Too hot for them

The Hindu , Tuesday, November 05, 2013
Correspondent : J. SUBRAMANEAN
Do you scream when you see a lizard? Read on to find out why lizards are important to us. Text and pictures J. Subramanean

Lizards are reptiles that primarily eat insects. However, some lizards do eat other vertebrates and sometimes even plants. Most lizards are herbivores. But some like the Komodo dragon in the Indonesian islands, feed on mammals.

In the shade

Lizards are ectotherms, meaning their activity depends on their external temperature. Global warming is the increase of Earth’s average surface temperature due to effect of greenhouse gases, such as carbon dioxide emissions from burning fossil fuels or from deforestation, which trap heat that would otherwise escape from Earth. This is a green house effect.

Lizards respond to global warming in two ways: adapt and survive, or die. In temperate zones like North America, lizards are vulnerable to climate change. Their reproduction is closely tied to narrow windows of time in the spring and summer. Heat does not kill the lizards but instead it prevents them from reproducing.

In tropical countries like India lizards cannot regulate their body temperature. On hot days, they tend not to move around much, preferring to laze in cool burrows so as not to get too hot. Global warming causes the weather to get hotter and stay hotter longer and lizards, especially species that live in the tropical areas spend more time seeking refuge out of the sun. Staying in the shade for such long periods causes irreparable damage to the breeding cycle and eggs do not hatch.

The disappearance of the lizard population is likely to cause a break in the food chain. Lizards are important prey for many birds, snakes, and other animals, and they are important predators of insects. Thus they are an important part of the food chain.

Climate change is occurring too rapidly for lizards to compensate with physiological adaptations to higher body temperatures.


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