Evolutionary convergence of sensory circuits in the pallium of amniotes

The amniote pallium contains sensory circuits structurally and functionally equivalent, yet their evolutionary relationshipremains unresolved. Our study employs birthdating analysis, single-cell RNA and spatial transcriptomics, and mathematical modeling to compare the development and evolution of known pallial circuits across birds (chick), lizards (gecko)and mammals (mouse). Wereveal that neurons within these circuits' stations are generated at varying developmental times and brain regions across species, and foundan early developmental divergence in the transcriptomic progression of glutamatergic neurons. Together, weshow divergent developmental and evolutionary trajectories in the pallial cell types of sauropsids and mammals. Our research highlights significant differences in circuit construction rules among species and pallial regions. Interestingly, despite these developmental distinctions, the sensory circuits in birds and mammals appear functionally similar, which suggestthe convergence ofhigh-order sensoryprocessing across amniote lineages. Overall design: Single cell RNA sequencing of birthdated cells from chicken and mouse were obtained by Birth-seq protocol (Rueda-Alaña et al, 2023). Birthdated cells with fluorescence EdU were FAC-Sorted and then droplet captured with 10X Genomics Chronium V3 pipeline. Libraries were sequenced with Novaseq 6000 for 50000 reads.