Functional diversity in fish assemblages of the Tropical Eastern Pacific Ocean: A review of two decades of progress in the functional diversity approach

Background. One of the most relevant topics in ecology and evolution is understanding the relationship between biological and functional diversity at the ecosystem level; both important in the evolutionary processes and the structuring of complex communities. Goals. In this essay, the explanatory hypotheses focused on global patterns of the distribution of species are described along with selected hypotheses relating species richness/biodiversity to ecosystem function, and the differentiation of the terms guild and functional group are discussed. Methods. Both biodiversity and functional diversity are key in the evolutionary processes and the structuring of complex communities and thus examples of functional equivalence of convergent evolution derivatives are presented in terms of the form and ecological habits of fishes of the Tropical Eastern Pacific Ocean. Finally, the importance of redundancy in ecosystem functioning is examined as well as the impact of environmental disturbances on ecosystem function. Results. In general, systems with low species richness and redundancy within functional groups are more vulnerable to disturbances. However, despite the extensive effort to understand the relationship between species richness/biodiversity and ecosystem functioning, there is no consensus on the effect of species loss on the functioning of the ecosystem. Some hypothesize that each species is unique and plays a unique role in the ecosystem whereas alternate hypotheses indicate that species overlap in function supporting sustainability at the ecosystem level, such that the removal of one species function may be replaced by another. Conclusions.The most widely accepted concept is that a greater number of species increases the efficiency in the use of resources and also provides resilience against environmental changes or impacts through functional redundancy.