page_title: Evolutionary mismatch
hierarchical_section_title: Evolutionary mismatch
caption_attribution_description: English: Timeline of mismatch theory
context_page_description: Evolutionary mismatch, also known as mismatch theory or evolutionary trap, is a concept in evolutionary biology that refers to evolved traits that were once advantageous but became maladaptive due to changes in the environment. This can take place in humans and animals and is often attributed to rapid environmental change.
  Mismatch theory represents the idea that traits that evolved in an organism in one environment can be disadvantageous in a different environment. This environmental change leading to evolutionary mismatch can be broken down into two major categories: temporal or spatial. Since environmental change occurs naturally and constantly, there will certainly be examples of evolutionary mismatch over time. However, because large-scale natural environmental change – like a natural disaster – is often rare, it is less often observed. Another more prevalent kind of environmental change is anthropogenic. In recent times, humans have had a large, rapid, and trackable impact on our environment, thus creating scenarios where it is easier to observe evolutionary mismatch.
context_section_description: Evolutionary mismatch, also known as mismatch theory or evolutionary trap, is a concept in evolutionary biology that refers to evolved traits that were once advantageous but became maladaptive due to changes in the environment. This can take place in humans and animals and is often attributed to rapid environmental change.
  Mismatch theory represents the idea that traits that evolved in an organism in one environment can be disadvantageous in a different environment.  This environmental change leading to evolutionary mismatch can be broken down into two major categories: temporal (change of the existing environment over time, e.g. a climate change) or spatial (placing organisms into a new environment, e.g. a population migrating). Since environmental change occurs naturally and constantly, there will certainly be examples of evolutionary mismatch over time. However, because large-scale natural environmental change – like a natural disaster – is often rare, it is less often observed. Another more prevalent kind of environmental change is anthropogenic (human-caused). In recent times, humans have had a large, rapid, and trackable impact on our environment, thus creating scenarios where it is easier to observe evolutionary mismatch.
  Because of the mechanism of evolution by natural selection, the environment ("nature") determines ("selects") which traits will persist in a population. Therefore, there will be a gradual weeding out of disadvantageous traits over several generations as the population becomes more adapted to its environment. Any significant change in a population's traits that cannot be attributed to other factors (such as genetic drift and mutation) will be responsive to a change in that population's environment; in other words, natural selection is inherently reactive. Shortly following an environmental change, traits that evolved in the previous environment, whether they were advantageous or neutral, are persistent for several generations in the new environment. Because evolution is gradual and environmental changes often occur very quickly on a geological scale, there is always a period of "catching-up" as the population evolves to become adapted to the environment. It is this temporary period of "disequilibrium" that is referred to as mismatch. Mismatched traits are ultimately addressed in one of several possible ways: the organism may evolve such that the maladaptive trait is no longer expressed, the organism may decline and/or become extinct as a result of the disadvantageous trait, or the environment may change such that the trait is no longer selected against.
caption: Timeline showing a period of mismatch following an environmental change.
exif: {}