Genome expression balance in a triploid trihybrid vertebrate

As polyploidy is increasingly recognized as a driver of biological diversity, understanding the impact of polyploidization on patterns of gene expression has become important to understand. While plant polyploidy has received considerable attention, how animals respond to and manage polyploidy events remain almost entirely uncharacterized. Here, we address this important knowledge gap by generating transcriptomes from a triploid hybrid animal, a unisexual Ambystoma salamander, and three sexual Ambystoma species that represent all three parental genomes in the unisexual. Our comparisons of gene expression levels across the three parental genomes revealed that the unisexual triploid displays a distinct pattern of genome balance, where 72% of the genes analyzed were expressed equally among the subgenomes, strikingly different from the genome imbalance typically observed in hybrid polyploid plants. This work provides the first analysis of gene expression in a triploid hybrid animal and introduces a novel bioinformatic framework for analyzing transcriptomic data.