Contribution of rare genera of aquatic insects to functional diversity in streams with multiple land use in the Amazon

Understanding the contribution of rare biological groups to functional diversity, especially in systems impacted by land use, is fundamental to comprehend the biodiversity patterns and establish more efficient conservation strategies. This study mainly aimed to identify the contribution of rare aquatic insects to functional diversity in environments of the forest, logging, and pasture. A total of 7517 immature insects were collected from 32 streams in the Amazon forest: the rare genera were classified by a rarity index and represented just over 2% of the sampled individuals. The results showed that there was a difference in the composition of aquatic insects among the land use. In streams of logging, there was greater functional dispersion and the rare genera presented functional characteristics sensitive to water temperature increase and channel width. The contribution of rare and common insects in the forest, pasture and areas of logging was equal. This study highlights the necessity for long-term studies since the loss or replacement of rare taxa is, among other factors, driven by environmental filters, which tend to simplify communities and reduce the functionality of the system.