The origins of life likely required the cooperation among a set of molecular species interacting in a network. If so, then the earliest modes of evolutionary change would have been governed by the manners and mechanisms by which networks change their compositions over time. For molecular events, especially those in a pre-biological setting, these mechanisms have rarely been considered. We are only recently learning to apply the results of mathematical analyses of network dynamics to prebiotic events. Here, we attempt to forge connections between such analyses and the current state of knowledge in prebiotic chemistry. Of the many possible influences that could direct primordial network, six parameters emerge as the most influential when one considers the molecular characteristics of the best candidates for the emergence of biological information: polypeptides, RNA-like polymers, and lipids. These parameters are viable cores, connectivity kinetics, information control, scalability, resource availability, and compartmentalization. These parameters, both individually and jointly, guide the aggregate evolution of collectively autocatalytic sets. We are now in a position to translate these conclusions into a laboratory setting and test empirically the dynamics of prebiotic network evolution.

Population bottlenecks may lead to diminished genetic variability and correlative effects on fitness. The Guadalupe fur seal was nearly exterminated by commercial sealers during the late 18th and early 19th centuries. To determine the genetic consequences of this population bottleneck, we compared the variation at a 181 bp section of the mitochondrial DNA (mtDNA) control region from the bones of 26 prebottleneck fur seals versus variation in the extant population. We found 25 different mtDNA genotypes in the prebottleneck fur seals and only 7 genotypes among 32 extant fur seals, including only one of the ancient genotypes. These data demonstrate a substantial loss of genetic variability correlating with the recent population bottleneck. We also found from several genetic measures that the prehistoric population of Guadalupe fur seals was robust and that it had been increasing at some time during the late prehistoric period. Continued recovery of this species may, however, owe more to more immediate nongenetic factors, such as poaching and local availability of food resources during the breeding season and consequent effects on pup survival, than on the reduced genetic variability.

RNA oligomers of length 40-60 nt can self-assemble into covalent versions of the Azoarcus group I intron ribozyme. This process requires a series of recombination reactions in which the internal guide sequence of a nascent catalytic complex makes specific interactions with a complement triplet, CAU, in the oligomers. However, if the CAU were mutated, promiscuous self-assembly may be possible, lessening the dependence on a particular set of oligomer sequences. Here, we assayed whether oligomers containing mutations in the CAU triplet could still self-construct Azoarcus ribozymes. The mutations CAC, CAG, CUU and GAU all inhibited self-assembly to some degree, but did not block it completely in 100 mM MgCl(2). Oligomers containing the CAC mutation retained the most self-assembly activity, while those containing GAU retained the least, indicating that mutations more 5' in this triplet are the most deleterious. Self-assembly systems containing additional mutant locations were progressively less functional. Analyses of properly self-assembled ribozymes revealed that, of two recombination mechanisms possible for self-assembly, termed 'tF2' and 'R2F2', the simpler one-step 'tF2' mechanism is utilized when mutations exist. These data suggest that self-assembling systems are more facile than previously believed, and have relevance to the origin of complex ribozymes during the RNA World.