4.3 Desiccation-adaptive mechanisms of C. japonica
Comparative genomics can provide insights into the unique adaptive plasticity of marine species (Han et al., 2021; Xu et al., 2021). In the present study, we hypothesized the adaptive mechanisms of desiccation tolerance based on comparative genomics. Previous studies suggested that crustaceans may continuously undergo the double stress of dehydration and hypoxia in a drought environment. Specifically, desiccation disrupts the internal osmotic pressure and metabolic capacity of crustaceans (Haupt et al., 2006; Carlson and Rowe, 2009). Moreover, desiccation can reduce the oxygen-binding ability of hemoglobin and result in hypoxic stress in crustaceans (Omori et al., 1998; Allen et al., 2012). The prolonged disruption of the respiratory mechanism may further impair the immune function of crustaceans and eventually lead to death (Madenjian et al., 1987). Additionally, the activity of the antioxidant enzyme system directly determines the desiccation tolerance of crustaceans (Jiang et al., 2014). Based on the annotation information, the desiccation-adaptive mechanisms ofC. japonica was supported by the marked expansion of gene families or the positive selection of genes related to metabolism rate, oxygen supply, oxidative stress, and various transporters.