Moving beyond body size in trait-based ecological prediction
Body size scales with key processes across all stages of environmental
filtering (e.g. desiccation tolerance, metabolism, prey consumption
rates, movement; Brown et al. 2004), so it is not surprising that
measures of organism size are applied so frequently in trait-based
ecology. While the inclusion of body size, particularly in descriptions
of food webs, has been of great benefit to describing ecological
structure and function (Woodward et al. 2005; Brose et al. 2006; Jacob
et al. 2011), this single trait explains a limited amount of variation
in terms of trait-driven biological and ecological processes. Moreover,
other morphological and physiological traits are also key mediators of
the influence of size, such as body shape and metabolic approach to
temperature regulation, respectively. Within size classes, variation in
key behavioural and life history traits can influence establishment and
persistence within ecological communities; for example, reproductive
behaviours are often incorporated into trait-based analyses that model
species’ and populations’ dispersal capabilities in changing and novel
ecosystems (Estrada et al. 2018). The inclusion of traits other than
body size can increase our understanding of current ecological community
structure/function (Gravel et al. 2016), but perhaps more importantly,
our ability to provide important insights for prediction of future
ecological states arising from ongoing global change. However, the role
of many behavioural, life history, physiological, and morphological
traits (other than size) identified in this review—ranging from
fecundity, to jaw strength, to flight initiation distance—are mediated
by organism size, illustrating the all importance of incorporating a
range of correlated traits into predictive analyses.