Abstract Detail

Botany 2015 Colloquium: Integrated perspectives on the ecology, genetics and coevolution of intimate mutualisms

McKain, Michael [1], Heyduk, Karolina [2], McNeal, Joel [3], Kellar, P. Roxanne [4], Linder, Peter [5], Pires, J. Chris [6], Eguiarte, Luis E. [7], Leebens-Mack, James [2].

Timing of rapid diversification and parallel origins of active pollination within Agavoideae (Asparagaceae).

The relationship between yuccas and yucca moths has long been held as an excellent example of coevolution. Both yuccas and yucca moths have developed multiple morphological and behavioral traits that facilitate the specialized mutualism that serves to provide yuccas with a reliable pollination strategy and yucca moths with a means to complete their reproductive cycle. Members of the yucca moth genera (Tegeticula and Parategeticula) have demonstrated specialization to single yucca species, though this is not always the case as there exist generalists, such as T. yuccasella, that will pollinate and thrive in multiple species. Additionally, yuccas are not the only members of Agavoideae to have a close relationship with yucca moths. The genus Hesperoyucca exhibits a parallel relationship with Tegeticulata maculata and possesses similar albeit different floral morphology to the genus Yucca. Previous studies have demonstrated that Yucca and Hesperoyucca are not closely related within Agavoideae, suggesting either independent origins of the yucca pollination syndrome or multiple losses. Here, we provide a well-supported phylogeny using both whole chloroplast genomes and low-copy nuclear loci for the Agavoideae subfamily further corroborating the evolutionary distance between these two lineages. We find that the genus Yucca, is allied with more southern-dispersed genera, like Agave, Beschorneria, and Polianthes. The genus Hesperoyucca is found within a clade with more northern genera, Hesperaloe and Schoenolirion. The phylogeny of the subfamily suggests that there was a rapid radiation in the establishment of major clades within the Americas. We tested this by estimating times of divergence for genera and major clades sampled. We found that the major clades of Agavoideae diverged from one another ~29-22 million years ago, which included a trans-Pacific dispersal event. The divergence of the Yucca and Hesperoyucca lineages occurred ~27 mya, a date that is much younger than the proposed age of yucca moth colonization and origin of active pollination, ~35 mya. Futhermore, the ages of divergence for Yucca (~20 mya) and Hesperoyucca (~16 mya) suggest that yucca moth colonization may have occurred even later than previously thought. Ultimately, we consider the possibility of independent origins of the yucca-yucca moth pollination syndrome in Agavoideae, which is very likely attributable to a host-shift from Yucca to Hesperoyucca.

1 - Donald Danforth Plant Science Center, Plant Biology, 975 N. Warson Rd., St. Louis, MO, 63132, USA
2 - University of Georgia, Department of Plant Biology, 2502 Miller Plant Sciences, Athens, GA, 30602
3 - Kennesaw State University, Department of Biology and Physics, 1000 Chastain Rd., Bldg. 12, Kennesaw, GA, 30144-5591
4 - University of Nebraska at Omaha, Biology, 6001 W. Dodge St. - AH 211A, Omaha, NE, 68182, USA
5 - University Of Zurich, Inst For Systematic Botany, Zollikerstrasse 107, Zurich, N/A, CH-8008, Switzerland
6 - University of Missouri, Division of Biological Sciences, 371b Bond Life Sciences Center, Columbia, MO, 65211
7 - Universidad Nacional Autonoma De Mexico, UNAM, , Instituto de Ecologia, Apartado Postal 70-275, C.U., Coyoacán, México,, Mexico City, DF, 04510, Mexico

Keywords:
Yucca
yucca moth
pollination
Agavoideae
whole chloroplast
divergence time
mutualism.

Presentation Type: Colloquium Presentations
Session: C4
Location: Hall C/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 1:30 PM
Number: C4001
Abstract ID:387
Candidate for Awards:None