c01

The role of niche construction and evolutionary capacitance for evolvability in the red flour beetle, Tribolium castaneum

Joachim Kurtz

Individual differences in niche construction activity contribute to the individualised niche and thus the selection imposed by this environment. Such selection acts on the niche constructors and also group members sharing the niche. This project explores how the individual immune experience of priming and wounding influences niche construction in a gregariously living insect, the red flour beetle Tribolium castaneum. Here, niche construction is achieved via stink gland secretions, which improve the microbiota of the flour inhabited by this species. We asked how information regarding individual immune experience is transferred to group members, and found strong effects of both, priming and wounding, on cuticular hydrocarbons (CHCs), which serve as important infochemicals in insects. To test whether niche construction improves adaptability, we experimentally impaired stink gland secretion in experimental evolution lines for adaptation to the entomopathogen Bacillus thuringiensis. In T. castaneum, individual immune experience is also closely connected to evolutionary capacitance via heat-shock protein 90 (HSP90), and experimental reduction of HSP90 repeatedly led to assimilation of a ‘reduced eye’ phenotype. We therefore studied the genetic basis of this phenotype, which appeared to be based on a single recessive locus with potential additional epigenetic modification. In the second phase of this CRC, we will make use of our experimentally evolved lines and these ‘reduced eye’ lines, to test for (epi-) genetic underpinnings that mediate differences in adaptation processes under niche construction and evolutionary capacitance. For this, we will expand our toolset for functional genetic analyses (CRISPR-Cas9) and epigenetics (ChIP-seq, ATAC-seq). We will also more deeply investigate the communication of individual immune status via CHCs with bioassays, and we will include another potentially HSP90-regulated phenotype: diurnal rhythmicity, which is relevant for temporal niche adaptation. Taken together, our project will experimentally test the influence of individualisation on two intensively debated, interconnected ways to enhance adaptability, niche construction and evolutionary capacitance.