PARENT SESSION
Contributed Oral Session 99: Populations and Genetics: Diversity and Population Dynamics
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 519 A, Level 5, Palais des congrès de Montréal
QTL mapping for ecologists: A novel experimental design provides a shortcut for linkage mapping in species with long generation times.
Woolbright, Scott*,1, 2, Martinsen, Gregory1, 2, Whitham, Thomas1, 2, Keim, Paul1, 2, 1 Department of Biological Sciences, Flagstaff, Arizona, USA2 Merriam-Powell Center for Environmental Research, Flagstaff, Arizona, USA
ABSTRACT- We tested the hypothesis that natural hybrids can be used as parents for segregating mapping populations in an outcrossing forest tree. Obligate outcrossing and long-generation intervals, make production of segregating mapping populations not feasible for many ecologically interesting species. Although 3-generation hybrid pedigrees have been used in genetic mapping studies of forest trees, such studies take decades to establish, and are not available for most species. Here we describe an effective crossing method to produce a mapping population in just one generation. We artificially backcrossed a naturally occurring F1 hybrid (Populus fremontii x P. angustifolia) to a pure P. angustifolia from the same population to produce 246 backcross mapping progeny. Three major results were obtained from this population. 1) Linkage analyses using 564 AFLP markers resulted in a dense genetic map consisting of 21 linkage groups covering 2549 centimorgans. 2) Patterns of segregation distortion, heterozygosity levels, estimated and observed genome lengths were all comparable to those reported for other maps of closely related species derived from conventional methods. 3) We have begun to identify QTL associated with traits of ecological significance for the population of interest, including: phenological, chemical, and architectural traits. These findings are important for three major reasons. 1) Because pedigreed families were not available for either of the species we studied, our results argue that a natural hybrid shortcut represents a viable alternative method for generating a genetic map. 2) Such a short cut may be particularly important where time and cost might otherwise prevent map construction, especially for long lived forest tree species that have long generation times and/or extended juvenile phases before becoming reproductive mature. 3) This technique allows for the production of genetic maps specific to populations of interest, providing a powerful tool for studying the genetic basis of ecological and/or evolutionary processes in natural systems.
Key words: populus, hybrid, linkage map, QTL