The role of observation scales, trait correlations and competitive
regimes in community assembly patterns
- Matthias Rohr,
- Wilfried THUILLER,
- Loïc Chalmandrier,
- Tamara Munkemuller
Matthias Rohr
Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, LECA
Corresponding Author:matthias.rohr@univ-grenoble-alpes.fr
Author ProfileWilfried THUILLER
Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, LECA
Author ProfileLoïc Chalmandrier
Laboratoire Interdisciplinaire de Physique
Author ProfileTamara Munkemuller
Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, LECA
Author ProfileAbstract
Inferring assembly processes from empirical community diversity patterns
has always been a major goal in Ecology. Many empirical studies rely on
the "filtering framework", which characterizes community assembly as a
sequence of abiotic and biotic filters. The success of the ecological
filtering framework lies in its theoretical foundation, linking
environmental filtering to niche theory, and competitive interactions to
coexistence theory. Empirical studies have provided evidence of
environmental filtering in a wide range of environments. However, while
competitive interactions are omnipresent, few applications of the
filtering framework found significant evidence of competition in
real-life settings. Consequently, the framework has been criticised for
being overly simplistic. We argue that this unbalanced picture is likely
due to specific conceptual challenges. First, many traits are commonly
used in empirical work without a clear distinction between traits that
capture species responses' to the environment vs. traits that capture
the competitive interactions between species, and without consideration
of how these two sets of traits may co-vary. Second, it neglects that
environmental filter and competition can produce the same traits
patterns. Third, the spatial scale at which the community is observed
strongly impacts the resulting patterns. Here, we explore these three
conceptual challenges and test how trait patterns vary depending on
different assembly processes, traits and scales vary. Using a
theoretical simulation model, we demonstrate that the trait patterns
resulting from environmental filtering and competition respond
differently to variations in traits' correlation structure and
observation scales. We then identify the actual conditions in which it
is possible to distinguish signals of distinct assembly processes from
patterns, given the correlation and relevance of traits and the inherent
constraints of the observational scale.