Temperature, energy metabolism, and adaptive divergence in two oyster subspecies

Abstract

Comparisons of related species that have diverse spatial distributions provide an efficient way to investigate adaptive evolution in face of increasing global warming. The oyster subjected to high environmental selections is a model species as sessile marine invertebrate. This study aimed to detect the adaptive divergence of energy metabolism in two oyster subspecies from the genus Crassostrea—C. gigas gigas and C. gigas angulata—which are broadly distributed along the northern and southern coasts of China, respectively. We examined the effects of acute thermal stress on energy metabolism in two oyster subspecies after being common gardened for one generation in identical conditions. Thermal responses were assessed by incorporating physiological, molecular, and genomic approaches. Southern oysters exhibited higher fluctuations in metabolic rate, activities of key energetic enzymes, and levels of thermally induced gene expression than northern oysters. For genes involved in energy metabolism, the former displayed higher basal levels of gene expression and a more pronounced downregulation of thermally induced expression, while the later exhibited lower basal levels and a less pronounced downregulation of gene expression. Contrary expression pattern was observed in oxidative stress gene. Besides, energy metabolic tradeoffs were detected in both subspecies. Furthermore, the genetic divergence of a nonsynonymous SNP (SOD‐132) and five synonymous SNPs in other genes was identified and validated in these two subspecies, which possibly affects downstream functions and explains the aforementioned phenotypic variations. Our study demonstrates that differentiations in energy metabolism underlie the plasticity of adaptive divergence in two oyster subspecies and suggest C. gigas angulata with moderate phenotypic plasticity has higher adaptive potential to cope with exacerbated global warming.

Restoring ancestral phenotypes by reduction of plasticity is a general pattern in gene expression during adaptation to different stressors in Tribolium castaneum

“…Studies found support for this hypothesis by showing that plastic responses of non-adapted individuals diminished differences to native populations (Lohman, Stutz, & Bolnick, 2017; Mäkinen, Papakostas, Vøllestad, Leder, & Primmer, 2016). Adaptive plasticity can also be indicated when plastic and evolutionary responses are in the same direction (Li, Li, Song, Wang, & Zhang, 2017), or when plasticity is higher in adapted populations (Hasan et al, 2017; McCairns & Bernatchez, 2009), suggesting that most plastic individuals were favored by selection. However, there are also examples for the reversed pattern suggesting that plasticity was maladaptive, at least on the long-term.…”

Seascape genomics of eastern oyster (Crassostrea virginica) along the Atlantic coast of Canada

“…Temperature can considerably affect oxygen consumption, energy metabolism, mitochondrial efficiency and response to hypoxia-reoxygenation, and thus ATP-related functions (Abele, Heise, Pörtner, & Puntarulo, 2002;Chamberlin, 2004;Cherkasov, Biswas, Ridings, Ringwood, & Sokolova, 2006;Ivanina et al, 2012;Sokolova, 2004). As several loci (containing nonsynonymous mutations) located within genes known to have ATP-related functions were also associated with temperature, it is possible that adaptive divergence observed in the studied system could be linked with thermal adaptation and energetic metabolism, as revealed in other Crassostrea species (Li, Li, Song, Wang, & Zhang, 2017) and other molluscs (Sokolova & Pörtner, 2001;Tomanek & Zuzow, 2010).…”

Transcriptomics and Fitness Data Reveal Adaptive Plasticity of Thermal Tolerance in Oysters Inhabiting Different Tidal Zones

“…Common garden experiments were conducted according to the methods of Li et al (2017) ( Supplementary Figure 2 ). Eggs from 30 uncontaminated mature female oysters of each population were mixed and divided into 30 replicates.…”