This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
Studies documenting Human-Induced Rapid Evolutionary Change (HIREC) routinely compare contemporary allele or morph frequency distributions with historical baselines. All too often, this involves the re-sampling of a population that was sampled at a single time point in the past. However, year-to-year fluctuations in magnitude and direction of evolutionary response may make such studies prone to erroneous conclusions, where long-term evolutionary trends are inferred from what in fact are short-term fluctuations. Here, we explore this problem by re-sampling three Dutch populations of the land snail Cepaea nemoralis, whose shell colour polymorphism is known to be under thermal and predatory selection. Each of these three populations was originally sampled in at least two different years in the past. We show that conclusions on evolutionary change are strongly dependent on which of the historical sample dates is used for comparison with the contemporary sample. Our study highlights the fact that year-to-year variation in allele frequencies may often be so strong that a simple two-point comparison is unreliable to detect long-term evolutionary trends.
"Following" is like subscribing to any updates related to a preprint.
These updates will appear in your home dashboard each time you visit PeerJ.
You can also choose to receive updates via daily or weekly email digests.
If you are following multiple preprints then we will send you
no more than one email per day or week based on your preferences.
Note: You are now also subscribed to the subject areas of this preprint
and will receive updates in the daily or weekly email digests if turned on.
You can add specific subject areas through your profile settings.