Question

1. (3 pts.) From textbook. Lemmings are small rodents that live in the Arctic tundra. Their populations fluctuate wildly. At high population densities, large numbers leave their homes and travel long distances, during which time many die, some by drowning as they attempt to cross rivers and lakes. One popular explanation for their behavior is that the travelers are actually committing suicide to relieve overpopulation. By heading off to die, the suicidal lemmings leave shelter and food for those who stay behind. These surviving individuals will perpetuate their species, saving it from extinction. How could you use Gary Larson's cartoon (Figure 1.15) to evaluate the hypothesis critically (Hint: notice one lemming is different from the others)? Larson ANIMAL BEHAVIOR 9e, Figure 1.15

Answer 1

1. As being said in the question lemmings undergo mass suicide in order to prevent overpopulation. Lemmings are rodents and they are widely found in Arctic areas. However, the population of lemmings does fluctuate heavily. Every three to four years a large increase in the population of lemmings is observed. There are several myths that revolve around this subject. It was widely believed in the earlier years that lemmings fall from the sky like stars, which resulted in their abrupt and sudden increase in population. Another myth was that lemmings explode on getting raged, which further increases their population. Due to such manifold increase in population, the lemmings commit mass suicide. As shown in the figure which is a drawing made by Gary Larson who was an American cartoonist, it is seen that the lemmings are jumping off a cliff to plunge in water which will ultimately cause their death. As the picture shows, one lemming is wearing a life jacket which is symbolic of his survival. It symbolizes the survival of the fittest and that particular lemming will eventually survive and reproduce.

However, all of this is just a myth that was made and then kept on moving with generations. The real deal is that lemmings reproduce rapidly and due to that one area gets overcrowded. This overcrowding causes a shortage of food and other resources. As a result of that few lemmings shift from that place and find other locations for their survival. Even though lemmings can, few of them die in the process.

2. In this question, we are studying the anti-predatory behavior of lizards against the predatory behavior of snakes. Here the snakes being talked about will be mostly broad-headed snakes, as they prey on geckos and lizards. Broad-headed snakes have an odor that is responsible for the repelling behavior of lizards. On the other hand, small snakes mostly prey on skinks. Here as shown in the map, the grey area is the part where snakes and lizards co-exist and the study os made there. In order to study their behavioral characteristics, we need to collect a good number of specimens from the given location. After collection of the specimens, which are lizards, broad-headed snakes and small snakes we keep them in the laboratory in different setups. The lizards are kept in plastic containers. The snakes are kept in glass containers which had clear lids and proper ventilation. Here study is made to evaluate the retreat site selection made by the lizards in the laboratory and is compared to the retreat site selection of the lizards in the real world.

A rock was used for the analysis. A large amount of study and survey was done priorly on the rocks and the places where the lizards and the snakes co-exist. And depending on that survey, rocks in the laboratory were made to mimic like those of the field. A proper temperature, humidity, and everything were maintained manually in a controlled setup. After that, the lizards were made to interact with the setup. It was observed that the lizards did not go to the rocks which were snake scented. The lizards ignored both the broad snake scented rocks, as well as the small snake scented rocks which shows that both the snakes are of an equal threat to the lizard. .The lizard is unable to differentiate between the degree of danger between the two snakes This study is based on the olfactory response of the lizard which acts as an antipredatory behaviour against the snakes.