Selection is the simplest way to explain Darwin's theory.
Animals produce offspring at a much more rapid rate than can possibly survive. Because of this, there is a constant struggle to survive. Think survival of the fittest. The ability for certain animals to survive is called selection.
-Natural selection-
Natural selection is the survival of animals based on their physical characteristics. Say there is a type of bird whose primary food source is deep underground. The birds with short beaks, who can't reach the food, die out quickly. However, the birds with long beaks can reach their food. The only birds to mate with are those who also have long beaks. The trait of long beaks will get passed form both parents to their offspring. Eventually, only birds with long beaks survive. This sort of bird, which started as all short- beaked, are all now long beaked birds. It is changes like these, in reaction to their environment, that changes animals slowly, very slowly over time.
Animals produce offspring at a much more rapid rate than can possibly survive. Because of this, there is a constant struggle to survive. Think survival of the fittest. The ability for certain animals to survive is called selection.
-Natural selection-
Natural selection is the survival of animals based on their physical characteristics. Say there is a type of bird whose primary food source is deep underground. The birds with short beaks, who can't reach the food, die out quickly. However, the birds with long beaks can reach their food. The only birds to mate with are those who also have long beaks. The trait of long beaks will get passed form both parents to their offspring. Eventually, only birds with long beaks survive. This sort of bird, which started as all short- beaked, are all now long beaked birds. It is changes like these, in reaction to their environment, that changes animals slowly, very slowly over time.
-Sexual selection-
Sexual selection is selection based on interest for potential mates. The mating calls of birds, or the show of feathers in peacocks show off the genes in that individual animal. A peacock with a particularly nice set of feathers, and therefore a nice set of genes, will have no problems finding a mate. In this way, we get animals with better and better genes because the unappealing animals never get a chance to produce offspring. So with sexual selection we have prettier, stronger animals now than we had in the past.
Sexual selection is selection based on interest for potential mates. The mating calls of birds, or the show of feathers in peacocks show off the genes in that individual animal. A peacock with a particularly nice set of feathers, and therefore a nice set of genes, will have no problems finding a mate. In this way, we get animals with better and better genes because the unappealing animals never get a chance to produce offspring. So with sexual selection we have prettier, stronger animals now than we had in the past.
-Artificial selection-
Artificial selection is basically breeding. Dogs are the perfect example of artificial selection. Everything from a Great Dane, to a Labrador, to a Poodle were all bred form a wolf. Humans bred wolves based on their appealing qualities. Some dogs were bred to hunt, some to retrieve, others just for human companionship. Humans have achieved dog's evolution in just a few thousand years- a very short time compared to the millions of years to evolve other animals.
Artificial selection is basically breeding. Dogs are the perfect example of artificial selection. Everything from a Great Dane, to a Labrador, to a Poodle were all bred form a wolf. Humans bred wolves based on their appealing qualities. Some dogs were bred to hunt, some to retrieve, others just for human companionship. Humans have achieved dog's evolution in just a few thousand years- a very short time compared to the millions of years to evolve other animals.
