Evolutionary adaptation and ecological community responses
In natural soils exposed to climate change, microbial evolutionary
adaptation is expected to interplay with ecological responses such as
species sorting or community shifts in species or functional group
abundances
(O’Brienet al. 2013; Boon et al. 2014; Strauss 2014). Indeed,
there is growing experimental evidence for soil bacterial communities
shifting, with functional consequences on decomposition, in response to
climate (Glassman et
al. 2018). This raises the challenge of assessing the relative
importance of evolutionary and ecological mechanisms in the response of
microbial decomposition to warming. Available empirical evidence suggest
that both could be significant. For example, recent experiments onPseudomonas bacteria showed that local evolutionary adaptation
was as important as community composition in shaping the community
response to elevated temperature over the course of a two-month
experiment (Gómez et
al. 2016).
Our model could be extended to integrate evolutionary adaptation and
ecological shifts in response to warming. To represent the functional
diversity of a microbial community exploiting a diversity of substrates,
different SOC pools could be included
(Wang et al. 2013),
alongside specifying different types of enzymes and different microbial
functional groups that produce them
(Allison 2012). In our
model parameterization, microbial functional groups would potentially
differ in traits such as MGE (\(\gamma_{M}\)), enzyme cost
(\(\gamma_{Z}\)) and uptake rate (\(v_{\max}^{U}\))
(Allison 2012), and
assuming heritable variation, the evolution of these traits would drive
the adaptive response of the microbial functional community to
environmental change. In an evolution experiment using Neurospora
discreta as a model system to assess adaptation of soil fungi to
warming (Romero-Olivareset al. 2015), Allison et al. (2018) did find evidence for
evolutionary responses in MGE and uptake rates. By letting multiple
traits evolve, our model extended to multiple substrates could be used
first to generate an evolutionarily stable community at a given
temperature (following Sauterey et al .’s
(Sauterey et al.2015) approach for including evolutionary dynamics in models of ocean
planktonic communities), and then evaluate both ecological and
evolutionary responses to warming.