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How porous are plant genomes? Introgressive hybridization in a Silene (Caryophyllaceae) species pair

Titel Englisch How porous are plant genomes? Introgressive hybridization in a Silene (Caryophyllaceae) species pair
Gesuchsteller/in Widmer Alexander
Nummer 104114
Förderungsinstrument Projektförderung (Abt. I-III)
Forschungseinrichtung Institut für Integrative Biologie Departement Umweltwissenschaften ETHZ
Hochschule ETH Zürich - ETHZ
Hauptdisziplin Genetik
Beginn/Ende 01.05.2004 - 30.04.2007
Bewilligter Betrag 248'300.00
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Alle Disziplinen (3)


Keywords (6)

biodiversity; evolutionary ecology; genetic architecture; introgressive hybridization; linkage mapping; molecular marker

Lay Summary (Englisch)

Lay summary
Hybridization is a common phenomenon in plants, but its role in plant evolution is only poorly understood. While some suggest that hybridization is a local and transient phenomenon that causes little more than “evolutionary noise”, others view it as a potent evolutionary force that creates opportunities for adaptive evolution and speciation in natural populations.For a better understanding of introgressive hybridization and its evolutionary consequences, it is necessary to study gene flow across species boundaries on a genome-wide scale, and in a diversity of plant lineages. This project asks the following questions:1) What is the genetic structure of the hybrid zone and the direction of introgression? Molecular markers will be used to estimate hybrid indices for plants growing at different positions along transects through two hybrid zones to determine whether the hybrid zones consist primarily of early generation hybrids or late generation backcross individuals, or a mixture of both. 2) How porous are Silene genomes?Hybrid zones may serve as bridges to gene flow across species boundaries. In situations where these are maintained outside of hybrid zones, introgression is expected to be confined to some parts of the genome, while other parts of the genome are sheltered from introgression. This expectation implies that genomes are porous, i.e. new genes can introgress in some parts of the genome, but not in others. In order to identify regions of the Silene genomes with either weak or strong introgression, we will map AFLP markers across the genome and then estimate the level of introgression for each of the mapped markers. This will provide us with an ‘isolation’ map of the genome that identifies regions that are open or closed to introgression.3) Does the position of genomic regions that are sheltered from introgression colocalize with genomic areas that confer reproductive isolation between the two species?Quantitative trait loci (QTL) for two traits that may be involved in reproductive isolation, namely flower color and pollen viability, will be mapped. The position of these QTL will be compared to the isolation map to test the hypothesis that areas of the genome that are sheltered from introgression are involved in reproductive isolation.The proposed research is expected to provide new insights into the genetic structure of hybrid zones, the genome-wide pattern of introgression, and may provide insights into the forces that shelter some parts of the genomes from introgression and thus may be responsible for the maintenance of species boundaries in the presence of gene flow.
Direktlink auf Lay Summary Letzte Aktualisierung: 21.02.2013

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