Can Animals get smaller or bigger depending on the environment? - VastlyCurious

     Have you ever pondered on why all the animals of the same species are of a similar size? Well, firstly they are not the same size. Have you ever heard of the term foster's rule or island rule? This theory states that when animals become isolated on an island, they undergo extreme changes in body size and this is due to the increase or decrease in the resources such as water and food. 

    So the dog-sized elephants could be real as shown in the movie 'Journey to the Center of the Earth'? Well, actually, yes.

Animals of Weird Sizes

    Since now we are experiencing the difficulties of living in isolation and not staying connected to our community, we can actually understand the position of animals that are living on isolated islands and staying not connected to their group. The theory behind foster's rule is that the island creatures evolve into smaller body sizes, whereas the others become larger in size.

What is Island rule?

    Island rule states that when members of species are isolated, the smaller animals had become larger but larger animals became smaller. Dr J Bristol Foster compared several island animals to their normal variants.

 He proposed that smaller creatures get larger because there is no predator pressure because of the absences of predators on the isolated islands and the larger creatures become smaller when the food resources are inadequate to them because of the smaller size of the islands.

Do Animals get big when Isolated?

     The smaller animals such as rodents had become larger when they are on isolated islands. Because the new environment is more suitable for them to live in and they often will find the resources more than adequate. There will also be no competition for food and water and there will be also no fear of predators as they are isolated. Since they are no competition for food, the individuals can grow above their maximum potential.

     When the Catalina ground squirrels arrived on the island, they were the only species of squirrels on the entire island and there were no natural predators there. This led the Catalina ground squirrels to grow larger than all the mainland squirrels.  

Giant Panda

Do Larger Species get dwarf?

    Curiously, they get smaller in size because, in the case of larger carnivores and larger animals, the islands, they live in have limited resources that simply could not support the animals of their size since the bigger the animal is, the more resources it might need. So the only way for these animals to survive. It is called Island dwarfism.

    Plus, it has its own benefits such as earlier reproduction and it will pose greater resistance to its extinction, as they become abundant when they get reduced in size.

Channel Island fox

    The living example of the island rule is the channel island fox. It is actually a direct descendant of the North American Gray fox, but it shrank due to the lack of resources. The Channel Island foxes are only half the size of grey found on the mainland.

Conclusion

    What a fascinating world it is! There seems to be too much that we don't know about nature and the concept of evolution. Animals tend to increase or decrease their body growth based on the environment. It is based on the environment and also the predator pressure. Can't wait to see what species behave when they are isolated.