Two interesting articles from PNAS

While looking for the article about the early panda mentioned in my last post, I came across a couple of interesting articles at Proceedings of the National Academy of Sciences that were open access.

One of them is about how geographic range affects the risk of extinction.

Wide geographic range is generally thought to buffer taxa against extinction, but the strength of this effect has not been investigated for the great majority of the fossil record. Although the majority of genus extinctions have occurred between major mass extinctions, little is known about extinction selectivity regimes during these "background" intervals. Consequently, the question of whether selectivity regimes differ between background and mass extinctions is largely unresolved. Using logistic regression, we evaluated the selectivity of genus survivorship with respect to geographic range by using a global database of fossil benthic marine invertebrates spanning the Cambrian through the Neogene periods, an interval of {approx}500 My. Our results show that wide geographic range has been significantly and positively associated with survivorship for the great majority of Phanerozoic time. Moreover, the significant association between geographic range and survivorship remains after controlling for differences in species richness and abundance among genera. However, mass extinctions and several second-order extinction events exhibit less geographic range selectivity than predicted by range alone. Widespread environmental disturbance can explain the reduced association between geographic range and extinction risk by simultaneously affecting genera with similar ecological and physiological characteristics on global scales. Although factors other than geographic range have certainly affected extinction risk during many intervals, geographic range is likely the most consistently significant predictor of extinction risk in the marine fossil record.

So, in other words, animals that live in large geographical range are less likely to become extinct than animals that live in a narrow geographical range. This is less notable during mass extinction (i.e. times where large numbers of species go extinct), but even then it can be measured.

This is something that was expected, but undocumented until now.

The other article, is also something that follows quite logically from what we know. It shows that resources have an influence on biodiversity

I probably explained the findings incorrectly, and would love to see any of the real biologist out there (e.g. Coturnix or PZ Myers) explain these papers to the rest of us.