Explorando o nicho de peixes de água doce: Uma abordagem evolutiva e conservacionista em igarapés de terra firme Amazônicos

Abstract

The main threats to freshwater ecosystems and organisms are habitat alteration by anthropic impact. The vulnerability of these ecosystems has been discussed over the last decade; however, little attention has been given to protect these ecosystems. The most threatened vertebrates are the freshwater fishes, whose highest richness is in the Amazon basin, as the widest gap of information, especially for stream species. Species distribution modeling (SDM) has become an important tool in ecology, biogeography, evolution and conservation studies. SDM is based on a set of macroscale variables that determine the distribution of organisms. Thus, a set of environmental variables are used as an input for these models. However, insufficient attention is given to discussing the use of these environmental data for the modeling of aquatic organisms. Freshwater ecosystems are dependent on the surrounding landscape, and some models built with macroscale variables yielded similar results as models based on local variables for distribution of aquatic organisms. The knowledge of species ecological requirements could help understanding the local and/or regional biodiversity. Some authors attribute the high diversity of species in the tropics to conservation niche. They state that the diversity is due to the climatic stability of these regions, and that clades have more time to diversify. This tendency for close related species to have similar fundamental or realized niches is known as Phylogenetic Niche Conservatism. The conservatism of ecological niches could determine environmental conditions in which a taxon of a particular clade can be occupied by dispersing. Conversely, species that retain their niche for long periods of time could have difficulty adapting to environmental changes, and this characteristic could lead them to extinction. Thus, we tested whether the Amazon stream fishes are formally protected by the Amazon Protected Areas (PAs), the Megareserves.