Eusociality in a mammal (naked mole-rats) - Research Paper Example

Considering the three features of eusociality described above, naked mole-rats are the only eusocial mammals that we have ever known. Known taxonomically as Heterocephalus glaber, and belonging to group Rodentia of family Bathyergidae, the naked mole-rats are generally found in the hot, semiarid regions of Africa. They usually live in large colonies present underground in subterranean tunnels (Ciszek) where on average 75 mole-rats live in each colony. Only one female mole-rat reproduces by breeding with a few males of the community, while the rest of the males and females form the labor force which perform tasks like maintenance of colonies, nest building, transportation of soil, and defense.

The workers keep busy in construction and provision of food. Being sterile, they do not have a direct offspring but work cooperatively together to look after the offspring of the queen. However, as Ciszek states in his research, these workers are not “obligatory sterile”, meaning that they are capable of reproducing but when they have to live in colonies, they are not supposed to breed. But, if they are separated from their colonies, then they are able to actively reproduce. This is the concept of inclusive fitness (Hamilton 1; Axelrod and Hamilton 1390) according to which an individual is fit for reproduction even if he/she does not have a direct offspring.

This is the sharing of genes and the overall fitness is measured by also including the fitness of those who just share the genes even if they have not bred. Thus, the trouble that how the worker mole-rats are able to transmit their genes to the next generation if they are sterile, is solved through the concept of inclusive fitness according to which if the worker mole-rats share genes with their mother queen, then they are able to assist her in raising future queens thus enabling the workers to transmit their genes.

This assistance is a special feature of eusociality. Hence, we see close inbreeding in these mole-rats since there is high genetic similarity (Faulkes, Abbott and Mellor). This close inbreeding eliminates the chances of out-breeding in mole-rats which increases their relatedness to the queen’s offspring. This close genetic relatedness maximizes the workers’ potential to do more work. Jarvis (571) talks about frequent workers, infrequent workers, and non-workers. Frequent workers are those who are assigned the responsibilities of digging the soil, construction, maintenance, and food provision.

They make trips inside the colonies with food without taking pauses to eat themselves. Infrequent workers assist the frequent workers in work and make half the amount of effort frequent workers make. It is interesting that Jarvis found that the largest proportion of mole-rats is that of non-workers and that their roles are not clearly identified (571). He claims that the male members of these non-workers mate with the breeding female. He studied that since most of these non-workers are most of the time sleeping, thus the overall energy requirement for the colony is reduced.

Their main role, he guesses, is the assistance in the brought up of the offspring. Jarvin further affirms that female mole rats of all these categories are non-breeding and will never reproduce.