Role Of Lizards: A Social And Ecological Perspective

Ms Ankita Rajpoot, Women Scientist (DST, WOSB) Zoological Survey of India, Dehradun

2016-11-04 12:52:53



Interesting facts about lizard: Lizards can be inactive more than half the year, particularly at high latitudes or high altitudes. Lizards are directly affected by the temperature if the lizard’s eggs were incubated in approx 25°C -27 °C it will develop in female and if the temperature is increased up to 30°C -35°C it will develop into the male. Therefore if the temperature increases continuously, the lizard population declines automatically.

Reptiles are a group of tetrapod, cold-blooded  animals found in almost all the parts of the world comprising three living orders- Crocodylia (crocodiles), Testudines (turtles and tortoises) and Squamata (lizards and snakes). Reptiles play an important role in the ecosystem regarding food chains, bio-monitors in controlling many pests and also as excellent ecological indicators due to their high degree of sensitivity to even a minor change in the environment. Reptiles are the important constituent of the food web in most ecosystems. They fill a critical role both as predator and prey species. Lizards are a widespread reptiles group of order Squamata with approximately over 6,000 species ranging across all continents. In India reported 518 species of reptiles which includes 34 species of turtles, 3 species of crocodiles, 202 species of lizards and tortoises, and 279 species of snakes belonging to 28 families recorded till date from India. 

When we saw a lizard in our house or garden the first question is stuck in our mind is that Do these lizards could have any positive role in our life? So we will find out the answer to this question in this article. Moreover, people fear or dislike Lizards; they tend to be killed whenever they are seen. Lizards are often misunderstood and large numbers of poisoning cases are blamed on this innocent creature for lack of knowledge. The wall lizard found in most homes in India is not poisonous at all. They don’t have any venomous apparatus and just helps in controlling the insect population. However, only two species namely, Heloderma suspectum and Heloderma horridum are poisonous (which are not found in India). The literature surveys indicated that gecko species from Hemidactylus feed on the various type of nocturnal insects and occasionally are cannibalistic, eat rice grain and appreciate sugar also, at times seeds of wild plants and rarely hibiscus flower too. In many countries, the wall lizard or gecko is a welcome house guest, chasing and eating many irksome insects. They walk the walls and ceilings and live their lives unharmed by peacefully understanding their niche. A recent research reported that geckos were the best link in controlling mosquitoes and other harmful insects. A species of lizard Hemidactylus frenatus (Common House Lizard) is of considerable importance as it is a predator for mosquitoes and has potential as a mosquito control measure. They feed on insects and control pests. The spiny-tailed lizard (Sara Hardwickii) is known as a friend of the farmer due to their capability to eats locusts which are pests of crops. Many lizards serve as prey for a variety of birds, including some of the small lizards also act as a prey for snakes and their own kind. Mostly Lizards are not harmful to our crops while lizards have traditionally been considered as a poor plant consumer due to their lack of particular adaption to this type of food. Lizards work as a biological pest control and helpful for farmers. When we go to a survey we noticed a that some agamids are found under the large rocks and inside the walls, they come out in agricultural land for feeding insects at around 11.00 am to 12.30 pm and they eat insects continuously and go back to their crevices in rocks/stones, where they reside and again they come out at around 3.00 pm for an hour to eat insects. This way they are serving as a pest control for crop cultivation in their range of distribution. The lizards become a exotic pet in Western Countries. So the authors suggest that our farmers can also pet the agamid lizards to control the insects as a biological pest control. Monitor Lizards act as potential biocontrol agents of pest rodents in plantation areas. Monitor lizards are main polyphagus predators of field rats. Local people in many parts of India protect the monitor lizards, recognising their beneficial roles as enemies of snakes.

Some herbivorous lizard species can also be important seed dispersers, particularly on Island Habitats. They are also known to act as a pollinator eg. Blue-tailed gecko (Phelsuma cepediana) is now the only pollinator for the rare plant Trochetia burniana on the Island of Mauritius, since the disappearance of the plant's key pollinator, the olive White-eye. Lizards are important for several reasons, including their medicinal value.

Lizards have been around since the time of the dinosaurs and since that time, innumerable species has been extinct but lizards survive with the environment, but now lizards are at serious risk of disappearing from the face of the earth as a result of climate change. According to a recent study, if global temperatures continuously rise as predicted approx 20% of the 3,800 species of lizards could be extinct by 2080. In some parts of the world, 12 percent of the lizard populations that have been studied since 1995 have already disappeared due to the climate change. Lizards are cold-blooded animals, their body temperature rises and fall with the environment. They have to bask in the sun to raise their body temperature, and seek shade when it gets too warm. If the external temperature rises continuously body temperature of lizards will also increase and not be able to stay out during the hottest part of the day to catch enough food, causing the animals to weaken and die. Habitat alteration is another major threat to the lizard species.  Forest species are more vulnerable due to their lack of ability to resist the high temperatures of open formations.  Most common and widely distributed species are more resistant, but many will disappear when their habitats are totally eliminated. Agrochemicals are another major threat and may be especially serious in small protected areas surrounded by agricultural land. The disappearance of lizard populations is likely to have repercussions up and down the food chain. Lizards are important prey for many birds, snakes, and other animals, and they are important predators of insects. We could see other species collapse on the upper end of the food chain, and a release on insect populations.

Some species of lizards declining due to habitat destruction and increase in temperature. Humans have directly disturbed most habitats resulting in reduced biodiversity and ecological changes. Hence efforts should be made to protect these lizards, and one way is to habitats protected from human exploitation. However, humans should play an active role in the management of ecosystems for fauna and flora conservation. The long-term effects of these threats need to be understood in order to delineate appropriate conservation strategies.