Analysis of the accuracy and consistency of the behavioral ecology literature that investigates Tinbergen’s question “What does the behavior exist for?”

Tinbergen’s question “What does the behavior exist for?” has contributed to the establishment of behavioral ecology. However, communication within this discipline could be impaired if one does not realize that the question may refer to distinct temporal scopes. Answering it requires specific methodological approaches for each scope: different interpretations of the question refer to different processes. Here we evaluate whether the behavioral ecology literature avoids these pitfalls. We analyze a sample of the articles related to Tinbergen’s question, evaluating if they: precisely delimit the temporal scope of the question; use methodology appropriate to the temporal scope of the article; accurately define the terms used to refer to the survival value of behavior; and use the terms consistently. Additionally, we evaluate whether the citation of these articles is impaired by misinterpretations regarding the temporal scope and terms associated with the question. Of the 22 analyzed articles, three present problems in defining the time of the question, but in the other 19, methods suited to the time studied were used. Four terms (fitness, effect, adaptation, and function) were used to refer to the utility of the behavior, but only one article defined all of them. We found no communication problems in the citing process regarding the time of interest of the question and the terms used to refer to the usefulness of the behavior in the 16 analyzed citation events. Low/medium- and high-impact articles were similar in terms of the problems found. We suggest future articles should define the terms used, in order to avoid miscommunication in the field.

Fecundity selection theory: concepts and evidence

Fitness results from an optimal balance between survival, mating success and fecundity. The interactions between these three components of fitness vary depending on the selective context, from positive covariation between them, to antagonistic pleiotropic relationships when fitness increases in one reduce the fitness of others. Therefore, elucidating the routes through which selection shapes life history and phenotypic adaptations via these fitness components is of primary significance to understanding ecological and evolutionary dynamics. However, while the fitness components mediated by natural (survival) and sexual (mating success) selection have been debated extensively from most possible perspectives, fecundity selection remains considerably less studied. Here, we review the theoretical basis, evidence and implications of fecundity selection as a driver of sex-specific adaptive evolution. Based on accumulating literature on the life-history, phenotypic and ecological aspects of fecundity, we (i) suggest a re-arrangement of the concepts of fecundity, whereby we coin the term 'transient fecundity' to refer to brood size per reproductive episode, while 'annual' and 'lifetime fecundity' should not be used interchangeably with 'transient fecundity' as they represent different life-history parameters; (ii) provide a generalized re-definition of the concept of fecundity selection as a mechanism that encompasses any traits that influence fecundity in any direction (from high to low) and in either sex; (iii) review the (macro)ecological basis of fecundity selection (e.g. ecological pressures that influence predictable spatial variation in fecundity); (iv) suggest that most ecological theories of fecundity selection should be tested in organisms other than birds; (v) argue that the longstanding fecundity selection hypothesis of female-biased sexual size dimorphism (SSD) has gained inconsistent support, that strong fecundity selection does not necessarily drive female-biased SSD, and that this form of SSD can be driven by other selective pressures; and (vi) discuss cases in which fecundity selection operates on males. This conceptual analysis of the theory of fecundity selection promises to help illuminate one of the central components of fitness and its contribution to adaptive evolution.