Although this pilot study was limited by an unstandardized design of sample collection, our preliminary findings suggest that the occurrence of SARS might not be due to an isolated cross-species transmission event, but rather to the rapid evolution of a related virus that has taken root in the human population.
Rather, historical events have led to the evolution of proximate causes of the migratory behaviour by selecting for heritable variation that predisposes birds to respond to appropriate cues with migration.
Ignorance can be bliss: I'm afraid of delving too deeply into a composer's mind for fear of discovering that a masterpiece came into being to enable him to put food on the table rather than to further the evolution of the human spirit.
"Their mode of locomotion is intimately tied to the exploitation of their food resources and has led to the evolution of walking rather than swimming," he says.
This simple model also highlights the point made previously, that donor-recipient correlation, rather than genetic relatedness, is the key to the evolution of altruism.
From a comparative perspective, this would imply that differences between species in traits associated with tool use may be due to differences in the specific ecological conditions that make tool use advantageous, possibly leading to the evolution of motivational rather than cognitive differences.
Hence, novel genes (albeit associated with the expansion of a gene family rather than orphans) could have been central to the evolution of this case of specialization.
However, previous studies focused mainly on elucidating the function rather than the evolution of PL10, which elicited our interest to investigate the evolutionary history behind PL10, DDX3X, and DDX3Y.
While overprinting has been shown to be rather frequent in the evolution of new genes in viruses, our results suggest that this mechanism has also contributed to the origin of a novel gene in a prokaryote.
We take up the idea of subpopulations here, but our goal is to predict rather than model the evolution of the subpopulations.
