EECRG in both Science AND Nature
EECRG members are authors of two publications: one in Nature and one in Science
Richard Telford, Joe Chipperfield, Hilary Birks, and John Birks have published How foreign is the past? (readcube: http://rdcu.be/l0kJ) a brief communication arising from Lyons et al. 2016 (doi: 10.1038/nature16477) in Nature. Lyons et al. analysed presences and absences of animal and plant taxa in about 80 fossil and modern datasets ranging from 300 million years to the present. They concluded that community assembly rules changed 6000 years ago due to human impact. The communication by the EECRG authors questions the validity of the ‘breakpoint’ 6000 years ago, both the methodology and its interpretation, and the suitability of some of the datasets used. Human populations were sparse in North America at that time (much of the Lyons et al. data for the last 11,000 years come from North America) and humans were just beginning to have an impact on Eurasian ecosystems in the Neolithic period. Co-occurrence analysis of presence/absence data used by Lyons et al. may not be a sensitive enough approach to detect fundamental changes in community assembly and structure, especially with such heterogeneous fossil and modern datasets. Lyons et al. show in their response to our communication that their computer software gives the same breakpoint of 6000 years even with so-called ‘corrected’ and ‘filtered’ data only. Both their breakpoints and the breakpoint we generate have 95% credible intervals that extend over almost the entire temporal extent of the data. The Lyons et al. conclusion that community assembly rules changed in the mid-Holocene due to human impact in North America cannot be upheld.
John and Hilary along with Brigitta Ammann from the University of Bern also have a Perspective article in the Insights section of Science on the Fourth dimension of vegetation – 100 years ago, Lennart von Post first used pollen analysis to reconstruct past ecosystems. The Perspective discusses the legacy of von Post since he first presented quantitative pollen data in 1916 and presented ideas which have been taken up and developed in the last 100 years. Von Post used pollen data as a stratigraphic and relative dating tool, but the development of radiocarbon dating in the 1950s released pollen analysis from this role, thus allowing palaeoecology to develop. Technological improvements in pollen morphology, microscopy, computers, and statistics have enriched the method. Today pollen analysis is widely used to reconstruct past ecosystems and to test hypotheses about drivers of ecosystem change. There is a wealth of exciting research to be done in the future, as noted in the short video that Science has created about 100 years of pollen analysis. Appropriately the Royal Swedish Academy of Sciences is hosting a symposium in Stockholm on 24 and 25 November to celebrate von Post’s legacy.