| A region's climate may alter over time becoming | | | | strategies include heat avoidance (by going |
| hotter, cooler, drier or wetter. Natural selection will | | | | underground, or into water), or sweating and |
| determine the organisms with characteristics | | | | panting to induce evaporative temperature reduction. |
| appropriate to the new climate. Over hundreds and | | | | Plants must adapt to heat and drought by using leaves |
| thousands of generations constant minute changes will | | | | to minimise heat stress and water loss. |
| eventually lead to a new species that can survive and | | | | In cold climates, some endothermic animals continue to |
| thrive in the altered climate. | | | | be active at night and during the winter, but eat |
| The success or failure of an organism is reliant upon its | | | | constantly to keep their core temperature steady. |
| ability to reproduce young that mature to produce | | | | Some other approaches adopted by endotherms |
| more young. Only the young with the greatest survival | | | | include minimising heat loss with body insulation such as |
| traits for any given habitat will endure. These surviving | | | | fat, feathers or hair, or avoidance of adverse |
| young will transfer their adaptive characteristics to the | | | | temperatures by migration to a cooler environment or |
| subsequent generations. This process is known as | | | | burrowing underground, or reducing body temperature |
| natural selection. | | | | by hibernating. |
| If climatic or environmental changes occur too abruptly | | | | But even man, so often adaptable to the conditions |
| some species may not be able to adapt quickly | | | | we find ourselves, can be vulnerable to rapid climatic |
| enough and can become extinct. This has become a | | | | change. The Icelandic Vikings that settled on the south |
| large problem in recent times with human altered | | | | western coast of Greenland in the 10th Century |
| environments changing so rapidly that there has been | | | | eventually died out within 500 years as they were |
| an ominous rise in the extinction rate. | | | | caught by the grip of the Little Ice Age. This was a |
| Birds and mammals are warm-blooded (endothermic). | | | | period of cooling after a warmer period, known as the |
| This means they can keep their body at a fairly | | | | Medieval Warm Period. The Little Ice Age brought |
| constant, warm temperature by processing body fat | | | | bitterly cold winters to the Northern Hemisphere and |
| and carbohydrates. All other groups of animals are | | | | the Greenland Viking colonies died out simply because |
| termed ectothermic as their body temperature is | | | | they could no longer grow enough food there to |
| dictated by the temperature of the environment | | | | support themselves. They had arrived on Greenland in |
| around them. The term cold-blooded is used to | | | | much more favourable climatic times. |
| describe ectotherms, but this is something of a | | | | So whether endothermic or ectothermic life has a |
| misnomer, particularly in hot, arid climates. As an | | | | way of surviving, and although our current global |
| example a "cold-blooded" lizard basking in the hot | | | | warming trend is a serious cause for concern, the |
| midday sun can easily increase its body temperature | | | | earth has seen it all before, and I am sure life will |
| to over 100 degrees F, giving it warm blood. | | | | endure. |
| In warm climates organisms need to cool off. Animals' | | | | |