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.

果蝇属（Drosophila）各物种的已知基因组大小存在3倍的变异范围，从布氏果蝇（Drosophila busckii）的约135 Mb，到嗜湿酪蝇（Chymomyza amoena）的约400 Mb不等。然而，携带蛋白编码基因的穆勒F元件（Muller F Element，与黑腹果蝇Drosophila melanogaster的四号染色体同源）的组装区域，其大小呈现近14倍的变异，范围从约1.3 Mb直至超过18 Mb。本研究报道了4个携带扩增型F元件的果蝇属物种的染色体级长读长基因组组装（chromosome-level long read genome assemblies）结果，这些物种的F元件大小介于2.3 Mb至20.5 Mb之间。在每份组装结果中，每条穆勒元件均以单一支架序列（scaffold）的形式存在。上述组装结果将为解析染色体大小扩增的进化成因与进化后果提供全新的研究视角。