Overview

Several factors render niche construction of evolutionary significance:

(1) Niche construction biases natural selection

Organisms do not modify environments at random. Rather, they create environmental states, such as nests, burrows or benign conditions, that are adaptive for the constructor or its descendants. They can also destroy environments, or produce conditions that impact negatively on fitness. Studies show that environmental features constructed by organisms have different properties, and generate different patterns of selection, to aspects of environments that change independently of the organism (Clark et al. 2020). For instance, selection in response to environmental components regulated by organisms is consistently weaker and less variable than selection arising from autonomous aspects of environments. Organisms modify environments in distinctive, nonrandom ways, thereby imposing a systematic bias on natural selection.

The orderly nature of niche construction follows largely because it has evolved through earlier natural selection. However, this does not mean it can be disregarded. Organisms are influenced, but not determined, by their genes, and their activities are shaped by developmental information-gaining processes as well as natural selection. Organisms are not merely objects through which the causal explanatory power of natural selection flows; rather they are active agents that transduce and filter genetic inputs that derive from prior selection, as well as environmental inputs.

(2) Niche construction generates ecological inheritance

Ecological inheritance refers to the inherited resources and conditions, and associated modified selection pressures, that ancestral organisms pass on to their descendants as a direct or indirect result of their niche construction. For instance, if a beaver builds a dam transforming its local ecology, the modified selection will remain in the beaver’s environment just so long as the dam, lake, and modified environment persist, which can be decades. Likewise, the changes that earthworms produce in the soil can last many generations and can increase the fitness of the descendants (see Blog: Evolution’s Engineers).

It is well-recognized that environments can exhibit constancy across generations, but this is not generally viewed as an inheritance. Yet these ecological legacies have been shown to affect evolutionary dynamics strongly, and to contribute to parent-offspring similarity (Odling-Smee et al. 2003; Badyaev & Uller 2009; Odling-Smee et al. 2013). The stable inheritance of traits results in part from parents constructing developmental environments for their offspring (Badyaev & Uller 2009).

In recent years many evolutionary biologists have sought to expand the concept of inheritance within evolutionary biology, and ecological inheritance is now commonly incorporated into these schemes (Danchin et al. 2011; Bonduriansky 2012).

(3) Learning can be evolutionarily significant

There is considerable interest among evolutionary biologists in the role that imprinting, song learning, habitat imprinting, cultural transmission and various other forms of learning, play in speciation, the evolution of adaptive specializations, adaptive radiations, the colonization of new habitats, brood parasitism and sexual selection in vertebrates (ten Cate 2000; Laland et al. 2019; Whitehead et al. 2019).

From the niche-construction perspective, acquired characters, such as learned behaviour, can be evolutionarily important. Social learning in particular, is likely to exert a widespread influence on animal evolution. For instance, different clans of killer whales feed on very different prey species, with individuals learning their dietary preferences from older group members. As a consequence, clans have evolved specific jaws and digestive systems adapted to cope with their learned diets. Killer whales may currently be evolving into multiple separate species because of their cultural differences (Foote et al. 2016).

The learning of one species can influence the evolution of another. Reed warblers, for instance, learn to recognize cuckoos as brood parasites by attending to the alarm calls of other birds, a knock-on consequence of which is that natural selection favors cuckoos with unusual plumage patterns (Thorogood & Davies 2012). This gene-culture coevolution is of particular relevance to human evolution (Laland et al. 2010).

(4) Byproducts are evolutionarily significant

The niche-construction perspective highlights the important roles that byproducts can play in ecosystems. Such roles are not intuitive. For instance, it is far more apparent that the beaver’s dam may drive coevolutionary episodes than beaver’s dung may, yet the latter is a very real possibility. Numerous examples have been documented of seemingly inconsequential and inadvertent acts by organisms whose aggregate activity generates important consequences. For example, consider Euchondrus snails whose consumption of endolithic lichens inadvertently generates tonnes of soil, thereby playing a vital role in desert ecosystems (Jones & Shachak 1990).

Typically, biologists assume that if a niche-constructing activity generates evolutionary feedback to the constructor, then it must be an adaptation. In fact, theory shows this need not be the case. Byproducts can induce selection on other traits in the same population and hitchhike to fixation on the back of this selection (Silver & Di Paolo 2006). Here, spatial structure (local dispersal and mating) gives rise to statistical associations between niche-constructing traits and genotypes favored in the constructed environments. There is selection of the niche-constructing trait, but not selection for it, and only the latter meets the definition of an adaptation (Williams 1966; Sober 1984). Nonetheless, in such hitchhiking cases, there remains evolutionarily consequential feedback to a niche-constructing population stemming from its constructing activities.

(5) Niche construction creates a second route to adaptation

Evolutionary theory has historically focused on how organisms are shaped by natural selection to become suited to their environments. The niche-construction perspective emphasizes that through niche construction, environments can be changed by organisms to suit themselves. For instance, Turner (2000) notes that, despite living on land for millions of years, earthworms have retained the physiology characteristic of the freshwater worms from which they evolved. The earthworms process the soil in ways that allow them to draw water into their bodies more effectively, constructing a simulated aquatic environment on land. The adaptive complementarity of earthworms and soils results to a large extent from the worms changing the soil through niche construction, rather than the worms evolving a typical terrestrial physiology through natural selection.

These findings have led to the claim that niche construction is more than just a product of evolution, or source of environmental change, but should be recognized as a causal evolutionary process through its guiding influence on selection.

(6) Niche construction opens up new ecological niches

Through their niche construction, organisms can open up new ecological niches, both for themselves and for other species. Experiments have shown that niche construction evolves rapidly, under a broad range of conditions (Callahan et al. 2014), often leading to the creation of new niches. For instance, San Roman & Wagner’s (2018) experimental evolution investigation in bacteria showed that huge biodiversity could emerge in a completely homogeneous environment through niche construction. They found that bacteria created new ecological niches when they excrete nutrient-rich waste products that could sustain other bacteria, and identified thousands of such niches that had been created in this manner. Rather than lineages simply diversifying to “fill” available niches, niches themselves may be diversifying (Erwin 2005). Recent theoretical work shows that the construction of new niches by organisms has long-term, macro-evolutionary effects, for instance, increasing the branching patterns of phylogenetic trees (Xue et al. 2020).

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