TY - JOUR
T1 - Insights into the genomic evolution of insects from cricket genomes
AU - Ylla, Guillem
AU - Nakamura, Taro
AU - Itoh, Takehiko
AU - Kajitani, Rei
AU - Toyoda, Atsushi
AU - Tomonari, Sayuri
AU - Bando, Tetsuya
AU - Ishimaru, Yoshiyasu
AU - Watanabe, Takahito
AU - Fuketa, Masao
AU - Matsuoka, Yuji
AU - Barnett, Austen A.
AU - Noji, Sumihare
AU - Mito, Taro
AU - Extavour, Cassandra G.
N1 - Funding Information:
This work was supported by Harvard University and MEXT KAKENHI (No. 221S0002; 26292176; and 17H03945). The computational infrastructure in the cloud used for the genome analysis was funded by AWS Cloud Credits for Research. The authors are grateful to Hiroo Saihara for his support in the management of a genome data server at Tokushima University.
Publisher Copyright:
© 2021, The Author(s).
PY - 2021/12
Y1 - 2021/12
N2 - Most of our knowledge of insect genomes comes from Holometabolous species, which undergo complete metamorphosis and have genomes typically under 2 Gb with little signs of DNA methylation. In contrast, Hemimetabolous insects undergo the presumed ancestral process of incomplete metamorphosis, and have larger genomes with high levels of DNA methylation. Hemimetabolous species from the Orthopteran order (grasshoppers and crickets) have some of the largest known insect genomes. What drives the evolution of these unusual insect genome sizes, remains unknown. Here we report the sequencing, assembly and annotation of the 1.66-Gb genome of the Mediterranean field cricket Gryllus bimaculatus, and the annotation of the 1.60-Gb genome of the Hawaiian cricket Laupala kohalensis. We compare these two cricket genomes with those of 14 additional insects and find evidence that hemimetabolous genomes expanded due to transposable element activity. Based on the ratio of observed to expected CpG sites, we find higher conservation and stronger purifying selection of methylated genes than non-methylated genes. Finally, our analysis suggests an expansion of the pickpocket class V gene family in crickets, which we speculate might play a role in the evolution of cricket courtship, including their characteristic chirping.
AB - Most of our knowledge of insect genomes comes from Holometabolous species, which undergo complete metamorphosis and have genomes typically under 2 Gb with little signs of DNA methylation. In contrast, Hemimetabolous insects undergo the presumed ancestral process of incomplete metamorphosis, and have larger genomes with high levels of DNA methylation. Hemimetabolous species from the Orthopteran order (grasshoppers and crickets) have some of the largest known insect genomes. What drives the evolution of these unusual insect genome sizes, remains unknown. Here we report the sequencing, assembly and annotation of the 1.66-Gb genome of the Mediterranean field cricket Gryllus bimaculatus, and the annotation of the 1.60-Gb genome of the Hawaiian cricket Laupala kohalensis. We compare these two cricket genomes with those of 14 additional insects and find evidence that hemimetabolous genomes expanded due to transposable element activity. Based on the ratio of observed to expected CpG sites, we find higher conservation and stronger purifying selection of methylated genes than non-methylated genes. Finally, our analysis suggests an expansion of the pickpocket class V gene family in crickets, which we speculate might play a role in the evolution of cricket courtship, including their characteristic chirping.
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U2 - 10.1038/s42003-021-02197-9
DO - 10.1038/s42003-021-02197-9
M3 - Article
C2 - 34127782
AN - SCOPUS:85107957355
VL - 4
JO - Communications Biology
JF - Communications Biology
SN - 2399-3642
IS - 1
M1 - 733
ER -