Glander S, He F, Schmitz G, Witten A, Telschow A, de Meaux JPlease use the format "First name initials family name" as in "Marie S. Curie, Niels H. D. Bohr, Albert Einstein, John R. R. Tolkien, Donna T. Strickland"
The selective impact of pathogen epidemics on host defenses can be strong but remains transient. By contrast, life-history shifts can durably and continuously modify the balance between costs and benefits of immunity, which arbitrates the evolution of host defenses. Their impact, however, has seldom been documented. Here, we show with a simple mathematical model how the optimal investment into defense is expected to increase with increasing lifespan. We further document that in natural populations of the model plant Arabidopsis thaliana, the expression levels of defense genes correlate positively with flowering time, a proxy for the length of lifespan. Using a novel genetic strategy based on bulk segregants, we partitioned lifespan dependent from lifespan independent defense genes and could demonstrate that this positive covariation can be genetically separated. It is therefore not explained by the pleiotropic action of some major regulatory genes controlling both defense and lifespan. Moreover, we find that defense genes containing variants reported to impact fitness in natural field conditions are among the genes whose expression covaries most strongly with flowering time. In agreement with our model, this study reveals that natural selection has likely assorted alleles promoting higher expression of defense genes with alleles that increase the duration of vegetative lifespan in A. thaliana and vice versa. This is the first study documenting the pervasive impact of life history variation on the maintenance of diversity in host immunity within species.
Co-evolution, Defense, Flowering time, Lifespan, Arabidopsis thaliana, Transcriptomics, Trade-off, Pleiotropy, Bulk-segregant sequencing
Adaptation, Evolutionary Ecology, Expression Studies, Life History, Phenotypic Plasticity, Quantitative Genetics, Species interactions