Phenotypic Selection

by

Ryan Calsbeek

• LAST REVIEWED: 23 May 2012
• LAST MODIFIED: 23 May 2012
• DOI: 10.1093/obo/9780199830060-0059

Introduction

Natural and sexual selection are the two most important facets of adaptive evolution. The two processes are closely related but may be differentiated by various components of each type. Natural selection is marked by differential viability and fecundity, while sexual selection is distinguished by variation in mating success linked to both finding mates and fertilizing eggs. Darwin distinguished between natural and sexual forms of selection because sexual selection may favor the evolution of phenotypes that are disfavored by natural selection. Irrespective of their differences, natural and sexual selection both operate by selecting individuals through variation in fitness associated with some phenotype or combination of phenotypes. Though these phenotypes must have a heritable genetic basis for evolution to occur, selection itself acts on phenotypes whether or not the traits themselves are heritable. This distinction was first realized during early work by plant and animal breeders who were subjecting stock populations to artificial selection. This work eventually led to the fields of quantitative genetics, population genetics, the “adaptive landscape” metaphor, and, later, the modern evolutionary synthesis. The readings included in this bibliography on the topic of phenotypic selection include exploration of the different forms selection can take, statistical techniques for measuring and visualizing selection, the biological changes that arise due to selection, and empirical examples of selection measured in the field and the laboratory.

Recent Reviews

Kingsolver, et al. 2001 reviews the literature to ask how strong phenotypic selection is, on average. The authors summarize data from thirteen years of selection studies. Hoekstra, et al. 2001 uses a closely related data set to ask questions about sexual and viability selection. Hereford, et al. 2004 presents a different view of the average strength of selection by using an alternative statistical approach. Cox and Calsbeek 2009 reviews the literature on sexual conflict, while Siepielski, et al. 2009 reviews the evidence for temporal variation in selection among replicate studies. Hersch and Phillips 2004 makes an important point about the sample sizes that are necessary to measure selection—especially weak selection—and illustrates the potential bias that may exist in the literature on selection gradients. Finally, Rice 2004 provides a more up-to-date review of selection and mechanisms of evolution.

• Cox, Robert M., and Ryan Calsbeek. 2009. Sexually antagonistic selection, sexual dimorphism, and the resolution of intralocus sexual conflict. American Naturalist 173.2: 176–187.

  DOI: 10.1086/595841

  An up-to-date review of the literature on sexual conflict and the evolution of sexual dimporphism. Compares the relative importance of viability, sexual, and fecundity selection to the evolution of sexual dimorphism.

• Hereford, Joe, Thomas F. Hansen, and David Houle. 2004. Comparing strengths of directional selection: How strong is strong? Evolution 58.10: 2133–2143.

  Lande and Arnold 1983 (cited under Statistical Detection) provides a method of quantifying selection that may bias comparisons among studies. This paper provides an alternative method for calculating gradients using mean-centered trait values.

• Hersch, Erika, and Patrick C. Phillips. 2004. Power and potential bias in field studies of natural selection. Evolution 58.3: 479–485.

  A review of the literature, combined with power analyses, suggesting that many studies fail to use sample sizes sufficient for detecting weak selection. Design modifications are suggested.

• Hoekstra, H. E., J. M. Hoekstra, D. Berrigan, et al. 2001. Strength and tempo of directional selection in the wild. Proceedings of the National Academy of Sciences of the United States of America 98.16: 9157–9160.

  DOI: 10.1073/pnas.161281098

  Using the same meta-analysis framework as Kingsolver, et al. 2001, this paper summarizes the data in terms of sexual and viability selection.

• Kingsolver, J. G, H. E. Hoekstra, J. M. Hoekstra, et al. 2001. The strength of phenotypic selection in natural populations. American Naturalist 157.3: 245–261.

  DOI: 10.1086/319193

  This review of the literature on selection gradients provides a comprehensive assessment of the average strength of selection and points out the dramatic underrepresentation of nonlinear selection gradients relative to directional selection.

• Rice, Sean. 2004. Evolutionary theory: Mathematical and conceptual foundations. Sunderland, MA: Sinauer Associates.

  A quantitative overview of the fundamental mechanisms of evolution and selection. The first half of the book is a highly gene-centric view, while the second half focuses on phenotypic evolution. The book is suitable for graduate students, postdoctoral researchers, and higher-level undergraduates.

• Siepielski, Adam M., Joseph D. DiBattista, and Stephanie M. Carlson. 2009. It’s about time: The temporal dynamics of phenotypic selection in the wild. Ecology Letters 12.11: 1261–1276

  DOI: 10.1111/j.1461-0248.2009.01381.x

  This review focuses on how much variation in selection may arise among temporal replicates. Though the data are interesting, the results should be interpreted with caution, since it remains unclear whether the variation is biologically real or can be attributed to statistical variation arising from power limitations (see Hersch and Phillips 2004).