Evolutionary landscape

An evolutionary landscape is a metaphor^[1] or a construct used to think about and visualize the processes of evolution (e.g. natural selection and genetic drift) acting on a biological entity^[2] (e.g. a gene, protein, population, or species).^[3] This entity can be viewed as searching or moving through a search space. For example, the search space of a gene would be all possible nucleotide sequences. The search space is only part of an evolutionary landscape. The final component is the "y-axis", which is usually fitness. Each value along the search space can result in a high or low fitness for the entity.^[1] If small movements through search space cause changes in fitness that are relatively small, then the landscape is considered smooth. Smooth landscapes happen when most fixed mutations have little to no effect on fitness, which is what one would expect with the neutral theory of molecular evolution. In contrast, if small movements result in large changes in fitness, then the landscape is said to be rugged.^[1] In either case, movement tends to be toward areas of higher fitness, though usually not the global optima.

What exactly constitutes an "evolutionary landscape" is frequently confused in the literature; the term is often used interchangeably with "adaptive landscape" and "fitness landscape", although some authors have different definitions of adaptive and fitness landscapes. Additionally, there is a large disagreement whether the concept of an evolutionary landscape should be used as a visual metaphor disconnected from the underlying math, a tool for evaluating models of evolution, or a model in and of itself used to generate hypotheses and predictions.