Sabhrina Aninta
Joanna MaselOur latest #preprint https://ecoevorxiv.org/repository/view/6959/ explains why fitness can be defined in so many ways, and which version(s) you should use when. Fitness quantifies what #NaturalSelection favors. @gdoulcier #EvolGenPaper #Evolution 1/
Mathematical models assign short-term fitness to organisms, and derive longer-term outcomes for genetic lineages. Traditional relative or absolute fitness implicitly describe all 3 vital rates: births, deaths, and growth. Invasion fitness also summarizes (derived) instantaneous vital rates. Long-term fitness outcomes include sojourn time, fixation probability, and the fixation : counter-fixation ratio (probability of being in one vs another state at the limit of rare symmetric mutation). 2/
Different fitness operationalizations describe different behaviors – the invasion speed used eg in adaptive dynamics does not necessarily correspond with propensity to avoid extinction. 3/
We couldn’t find a good fitness operationalization for the case of balancing selection, so we invented one: the ratio of the time-integrals of abundance from appearance to extinction, given a reflecting boundary such that fixation is impossible. It is approximately equal to the product of 3 informative components: ratio of establishment, ratio of sojourn time given establishment, and mean abundance during sojourn. 4/