Thanks!!!!

Thirty days of evolution… totally worth it! 🥹

Huge thanks to all the authors behind this paper 🙌

@nachodequinto.bsky.social, Laura Jaraba-Soto, Val F.Lanza, @crisherencias.bsky.social, Adrián González Casanova, @penamiller.bsky.social, and @jerorb.bsky.social

So excited to see it finally out! 🥳

In summary, plasmids are not just gene delivery platforms.

They significantly boost the availability of mutations, enabling rapid evolution of traits like resistance, metabolism, and virulence, highlighting their role as evolutionary powerhouses of bacterial cells.

PCN is key to evolvability 🫧🤩

Do natural plasmids show the same results?

We analyzed 1,598 plasmids (NCBI) 💻 to detect mutations arising during culture growth by comparing sequencing reads to consensus assemblies.

High-copy plasmids exhibited significantly higher mutation rates, just like theory (and experiments!) predicted!

Experiments confirm it: plasmid mutation rate rises logarithmically with copy number 🚀

At more copies, mutation supply dominates drift! 💥

We conducted a mutation accumulation experiment to test our predictions using a plasmid with a tunable copy number 🫧

We established three PCN conditions: low (~1), medium (~10), and high (~60 copies). Lines were evolved for 30 days under severe bottlenecks.

We modelled plasmid inheritance using a Cannings model and validated it with computational simulations 🧫 Each plasmid copy is like an evolutionary unit, randomly split at division, then copied.

Prediction: the mutation rate rises with PCN, but with diminishing returns, increasing logarithmically.

Plasmids face opposing evolutionary forces:

🔹 More copies = more chances to mutate 📈
🔹 But random segregation = drift, purging mutations 📉

So mutation supply ↑ with PCN, but the probability of fixation ↓

Which force dominates: the boost in mutation rate or the loss from segregational drift?