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Definition. Functional diversity (FD) measures differences in the physiological, behavioral, and ecological characteristics of organisms, and how biological trait values (such as body mass of animals, and life form or habit of plants) affect ecological and evolutionary processes. Knowledge about species traits and ecological functions (such as a species trophic level, and including the variation in traits within and among species) is a crucial component of biodiversity. However, this is one of the major shortcomings in current biodiversity knowledge, especially in tropical areas. Few studies to date have mapped large-scale patterns of functional diversity, although efforts in this direction are underway (see for fishes e.g., Arbour & López-Fernández, 2014; Toussaint et al., 2016). |
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Metrics and usage. Apart from the lack of data, the theory behind functional diversity is not yet well consolidated. We still do not know which traits are ecologically and evolutionarily important for different groups, how to compare traits for different sets of organisms, and how functional diversity affects ecosystem productivity, stability, and resilience, especially in the tropics. An additional shortcoming is associated with biotic interactions. Apart from basic information on pollination and dispersal syndromes, we know surprisingly little about most biotic interactions. Very few species interaction networks are available to date (Toju et al., 2017). |
