Ustilago maydis, the delightful blight.

Recent studies of the corn smut fungus life cycle and its regulation by two mating type loci and other genes provide a cornucopia of challenges in cell biology, genetics and protein structure. The fungus can exist in two states: nonpathogenic and pathogenic. The change from one state to the other is accompanied by a change in morphology (yeast-like to filamentous) and growth properties (saprophytic to parasitic).     

The Extended Synthesis: Something Old, Something New

The eclipse of Darwinism began to end in the 1980s and hangs in the balance today. We need an Extended Synthesis, using “extension” metaphorically. We must extend back in time to recover important aspects of Darwinism that were set aside, and then lost during neo-Darwinism, then move forward beyond neo-Darwinism to encompass new data and concepts. The most comprehensive framework for the Extended Synthesis is the Major Transitions in Evolution. The Extended Synthesis rests comfortably within a philosophical perspective in which biology does not need to be connected with other areas of science in order to justify itself. I am attracted to an older concept in which biology needs a covering law to connect it with the rest of the natural sciences. Darwin implicated a “higher law,” but did not specify it. If we can elucidate that law, the Extended Synthesis will become the Unified Theory of Biology called for by Brooks and Wiley 25 years ago.     

How humans drive speciation as well as extinction

A central topic for conservation science is evaluating how human activities influence global species diversity. Humanity exacerbates extinction rates. But by what mechanisms does humanity drive the emergence of new species? We review human-mediated speciation, compare speciation and known extinctions, and discuss the challenges of using net species diversity as a conservation objective. Humans drive rapid evolution through relocation, domestication, hunting and novel ecosystem creation—and emerging technologies could eventually provide additional mechanisms. The number of species relocated, domesticated and hunted during the Holocene is of comparable magnitude to the number of observed extinctions. While instances of human-mediated speciation are known, the overall effect these mechanisms have upon speciation rates has not yet been quantified. We also explore the importance of anthropogenic influence upon divergence in microorganisms. Even if human activities resulted in no net loss of species diversity by balancing speciation and extinction rates, this would probably be deemed unacceptable. We discuss why, based upon ‘no net loss’ conservation literature—considering phylogenetic diversity and other metrics, risk aversion, taboo trade-offs and spatial heterogeneity. We conclude that evaluating speciation alongside extinction could result in more nuanced understanding of biosphere trends, clarifying what it is we actually value about biodiversity.     

Yeasts that ferment D-cellobiose as well as D-xylose

Summary Yeasts that ferment both D-cellobiose and D-xylose have been identified. Such organisms may have advantages in the simultaneous saccharification and fermentation of cellulosics by obviating D-cellobiose inhibition of cellulase activity, and by allowing concurrent processing of the hemicellulose and cellulose.