Exploring the missing link between traits and the genome: a full-genome gene expression approach to understand the molecular underpinning of anti-predator strategies in the water flea Daphnia.

Rapid evolutionary adaptation to environmental change is common in natural populations. Identifying the genetic underpinning of adaptation is a key challenge in evolutionary biology. Fish predation is an important stressor for natural populations of the water flea Daphnia. We will study evolutionary changes under predation risk at the gene expression level. A unique set of 36 D. magna clones representing three time frames of a natural population that genetically adapted to a well-documented change in fish predation pressure will be used (Cousyn et al. 2001). This clonal set has been characterized for genotypic values at 16 life history, behavioural and biochemical traits as well as for >150 molecular markers. We will use RNAseq and full-genome microarrays to study how genetic adaptation to fish predation is mediated by differences in gene expression. Our results will allow establishing a direct link between one of the most detailed studies on genetic changes in trait values in a natural population and changes at the genome level, further strengthened by an ongoing study of genome variation among these clones using a newly developed D. magna SNP microarray (>5000 SNPs; STRESSFLEA project). The approach to study gene expression is especially important as it captures both changes in target genes and in gene regulation and allows studying the mechanistic underpinning of adaptation through genetic changes in phenotypic plasticity, an important mechanism of adaptation to environmental change in Daphnia.

Keywords:Fish predation, Gene expression, RNA seq, Daphnia magna

Disciplines:Ecology, Environmental science and management, Other environmental sciences