The distribution of life.

It is striking to a traveller that animals of one continent look totally different from others in another continent. The question to the biologists and all other people  like me, to which we seek an answer is that " what causes such differences? Or quite complex, what is the origin of the many different organisms that exist today?"

Quite clearer with scientific support, I will try to explain why the modern animals found in Africa are totally different from those that are found in south america and Australia despite the fact that all the three continents lie in the southern hemisphere with an almost same range of latitude. Then I will also answer the question why, unlike in the southern hemisphere, in the northern hemisphere, the animals look less or most similarly alike.

It is suggested that animals of the present southern hemisphere, all originated and migrated from the northern hemisphere. From there, they moved into Africa through the strait of Gibraltar; to south america via isthmus of panama, and to Australia via southeast Asia. Indeed, fossil records trace the ancestors of today's animals in the north. You may wonder if the animals of the three southern continents have the same origin inspire of their clear cut differences. Yes, the puma in south america and the lion in Africa have a common ancestor in the north. But what happened to cause these differences? The answer is that after migration, these animals underwent adaptive radiation in which they were isolated and became independently adapted to their new continents. It is those characters they evolved that they passed on to the next generation which we are seeing today.

Now you may have been in Asia and north america and realised, unlike here in Africa, Australia and south america, the similarity among their fauna. You may have got surprised or quite simply amazed or even astonished by the similarity. Perhaps it did not come to your mind, a question of the observation. But it was a good observation for which is worth the following explanation. It should be in your mind, if not already, that north america and Asia are separated by Bering strait. This strait is shallow and less than 100km wide. It is therefore obvious to realise that it was simpler for animals to migrate from either continents. May be I should echo that in the south, the difference was geared by total separation of the continents, which did not happen in the north.

If you are a reader of books, you stand a chance to have read about a reptile known as mesausorus. It has sharp teeth, long tail and webbed feet. In it, may be to a biologist, it is of no great interest. However, my interest lies in its distribution. In this world, it is found in two places: west of south Africa and east of south america. My question to you is that, " how did it reach south america given it migrated from Africa or there other way round?"

I know the explanation that gives a possible answer to the question. We cannot say that it migrated via the north leaving no fossil records behind. In the name of common sense, that is impossible! And it is unlikely possible to say that because it was well adapted to aquatic life, it swum. No one can ever believe that it swum over 3000 miles.( you bare me witness, it cannot happen).

So my explanation is explained by continental drift, which is the breaking up of land  mass. The truth is that when pangea(land mass) split up, that is when Africa split separate from south america, some of the reptiles remained in Africa while others drifted with the broken piece to form south america. Actually, my defence for my explanation is that, if you try to bring the map of the world into close proximity, you realise that each piece fits in another in form of a jigsaw puzzle. That is enough to make us understand that world was one large land mass.

Continental drift can also help me to explain to you why some organisms are restricted to defined places. Say for example  the primitive egg laying mammals, the monotremes  which are found in Australia and south america. We cannot say that they got into Australia from the north via south east Asia like I said above because they would be represented in the north too, but they are absent there. It said thus that they enters through Antarctica from south america to Australia. This is because the last pangea to break happened during the times of primitivity and that is why I did not use it to explain the distribution of modern animals.

If you want to understand more about the biology in our vicinity, you may contact me at reganlugoloobi@gmail.com.
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