Thus, a pair of molecules, one serving as a catalyst and the other as a template, form a complex at a catalyst-dependent rate k ( figureВ 1 b, top). Molecules within a protocell were assumed to have very similar sequences, so that the template specificity of catalysts is ignorable. These molecules can serve both as catalysts and templates for replication. The model assumes a population of protocells, each containing a population of replicating molecules ( figureВ 1 a see the next section for details). Using the model, we show that conflicting multilevel evolution can lead to a novel class of evolutionary dynamics, in which ongoing evolution is hidden behind an apparently stationary population. This consideration led us to investigate a minimal model of conflicting multilevel evolution, taking protocells as the simplest paradigm of hierarchically structured evolving systems. Such conflicting multilevel evolution might substantially increase the complexity of evolutionary dynamics even if different forces of evolution are constant in space and time, thereby potentially rendering the above notion of evolution inadequate. Similar examples abound throughout the biological hierarchy: the evolution of eukaryotes and selfish organelles, the evolution of multicellular organisms and cancer cells, and the evolution of social insects and cheating individuals. The former is evident from the evolution of cell-level function such as metabolism the latter manifests itself in the evolution of selfish genetic elements such as transposons. Cells tend to evolve toward ensuring the survival of the cells, whereas genes, toward ensuring the survival of the genes.

For example, the genome of a cell consists of a number of genes. Evolution can operate at multiple levels of hierarchy, and evolutionary tendencies at different levels can be in conflict with one another. Life is structured in a hierarchical manner. The answer might be вЂnoвЂ™ as suggested by the following consideration. Although this notion is likely to be valid under many circumstances, does it exhaust the possible dynamics of evolution? According to the above notion of evolution, no evolutionary changes are expected to occur at such equilibrium, except random fluctuations due to genetic drift. When different forces of evolution are constant in space and time, these properties eventually reach equilibrium, a well-known example being the mutation-selection balance. Therefore, ongoing evolution can be hidden behind an apparently stationary population owing to conflicting multilevel evolution.Д®volution is often conceived as changes in the properties of a population over generations. This oscillation, however, occurs independently in different lineages, so that the population as a whole appears stationary. high and low fitness, along their lines of descent. These conflicting evolutionary tendencies at different levels and genetic drift drive the lineages of protocells to oscillate endlessly between high and low intracellular catalytic activity, i.e. Protocells are selected towards maximizing the catalytic activity of internal molecules, whereas molecules tend to evolve towards minimizing it in order to maximize their relative fitness within a protocell. The model assumes a population of primitive cells (protocells, for short), each containing a population of replicating catalytic molecules. Using a minimal model of such conflicting multilevel evolution, we demonstrate the possibility of a novel mode of evolution that challenges the above notion: individuals ceaselessly modify their genetically inherited phenotype and fitness along their lines of descent, without involving apparent changes in the properties of the population. Does this notion exhaust the possible dynamics of evolution? Life is hierarchically organized, and evolution can operate at multiple levels with conflicting tendencies. Evolution is often conceived as changes in the properties of a population over generations.

Endless space 2 remove population