Contamination represents environmental stress that can affect genetic
variability of populations, thus influencing the evolutionary processes. In
this study, we evaluate the relationship between heavy metal contamination
(Pb) and phenotypic variation, assessed by coefficients of variation (CV) of
life-history traits. To investigate the consequences of population origin on
variation of life history traits in Drosophila subobscura in response to
different laboratory conditions we compared populations from relatively
polluted and unpolluted environments. Prior to experiment, flies from natural
populations were reared for two generations in standard Drosophila laboratory
conditions. Afterwards, all flies were cultured on three different media: one
medium without lead as the control, and the other two with different
concentrations of lead. Coefficients of variation (CV) of life- history
traits (fecundity, egg-to-adult viability and developmental time) were
analyzed on flies sampled in generations F2, F5 and F8 from these three
groups. In later generations samples from both polluted and unpolluted
environments showed the increased fecundity variation on media with lead.
This increase is expressed more in population from unpolluted environment. On
contrary, population from unpolluted environment had increased variation of
developmental time in earlier, F2 generation, compared to the population from
polluted environment. Our results showed that the response to heavy metal
contamination depends on the evolutionary history of the populations
regarding habitat pollution.
LABORATORY EVOLUTION OF LIFE-HISTORY TRAITS IN THE BEAN WEEVIL (ACANTHOSCELIDES OBTECTUS
): THE EFFECTS OF SELECTION ON DEVELOPMENTAL TIME IN POPULATIONS WITH DIFFERENT PREVIOUS HISTORY
