Analysis of statistical correlations between properties of adaptive walks in fitness landscapes

Abstract

The fitness landscape metaphor has been central in our way of thinking about adaptation. In this scenario, adaptive walks are idealized dynamics that mimic the uphill movement of an evolving population towards a fitness peak of the landscape. Recent works in experimental evolution have demonstrated that the constraints imposed by epistasis are responsible for reducing the number of accessible mutational pathways towards fitness peaks. Here, we exhaustively analyse the statistical properties of adaptive walks for two empirical fitness landscapes and theoretical NK landscapes. Some general conclusions can be drawn from our simulation study. Regardless of the dynamics, we observe that the shortest paths are more regularly used. Although the accessibility of a given fitness peak is reasonably correlated to the number of monotonic pathways towards it, the two quantities are not exactly proportional. A negative correlation between predictability and mean path divergence is established, and so the decrease of the number of effective mutational pathways ensures the convergence of the attraction basin of fitness peaks. On the other hand, other features are not conserved among fitness landscapes, such as the relationship between accessibility and predictability.

Algoritmos bio e socio-inspirados na busca pelos máximos globais de relevos adaptativos

“…O modelo NK encontra aplicações em diversas áreas como, por exemplo, imunologia teórica, 17 genética de populações, [18][19][20] modelagem de proteínas, [21][22][23] administração de empresas e organização do trabalho [24][25][26][27] e, naturalmente, teste para algoritmos de otimização. 28 Essa popularidade se deve ao modelo NK permitir a construção de uma medida de performance para sistemas nos quais cada componente pode estar associada a vários estados e onde há algum tipo de interação entre as componentes, permitindo o controle do tamanho do sistema e do nível de complexidade das interações através dos parâmetros N e K.…”