersal remain unknown. Here we describe the evolution of Viburnum endocarp shape using morphometric analysis and phylogeny. We quantified the endocarp shape of 138 species of Viburnum sampled from herbarium specimens (YU, A), living collections (A), and field collections. Measurements and cross-sectional endocarp shapes were obtained from digital images and camera lucida drawings using light microscopy. Endocarp shape was analyzed independent of size using Elliptical Fourier analysis as implemented in MOMOCS, and the results were used in ancestral character state reconstruction. Additionally, we conducted a study of intraspecific variation of endocarp shape in four species that represent four distinct lineages of Viburnum. The intraspecific study revealed that endocarp shapes with more grooving had higher levels of variation. The most variable trait was endocarp length, which did not contribute to our measurements of shape. The clade-wide analysis revealed that the ancestral endocarp shape of Viburnum appears to have had multiple grooves or undulations. We recovered two instances of convergent evolution: (1) a flattened endocarp shape without grooving in the clades Lentago and Opulus, and (2) a spherical endocarp shape in the clades Tinus and Oreinotinus. We combine these findings on endocarp shape with other fruit traits, such as color and mesocarp texture, to delimit a set of dispersal strategies in Viburnum.

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

Keywords:
Fruit
Seed
Seed dispersal
morphometrics
character evolution
Dipsacales.

Presentation Type: Oral Paper
Session: 10, Macroevolution
Location: 202/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 4:15 PM
Number: 10011
Abstract ID:696
Candidate for Awards:None