My research interests are primarily in the evolutionary ecology of species interactions and coevolution, with foci primarily on pollination biology and herbivory. Most current work deals with the evolution and maintenance of mutually beneficial interactions, and for the last several years I have used one of the classical cases of coevolution - yucca and yucca moths – as a model system for this purpose.  My lab is divided in two work spheres to integrate fieldwork and lab-based analyses.  Most projects combine ecological, behavioral,  phylogeographic, and phylogenetic tools that together can test hypotheses about micro- and macroevolutionary aspects of plant-animal interactions.  I have done fieldwork on most continents, with most active work going on in the U.S. and Mexican deserts and in Florida.

Why yuccas and yucca moths?

Yucca moths serve as the exclusive pollinators of yuccas, actively pollinate the flowers, and their larvae in turn require some of the developing seeds as the only acceptable food source. There is only a handful of known pollination systems with similar biology – trading “seeds for seeds” - and their specificity make them very useful for addressing a range of general questions about the evolution and ecology of species interactions in general and mutualism in particular.  For example:

• What is the role of preadaptations v. novel traits in evolving interactions?
• What mechanisms prevent mutualisms from evolving toward increased exploitation and eventual extinction?
• What proximal mechanisms determine host specificity in herbivorous insects, and what  is the probability that such factors lead directly or indirectly to speciation?
• Under what circumstances is ecological speciation probable to occur?
• How do sensory cues, such as olfactory and visual stimuli, interact in mediating plant-pollinator interactions?

We combine ecological experiments with phylogenetic studies at the species level and below, sometimes on a continental scale.  Other labs are performing studies of other seed-for-seed mutualisms, and it will soon be a reasonable goal to synthesize across these models.

Some specific projects

Current NSF-funded projects in the lab focus on trait evolution leading to loss of mutualism and on trait-level coevolution between yuccas and yucca moths.

In the first project, we focus on recent loss of pollination; twice, moths have turned cheaters and now lay their eggs directly into fruits, rather than flowers. They thus rely on their pollinating ancestors for creation of yucca seeds. Phylogenetic and ecological data led to the hypothesis that one of these transitions to cheating may have originated recently in Florida. We are completing several years of ecological experiments and phylogeographic analyses to test this hypothesis.

Pollinating yucca moth

For the second project, which is a collaboration with former postdoc Jim Leebens-Mack, we are compiling molecular data sets to establish well-resolved phylogenies for both the plants and the insects.  We will then use these frameworks to estimate the component of coevolution on specific plant and insect traits that may be candidates for reciprocal selection.

Yucca pods with larval exit holes at White Sands, N.M.

Our understanding of yucca moth diversity is still limited, with the number of recognized species growing quickly. We are producing systematic revisions of all major moth genera - a foretaste of this project can be had on The Tree of Life, where currently described species are described for the entire moth family, the Prodoxidae.

You can learn more about folks in the lab, what we do and where we do it, and download publications from the lab by going to the Lab Website.

 

Joshua tree and flowers at Yucca,  Arizona
 

Courses

• Advanced Evolution & Population Dynamics (BIOL 421)
• Plant-Animal Interactions (BIOL 448)

Read more about Dr. Pellmyr in the current  issue of the BIOTA newsletter.
 

Selected Publications

for PDF links go to the Lab Website

Herrera, C.M. & O. Pellmyr (eds.)  2002  Plant-Animal Interactions: An Evolutionary Approach.  Blackwell Science, Oxford.  Edited text by 13 contributors, intended for advanced undergraduate-graduate level.  

Pellmyr, O. & H.W. Krenn.  2002. Origin of a complex key innovation in an obligate plant-insect mutualism. Proceedings of the National Academy of Sciences, 99:5498-5502.

Althoff, D.M. & O. Pellmyr. 2002. Examining genetic structure in a bogus yucca moth: a sequential approach to phylogeography. Evolution 56:1632-1643.

Segraves, K. & O. Pellmyr. 2001. Phylogeography of the yucca moth Tegeticula maculata: the role of historical biogeography in reconciling high genetic structure with limited speciation. Molecular Ecology 10:1247-1253.

Marr, D.L., M.T. Brock & O. Pellmyr. 2001. Coexistence of mutualists and antagonists: exploring the impact of cheaters on the Yucca-yucca moth mutualism. Oecologia 128:454-463.

Althoff, D.M., J. Groman, K.S. Segraves & O. Pellmyr.  2001. Phylogeographic structure in the bogus yucca moth Prodoxus quinquepunctellus (Prodoxidae): comparisons with coexisting pollinator yucca moths.  Molecular Phylogenetics and Evolution, 21:117-127.

Pellmyr, O. & J. Leebens-Mack. 2000. Reversal of mutualism as a mechanism for adaptive radiation in yucca moths. American Naturalist 156:S62-S76.

Groman, J.D. & O. Pellmyr. 2000. Rapid evolution and specialization following host colonization in a yucca moth. Journal of Evolutionary Biology 13:223-236.

Huth, C.J. & O. Pellmyr. 2000. Pollen-mediated selective abortion promotes evolutionary stability of mutualism between yuccas and yucca moths. Ecology 81:1100-1107.

Marr, D.L., J. Leebens-Mack, L. Elms & O. Pellmyr. 2000. Pollen dispersal in Yucca filamentosa (Agavaceae): the paradox of self-pollination behavior by Tegeticula yuccasella (Prodoxidae). American Journal of Botany 87:670-677.

Pellmyr, O. 1999. A systematic revision of the yucca moths in the Tegeticula yuccasella complex north of Mexico. Systematic Entomology 24:243-271.

Huth, C.J. & O. Pellmyr. 1999. Yucca moth oviposition and pollination behavior is affected by past flower visitors: evidence for a host-marking pheromone. Oecologia 119:593-599.

Pellmyr, O. & J. Leebens-Mack. 1999. Forty million years of mutualism: evidence for an Eocene origin of the yucca-yucca moth association. Proceedings of the National Academy of Sciences 96:9178-9183.

Leebens-Mack, J., O. Pellmyr & M. Brock. 1998. Host specificity and the genetic structure of two yucca moth species in a yucca hybrid zone. Evolution 52:1376-1382.

Pellmyr, O., J. Leebens-Mack & C.J. Huth. 1996. Non-mutualistic yucca moths and their evolutionary consequences. Nature 380:256-257.

Pellmyr, O., and C.J. Huth.1994. Evolutionary stability of mutualism between yuccas and yucca moths. Nature 372:257-260.