Jan Hrcek (@janhrcek)

Infection, Immunity & Microbionts SIG 📅 Join us on 16-17 April for: 🔬 Day 1: Symbionts & Microbiomes 🦠 Day 2: Pathogens & Immunity

Researchers working on insect infection, immunity and microbionts are invited to share their work at the upcoming two-day Infection, Immunity & Microbionts Special Interest Group Meeting at @uniofbath.bsky.social.

📅 16-17 April
📄 Abstracts Deadline: 17:00 (GMT), Friday 13 March 🔽

09.03.2026 14:00 👍 2 🔁 3 💬 0 📌 0

Phenotypic divergence is driven by mobile genetic elements in a heritable insect symbiont Heritable microbes profoundly influence insect biology, yet the traits they confer often evolve rapidly and differ among closely related symbiont strains. Despite their importance, we lack a clear understanding of how novel traits arise in symbiosis and how this diversity influences host ecology in natural populations. The aphid facultative symbiont Regiella insecticola is ideally suited to this question because of its strong lineage-specific variation in host benefits. By generating 20 high-quality genomes, we found that Regiella ’s evolution is driven largely by gene gains mediated by mobile genetic elements. We identified a plasmid (pRILSR1) that encodes a type IV secretion system and a highly expressed predicted effector that has been convergently acquired by Regiella strains from pea aphids. Notably, only pRILSR1-bearing strains confer protection against the specialist fungal pathogen Pandora neoaphidis , indicating that gains and losses of the plasmid underlie the evolution of this key defensive phenotype. Using a multi-year field study, we further show that the pRILSR1 plasmid is strongly associated with Regiella found in pea aphid populations adapted to specific host plants, driving variation in symbiont-mediated defense across populations. Together, our results show that mobile genetic elements generate key adaptive traits in microbial symbionts and, in doing so, drive phenotypic divergence among host populations. ### Competing Interest Statement The authors have declared no competing interest.

New preprint! Symbionts provide critical functions—but how do they impact host phenotypes in nature? We show a horizontally transferred plasmid in a heritable symbiont drives divergence in defensive traits across insect populations, revealing how mobile DNA rapidly shapes pathogen resistance. 👇

28.01.2026 15:41 👍 7 🔁 4 💬 0 📌 0

Warming weakens natural enemies of insects. We found that higher temperatures strongly reduce the success of parasitoids – tiny wasps that help regulate insect populations in nature - and narrows their diet. Published in Ecology Letters dx.doi.org/10.1111/ele....

28.01.2026 09:59 👍 28 🔁 18 💬 0 📌 1

FoS - Přírodovědecká fakulta JU FoS - Přírodovědecká fakulta JU

PhD position available at the Czech Academy of Sciences for researching butterfly evolution at high elevations. Apply by Jan 11, 2026. More info: https://www.prf.jcu.cz/en. Email: pavel.matos@entu.cas.cz. #phd

01.12.2025 13:38 👍 2 🔁 2 💬 0 📌 0

Hrcek lab Hrcek lab

PhD Studentship available in eco-evolutionary dynamics at the Biology Centre, Czech Academy of Sciences. Apply by January 7, 2026. Details: http://lab.hrcek.net. Contact Jan Hrcek: janhrcek@gmail.com. #phd

25.11.2025 20:23 👍 2 🔁 2 💬 0 📌 0

Ilustration of evolution in ecological communities, feuturing Drosophila

PhD-position vacancy in Jan Hrcek's lab lab.hrcek.net, Czech Academy of Sciences: Exploring how rapid evolution in communities allows maintenance of genetic variation and species diversity. @erc.europa.eu 🪰 🧬 🌏 🧪Application deadline: January 7th 2026

25.11.2025 12:41 👍 24 🔁 18 💬 0 📌 0

Jan Hrcek

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