PT - JOURNAL ARTICLE AU - Shirin Glander AU - Fei He AU - Gregor Schmitz AU - Anika Witten AU - Arndt Telschow AU - J. de Meaux TI - Signature of co-evolution between defense and vegetative lifespan strategies in <em>Arabidopsis thaliana</em> AID - 10.1101/131136 DP - 2017 Jan 01 TA - bioRxiv PG - 131136 4099 - http://biorxiv.org/content/early/2017/04/26/131136.short 4100 - http://biorxiv.org/content/early/2017/04/26/131136.full AB - 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 vegetative lifespan. Using a genetic strategy to partition lifespan-dependent and –independent defense genes, we demonstrate that this positive co-variation 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 co-varies 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.