Long-read genome assemblies for the study of chromosome size expansion: Drosophila kikkawai, Drosophila takahashii, Drosophila bipectinata, and Drosophila ananassae

Known genome sizes among species of Drosophila show a 3-fold variation, ranging from ~135 Mb in Drosophila busckii to ~400 Mb in Chymomyza amoena. However, the assembled portion of the Muller F Element (orthologous to the fourth chromosome in Drosophila melanogaster) that contains protein-coding genes shows a nearly 14-fold variation in size, ranging from ~1.3 Mb to > 18 Mb. Here, we present chromosome-level long read genome assemblies for four Drosophila species with expanded F Elements ranging in size from 2.3 Mb to 20.5 Mb. Each Muller Element is present as a single scaffold in each assembly. These assemblies will enable new insights into the evolutionary causes and consequences of chromosome size expansion.