What does Arabidopsis polymorphism look like genome-wide?

A. thaliana shows clear global population structure and isolation by distance; demography can mimic selection in standard tests.

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What global pattern of variation did they find?

Clear global population structure.

What geographic pattern emerges?

Isolation by distance.

Is selfing A. thaliana a collection of asexual ecotypes?

No—that view is completely false.

How does polymorphism compare?

Somewhat lower than Drosophila, considerably higher than humans—not unusually low.

Why can demography confuse selection scans?

Structure and growth can make genome-wide variation deviate from neutral models in ways that mimic selection.

What clustering tool was used?

STRUCTURE on genotypes.

Sampling design included?

Hierarchical population samples plus worldwide stock-center accessions.

Marker density claim?

Orders of magnitude more markers than prior studies.

Are local populations usually single inbred sibships?

Typically not—most sampled populations were polymorphic.

Teaching point?

Know demography before claiming selection from polymorphism patterns.

Species?

Arabidopsis thaliana.