Question

In addition to their use for hearing, ears contain many blood vessels that allow heat to escape into the air. Animals that live in warm climates tend to have ears with large areas exposed to the environment. Animals in cold climates have a more compact ear that keeps exposure to the environment to a minimum. The photographs below show a jackrabbit from desert regions of the southwestern United States and a fennec fox from northern Africa with large ears, and a snowshoe hare and an arctic fox with small ears. Discuss how differences in ear size in these organisms might have occurred. In your answer, be sure to:

A) Explain how the size of these animals' ears can help the animals survive in their environment.
B) Identify one process that most likely resulted in the animals in warm climates having large ears, while animals in cold climates have small ears.
C) State how the overproduction of offspring in each species for many generations contributed to the presence of different ear sizes.

Answer 1

Variations in ear size among mammals in warm and cold climates result from the process of natural selection, where larger ears aid in dissipating heat in hot environments, and smaller ears help in conserving heat in cold environments. Over many generations, species with beneficial traits have a higher survival rate and are more likely to pass on these traits to their offspring.

Step-by-step explanation:

The difference in ear size among animals living in different climates can be explained through the process of natural selection. In environments with hot climates, such as those inhabited by the jackrabbit and the fennec fox, animals benefit from having larger ears. These large ears have an extensive network of blood vessels that promote heat dissipation through vasodilation, thereby preventing overheating. Conversely, smaller ears, as seen in animals like the snowshoe hare and the arctic fox, reduce the amount of heat lost to the environment in cold climates, thus conserving warmth.

The contribution of the overproduction of offspring to the presence of different ear sizes is significant. Over many generations, each species produces more offspring than the environment can support. Those with genetic variations suitable for their habitat's thermal conditions - larger ears for heat release in warm climates or smaller ones for heat conservation in cold climates - are more likely to survive, reproduce, and pass these advantageous traits onto their offspring. This selection pressure over time results in populations with ear sizes adapted to their respective climates.