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Fig. 4 | BMC Biology

Fig. 4

From: Sexual conflict drives micro- and macroevolution of sexual dimorphism in immunity

Fig. 4

Microevolutionary change in tolerance to bacterial infection during experimental evolution under alternative mating regimes. Response to bacterial infection was estimated by the change in mortality rate between individuals infected with two doses of bacteria and a sham control. When infected with the gram-positive bacteria B. thuringiensis, monogamous females (a, b) had significantly higher survival under infection compared with polygamous females (c, d), while virgin (a, c) and mated (b, d) females had similar responses. Shown are survival curves for each replicate evolution line (thin lines) together with mean survival (thick line) and 95% confidence limits (shaded area) based on all three replicate lines per regime and mating treatment. Virgin males (triangles) from monogamous (e) and polygamous (f) regimes did not show the strong differences seen in virgin females (circles), resulting in an apparent increase in sexual dimorphism in response to infection in the polygamy regime (compare panels e and f) (means ±1SE; lower dose = 1.0 OD, higher dose = 2.0 OD for females and 2.5 OD for males). When mated females were infected with the gram-negative bacteria, P. entomophila, which allowed assaying of in vivo bacterial counts in infected individuals, monogamous lines (g) again showed higher survival under infection compared with polygamous lines (h) (lower dose = 0.5 OD, higher dose = 1.0 OD). (i) Counts of bacterial loads in females 12 h post infection showed that difference in survival were likely not due to more efficient clearance of bacteria in monogamous lines. Means ± 1 SE per replicate line (two lines used per regime and dose) and individual data points per assay

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