Latitudinal clines in climate and sleep patterns shape disease outcomes in Drosophila melanogaster infected by Metarhizium anisopliae

Abstract

Major latitudinal clines have been observed in Drosophila melanogaster, a human commensal that originated in tropical Africa and has spread world-wide to colonize temperate habitats. However, despite the significant impact of pathogens on species distribution, the influence of geographical factors on disease susceptibility remains poorly understood. This study investigated the effects of latitudinal clines and biomes on disease resistance using the common fly pathogen Metarhizium anisopliae and 43 global Drosophila melanogaster populations. The results showed that disease resistance was correlated with latitudinal gradients of sleep duration, temperature and humidity. While fungal diversity at tropical latitudes may drive enhanced defenses, the most disease-resistant males were also the most susceptible to desiccation, indicating potential trade-offs between abiotic stress resistance, necessary for survival in temperate habitats, and disease resistance. The study also found that sex, mating status, and sleep interacted with abiotic stresses to impact disease resistance, with longer-sleeping males and virgin flies surviving infections longer, and extra daytime sleep post-infection being protective, especially in the most resistant fly lines. These findings promote the idea that sleep and defense against disease are intertwined traits related to organismal fitness and subject to joint clinal evolution. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=161 SRC="FIGDIR/small/617675v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@10057bborg.highwire.dtl.DTLVardef@17fecdeorg.highwire.dtl.DTLVardef@19815daorg.highwire.dtl.DTLVardef@1c2ce4b_HPS_FORMAT_FIGEXP M_FIG C_FIG