Local-scale patterns of genetic variability, outcrossing, and spatial structure in natural stands of Arabidopsis thaliana

As Arabidopsis thaliana is increasingly employed in evolutionary and ecological studies, it is essential to understand patterns of natural genetic variation and the forces that shape them. Previous work focusing mostly on global and regional scales has demonstrated the importance of historical events such as long-distance migration and colonization. Far less is known about the role of contemporary factors or environmental heterogeneity in generating diversity patterns at local scales. We sampled 1,005 individuals from 77 closely spaced stands in diverse settings around Tübingen, Germany. A set of 436 SNP markers was used to characterize genome-wide patterns of relatedness and recombination. Neighboring genotypes often shared mosaic blocks of alternating marker identity and divergence. We detected recent outcrossing as well as stretches of residual heterozygosity in largely homozygous recombinants. As has been observed for several other selfing species, there was considerable heterogeneity among sites in diversity and outcrossing, with rural stands exhibiting greater diversity and heterozygosity than urban stands. Fine-scale spatial structure was evident as well. Within stands, spatial structure correlated negatively with observed heterozygosity, suggesting that the high homozygosity of natural A. thaliana may be partially attributable to nearest-neighbor mating of related individuals. The large number of markers and extensive local sampling employed here afforded unusual power to characterize local genetic patterns. Contemporary processes such as ongoing outcrossing play an important role in determining distribution of genetic diversity at this scale. Local "outcrossing hotspots" appear to reshuffle genetic information at surprising rates, while other stands contribute comparatively little. Our findings have important implications for sampling and interpreting diversity among A. thaliana accessions.Financial support came from an NIH Ruth Kirschstein NRSA Postdoctoral Fellowship (KB), a Human Frontiers Science Program Postdoctoral Fellowship (RAL), grants DFG ERA-PG ARelatives and FP6 IP AGRON-OMICS (contract LSHG-CT-2006-037704), from a Gottfried Wilhelm Leibniz Award of the DFG, and the Max Planck Society (DW)

Prospecuts, April 8, 2009

https://spark.parkland.edu/prospectus_2009/1010/thumbnail.jp

Prospectus, November 11, 2009

https://spark.parkland.edu/prospectus_2009/1030/thumbnail.jp

Prospectus, December 1, 2010

PARKLAND SERVICE LEARNING GIVES BACK TO COMMUNITY; Parkland stands out at national summit; Chuck Shepherd\u27s News of Weird; My Beautiful Dark Twisted Fantasy raises a toast to the jerks, Kanye included; Tony Noel Diesel Technology addition up and running; Training better teachers; Better than a Gift; Just a Little Food tor Thought; Prospectus Pick: Tumblr; In this league, \u27mediocre\u27 is the new \u27good\u27; Dr. Gina Walls recognized for teaching excellence; Give the Gift of Techhttps://spark.parkland.edu/prospectus_2010/1031/thumbnail.jp

Prospectus, June 2, 2010

HERE\u27S TO THE GRADUATING CLASS OF 2010; Parkland taking steps to conserve energy, reduce costs; Starting this summer, Uncle Sam will be your banker for federal student loans; Chuck Shepherd\u27s News of the Weird; When metal comes home; Events you need to check out this summer; Meteorologist\u27s star is rising in climate change maelstrom; Is it technology or is it magic?; You can inhale now; Students in action a volunteer army—ready to serve; Parkland Art Gallery summer exhibitions; Stanford University prepares for \u27bookless library\u27; The CSIT department and what it can do for you; Before it was a perfect game, it was unique\u27; Parkland Commencementhttps://spark.parkland.edu/prospectus_2010/1015/thumbnail.jp

Prospectus, June 23, 2010

A PROSPECTUS GUIDE TO CAMPING; Parents deported, he pushed on and won a full college scholarship; Chuck Shepherd’s News of the Weird; Mainstream came a knocking; A tribute to Krist Novoselic; Green graduation: Many campuses are adopting environmentally friendly garb; Human Figure portrait exhibit; Making college sports clean again; Working-class fathers are suffering amid a ‘mancession’; Burned by the sunscreen chemicals; Summer common sense: Things you need to know to survive the summer; Prospectus Pick: A Crepe to die for; Cobras earn recognition and awards for outstanding spring; Parkland Master Plan Underway; Deepening disasterhttps://spark.parkland.edu/prospectus_2010/1016/thumbnail.jp

Prospectus, October 28, 2009

https://spark.parkland.edu/prospectus_2009/1029/thumbnail.jp

Time reversal symmetry breaking superconductivity

We study time reversal symmetry breaking superconductivity with $\Delta_k = \Delta_{x^2-y^2} (k) +e^{i\theta} \Delta_{\alpha}$ ($\alpha = s$ or $d_{xy}$) symmetries. It is shown that the behavior of such superconductors could be {\em qualitatively} different depending on the minor components ($\alpha$) and its phase at lower temperatures. It is argued that such {\em qualitatively different} behaviors in thermal as well as in angular dependencies could be a {\em source} of consequences in transport and Josephson physics. Orthorhombicity is found to be a strong mechanism for mixed phase (in case of $\alpha = s$). We show that due to electron correlation the order parameter is more like a pure $d_{x^2-y^2}$ symmetry near optimum doping.Comment: 5 pages, 5 figures (attached), to be published in Physical Review

Prospectus, May 27, 2009

https://spark.parkland.edu/prospectus_2009/1015/thumbnail.jp

Prospectus, March 31, 2010 - April Fool\u27s Edition

BIG NEW THINGS TO HAPPEN AT PARKLAND; Parkland announces new classes, future aquarium; Parkland hires all-star processor to teach new course; Metered spaces now a sure bet for Parkland; Chuck Shepherd\u27s News of the Weird; music downloads; In keeping April showers and May flowers green; The benefits of being illiterate; Prospectus Pick: Laser Cats; New sports on the way for Parkland; Students and faculty gear up for unofficial ; 2010 Staff Excellence Awards; April Fool\u27s Pranks!https://spark.parkland.edu/prospectus_2010/1010/thumbnail.jp