Example of a dampening effect: Daphnia developed a toxin tolerance in response to toxic cyanobacteria. I Photo: Saskia Rehse
Historically, many biologists assumed that evolution occurred over time periods and distances too great to influence most ecological patterns, like environmental gradients or the presence of species.
There is, however, much evidence that small-scale evolutionary differentiation is common. In this systematic review, the research team concluded that it can both, intensify or dampen ecological patterns. In some cases it can even create entirely new patterns.
Reducing the roughness of ecological patterns is the most frequent effect of small-scale evolutionary processes – it is characterising 85 per cent of the 500 studies reviewed. One typical example would be that a species might be expected to disappear because of a predator, so that this would reduce species diversity. This pattern can, however, be attenuated if the species adapts to coexist with the predator. Local adaptation evens out fitness across environments and thus counteracts the variation in associated ecological patterns. In some cases, evolution can intensify ecological patterns, but that is a minority of cases.
Consequently, we often do not observe the true spatial heterogeneity of nature because evolution has smoothed it out and hidden its rough edges. ”Evolution makes the world less ragged, which to me is a pretty cool take-home message,” states Professor Mark Urban, first author of the study, from the University of Connecticut.
Luc De Meester adds: ”The most famous citation concerning evolution – survival of the fittest – by Charles Darwin is often misunderstood as reflecting an eternal battle. But evolution is an important driver not only of diversity, but also in contributing to the capacity of organisms to deal with and buffer for strong environmental changes in space and time. In the current era of the Anthropocene this is actually a very important aspect that we are only starting to uncover.”
Read the article online in PNAS >
The text is based on a text by the University of Connecticut.
