THE GENETIC ARCHITECTURE OF REPRODUCTIVE ISOLATION IN LOUISIANA IRISES: POLLINATION SYNDROMES AND POLLINATOR PREFERENCES

Authors

  • Noland H. Martin,

    Corresponding author
    1. Department of Genetics, University of Georgia, Athens, Georgia 30602
    2.  E-mail: nm14@txstate.edu
    • 3 Current address: Department of Biology, Texas State University, San Marcos, Texas 78666

      4 Current address: Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel

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  • Yuval Sapir,

    Corresponding author
    1. Department of Genetics, University of Georgia, Athens, Georgia 30602
    • 3 Current address: Department of Biology, Texas State University, San Marcos, Texas 78666

      4 Current address: Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel

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  • Michael L. Arnold

    1. Department of Genetics, University of Georgia, Athens, Georgia 30602
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Abstract

In animal-pollinated plants, pollinator preferences for divergent floral forms can lead to partial reproductive isolation. We describe regions of plant genomes that affect pollinator preferences for two species of Louisiana Irises, Iris brevicaulis and Iris fulva, and their artificial hybrids. Iris brevicaulis and I. fulva possess bee and bird-pollination syndromes, respectively. Hummingbirds preferred I. fulva and under-visited both I. brevicaulis and backcrosses toward this species. Lepidopterans preferred I. fulva and backcrosses toward I. fulva, but also under-visited I. brevicaulis and I. brevicaulis backcrosses. Bumblebees preferred I. brevicaulis and F1 hybrids and rarely visited I. fulva. Although all three pollen vectors preferred one or the other species, these preferences did not prevent visitation to other hybrid/parental classes. Quantitative trait locus (QTL) mapping, in reciprocal BC1 mapping populations, defined the genetic architecture of loci that affected pollinator behavior. We detected six and nine QTLs that affected pollinator visitation rates in the BCIb and BCIf mapping populations, respectively, with as many as three QTLs detected for each trait. Overall, this study reflects the possible role of quantitative genetic factors in determining (1) reproductive isolation, (2) the pattern of pollinator-mediated genetic exchange, and thus (3) hybrid zone evolution.

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