Consider alternative designs and trait integration level for better ecosystem analysis

To fully understand how an ecosystem fits together, consider how alternate designs may achieve the same end.

In nature, it’s common for different suites of traits to result in the same overall function, essentially representing alternative solutions to specific environmental challenges. One example is the presence of both annuals and succulents in seasonally dry ecosystems: one deals with drought by avoiding it, the other by tolerating it. When ecosystem function is studied, however, these ‘alternative designs’ are usually not considered as such, nor is the fact that a species’ fitness is in part defined by combinations of traits and the trade-offs between them. Often, ecologists seek to collapse and simplify multiple traits for the purposes of analysis, rather than considering their potential interactions and how these may affect performance.

Conceptual model modified from Arnold (1983) to include the concept of the organism integration level (Marks, 2007), ranging from organ-level traits (traits 1–6) to whole-organism traits (traits 7 and 8).  Source: Dias et al. 2020.

In a viewpoint recently published in Annals of Botany, André Tavares Corrêa Dias and colleagues make a case for the importance of alternative designs as well as suggesting approaches that will aid other researchers in incorporating this concept into their analyses. The authors argue that it is critical that trait integration level be taken into account, because “two species can be considered very different when looking at single traits, but they might actually display very similar resistance to a given environmental condition or competitive ability to a given resource.” They point out that whole-organism traits are more under the influence of environmental selection, while organ-level traits should be more evolutionarily conserved, making the former better predictors of performance.

“Both substitutable traits and alternative strategies can be considered as alternative organism designs,” write the authors, explaining that alternative designs may lead to trait divergence, which allows both adaptation to local conditions and coexistence within a community through different resource use strategies. They assert that incorporating the concept of alternate design may aid in understanding how both species and communities influence ecosystem function as a whole. “The open challenge,” they write, “lies in the identification of different trait combinations that cause species to have a similar performance in a given ecological condition.”