Answer:
Major greenhouse gases include carbon dioxide, methane, nitrous oxide, and various synthetic chemicals. ... Carbon dioxide occurs naturally as part of the global carbon cycle, but human activities have increased atmospheric loadings through combustion of fossil fuels and other emissions sources
The answer is Because they are able to adapt to different conditions.
The least specialized animals are those animals that can survive in a wide range of different environmental factors, unlike specialized animals which are very sensitive to changes. If environment changes suddenly and drastically, highly-specialized animals could not survive because those changes are beyond a range of different factors that affects them. The least specialized animals could adapt to different conditions. For example, one species (specialized) lives in a temperature of 20-25°C. The other species (the least specialized) lives in a range of temperature 5-50°C.
If temperature changes drastically from 22°C to 10°C, the specialized species could not survive and the least specialized would just adapt to those conditions.