How would you describe evolution, I am studing biology and i have never been sure about the evolution theroy, sure some form of it does exist but now it works is different to what most people believe. I mean how do you explain how humans or any living things works and how evolution has made it that way
To put it simply - evolution is the change in species over time. The public's view on evolution though is more of a collection of things: Abiogenesis and speciation are ones which stand out
Right at the bottom we have mutations in the DNA. Some of these will be beneficial and will give this individual a slight advantage. This makes it more likely to survive and pass on that successful gene. Thus, the gene is likely to spread. Evolution is driven by selection pressures. Imagine a prey in the desert - they need to be hidden. An easy way is to blend in with the sand. Mortality rates will be higher for those less camouflaged, and so the gene for the sand colour becomes more widespread and may eventually become fixed in the population. Another example is antibiotic resistant bacteria. Bacteria have a high degree of variation. Many can exchange DNA between each other. If you use an antibiotic against the bacteria, a few may be resistant. They'll replicate to fill the gap of the dead bacteria. What's happening is a selection pressure is added against those that are not resistant to it, so populations of those that are will increase.
Speciation can occur in similar, but different ways:
Allopatric speciation is when a population becomes divided, so they can't interbreed. eg. Rising sea levels cause an island to be blocked off. We now have 2 populations and the mutations in each population are independent of each other. Selection pressures may differ. They will evolve differently until they are different species.
Parapatric speciation occurs when a small population adopts a slightly different niche. This can affect how the two types breed.
Sympatric speciation occurs when they are in the same area but they don't breed together (although it's physically possible). This could be if some plants begin to flower at a different time. Or perhaps some insects use a different host plant to breed on.
The eye is quite a well documented case on the evolution of a complex organ from a simple one. It's simply lots of small steps. In fact, the eye isn't perfect. It's actually inside-out! The light has to pass through many layers of cells associated with the nerves to reach the photoreceptors. We have a blindspot where the nerve to the eye joins because of this.
You'll do way, way better at the library.
