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rachelmoran.bsky.social
Rachel Moran
@rachelmoran.bsky.social
1.6K followers 1.4K following 28 posts
Assistant Professor in Ecology & Evolution at UChicago. Evolutionary genomics and behavior in fishes. (she/her)
https://rachelmoranlab.com
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rachelmoran.bsky.social
Thanks, Sara!
October 13, 2025 at 8:02 PM
rachelmoran.bsky.social
New sex determining regions can trap or release nuclear-encoded mitochondrial genes, creating pulses of hybrid breakdown and leaving genomic scars.
Broadly, this raises the possibility that speciation may follow predictable patterns shaped by inheritance asymmetries and genomic conflict.
Schematic chromosomes illustrate two genomic contexts for nuclear-encoded mitochondrial (N-mt) genes (orange). (A) N-mt genes within autosomal or pseudo-autosomal regions recombine freely and can track mitochondrial evolution, minimizing mitonuclear conflict. (B) Local capture of N-mt genes in a non- recombining sex-linked stratum (purple) constrains compensatory evolution, intensifying mitonuclear conflict (lightning bolts) and often generating heterogametic-biased hybrid breakdown. Conceptual timeline showing how cycles of sex-chromosome turnover modulate the intensity of mitonuclear conflict through time. Conflict is low under the ancestral sex-determining region (SDR). When a turnover event establishes a new SDR that captures an N-mt locus, conflict is amplified (upslope) as compensatory evolution is constrained in the non-recombining stratum. A subsequent turnover that frees that locus from the SDR relieves conflict (downslope). If a later turnover again captures a different N-mt locus, conflict rises anew. These repeated amplification-then-relief cycles predict pulses of hybrid incompatibility and leave alternating genomic “scars” of reduced introgression at formerly sex-linked regions.
October 10, 2025 at 3:54 PM