Modelling the ecological niche from functional traits

Abstract

The niche concept is central to ecology but is often depicted descriptively through observing associations between organisms and habitats. Here, we argue for the importance of mechanistically modelling niches based on functional traits of organisms and explore the possibilities for achieving this through the integration of three theoretical frameworks: biophysical ecology (BE), the geometric framework for nutrition (GF) and dynamic energy budget (DEB) models. These three frameworks are fundamentally based on the conservation laws of thermodynamics, describing energy and mass balance at the level of the individual and capturing the prodigious predictive power of the concepts of 'homeostasis' and 'evolutionary fitness'. BE and the GF provide mechanistic multi-dimensional depictions of climatic and nutritional niches, respectively, providing a foundation for linking organismal traits (morphology, physiology, behaviour) with habitat characteristics. In turn, they provide driving inputs and cost functions for mass/energy allocation within the individual as determined by DEB models. We show how integration of the three frameworks permits calculation of activity constraints, vital rates (survival, development, growth, reproduction) and ultimately population growth rates and species distributions. When integrated with contemporary niche theory, functional trait niche models hold great promise for tackling major questions in ecology and evolutionary biology.

Dynamic energy budget theory restores coherence in biology

“…With this model they detected food preferences in cockles and mussels, inferring the importance of detritus and intraspecific competition under field situations. Kearney et al (2010) position DEB theory in a wider ecological setting, linking it to the theories of biophysical ecology and the Geometric Framework for Nutrition. The combination of these fields stimulates the development of models at their interfaces that can shed more light on the detailed interaction of organisms and their environment.…”

“…There are several DEB solutions to this problem. Kearney et al (2010) consider that food quality required by the individual depends on size. Large individuals mainly have to cover their maintenance cost (reproduction is low at the carrying capacity, where competition is strongest) while small individuals need to grow.…”

“…Lorena et al (2010) use SUdynamics to model the co-limitation of photosynthesis by light and carbon dioxide and the co-limitation of growth by a carbon and nitrogen reserves. While Kearney et al (2010) use SU-dynamics to transform food into separate nutrient reserve pools, and then regulate the assignment of reserves mobilized from each pool into maintenance, structure, maturity maintenance and reproductive output.…”

Micro-scale environmental variation amplifies physiological variation among individual mussels

“…Further complexity arises when considering the often substantial degree of micro-scale variation in how individual organisms experience their environment [4,11], a pattern that likely interacts with genetic variation to contribute to variation among individuals in the physiological capacity to cope with environmental variation. In the context of thermal stress, such considerations have fostered a renewed emphasis on the causes and consequences of spatial and temporal patterns of variation in body temperature per se, in lieu of reliance on habitat temperatures and 'climate envelopes' [12,13].…”

Influence of environmental factors and biogenic habitats on intertidal meiofauna

“…Helmuth, 1998), in small organisms like meiofauna it is not possible to get highresolution series of BT due to their miniscule size. As a main consequence, we obtained the BT for these small organisms via a modelling approach, applying the Helmuth (1998Helmuth ( , 1999) biophysical heat budget model (BE) (Kearney et al, 2010;Sarà et al, 2011Sarà et al, , 2013. We know that many intertidal organisms live very close to their physiological limits, particularly in the intertidal zone, where they contend with both BT and food acquisition.…”