Bacterial taxa-area and distance-decay relationships in marine environments - PubMed (original) (raw)

Bacterial taxa-area and distance-decay relationships in marine environments

L Zinger et al. Mol Ecol. 2014 Feb.

Abstract

The taxa-area relationship (TAR) and the distance-decay relationship (DDR) both describe spatial turnover of taxa and are central patterns of biodiversity. Here, we compared TAR and DDR of bacterial communities across different marine realms and ecosystems at the global scale. To obtain reliable global estimates for both relationships, we quantified the poorly assessed effects of sequencing depth, rare taxa removal and number of sampling sites. Slope coefficients of bacterial TARs were within the range of those of plants and animals, whereas slope coefficients of bacterial DDR were much lower. Slope coefficients were mostly affected by removing rare taxa and by the number of sampling sites considered in the calculations. TAR and DDR slope coefficients were overestimated at sequencing depth <4000 sequences per sample. Noticeably, bacterial TAR and DDR patterns did not correlate with each other both within and across ecosystem types, suggesting that (i) TAR cannot be directly derived from DDR and (ii) TAR and DDR may be influenced by different ecological factors. Nevertheless, we found marine bacterial TAR and DDR to be steeper in ecosystems associated with high environmental heterogeneity or spatial isolation, namely marine sediments and coastal environments compared with pelagic ecosystems. Hence, our study provides information on macroecological patterns of marine bacteria, as well as methodological and conceptual insights, at a time when biodiversity surveys increasingly make use of high-throughput sequencing technologies.

Keywords: distance-decay; global scale; methodological biases; microbes; pyrosequencing; species-area.

© 2013 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

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Figures

Fig 1

Fig 1

Taxa–area (a) and distance–decay (b) relationships of marine bacterial communities in surface-sea waters (n = 70), deep-sea waters (n = 61) and coastal sediments (n = 72), standardized at 5000 sequences per sample. Error bars in (a) represent the standard deviation of OTU richness according to the reference sample used. In both panels, dotted lines correspond to the 95% confidence intervals for linear regressions.

Fig 2

Fig 2

Effect of the removal of rare taxa on z (a) and |β| (b) in the three ecosystem types studied (5000 sequences per sample initially).

Fig 3

Fig 3

Effect of sequencing depth (a,c) and sampling effort (b,d) on z (a,b) and |β| (c,d) obtained with 100 random resampling for each sequencing/sampling depth. A local-fitting algorithm (LOESS smoother, black continuous lines) was used, and numbers of samples/sequences were slightly modified for surface waters and coastal sediment to help to visualize changes in z and |β|. Continuous and dotted coloured straight lines correspond to slopes and their standard errors, respectively, obtained for the initial data set (Fig.1) for comparative purposes.

Fig 4

Fig 4

Variation of z (a) and |β| (b) according to realms and ecosystem type. z and β values per ecosystem type were obtained by randomly resampling 40 samples and 5000 sequences per sample 1000 times in the initial community tables. Upper/lower case letters indicate significant differences (Mann–Whitney tests, Holm-corrected P < 0.05) between realms/ecosystem types.

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