Juan L. Cantalapiedra

🧵🪸📖 1/ A brief thread to one of the most useful metaphors in evolutionary biology [Galton’s polyhedron] using quotes from chapter 5 of Gould’s “The Structure of Evolutionary Theory” #evolution

A new mechanism for “RNA memory”! 😱 Thrilled to share another crazy paper from the lab (can’t believe we posted 2 in 2 days!), summarizing >10 years of research: Work on transgenerational inheritance of small RNAs in the powerful model organism C. elegans changed how we think about what’s possible in inheritance and evolution, because it allows the most heretical thing: inheritance of parental responses to the environment! However, it’s still unclear whether RNAs are inherited across generations in other animals, largely because the RNA-dependent RNA polymerases that amplify heritable small RNAs and prevent their dilution in C. elegans are not conserved in mammals. In this new work, an amazing collaboration with the Rink and Wurtzel labs, we show that planarians establish long-lasting and heritable small RNA–based gene regulatory states despite lacking canonical RNA-dependent RNA polymerases and nuclear RNAi machinery (that are required in C. elegans). You might say “they are both worms…” BUT planarians are evolutionarily very distant from C. elegans (flatworms vs. roundworms, diverged more than 500 million years ago), making this particularly surprising. These are totally different animals. We find that ingestion of double-stranded RNA induces sequence-specific silencing that persists for months and survives repeated cycles of whole-body regeneration. Even more strikingly, RNAi can be transferred between animals, echoing James V. McConnell’s controversial “RNA memory” experiments from the 1970s (his lab was targeted by the Unabomber terrorist Ted Kaczynski, who sent McConnell a bomb. This and other controversies ended this line of experiments…) Mechanistically, we find that the response transitions from a transient systemic dsRNA-triggered phase to a stable, cell-autonomous post-transcriptional “memory phase” maintained by antisense small RNAs. Using a new luminescence reporter (transgenesis is currently impossible in planarians), we show that silencing spreads along the targeted gene and identify a weird type of planarian small RNAs with untemplated polyA tails. RNAi inheritance without canonical RdRPs establishes planarians as a powerful system for studying RNA-based regulatory inheritance beyond C. elegans and raises the possibility that RNA-mediated inheritance may be more broadly conserved in animals, potentially even in mammals. Here’s a video of a planarian that is treated by RNAi against β-catenin and develops multiple heads instead of just one. This is one of the phenotypes that is inherited. Another phenotype is “loss of eyes” (which we show is not only inherited across multiple regeneration cycles, but can also be transmitted between animals in transplantation experiments). Amazing work led by first authors Prakash Cherian and Idit Aviram (co-supervised by Omri and me). Please read the preprint, the link is in the next tweet, and share!

El próximo martes 3 de marzo en el MARPA os cuento mis métodos de reconstrucción y novedades sobre la apariencia y paleobiología de los félidos de dientes de sable. ¡Nos vemos a las 19h en Alcalá de Henares!

Bienvenido Gorgonavis!! First longirostrine enantiornithine from outside of China. Paper here: sjp.pensoft.net/article/182813/

@ignacioqevo @TransmitScience Julia! youtu.be/A0HFtcCRVNc?si…

Want to learn the ins and outs of diversification, trait and biogeographic evolution models? I will be giving another edition of "Dive Deep into Probabilistic Phylogenetic Comparative Methods" in Oct! @TransmitScience transmittingscience.com/courses/evolut…

¿Por qué hay tantas especies de ardillas y por qué no están repartidas de forma uniforme por el planeta? ucm.es/especies-ardil… sobre doi.org/10.1111/jbi.70…

Biome specialisation in squirrels: Phylogenetic and geographic patterns doi.org/10.1111/jbi.70… by @PALEOiris et al.

Our new paper is online in @CurrentBiology! We found that; 1) today's sharks & ray diversity was already reached ~100Ma; 2) that the K/Pg extinction was not catastrophic; 3) that the max diversity was reached ~50Ma; and 4) that today's diversity is depleted compared to the past.

Do not miss this course by @singerstone at @TransmitScience 👇

Last Thursday I shared some of our recent projects in the Palaeoverse channel, exploring phylogenetic methods and the exciting new wave of Bayesian diversification models. #paleobiology #paleontology #macroevolution youtu.be/vd-E4E6iFNg?si…

@niles_eldredge @ignacioqevo @AndrejSpiridon4 @CoelhoPre @Trilolight 👀

Yes, the rejoinder. Looking forward to the next generation of trait analysis on phylogenetic trees. @ignacioqevo @AndrejSpiridon4 @singerstone @CoelhoPre @Trilolight

Celebrate #fossilfriday by checking out this profile of @valdosaurus on the BBC. The medical doctor who's now putting his anatomy knowledge to use studying dinosaurs!! bbc.co.uk/news/articles/…

Biological accommodation of climatic variability is a first order factor enabling success of species. An excellent study of temperature niche breadth and geographical ranges of terrestrial plants. doi.org/10.1073/pnas.2… cc: @svalver @niles_eldredge

We keep on exploring fossils in the making! This time we analyzed bone weathering at a Mediterranean ecosystem. Where? At Doñana NP, a great natural laboratory for taphonomy! doi:10.1371/journal.pone.0335508

New bird paper led by the brilliant and talented Andrew Orkney! 🦆 We show that more parental care is associated with more evolutionary freedom in how birds fly.🕊️ royalsocietypublishing.org/doi/10.1098/rs…

Benson, R.B.J., Walsh, S.A., Griffiths, E.F. et al. Mosaic anatomy in an early fossil squamate. Nature (2025). doi.org/10.1038/s41586…

@johnhawks I see. Would a total-evidence approach with morphology help? Someone should try!

That's a great question. My impression of the analysis is that the actual tree makes little sense. As an example, Penghu, Denisova, and Xujiayao are rendered as sisters with a trichotomy connecting them. But Penghu and Denisova samples share literally zero characters! I don't see how morphological evidence can connect them at all. Xujiayao has very little to connect it to either.

Could there be a connection between a squashed million-year-old skull and the Denisovans? I look at whether a provocative new study can be squared with what we already know from ancient genomes. I think there's a way. johnhawks.net/p/the-problem-…

Iberian harvester ants are the only known organism that propagates two species by itself, according to new research. Learn more: scim.ag/463AjWb @NewsfromScience