Measuring the contribution of evolution to community trait structure in freshwater zooplankton

Abstract

There are currently few predictions about when evolutionary processes are likely to play an important role in structuring community features. Determining predictors that indicate when evolution is expected to impact ecological processes in natural landscapes can help researchers identify eco‐evolutionary ‘hotspots', where eco‐evolutionary interactions are more likely to occur. Using data collected from a survey in freshwater cladoceran communities, landscape population genetic data and phenotypic trait data measured in a common garden, we applied a Bayesian linear model to assess whether the impact of local trait evolution in the keystone species Daphnia magna on cladoceran community trait values could be predicted by population genetic properties (within‐population genetic diversity, genetic distance among populations), ecological properties (Simpson's diversity, phenotypic divergence) or environmental divergence. We found that the impact of local trait evolution varied among communities. Moreover, community diversity and phenotypic divergence were found to be better predictors of the contribution of evolution to community trait values than environmental features or genetic properties of the evolving species. Our results thus indicate the importance of ecological context for the impact of evolution on community features. Our study also demonstrates one way to detect signatures of eco‐evolutionary interactions in communities inhabiting heterogeneous landscapes using survey data of contemporary ecological and evolutionary structure.

Quantifying eco‐evolutionary contributions to trait divergence in spatially structured systems

“…More specific eco‐evolutionary hypotheses, for example whether or not populations with a longer history of exposure to a selection pressure (Ghalambor et al, 2007; Oostra et al, 2018), different selection pressures (Huang & Agrawal, 2016), or with a different degree of environmental variability (Chevin & Hoffmann, 2017; Reed et al, 2010) demonstrate a larger fraction of genetic evolution versus plasticity could be tested by comparing the different fractions to these site properties. For example, a recent study by Govaert et al (2021) demonstrated spatial variation in the contribution of evolution in a focal zooplankton species D. magna for community trait values and showed that this variation was better explained by ecological properties of the zooplankton communities in which the focal species was embedded than by its population genetic properties.…”

“…However, very few studies collected the necessary data to decompose all potential sources of trait shifts at the community level. We anticipate an increase in the number of studies that attempt to combine surveys of genetic and nongenetic trait variation at the population level with species composition and associated trait shifts at the community level (e.g., Govaert et al, 2021). The data gathered by such studies can be used to quantify the contributions of evolutionary and nonevolutionary processes to among‐site variation in community trait values, quantifying the structure of the evolving metacommunity.…”

“…Then the input required for these analyses might help determine which spatial modification should be used. For example, if calculated contributions for each population would be used further as a response variable in a regression analysis to assess whether these contributions are linked to particular site properties (e.g., environmental gradient or species diversity at a site; for an example see Govaert et al, 2021), then a common reference among spatially separated populations might be the preferred option. However, if one wants to compare contributions to pairwise differences between sites such as genetic distances between populations, then calculating pairwise ecological and evolutionary contributions between spatially separated populations is more preferable.…”

“…Therefore, spatially separated populations or communities may be structured by nonevolutionary (i.e., phenotypic plasticity and species sorting) and evolutionary processes. Quantifying these processes in spatial study systems may improve our understanding of how geographical, environmental, and community features structure evolutionary and nonevolutionary contributions to trait variation in populations and communities inhabiting natural landscapes (e.g., Govaert et al, 2021).…”

Inferring the ecological and evolutionary determinants of community genetic diversity

“…This model favours individuals with trait values that are farther from the local trait mean, in essence, individuals that dwell in unoccupied niche space, and should increase the variance in local trait values (see, e.g. Govaert et al, 2021). The functional form of both equations is structured such that the effect of different e s values is comparable between the two non‐neutral models.…”