Year: 2022

EXPERIMENTAL TRANSITION. "Here we describe an evolutionary transition that occurs in experimental populations of Pseudomonas fluorescens propagated in a spatially heterogeneous environment. Cooperating groups are formed by over-production of an adhesive polymer, which causes the interests of individuals to align with those of the group." http://www.nature.com/nature/journal/v425/n6953/abs/nature01906.html View in LinkedIn

TRANSITIONAL OBSERVATIONS. "The costs and benefits of cooperation, plus evolutionary susceptibility to defecting genotypes, were analysed to determine conformation to theory. Cooperation was costly to individuals, but beneficial to the group. Defecting genotypes evolved in populations founded by the cooperating type and were fitter in the presence of this type than in its absence." http://www.nature.com/nature/journal/v425/n6953/abs/nature01906.html View in LinkedIn

DEFECTORS. "In the short term, defectors sabotaged the viability of the group; but these findings nevertheless show that transitions to higher orders of complexity are readily achievable, provide insights into the selective conditions, and facilitate experimental analysis of the evolution of individuality." http://www.nature.com/nature/journal/v425/n6953/abs/nature01906.html View in LinkedIn

LOST BETWEEN THE CRACKS. "Natural selection works systematically to adapt populations to their prevailing environments. However, selection requires heritable variation generated by random mutation, and even beneficial mutations may be lost by random drift." https://lnkd.in/dbxjmju View in LinkedIn

EVOLUTION AS UNPREDICTABLE. "Accidents of history may even determine the survival or extinction of entire lineages, given the capricious and sudden nature of some environmental changes. Stephen Jay Gould maintained that these historical contingencies make evolution largely unpredictable." http://www.pnas.org/content/105/23/7899.full View in LinkedIn

TAPE OF LIFE. "Gould argued that contingency renders evolution fundamentally quirky and unpredictable, and he famously suggested that replaying the “tape of life” from some point in the distant past would yield a living world far different from the one we see today." http://www.pnas.org/content/105/23/7899.full View in LinkedIn

EXPERIMENTAL EVOLUTION experiment using a defined population of E. Coli follows. This experiment is particularly informative about difficult and sudden trait development. View in LinkedIn

DEFINING. "E. coli cells cannot grow on citrate under oxic conditions, and that inability has long been viewed as a defining characteristic of this important, diverse, and widespread species." This is to be exploited in an experiment of unicellular evolution. http://www.pnas.org/content/105/23/7899.full View in LinkedIn

TEST POPULATION. "Twelve initially identical populations of Escherichia coli were founded in 1988 to investigate this issue. They have since evolved in a glucose-limited medium that also contains citrate, which E. coli cannot use as a carbon source under oxic conditions. No population evolved the capacity to exploit citrate for >30,000 generations, although each population tested billions of mutations." http://www.pnas.org/content/105/23/7899.full View in LinkedIn

LONG LINEAGE. "Environmental conditions have been controlled, constant, and identical for all 12 lines. To date, each population has evolved for >44,000 generations, and samples have been frozen every 500 generations, providing a rich “fossil record”." http://www.pnas.org/content/105/23/7899.full View in LinkedIn