Does the position in the river network influence the rarity and uniqueness of aquatic insects in tropical streams?

• Grant number: 23/18139-7
• Support Opportunities: Scholarships in Brazil - Master
• Start date: November 01, 2024
• End date: August 31, 2026
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Principal Investigator: Danielle Katharine Petsch
• Grantee: Caroline de Mello Correia
• Host Institution: Faculdade de Ciências e Letras (FCL-ASSIS). Universidade Estadual Paulista (UNESP). Campus de Assis. Assis , SP, Brazil

Abstract

The dendritic network structure of lotic ecosystems maintains high species diversity throughout their watercourses, including headwater and central areas. Headwater streams, located in the upper parts of dendritic networks, are more isolated but can harbor a great diversity of habitats and rare aquatic insects. Although most species are rare, they are more vulnerable to extinction than common species. The main objective of the research project is to investigate the relationships between the rarity of aquatic insects and the position of the stream in the dendritic network (i.e., headwater or central). We will investigate whether headwater streams (i) are composed of more rare species of aquatic insects than centrally positioned streams, and whether (ii) headwater streams have a greater contribution to beta diversity (LCBD), (iii) especially the more geographically distant. We also expect (iv) a greater contribution to beta diversity (SCBD) of rare species than more common ones. We will collect aquatic insects in 15 pairs of streams located in the Atlantic Forest conservation areas: a first or second order stream (headwater), and another third or fourth order stream (central position). We will estimate the occupancy and abundance of each species separately between central and headwater streams to perform a paired t-test. We will also estimate the variability of headwater streams and the central region using a multivariate dispersion analysis (PERMDISP). We will calculate the LCDB as its values are comparative indicators of the ecological uniqueness of the locations, and we will relate it to the geographic isolation of the headwater streams. Finally, we will analyze the relationship between SCBD and rarity in terms of abundance and occupancy.