Collaborative Research: Behavioral Syndromes as Evolutionary Constraints: the Role of Genetic Architecture

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In this project, the Drs. Dochtermann and Hedrick will study the evolutionary causes and consequences of correlations among behaviors. It is now well understood that the behaviors of individual animals are often correlated, and most previous research has focused on characterizing these correlations. Much less attention has been paid to understanding why behaviors are correlated. There are generally two explanations for why behaviors might be correlated. First, correlations might be present because particular combinations of behaviors have been evolutionarily favored (i.e. selection). Second, underlying molecular mechanisms,such as a single gene affecting multiple behaviors,might produce correlations. By comparing genetic correlations among populations, the PIs will attempt to see if selection has shaped correlations or not. Following this, the researchers will conduct an artificial selection experiment with the aim of breaking apart behavioral correlations. This artificial selection experiment will provide additional evidence regarding the degree to which either of the above explanations might produce behavioral correlations. Moreover, this experiment will illustrate the degree to which behavioral correlations affect and constrain evolutionary outcome.Although Behavioral Syndromes, among-individual behavioral correlations, are now well described across taxa, the evolutionary causes and consequences of syndromes are still poorly understood. The evolutionary causes of syndromes can generally be grouped into two classes of mechanisms: selection-induced linkage disequilibrium (SILD) wherein particular combinations of behaviors have been favored, and molecular mechanisms such as pleiotropy. These two classes of mechanisms have very different evolutionary implications. If molecular mechanisms such as pleiotropy underlie syndromes, then constraints may be placed on evolutionary outcomes which are not present with SILD (importantly, these mechanisms are not mutually exclusive, as both may jointly influence the expression of syndromes). In this project, the researchers will conduct population comparisons and artificial selection experiments to distinguish between these two classes of mechanisms. Specifically, genetic correlations and heritabilities of multiple populations will be estimated and compared relative to ecological variables. These comparisons can allow the detection of SILD if the populations differ such that selective pressures might favor different combinations of behaviors among populations. Follow up artificial selection experiments designed to break apart behavioral correlations will estimate the constraining effect of syndromes, and the ability of populations to respond to artificial selection will distinguish between SILD and molecular mechanisms.