Breeding out of water: life history adaptations of endemic Andean–Patagonian caddisflies in temporary wetlands

Abstract

The association between certain life history traits and species that inhabit temporary aquatic environments is a common pattern among invertebrates. This study examines the life history traits of two endemic genera of Patagonian limnephilid caddisflies that breed in temporary habitats: Verger Navas, 1918 and Austrocosmoecus Schmid. I studied reproductive phenology and egg mass characteristics across five wetlands in northwest Patagonia. A set of experiments was conducted to assess the desiccation tolerance of egg masses. Oviposition occurred between early February and late March; egg masses were found in microhabitats where relative air humidity was at least 50%, temperatures being lower in Austrocosmoecus than Verger microhabitats. Verger egg masses were often observed beneath herbaceous vegetation, while Austrocosmoecus masses were typically found under leaf litter. Egg masses of Verger were smaller than those of Austrocosmoecus but contained more eggs, which were smaller in size; newly hatched Verger larvae were also smaller than those of Austrocosmoecus. The egg masses of both genera demonstrated a degree of desiccation tolerance, but Austrocosmoecus exhibited higher survival rates across all desiccation treatments. Egg masses and early larval stages were found in the dry sediments of all wetlands, suggesting that the latter may act as refuges for these life cycle stages.