Oviposition strategies of Amazonian dragonflies in response to anthropogenic gradients.

Abstract

Odonata adults exhibit diverse oviposition strategies influenced by environmental conditions. However, transformed landscapes may diminish suitable oviposition sites due to environmental homogenization. We hypothesize that local environmental factors play a pivotal role for endophytic and epiphytic species, which selectively choose microhabitats for oviposition, leading to a Clementsian pattern along the Habitat Integrity gradient (HII). Conversely, exophytic species, depositing eggs directly in water without specific habitat preferences, would display a Clementsian pattern within the catchment area, characterized by the Catchment Disturbance Index (CDI). We sampled 72 streams across an anthropogenic impact gradient in the Capim watershed, northeast Pará, Brazil, and evaluated the HII and CDI. Odonata species were categorized into endophytic, epiphytic, and exophytic groups based on literature information, and the distribution patterns of the Odonata metacommunity were evaluated using Metacommunity Structure Elements analysis. Our results showed variations in the metacommunity structure depending on reproductive strategies. Endophytic oviposition species exhibited Clementsian patterns at both local and regional scales. Conversely, exophytic species demonstrated a Gleasonian structure locally and regionally within the catchment area with an anthropogenic gradient. This study emphasizes the significance of dragonfly reproductive strategies for monitoring and conservation efforts. Furthermore, understanding the interplay between reproductive behavior and anthropogenic impacts provides valuable insights for effective conservation planning in Amazonian streams.