How did climate and geologic changes create isolated relict populations of Lepidoptera?

Geologic and climatic changes have shaped the distribution of Lepidoptera by creating isolated, remnant colonies known as relict populations.1

During the ice ages, cold-adapted species expanded their ranges southward across vast areas of North America, Europe, and Asia. As the climate subsequently warmed, these populations were forced to retreat to survive. Many species migrated northward toward Arctic latitudes, while others moved uphill into high-altitude mountain ecosystems, where cooler temperatures persisted.21

These mountaintops effectively became "islands" of suitable habitat surrounded by warmer, inhospitable lowlands, preventing the isolated populations from reconnecting with their relatives. Consequently, these relict species have remained trapped in these restricted environments since the last glacial period. Additionally, broader geologic shifts have contributed to such isolation, as seen in regions like Australia and New Zealand, which harbor diverse relict populations of primitive moth families.12