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bioRxiv · 10.64898/2025.12.28.696746

Evolutionary persistence and divergence of the tdk killer meiotic driver family

Zhang, F.-Y.·Jia, G.-S.·Ren, J.-Y.·Suo, F.·Du, T.-Y.·Zhang, W.-C.·Li, W.·Wang, Q.-M.·Du, L.-L.·Hua, Y.
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Abstract

Killer meiotic drivers (KMDs) are selfish genetic elements that achieve super-Mendelian inheritance by selectively eliminating gametes lacking the driver. Although predicted to arise recurrently, KMDs are generally considered evolutionarily ephemeral--going extinct after fixation or host suppression. The identification of tdk1, a single-gene KMD in the fission yeast Schizosaccharomyces pombe, provides a model for studying KMD evolution. Here, we identify two divergent tdk1 homologs (tdk210 and tdk203) from S. cryophilus, a fission yeast species that diverged [~]100 million years ago from S. pombe, as active KMDs. These three KMDs all act via post-germination killing, disrupting chromosome segregation in noncarrier progeny. Notably, they also exhibit striking functional divergences: tdk1, tdk210, and tdk203 are mutually incompatible (showing no cross-resistance), and the latter two act independently of Bdf1/Bdf2--host chromatin proteins required for tdk1 killing. Phylogenetic analyses of the dozens of tdk family genes in Schizosaccharomyces support long-term persistence and rapid evolutionary dynamics of this gene family. Remarkably, homologs in distantly related fungal phyla display genomic and structural similarities to Schizosaccharomyces tdk genes, suggesting a deeply rooted origin of this KMD family in fungi. Our findings reveal that a single KMD family can undergo repeated functional innovation--generating mutually incompatible variants and rewiring host dependencies--while maintaining a conserved killing mode over deep evolutionary time.

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Zhang, F.-Y., Jia, G.-S., Ren, J.-Y., Suo, F., Du, T.-Y., Zhang, W.-C., Li, W., Wang, Q.-M., Du, L.-L., Hua, Y.. 2025-12-29. Evolutionary persistence and divergence of the tdk killer meiotic driver family. https://doi.org/10.64898/2025.12.28.696746

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