Understanding how ecological communities are organized and how they change through time is critical to predicting the effects of climate change. Recent work documenting the co-occurrence structure of modern communities found that most significant species pairs co-occur less frequently than would be expected by chance. However, little is known about how co-occurrence structure changes through time.

In a new paper now published in Nature from our Evolution of Terrestrial Ecosystems working group (supported by the Smithsonian and an NSF Research Coordination Network), we evaluated changes in plant and animal community organization over geological time by quantifying the co-occurrence structure of 359,896 unique taxon pairs in 80 assemblages spanning the past 300 million years. Co-occurrences of most taxon pairs were statistically random, but a significant fraction were spatially aggregated or segregated. Aggregated pairs dominated from the Carboniferous period (307 million years ago) to the early Holocene epoch (11,700 years before present), when there was a pronounced shift to more segregated pairs, a trend that continues in modern assemblages. The organization of modern and late Holocene plant and animal assemblages thus fundamentally differs from that of assemblages over the past 300 million years, suggesting that perhaps the rules governing the assembly of communities have recently been changed by human activity.

Kathleen Lyons, S., K. L. Amatangelo, A. K. Behrensmeyer, A. Bercovici, J. L. Blois, M. Davis, W. A. DiMichele, A. Du, J. T. Eronen, J. Tyler Faith, G. R. Graves, N. Jud, C. Labandeira, C. V. Looy, B. McGill, J. H. Miller, D. Patterson, S. Pineda-Munoz, R. Potts, B. Riddle, R. Terry, A. Tóth, W. Ulrich, A. Villaseñor, S. Wing, H. Anderson, J. Anderson, D. Waller, and N. J. Gotelli. 2016. Holocene shifts in the assembly of plant and animal communities implicate human impacts. Nature 529:80-83.

Also see the corrigendum and the following commentaries and response:

Telford, R. J., J. D. Chipperfield, H. H. Birks, and H. J. B. Birks. 2016. How foreign is the past? Nature 538:E1-E2.

Bertelsmeier, C., and S. Ollier. 2016. Questioning Holocene community shifts. Nature 537:E4-E5.

Lyons, S. K., J. H. Miller, K. L. Amatange, A. K. Behrensmeyer, A. Bercovici, J. L. Blois, M. Davis, W. DiMichele, A. Du, J. T. Eronen, J. T. Faith, G. R. Graves, N. Jud, C. Labandeira, C. V. Looy, B. McGill, D. Patterson, S. Pineda-Munoz, R. Potts, B. Riddle, R. Terry, A. Tóth, W. Ulrich, A. Villaseñor, S. Wing, H. Anderson, J. Anderson, and N. J. Gotelli. 2016. Lyons et al. reply. Nature 538:E3-E4.

 

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