Diet-induced changes in titer support a threshold effect ofWolbachia-associated plastic recombination inDrosophila melanogaster

Abstract

ABSTRACTPlastic recombination inDrosophila melanogasterhas been associated with a variety of extrinsic and intrinsic factors such as temperature, starvation, and parasite infection. The bacterial endosymbiontWolbachia pipientishas also been associated with plastic recombination inD. melanogaster. Wolbachiainfection is pervasive in arthropods and this infection induces a variety of phenotypes in its hosts, the strength of which can depend on bacterial concentration, or titer. Here we test the hypothesis that the magnitude ofWolbachia-associated plastic recombination inD. melanogasterdepends on titer. To manipulate titer, we raisedWolbachia-infected and uninfected flies on diets that have previously been shown to increase or decreaseWolbachiatiter relative to controls. We measured recombination in treated and control individuals using a standard backcrossing scheme with two X-linked visible markers. Our results recapitulate previous findings thatWolbachiainfection is associated with increased recombination rate across theyellow-vermillioninterval of the X chromosome. Our data show no significant effect of diet or diet byWolbachiainteractions on recombination, suggesting that diet-induced changes inWolbachiatiter have no effect on the magnitude of plastic recombination. These findings represent the first step toward investigating the mechanisms behindWolbachia-associated plastic recombination and demonstrate that the effect may be threshold-based as opposed to dose-dependent.