Effects of size selection versus density dependence on life histories: A first experimental probe

Ecol Lett. 2021 Jul;24(7):1467-1473. doi: 10.1111/ele.13767. Epub 2021 May 7.

Abstract

When prey experience size-based harvesting by predators, they are not only subject to selection due to larger individuals being preferentially harvested but also selection due to reductions in population density. Density-dependent selection represents one of the most basic interactions between ecology and evolution. Yet, the reduction in density associated with exploitation has not been tested as a possible driving force of observed evolutionary changes in populations harvested size-dependently. Using an artificial selection experiment with a mixture of Daphnia clones, we partition the evolutionary effects of size-based harvesting into the effects of removing large individuals and the effects of lowering the population density. We show that both size selection and density-dependent selection are significant drivers of life-history evolution. Importantly, these drivers affected different life-history traits with size-selective harvesting selecting for slower juvenile growth rates and a larger size at maturity, and low-density selecting for reduced reproductive output.

Keywords: Daphnia; density-dependent selection; harvesting; rapid evolution; size selection.

Publication types

  • Letter

MeSH terms

  • Animals
  • Biological Evolution*
  • Daphnia / genetics
  • Ecology*
  • Population Density
  • Reproduction