2.28: Refugia- How Life Goes On After Environmental Calamities

Refugia: How Life Goes On After Environmental Calamities

Even after any number of the great mass extinctions, life returned and flourished in abundance. Once the environmental calamity that caused the great mass extinction at the end of the Cretaceous Period ended, this allowed for the succession of living things from life forms that survived in place, or survived in refugia. A refugia is an area in which a populations of organisms can survived during an extended period of unfavorable conditions. Refugia are isolated or protected environmental setting that survive major climate changes—examples include:

• an unglaciated area on a south-facing mountain slope where plants and animals survive in isolation, surrounded by advancing continental glaciers.
• species surviving an isolated mountain peak cool and wet enough to allow some species to survive when surrounding lowlands change from forests to desert conditions.
• plants and animals that become isolated on islands when sea level rises, and relative species elsewhere are wiped out by disease and/or predation.
• a an isolated community surviving in a canyon with continuous water supply in a region of long-term extended drought.
• species living in an isolated bay far away from the annihilation caused by a massive asteroid impact elsewhere on the planet.

Many question remain why some species survive a mass extinction event. What was it about species turtles, snakes, crocodillians, birds, and mammals that allowed them to survive the K/T extinction event when all dinosaurs and other organisms did not?

Refugia In Our Modern Era

With the advance of human civilizations, we are witnessing unprecedented extinctions as cities and croplands replace forests and coastal plains. Some species are hunted to extinction, or environmentally sensitive species loose their refugia. Human activities, such as building interstate highways and expansion of urban corridors, are isolating populations that would otherwise be a part of a continuous breeding population across an area or region. For some species, surviving member of species now only exist in zoos or on isolated park lands and wildlife preserves. On the other hand, useful species, such as dogs, cats, goats, cows, chickens, etc., are protected, but are increasingly being genetically modified to suit the needs and interests of their human hosts.