Trait dimensions
We propose four basic trait dimensions to aid in linking rarity to
ecological processes: tolerance, movement, interactions, and life
history. These dimensions are based in part on the trait dimensions
proposed by for the study of metacommunities, and in part on concepts
from relevant macroecological theories. Tolerance captures the breadth
of conditions that a species can tolerate (or, conversely, the types of
conditions it requires). The interactions dimension includes both
interspecific and intraspecific interactions. These first two dimensions
overlap to some degree: for example, a plant’s requirement for light is
both a physiological requirement and a source of competitive
interactions. To distinguish between the two, we use tolerance for
non-consumable environmental conditions (e.g., pH, temperature), and
interactions for consumable resources (e.g., light, food, nesting
sites). Movement includes both dispersal and establishment, while life
history includes traits related to survival, mortality, sexual and
asexual propagation, ontogeny, and growth rates. Together, these four
trait dimensions capture numerous key ecological processes, including
demography (life history, interactions), colonisation (movement, life
history), density-dependence (interactions), competitive exclusion
(interactions), and environmental filtering (tolerance).