Climate change has the potential to affect the ecology and evolution of every species on Earth. Although the ecological consequences of climate change are increasingly well documented, the effects of climate on the key evolutionary process driving adaptation-natural selection-are largely unknown. We report that aspects of precipitation and potential evapotranspiration, along with the North Atla...

It is frequently assumed by the general public and also by some population experts that the value of replacement-level fertility is everywhere an average of 2.1 lifetime births per woman. Nothing could be farther from the truth. The global variation in replacement fertility is substantial, ranging by almost 1.4 live births from less than 2.1 to nearly 3.5. This range is due almost entirely to c...