Population consequences of mutational events: effects of antibiotic resistance on the r/K trade-off
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What are the effects of a mutational event on population dynamics? This eco-evolutionary question has relevance not only to basic biological theories but also to conservation applications. We evaluated the relationship between maximum population growth rate (r max) and carrying capacity (K) among strains of the bacterium Pseudomonas fluorescens. Each of 65 strains differed from their common ancestor by one naturally acquired phenotypic change conferring antibiotic resistance, brought about by a single mutational event, and each was grown in isolation in four environments. We found no evidence of a trade-off between r max and K. Rather, strains with rapid growth rates also had high carrying capacity, with little interaction between strain and environment. We conclude that the extensive variation in overall fitness resulting from single mutational events likely masks whatever population trade-offs may exist.
KeywordsPseudomonas fluorescens Genotype × environment interactions Fitness Antibiotic resistance Population dynamics Contemporary evolution Y-model Fitness components model
We thank Mufida Al-azzabi for technical assistance and Lauren Fitzsimmons and two anonymous reviewers for their constructive criticism of the manuscript. This work was supported by Natural Sciences and Engineering Research Council of Canada (NSERC) grants to J.T.K. and R.K., and a Tito Scaiano Ontario Graduate Scholarship in Science and Technology to J.M.F.
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