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Arbel Harpak
Population geneticist. fellow at Columbia University working with .
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Arbel Harpak retweeted
QinQin Yu 3h
1/7 Mutations can affect fitness, but can they also affect genetic drift/demographic noise? To find out, we developed a new method to assess genetic drift in hundreds of E. coli colonies.
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Arbel Harpak 5h
Replying to @arbelharpak
Yes, we have a couple of other pressing issues right now; but in this era of Zoom et al., has anyone solved the problem of voice confrontation (cringing at the sound of one's own recorded voice) yet??
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Arbel Harpak 5h
During a fun "visit" I gave a seminar about "Interpreting signals of polygenic adaptation in humans".
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Arbel Harpak 24h
. et al. measure the mutability of genetic drift (in microbial range expansions): Single gene deletions can alter the establishment probability of subsequent mutations by almost an order of magnitude
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Arbel Harpak retweeted
Vagheesh Narasimhan Oct 27
Multiple postdoc positions in my group () to work on human medical and population genomics. Come join us in sunny Austin - send me an email/DM!
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Arbel Harpak retweeted
Molly Przeworski Oct 21
I am looking to hire a postdoc at Columbia U., for a project modeling mutation processes. Applicants must have a strong quantitative background (in theoretical pop. gen., statistics or applied math/physics). Starting date flexible. If interested, email me. Grateful for RT.
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Arbel Harpak retweeted
Molly Przeworski Oct 8
Very much appreciated, and also a good opportunity to point out long-standing efforts in this direction by , , , and other colleagues
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Arbel Harpak Oct 8
Replying to @rasmansa @ShaiCarmi
I agree. We make both of these points in our preprint, but tl;dred it nicely
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Arbel Harpak Oct 8
Replying to @CharlestonCWKC
Perhaps my wording is confusing, but it simply means that if the relationship between height and fitness remained the same then, by definition, being 190cm tall confers to the same fitness as before
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Arbel Harpak Oct 7
Replying to @arbelharpak
Takeaway: We should expect some genetic differences between groups of different genetic ancestries, but in themselves they tell us nothing about trait differences--not without making all kinds of strong assumptions about environments, past and present.
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Arbel Harpak Oct 7
Replying to @arbelharpak
So evidence for adaptation in genetic data may point to a shift in the trait optimum, but it need not--it could simply reflect shifting environmental effects.
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Arbel Harpak Oct 7
Replying to @arbelharpak
For example, a group’s mean “genetic height” may increase not because taller people are now fitter than before, but to compensate for a shift towards poorer nutrition.
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Arbel Harpak Oct 7
Replying to @arbelharpak
As we highlight, genetic differences can arise even when the trait optimum has not changed. Under stabilizing selection, a shift in environmental effects can lead to rapid genetic change (polygenic adaptation), **even when the optimal trait value remains the same**.
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Arbel Harpak Oct 7
Replying to @arbelharpak
Mean trait differences cannot be ascribed to genetic differences without knowing a great deal about salient environmental effects. (This is true even in the absence of gene by environment interactions, let alone with them.)
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Arbel Harpak Oct 7
Replying to @arbelharpak
But a second, fundamental point is often missing from the discussion: While some genetic differences are expected, nothing follows from that about trait differences.
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Arbel Harpak Oct 7
Replying to @arbelharpak
A long-standing response to these arguments, focused on the first assertion, has been to point out that the genetic differences among genetic ancestry groups are expected to be small, particularly much smaller than the extent of variation within a group.
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Arbel Harpak Oct 7
Replying to @arbelharpak
Racialized arguments rely on the notion that there are important genetic differences among groups and that trait differences must necessarily follow.
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Arbel Harpak Oct 7
Replying to @arbelharpak
For that reason, it can be important to clarify what the science says--and more importantly what it does not say--even when the science isn’t ultimately the point.
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Arbel Harpak Oct 7
Replying to @arbelharpak
Population geneticists are interested in understanding the forces that shape the evolution of human complex traits and lead to heritable differences over time and across the globe. But findings in this area are often distorted to provide support for racist views.
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Arbel Harpak Oct 7
. & I wrote about how many complex traits may evolve under selection to maintain trait values in the face of changing environments. This scenario has implications for interpreting genetic signals of adaptation and combating racist arguments.
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