Swarming caddisflies in the mid-cretaceous

Area of Science:

• Paleontology
• Evolutionary Biology
• Entomology

Background:

• Swarming behavior in extant caddisflies (Trichoptera) is well-documented, but its evolutionary history is unclear due to limited fossil evidence.
• Distinguishing fossil aggregations as swarms versus other formation factors is challenging.

Purpose of the Study:

• To investigate the evolutionary origins and loss of swarming behavior in caddisflies using fossil evidence.
• To identify specific traits indicative of swarming in fossil aggregations.

Main Methods:

• Description of five new fossil species of caddisflies from mid-Cretaceous amber, preserved in aggregations.
• Identification of swarms based on wing shape and sexual dimorphism.
• Phylogenetic reconstruction using molecular and morphological data, ancestral-trait reconstruction, and tip-dating analysis.

Main Results:

• Five new species of aggregated caddisflies from Cretaceous amber are described, identified as swarms.
• Phylogenetic analyses suggest swarming was a feature of the ancestral caddisfly (Trichoptera) in the Triassic.
• A correlation was found between the rise of nocturnal bat predators and the loss of swarming in various caddisfly clades.

Conclusions:

• Swarming behavior in caddisflies has ancient origins, dating back to the Triassic.
• Bat predation significantly impacted the evolution of caddisfly behavior, leading to the loss of swarming in some groups during the Cenozoic.