Evolutionary Developmental Biology (Evo-Devo)
Landis, Jacob , Hileman, Lena .
The birds and the bees: investigating a role of MIXTA genes in pollinator shifts.
Pollination strategy is a critical aspect in the ecology and evolution of flowering plants, with selection on floral traits leading to adaptation and speciation. These adaptations and speciation events cause the angiosperms to be highly diversified, with different floral patterns evolving. Many flowers are animal pollinated, with petals functioning as attractants through color intensity, shape, and size. An important indicator of petal function is the presence of conical-shaped cells with roughly 80% of flowering plants containing conical cells on the petal epidermis, which increases insect visitation frequency. MIXTA-like genes have been characterized to control conical shaped cells in the bee-pollinated snapdragon, Antirrhinum majus (Plantaginaceae). Among close relatives of snapdragon, there have been multiple independent shifts from insect to bird pollination associated with new world species, along with several documented reversals to bee pollination. We hypothesize that hummingbird pollinated lineages in the tribe Antirrhineae have undergone phenotypic changes due to shifts in pollination syndrome, specifically loss of conical cells in their petals, at least to a certain degree compared to insect pollinated lineages. This loss of conical cells is likely due to changes in the expression patterns of MIXTA-like genes in these taxa. Initial surveys of cell shape in the petal epidermis of specified genera by scanning electron microscopy (SEM) do show a loss of conical cells in hummingbird pollinated lineages. To test predictions that MIXTA-genes are responsible for loss of conical cells, orthologs of MIXTA-like genes in 14 genera will be isolated and their expression will be characterized by RT-PCR and in-situ hybridization. Evidence that MIXTA-like genes have changed due to phenotypic variation caused by pollination syndrome will be if expression of MIXTA-like orthologs vary consistently between insect pollinated and hummingbird pollinated lineages. If expression patterns do not vary consistently, then other genes are responsible for phenotypic changes seen between pollination syndromes.
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1 - University of Kansas, Ecology and Evolutionary Biology, 1200 Sunnyside Avenue, Lawrence, KS, 66045, United States
2 - University of Kansas, Ecology and Evolutionary Biology, 1200 Sunnyside Ave., Lawrence, KS, 66045, USA
Presentation Type: Oral Paper:Papers for Topics
Location: 554A/Convention Center
Date: Monday, August 2nd, 2010
Time: 8:30 AM