Anna Himler

Department of Ecology & Evolutionary Biology
ahimler@email.arizona.edu
Phone: (520) 626-7009
Fax: (520) 621-9190
Office: BioSciences West 236
Mailing address: P.O. Box 210088, University of Arizona, Tucson, Arizona 85721-0088

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I am broadly interested in the evolution of mutualisms, in particular the evolution of host shifts and subsequent diversification between insects and their plant or fungal hosts. To approach this I have used a combination of molecular genetic techniques, field research, and behavioral experiments.

As a PERT Fellow, I’m currently working with Carlos Machado on divergence population genetics of sympatric species of Neotropical figs. Figs (Ficus sp., Moraceae) participate in an ancient pollination mutualism between the fig trees and the tiny fig wasps (Agaonidae, Chalcidoidea) that pollinate them. There are approximately 750 species of figs worldwide that function as keystone species in tropical and subtropical regions due to their year-round production of fruit that supports many frugivores. Contrary to previous widely held beliefs that one species of wasp pollinates one species of fig tree recent evidence shows that two or more fig wasps may occur on a single fig tree species. I use a combination of molecular genetic techniques, including sequencing and microsatellites, to assess whether Neotropical fig species exhibit evidence for hybridization and introgression among figs. Phylogenetic and population genetic data will test previous hypotheses of strict-sense cospeciation and investigate whether host switching or host sharing by the pollinating wasps has been a primary mechanism generating fig species diversity.

For my dissertation work I examined whether switching to a new fungal cultivar could trigger speciation events in two Central and South American species complexes of fungus-growing ants (Tribe Attini, Formiciadae). Using behavior experiments and molecular phylogenetics, I investigated whether cultivar switches are associated with ant genetic divergence. Results revealed more complex and diffuse ant-cultivar relationships than previously suspected in this symbiosis: in one species complex (Cyphomyrmex longiscapus and C. muelleri) each ant species specialized on a narrow group of fungal cultivars and did not switch, while the other species complex (Apterostigma auriculatum) exchanged fungal cultivars more frequently and the ants did not form monophyletic groups based on cultivar type. Varying degrees of host-fidelity will have different consequences for coevolutionary dynamics in this symbiosis.

Other aspects of my dissertation research included conducting natural history studies on North and Central American fungus growing ants, discovery of a potentially new fungus-growing ant species, and documenting the first completely asexual fungus-growing ant.