Genomics and Applied Biology 2024, Vol.15, No.5, 245-254 http://bioscipublisher.com/index.php/gab 250 Chen (2022) investigates the protein-coding genes (PCGs) and relative synonymous codon usage (RSCU) in six species of earwigs. Differences in sequencing completeness were noted, with A. feae having fully annotated PCGs, while D. flavicollis lacks certain genes like ND2 andCOX2. Both species primarily use standard ATN start codons, though A. feae employs special codons for ATP8 and COX3. Most PCGs terminate with standard TAN codons, except for A. feae’s ND4 and CYTB, which end with incomplete stop codons. The RSCU analysis reveals codon preference variations among species, with A. feae favoring TCT (Ser) and other species like E. metallica and D. flavicollis showing a preference for leucine codons. These findings contribute to understanding the mitochondrial gene evolution and codon bias in earwigs. 5.2 Insights into adaptive evolution from genome data Genomic data have provided valuable insights into the adaptive evolution of earwigs. The genome assembly and annotation of the European earwig, Forficula auricularia, have facilitated detailed genetic investigations, revealing a high-quality hybrid genome assembly with significant repeat elements and protein-coding genes (Bhattarai et al., 2022b). This genomic resource is instrumental in studying the molecular mechanisms underlying the ecological and physiological adaptations of earwigs. Furthermore, the de novo whole-genome sequencing and assembly of the yellow-throated bunting, although not an earwig, demonstrated the importance of adaptive genes in coping with environmental stressors, which can be paralleled in earwig studies to understand their adaptation to diverse ecological niches (Hu et al., 2022). 5.3 Convergent evolution in ecological niches Convergent evolution, where different species independently evolve similar traits, is evident in the ecological niches occupied by earwigs. The adaptation to new environments often involves complex genomic changes, as seen in the study of woody plants colonizing the land-sea interface, which identified pre-adaptive genomic features that facilitated the invasion of new habitats (Guo et al., 2022). Similarly, the genomic analysis of Sarcophaga peregrina, a species with significant ecological and medical importance, revealed expanded and positively selected genes related to its unique biological characteristics, such as ovoviviparous reproduction and carrion-feeding adaptations (Ren et al., 2020). These findings underscore the role of convergent evolution in shaping the ecological adaptations of earwigs and related species. 6 Case Study: Adaptation of a Specific Earwig Species in a Particular Environment 6.1 Selection of the case study species and environmental context For this case study, we selected the European earwig, Forficula auricularia, as the focal species. This species is widely distributed across Europe and is known for its adaptability to various environmental conditions. The European earwig is an important model organism for studies on maternal care, sexual selection, sociality, and host-parasite interactions (Bhattarai et al., 2022a). The environmental context for this study involves examining the earwig's adaptation to temperate climates, characterized by seasonal variations in temperature and humidity. 6.2 Genome analysis and ecological adaptation in the case study species The genome of Forficula auricularia has been sequenced and assembled to a high quality, providing a comprehensive resource for genetic studies. The genome assembly is 1.06 Gb in length with 31.03% GC content, consisting of 919 scaffolds with an N50 of 12.55 Mb. The genome annotation revealed 12,876 protein-coding genes and 21,031 mRNAs (Bhattarai et al., 2022a). This genomic resource allows for detailed investigations into the genetic basis of ecological adaptation. Studies on other species have shown that genomic adaptations often involve genes related to environmental interactions, such as those involved in neurobiology, development, and response to environmental stressors (Li et al., 2020; Colgan et al., 2021; Valero et al., 2021). In the case of the European earwig, similar genomic analyses can be conducted to identify candidate genes and pathways that contribute to its adaptation to temperate climates. For instance, genes involved in temperature regulation, water balance, and light response are likely to be crucial for the earwig's survival and reproduction in its environment (Li et al., 2020).
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