Frequency-dependent selection is the term used for an evolutionary process in which the fitness of a phenotype depends on its frequency relative to other phenotypes in a given population. Frequency-dependent selection is mainly the resultant of species interactions such as predation, parasitism, or competition or between genotypes within species (usually competitive or symbiotic). Frequency-dependent selection can lead to polymorphic equilibria, which result from interactions among genotypes within species, in the same way that multi-species equilibria require interactions between species in competition. In positive frequency-dependent selection, the fitness of a phenotype increases as it becomes more common and in negative frequency-dependent selection, the fitness of a phenotype increases as it becomes rarer.
Open access to the scientific literature means the removal of barriers (including price barriers) from accessing scholarly work. There are two parallel roads towards open access: Open Access articles and self-archiving. Open Access articles are immediately, freely available on their Web site, a model mostly funded by charges paid by the author (usually through a research grant). The alternative for a researcher is self-archiving (i.e., to publish in a traditional journal, where only subscribers have immediate access, but to make the article available on their personal and/or institutional Web sites (including so-called repositories or archives)), which is a practice allowed by many scholarly journals.
Open Access raises practical and policy questions for scholars, publishers, funders, and policymakers alike, including what the return on investment is when paying an article processing fee to publish in an Open Access articles, or whether investments into institutional repositories should be made and whether self-archiving should be made mandatory, as contemplated by some funders.
Last date updated on June, 2014