Validating niche-construction theory through path analysis

摘要

Under the conventional view of evolution, species over time come to exhibit those characteristics that best enable them to survive and reproduce in their preexisting environments. Niche construction provides a second evolutionary route to establishing the adaptive fit, or match, between organism and environment, viewing such matches as dynamical products of a two-way process involving organisms both responding to problems posed by environments as well as setting themselves new problems by changing their environments through further niche construction. Not surprising, the analysis of niche construction is complicated. For example, variables of interest might contain measurement error, or some variables might not be observable. In other cases, variables might not be datable and have to be measured at the same date. A time-series generalization of path analysis, which itself can be viewed as a version of simultaneous-equation analysis, offers a means of highlighting causal relationships in complex systems of niche construction by graphically representing a hypothesis of causality between variables and, in some instances, providing an estimated weight that a hypothesized causal variable has on another variable. Path analysis forces researchers to specify how variables relate to one another and encourages development of clear and logical theories concerning the processes that influence a particular outcome. As we show through a case study-the coevolution of cattle husbandry and the tolerance for milk consumption-path analysis can also call attention to potential areas of weakness and ambiguity in data sets and how they are used in constructing inferences.