SBE Professor Brian McGill Published in Science Magazine

Brian McGillDr. Brian McGill, assistant professor of biological sciences, recently co-published a comprehensive analysis of global biodiversity change and species loss in Science magazine.  Maria Dornelas and Anne Magurran of the Centre lead the international research team for Biological Diversity and Scottish Oceans Institute, University of St. Andrews, Scotland.

The analysis used data from 100 monitoring studies in which scientists from around the world tracked the biodiversity of plant and animal communities over many years. The compiled data consist of over 6 million observations for over 35,000 species monitored in terrestrial, freshwater, and marine habitats from the poles to the equator.

The study brought to light two key results. First, there was neither a systematic loss nor a systematic gain in the number of species recorded through time, with 59 communities showing an increase in species richness through time and 41 communities showed a decrease. The measured rate of change was small in most studies. The second finding the paper concluded was that that 79 of the 100 communities showed substantial changes in species composition, measured relative to the baseline of the first available survey of the community.

The group plans on doing some follow-up experiments in order to see what is actually happening, specifically looking at what species are coming in and coming out using the data that was already collected.  “It was a surprise,” said McGill. “I always think it’s fun when you expect one thing and get the opposite.  There is very good evidence that globally we are losing species a lot faster than new species are being created.  We expected that to carry down to the local scales…and the fact that it didn’t was a big surprise.”

Although global extinctions and declines of many species have been well documented, these results suggest that simple counts of species richness in a small area may not show consistent downward trends. However, the set of species living in these same small areas has changed substantially over relatively short time scales of years to decades.

The study found that there has been a change through time in the identity of species, but not, on average, in the number of species recorded in these monitoring studies. Species composition changed more often than species number, and these kinds of changes should be focused on for future study.