Recombination between divergent genes and genomes occurs commonly in nature and generates new gene combinations that appear to be important in the evolution of virulence, as well as resistance to antibiotics and disease. However, we know surprisingly little about the frequency with which wide recombination or hybridization contributes to adaptive evolution or the evolutionary conditions required for the establishment of new hybrid gene combinations. Given the ever-increasing opportunities for contact and gene exchange between previously isolated organisms, and the possible negative consequence of these interactions for human health, it is important that we understand the principles that govern the outcomes of hybridization. The proposed research will address fundamental questions about the role of hybridization in evolution, the limits to ecological divergence, the efficacy of different kinds of chromosomal rearrangements as reproductive barriers, the proportion of genes under positive selection during speciation, the reconstruction of reticulate phylogenies, and the tempo of hybrid speciation. The research will be conducted using the wild, annual sunflowers (Helianthus) because this group is widely cited as a model system for the study of interspecific hybridization and its consequences. The experimental plan employs a broad array of approaches, ranging from classic selection experiments comparing the response to selection of hybrid and pure parental populations, to candidate gene mapping, to single nucleotide polymorphism analyses that will assess the scale of recombination between the parental genomes in hybrid lineages. The proposed work represents an important step toward understanding the contribution of hybridization to adaptive evolution and speciation.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM059065-06
Application #
6988502
Study Section
Genetics Study Section (GEN)
Program Officer
Eckstrand, Irene A
Project Start
2000-04-01
Project End
2006-06-30
Budget Start
2005-12-01
Budget End
2006-06-30
Support Year
6
Fiscal Year
2006
Total Cost
$177,698
Indirect Cost
Name
Indiana University Bloomington
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
006046700
City
Bloomington
State
IN
Country
United States
Zip Code
47401
Blackman, Benjamin K; Rasmussen, David A; Strasburg, Jared L et al. (2011) Contributions of flowering time genes to sunflower domestication and improvement. Genetics 187:271-87
Blackman, Benjamin K; Michaels, Scott D; Rieseberg, Loren H (2011) Connecting the sun to flowering in sunflower adaptation. Mol Ecol 20:3503-12
Donovan, L A; Rosenthal, D R; Sanchez-Velenosi, M et al. (2010) Are hybrid species more fit than ancestral parent species in the current hybrid species habitats? J Evol Biol 23:805-16
Blackman, Benjamin K; Strasburg, Jared L; Raduski, Andrew R et al. (2010) The role of recently derived FT paralogs in sunflower domestication. Curr Biol 20:629-35
Strasburg, Jared L; Scotti-Saintagne, Caroline; Scotti, Ivan et al. (2009) Genomic patterns of adaptive divergence between chromosomally differentiated sunflower species. Mol Biol Evol 26:1341-55
Kane, Nolan C; King, Matthew G; Barker, Michael S et al. (2009) Comparative genomic and population genetic analyses indicate highly porous genomes and high levels of gene flow between divergent helianthus species. Evolution 63:2061-75
Donovan, L A; Ludwig, F; Rosenthal, D M et al. (2009) Phenotypic selection on leaf ecophysiological traits in Helianthus. New Phytol 183:868-79
Hoffmann, Ary A; Rieseberg, Loren H (2008) Revisiting the Impact of Inversions in Evolution: From Population Genetic Markers to Drivers of Adaptive Shifts and Speciation? Annu Rev Ecol Evol Syst 39:21-42
Strasburg, Jared L; Rieseberg, Loren H (2008) Molecular demographic history of the annual sunflowers Helianthus annuus and H. petiolaris--large effective population sizes and rates of long-term gene flow. Evolution 62:1936-50
Sambatti, Julianno B M; Ortiz-Barrientos, Daniel; Baack, Eric J et al. (2008) Ecological selection maintains cytonuclear incompatibilities in hybridizing sunflowers. Ecol Lett 11:1082-91

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