Behavioral syndromes: carryover effects, false discovery rates, and a priori hypotheses

Abstract

Behavioral syndromes and animal personalities are an increasingly active area of research within behavioral ecology (Bell 2007), and this interest stems in part from their potential evolutionary implications. In other areas of evolutionary ecology, trait covariances—like those observed in behavioral syndromes—have been demonstrated to have profound evolutionary implications (Lande and Arnold 1983). Trait covariances can dramatically affect how populations respond to selection by potentially constraining responses, generating trade-offs, or otherwise shaping evolutionary trajectories (Blows and Hoffmann 2005; Roff and Fairbairn 2007; Walsh 2007). Via these same evolutionary responses, behavioral syndrome research may well have similarly profound ramifications for our understanding of behavioral evolution. However, as with many novel areas of research, methodologies for the study of behavioral syndromes are still developing (e.g., Dingemanse et al. 2010). While examining behavioral syndrome structure in hissing cockroaches (Gromphadorhina portentosa), Logue et al. (2009) discussed 2 key methodological issues for the study of behavioral syndromes: 1) How the order in which behaviors are assayed can affect subsequent behavioral responses and 2) How the evaluation of numerous behaviors results in a risk that correlations are statistical artifacts. Both of these aspects are of importance for the study of behavioral syndromes and warrant additional discussion as they may influence the inferences that researchers draw. Here, I focus on extending the discussion of order effects, their implications to behavioral syndrome research, and how to methodologically treat them. I also expand on some of the points made by Logue et al. (2009) regarding the evaluation of numerous behavioral correlations and discuss the role of confirmatory analyses.