Population growth rate and genetic variability of small and large populations of Red flour beetle (Tribolium castaneum) following multigenerational exposure to copper
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We reared large (1000 individuals) and small (20 individuals) populations of Tribolium castaneum on diet contaminated with copper in order to determine if the size of a population affects its ability to adapt to adverse environmental conditions. After 10 generations, we used microsatellite markers to estimate and subsequently compare the genetic variability of the copper-treated populations with that of the control populations, which were reared on uncontaminated medium. Additionally, we conducted a full cross-factorial experiment which evaluated the effects of 10 generations of “pre-exposure” to copper on a population’s fitness in control and copper-contaminated environments. In order to distinguish results potentially arising from genetic adaptation from those due to non-genetic effects associated to parental exposure to copper, we subjected also F11 generation, originating from parents not exposed to copper, to the same cross-factorial experiment. The effects of long-term exposure to copper depended on population size: the growth rates of small populations that were pre-exposed to copper were inhibited compared to those of small populations reared in uncontaminated environments. Large Cu-exposed populations had a higher growth rate in the F10 generation compared to the control groups, while the growth rate of the F11 generation was unaffected by copper exposure history. The only factor that had a significant effect on genetic variability was population size, but this was to be expected given the large difference in the number of individuals between large and small populations. Neither copper contamination nor its interaction with population size affected the number of microsatellite alleles retained in the F10 generation.
KeywordsExtinction vortex Metals Toxicity Population size Inbred Outbred
We thank Patrycja Gibas for assistance in the laboratory and Magda Herdegen for advice on genetic analyses. We also thank Lindsay Higgins for the text editing and her comments on the manuscript. The project was supported by Grant No. PL0419 from the Norwegian Financial Mechanism and EEA Financial Mechanism (EOG funds), Grant No. N N304 027334 from the State Committee For Scientific Research and Jagiellonian University (DS/WBINOZ/INOŚ/762/12).
Conflict of interest
The authors declare that they have no conflict of interest.
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