CoMSES Catalog

SOLVING THE PARADOX OF STASIS: SQUASHED STABILIZING SELECTION AND THE LIMITS OF DETECTION

Authored by Benjamin C Haller, Andrew P Hendry

Date Published: 2014

Sponsors: National Science and Engineering Research Council of Canada (NSERC) United States National Science Foundation (NSF)

Platforms: No platforms listed

Model Documentation: ODD Mathematical description

Model Code URLs: Model code not found

Abstract

Despite the potential for rapid evolution, stasis is commonly observed over geological timescales-the so-called ``paradox of stasis.{''} This paradox would be resolved if stabilizing selection were common, but stabilizing selection is infrequently detected in natural populations. We hypothesize a simple solution to this apparent disconnect: stabilizing selection is hard to detect empirically once populations have adapted to a fitness peak. To test this hypothesis, we developed an individual-based model of a population evolving under an invariant stabilizing fitness function. Stabilizing selection on the population was infrequently detected in an ``empirical{''} sampling protocol, because (1) trait variation was low relative to the fitness peak breadth; (2) nonselective deaths masked selection; (3) populations wandered around the fitness peak; and (4) sample sizes were typically too small. Moreover, the addition of negative frequency-dependent selection further hindered detection by flattening or even dimpling the fitness peak, a phenomenon we term ``squashed stabilizing selection.{''} Our model demonstrates that stabilizing selection provides a plausible resolution to the paradox of stasis despite its infrequent detection in nature. The key reason is that selection ``erases its traces{''}: once populations have adapted to a fitness peak, they are no longer expected to exhibit detectable stabilizing selection.

SOLVING THE PARADOX OF STASIS: SQUASHED STABILIZING SELECTION AND THE LIMITS OF DETECTION

Abstract

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