Sasha (Alexandra) Khristich
@khristich.bsky.social
postdoc at the Petrov lab at Stanford studying evolution & evolvability
Pinned
Adaptive evolution can overwrite initial natural fitness variation only in highest-fitness yeast isolates
The fitness of an organism determines its likelihood of succeeding in short-term competition, but many other factors can influence its long-term success. In this study, we investigate the relative con...
www.biorxiv.org
I’m excited to share our preprint with @oliviamghosh.bsky.social, where we explore what it takes to ‘win’ in long-term evolutionary competition: www.biorxiv.org/content/10.1...
Reposted by Sasha (Alexandra) Khristich
New Perspective w/ @petrovadmitri.bsky.social and Paul Schmidt! We ask what evolution-in-action studies tell us about an old question: what genetic variation matters for fitness, and what maintains it? ecoevorxiv.org/repository/v...
Common, consequential, and actively maintained: a neo-balance view of genetic variation
ecoevorxiv.org
October 1, 2026 at 6:28 PM
New Perspective w/ @petrovadmitri.bsky.social and Paul Schmidt! We ask what evolution-in-action studies tell us about an old question: what genetic variation matters for fitness, and what maintains it? ecoevorxiv.org/repository/v...
I’m excited to share our preprint with @oliviamghosh.bsky.social, where we explore what it takes to ‘win’ in long-term evolutionary competition: www.biorxiv.org/content/10.1...
Adaptive evolution can overwrite initial natural fitness variation only in highest-fitness yeast isolates
The fitness of an organism determines its likelihood of succeeding in short-term competition, but many other factors can influence its long-term success. In this study, we investigate the relative con...
www.biorxiv.org
September 22, 2026 at 6:34 PM
I’m excited to share our preprint with @oliviamghosh.bsky.social, where we explore what it takes to ‘win’ in long-term evolutionary competition: www.biorxiv.org/content/10.1...
Reposted by Sasha (Alexandra) Khristich
Really excited that this major work from my PhD is finally published in @plosbiology.org ! In it, we were trying to tackle a fundamental question in evolution - how do genetic mutations map onto evolutionary fitness? (1/n)
journals.plos.org/plosbiology/...
journals.plos.org/plosbiology/...
Genotype-fitness mapping of adaptive mutants reveals shifting low-dimensional structure across divergent environments
Predicting the effect of a genetic mutation on fitness is a major challenge in evolutionary biology. This study uses fitness effects of a large collection of adaptive yeast mutants in multiple lab env...
journals.plos.org
March 30, 2026 at 7:11 PM
Really excited that this major work from my PhD is finally published in @plosbiology.org ! In it, we were trying to tackle a fundamental question in evolution - how do genetic mutations map onto evolutionary fitness? (1/n)
journals.plos.org/plosbiology/...
journals.plos.org/plosbiology/...
Reposted by Sasha (Alexandra) Khristich
One of the most exciting works of my career, years in the making. We used high-throughput precision genome editing to test the fitness effects of thousands of natural variants. Our findings challenge the long-held assumption that common variants are inconsequential.
www.biorxiv.org/content/10.1...
www.biorxiv.org/content/10.1...
Massively parallel interrogation of the fitness of natural variants in ancient signaling pathways reveals pervasive local adaptation
The nature of standing genetic variation remains a central debate in population genetics, with differing perspectives on whether common variants are almost always neutral as suggested by neutral and n...
www.biorxiv.org
October 22, 2025 at 5:46 PM
One of the most exciting works of my career, years in the making. We used high-throughput precision genome editing to test the fitness effects of thousands of natural variants. Our findings challenge the long-held assumption that common variants are inconsequential.
www.biorxiv.org/content/10.1...
www.biorxiv.org/content/10.1...
Reposted by Sasha (Alexandra) Khristich
How is functional variation at large-effect loci maintained in natural populations?
Thrilled to share our work showing how beneficial dominance reversal helps fruit flies maintain a resistance polymorphism as selection varies in their environment! A thread 🧵 1/n
www.biorxiv.org/content/10.1...
Thrilled to share our work showing how beneficial dominance reversal helps fruit flies maintain a resistance polymorphism as selection varies in their environment! A thread 🧵 1/n
www.biorxiv.org/content/10.1...
Dominance reversal maintains large-effect resistance polymorphism in temporally varying environments
A central challenge in evolutionary biology is to uncover mechanisms maintaining functional genetic variation1. Theory suggests that dominance reversal, whereby alleles subject to fluctuating selectio...
www.biorxiv.org
January 22, 2025 at 7:44 PM
How is functional variation at large-effect loci maintained in natural populations?
Thrilled to share our work showing how beneficial dominance reversal helps fruit flies maintain a resistance polymorphism as selection varies in their environment! A thread 🧵 1/n
www.biorxiv.org/content/10.1...
Thrilled to share our work showing how beneficial dominance reversal helps fruit flies maintain a resistance polymorphism as selection varies in their environment! A thread 🧵 1/n
www.biorxiv.org/content/10.1...
Our paper on the role of nicks in GAA repeat expansions is out in PNAS—www.pnas.org/doi/10.1073/pnas.2413298121! Thank you so much to our anonymous reviewers, who helped us strengthen our paper and provided an example of peer review at its absolute finest.
Recurrent DNA nicks drive massive expansions of (GAA)n repeats | PNAS
Over 50 hereditary degenerative disorders are caused by expansions of short tandem
DNA repeats (STRs). (GAA)n repeat expansions are responsible for...
www.pnas.org
November 25, 2024 at 9:44 PM
Our paper on the role of nicks in GAA repeat expansions is out in PNAS—www.pnas.org/doi/10.1073/pnas.2413298121! Thank you so much to our anonymous reviewers, who helped us strengthen our paper and provided an example of peer review at its absolute finest.
Reposted by Sasha (Alexandra) Khristich
Our latest paper showing that DNA nicks drive expansions of both normal and disease-size alleles. All credit goes to a fantastic graduate student Liangzi Li as well as to a terrific team of current and former undergraduate and graduate students in the lab.
www.pnas.org/doi/10.1073/pnas.2413298121
www.pnas.org/doi/10.1073/pnas.2413298121
Recurrent DNA nicks drive massive expansions of (GAA)n repeats | PNAS
Over 50 hereditary degenerative disorders are caused by expansions of short tandem
DNA repeats (STRs). (GAA)n repeat expansions are responsible for...
www.pnas.org
November 25, 2024 at 9:08 PM
Our latest paper showing that DNA nicks drive expansions of both normal and disease-size alleles. All credit goes to a fantastic graduate student Liangzi Li as well as to a terrific team of current and former undergraduate and graduate students in the lab.
www.pnas.org/doi/10.1073/pnas.2413298121
www.pnas.org/doi/10.1073/pnas.2413298121