Biology session

The protection of rare species is one important task of nature conservation. It is known that rarity increases the probability of disappearance of species. Despite rarity has several forms, it has not been considered enough when determining the conservation value of species. For example, species can be considered rare not only taxonomically but also functionally based on their ecological roles and functions. Discovering the pattern of taxonomic and functional rarity altogether might provide a basis of determining the vulnerability of assemblages and single species and possible effects of their disappearance. Streams are afflicted hardly by biodiversity decline. Although, only a few studies are concerned with the different forms of rarity in freshwaters.

We characterized the taxonomic and functional rarity of native fish fauna in Hungarian streams using a database that covers the whole area of the country. We examined the relationships between different forms of rarity. Also, we investigated how human-induced habitat alteration affects rarity.

We could not reveal a significant relationship between functional and taxonomic rarity. Functional uniqueness of species increased along the gradient of habitat alteration. As for taxonomic rarity forms, we found a diverse pattern.

The lack of relationship between taxonomic and functional rarity suggests the importance of better discovering and protecting the ecological roles of functionally unique species. We generated a species categorization that can help identifying both functionally and taxonomically rare species, which may directly help nature conservation efforts.