Niche construction theory contrasts with conventional conceptualizations of evolution in recognizing niche construction as an evolutionary cause or process. The niche-construction perspective seeks to explain the adaptive complementarity of organism and environment in terms of a dynamic, reciprocal interaction between the processes of natural selection and niche construction.
The distinctive aspects of the niche-construction perspective are illustrated by the familiar example of the beaver. Generally, the evolutionary consequences of beaver dam building are modeled in terms of fitness ‘payoffs’ to the underlying genes; selection favors dam-building alleles over their alternatives. According to Richard Dawkins (1982), who exemplifies the traditional standpoint, dams can be viewed as ‘extended phenotypes’ – adaptations expressed outside of the constructor’s body, but that evolve in a manner no different from other adaptations.
From the niche-construction perspective this stance is unsatisfactory, both because it misses part of the causal story and because it discourages consideration of additional forms of selective feedback. When a beaver builds a dam, creating a lake and influencing river flow, it not only affects the propagation of dam-building genes but dramatically changes its local environment, affecting nutrient cycling, decomposition dynamics, the structure of the riparian zone, and plant and community composition and diversity. It follows that beaver dam building must also transform selection acting on a host of other beaver traits. The active agency of beavers in constructing these modified selection pressures and thereby acting as co-directors of their own evolution (not to mention that of other species) currently goes unrecognized.
Often the modifications produced by niche-constructing organisms persist for longer than the individual constructors, continuing to modulate the impact of environment on subsequent generations, a legacy described as an ‘ecological inheritance’. Descendants of the dam builder will experience modified selection so long as the dam, lake, and transformed environment remain. Given that dams are frequently maintained by families of beavers for decades, that could be considerably longer than the lifetime of an individual beaver. In addition to genes, offspring inherit a modified selective environment.
While it is possible to study this feedback using established evolutionary theory, for instance through models of habitat selection, co-evolution or maternal effects, nonetheless the magnitude and significance of niche construction remains underappreciated, in part because standard evolutionary theory does not encourage attention to such phenomena.
Conversely by treating niche construction as an evolutionary process – one that is influenced by, but not solely reducible to, earlier natural selection – niche construction theory generates novel hypotheses and new methods that stimulate research. The perspective is rapidly growing, precisely because researchers from multiple disciplines find it useful.
