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Resumen:
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Inbreeding depression for ?tness traits is a key issue in evolutionary biology and conservation genetics. The magnitude ofinbreeding depression, though, may critically depend on the ef?ciency of genetic purging, the elimination or recessive deleteriousmutations by natural selection after they are exposed by inbreeding. However, the detection and quanti?cation of genetic purgingfor nonlethal mutations is a rather dif?cult task. Here, we present two comprehensive sets of experiments with Drosophila aimedat detecting genetic purging in competitive conditions and quantifying its magnitude. We obtain, for the ?rst time in competitiveconditions, an estimate for the predictive parameter, the purging coef?cient (d), that quanti?es the magnitude of genetic purging,either against overall inbreeding depression (d ? 0.3), or against the component ascribed to nonlethal alleles (dNL? 0.2). We ?ndthat competitive ?tness declines at a high rate when inbreeding increases in the absence of purging. However, in moderate sizepopulations under competitive conditions, inbreeding depression need not be too dramatic in the medium to short term, as theef?ciency of purging is also very high. Furthermore, we ?nd that purging occurred under competitive conditions also reduced theinbreeding depression that is expressed in the absence of competition.
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