Elevational diversity pattern and allochronic divergence of scorpionflies in the Qinling Mountains

Scorpionflies (Mecoptera, Panorpidae) as a relict group of holometabolous insects normally inhabit dense vegetations of mountain regions in the northern hemisphere. They are vulnerable to temperature changes and deforestation and thus play a significant role in insect conservation as ecological indicators. However, their elevational distribution and seasonal emergence patterns remain largely unknown. We documented the elevational richness gradient of scorpionflies in the Qinling Mountains, central China. The result revealed a distinct pattern of mid-elevational peak (hump-shaped) in species richness. The linear relationship between elevational locations of the whole community and emergence dates showed a gradual movement from lower to higher elevations over time. Niche divergence is an important ecological mechanism for closely related species to co-exist in the same region. Our investigation showed that allochronic divergences of adult emergence occurred mainly in intermediate elevations to reduce interspecific competition for resources. Spatio-temporal niche divergence was also detected in closely related species, especially in Cerapanorpa scorpionflies. Our results showed a clearer pattern of elevational diversity of scorpionflies and indicated that niche conservatism and divergence could explain the richness pattern at the same time. The area of intermediate elevations with the greatest species richness should receive a priority consideration for insect conservation for such a cool-adapted group of insects.