There is an error in §3c. ITVOTHER represents non-genetic phenotypic trait variation due to other environmental gradients or ontogenetic changes. The corrected paragraph is provided here.
(c) The relative contribution of genotypic trait variation, non-genetic intraspecific trait variation and interspecific trait turnover
For communities in which D. magna was present, a tendency towards an increased average community body size was detected with increasing levels of urbanization (figure 4a, 3200 m scale), similar to the pattern found for the total set of communities dominated by large species. Owing to the low number of communities, however, the full model was not significant (SPT + ITV, p = 0.423, electronic supplementary material, table SA6; for results without outlier removal, see the electronic supplementary material, table SB5 and figure SB8). ITV of D. magna explained 32.43% of the total observed trait turnover along the urbanization gradient (marginally non-significant, p = 0.056, electronic supplementary material, table SA6). ITV was clearly the larger contributor, explaining 95.78% of the total variation explained by both ITV and SPT together. Including genotypic trait values at 20°C and 24°C in the analysis enabled us to disentangle three types of ITV along the urbanization gradient: genotypic trait variation (GTV), non-genetic phenotypic trait variation due to increased temperatures (ITVPLAST-T) and non-genetic phenotypic trait variation due to other environmental gradients or ontogenetic changes (ITVOTHER; figure 4b). Only the latter component showed a significant contribution to the observed increase in average community body size (electronic supplementary material, table SA6, p = 0.047). ITVOTHER explained 92.89% of the total explained variation by all trait components, while GTV and SPT contributed 4.55% and 2.56%, respectively. Regression analysis on the difference in D. magna body size measurements on all individuals (i.e. including juveniles) versus adults only plotted against degree of urbanization, suggests that the large impact of ITVOTHER might be due to a change in relative abundance of juveniles along the urbanization gradient (β1 = 20.048, p = 0.032; electronic supplementary material, figure SA6).
- © 2017 The Author(s)
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