Daphnia similoides Raw sequence reads. Daphnia similoides

As dominant zooplankton grazers in freshwater ecosystems, cladocerans displayed phenotypic variation in tolerating cyanobacteria with an increasing gradient in eutrophication history. However, little is known on whether Daphnia reduces tolerance to Microcystis after short-term good living. From the perspective of integrative biology, the present study conducted morphology and transcriptome analysis on two different Daphnia similoides clones: clone TH09 was isolated in the spring of 2009 and then maintained in population beakers under good environment; and clone TH14 was isolated in the spring of 2014, two weeks prior to the commencement of the study. We found that the tolerance of D. similoides to cyanobacteria decreased after 5-year good living. Furthermore, transcriptomic approach revealed that five significantly enriched pathways involved with decreased penetration of toxic substance into the tissue, inhibited detoxification, dysfunction in protein folding, acceleration of cell apoptosis, and hampered alternation of cycle molting metabolic pathway. These pathways could explain at large-scale level lower phenotypic fitness to Microcystis in the Daphnia which had been cultured in the good living. Our study provides new insights in clone-dependent molecular processes involved in Microcystis-mediated phenotypic plasticity in Daphnia and, therefore, results in molecular annotation for ecological variation of phenotypic plasticity.