Science Additional- Speciation and Extinction

Extinction Extinction is officially defined as the disappearance of a species from the earth. Something pretty awesome about us humans is that we are intelligent enough to know about species that once existed. This is because some people have superpowers so they can look into the past!Haha... no that's a down right joke! Really, what we can do is use fossils which indicate the previous presence of a type of animal. Minerals replace the contents of the animal and preserves the shape and size of these old species even if the bones, teeth or shells can't remain as proof for us.Okay, so that's cool. We can learn about old species. But why does extinction even happen in the first place?This may be due to a number of factors: Let's see...1. There may be a disease which wipes out the entire population.2. Their may be a dramatic change in the climate or a natural disaster like a volcanic eruption which wipes out the population.3. There may be a new predator and due to natural selection, it may cause the old species to find it difficult to survive in such competition4. There may be a lack of prey or food.5. Some evil humans may destroy their habitats! :(6. A really weird one is the factor of speciation- and this means that the old species becomes extinct because a new species develops from it.Here, I'll explain it to you...

Speciation Speciation is a weird concept, but still very interesting. It all starts off with a single population of a specific specie. Then, a physical barrier may separate the specie into half. This may be a large river or a forest. So now the two groups of species are regarded as ISOLATED from each other. On one side of the whole land mass, the climate may alter. This means that one half of the species have to evolve in a different way to adapt to their new environment. They'll develop new physical characteristics which is all thanks to alleles (different forms of a specific gene. e.g.: gene= eye colour, allele= green eyes.)Eventually, the two populations may evolve so much that they can no longer breed together to form fertile off spring. The alleles which produce the beneficial characteristic are more likely to be passed onto the next generation, so this process is likely to continue. When two populations cannot do this, they're officially acknowledged as two different species. Wow! Quite a story that is! However, don't get confused. They may still be able to breed, but the key point is that the two populations cannot make FERTILE offspring. Rather, they can only make hybrids.

Speciation and Extinction!