Variation and Evolution

• Variation in both genes and environment can lead to huge variation between different individuals and over time can lead to the evolution of new species by a process called natural selection.
• A group of individuals in a population are all different and in biology, this is referred to as variation.
• Genes code for proteins and a genome which is all of your genes combined codes for an entire organism.
• Each individual in the world has a unique genome which means they have slightly different combinations of proteins inside them and so they look different.
• The way we look and function isn't just due to our genes, it's also due to the environment that we're exposed to.
• Most of our characteristics are determined by the interaction of our genes and our environment.
• Most of our traits are influenced by lots of different genes and lots of different environmental factors.
• There are so many different environmental factors because we all do different things, eat different foods, and so on.
• The reason there are so many different genes is because of mutations, a mutation is a change in the DNA code so that the protein it codes for may be different.
• Most mutations don't actually have any effect on the proteins and so don't change the organism's phenotype at all.
• In those cases where mutations do change proteins, the phenotype may change slightly, this change will usually be something bad and unwanted but very occasionally the mutations are beneficial.
• Individuals with beneficial mutations are more likely to survive and are more likely to be able to reproduce and pass on their genes to the next generation.
• Charles Darwin observed that the fittest individuals are more likely to survive and this concept of survival of the fittest is a key part of the theory of evolution.
• The theory of evolution by natural selection describes how the inheritance of certain characteristics in a population over multiple generations can lead to changes in the whole species or sometimes even the development of an entirely new species.
• All current species must have evolved from different species sometime in the past.
• The theory of evolution by natural selection implies that all living species must have evolved from the simple life forms that first developed more than 3 billion years ago.
• Darwin's theory of evolution by natural selection took a long time to become properly accepted by the scientific community but it has now been proven multiple times over from things such as the development of antibiotic resistance in bacteria where we can literally see evolution taking place or by looking at fossil records.
• Evolution occurs through natural selection of certain genetic changes that give rise to the phenotypes that are best suited to the environment and given enough time the phenotypes of two different populations within a species may become so different that they can no longer interbreed to produce fertile offspring, at which point we can say that a new species has been formed.