Natural Selection
Natural selection is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift.
Darwin's grand idea of evolution by natural selection is relatively simple but often misunderstood. To find out how it works, imagine a population of beetles:
- There is variation in traits.
For example, some beetles are green and some are brown. - There is differential reproduction.
Since the environment can't support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do. - There is heredity.
The surviving brown beetles have brown baby beetles because this trait has a genetic basis. - End result:
The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. If this process continues, eventually, all individuals in the population will be brown.
If you have variation, differential reproduction, and heredity, you will have evolution by natural selection as an outcome. It is as simple as that.
When discussing about the animals there are 5 steps of Natural Selection. They include:
1. Variation: individuals within a population that have differences in their characteristics
2. Overpopulation: leads to lack of resources needed
3. Competition: Have to struggle for existence
4 'Survival of the Fittest': Those suited to environment survive
5. Passing on your genes: Those with 'fit' genes reach reproductive age and pass genes to offspring
Selection Pressure
Selection pressure can be regarded as a force that causes a particular organism to evolve in a certain direction. It is not a physical force, but an interaction between natural variation in a species and factors in its environment that cause a certain form to have an advantage over the others. This can be thought of as a “pressure” that pushes the evolution of that organism toward a greater prevalence of this variation.
Evolution and Natural Selection is when organisms reproduce, random mutations can occur, which cause the offspring to vary in some way from their parents. These changes may be damaging, but they may sometimes give an advantage. For example, a change that allows an animal to run slightly faster may increase its ability to catch prey or to escape predators.
A favorable mutation may increase an individual’s chances of surviving long enough to reproduce and pass this new trait on to its offspring, and so it will become more common. Eventually, all members of the species may have this characteristic. Unfavorable mutations quickly disappear, as they are less likely to be passed on to the next generation.
A classic example of selection pressure in action is the case of the peppered moth. Until the middle of the 19th century, almost all specimens of this insect were light colored. It spent a lot of its time resting on tree trunks, and blended in well with the light colored lichens that grew there. In urban areas, however, industrial pollution began to kill off the lichens, and darken the tree trunks with soot. A dark form of the moth that was better camouflaged rapidly became more common, until almost all specimens collected in urban areas were dark.
Attempts by humans to control undesirable organisms can sometimes result in a selection pressure that leads to new forms that are resistant to the methods used. For example, insect pests that are resistant to insecticides, and weeds that are unaffected by herbicides have been seen to emerge. Some other examples of man’s influence are more worrying. The widespread use of antibiotics has resulted in some disease-causing bacteria to evolve into strains that are resistant to many of these compounds.
'Survival of the Fittest'
Selection pressure can be regarded as a force that causes a particular organism to evolve in a certain direction. It is not a physical force, but an interaction between natural variation in a species and factors in its environment that cause a certain form to have an advantage over the others. This can be thought of as a “pressure” that pushes the evolution of that organism toward a greater prevalence of this variation.
Evolution and Natural Selection is when organisms reproduce, random mutations can occur, which cause the offspring to vary in some way from their parents. These changes may be damaging, but they may sometimes give an advantage. For example, a change that allows an animal to run slightly faster may increase its ability to catch prey or to escape predators.
A favorable mutation may increase an individual’s chances of surviving long enough to reproduce and pass this new trait on to its offspring, and so it will become more common. Eventually, all members of the species may have this characteristic. Unfavorable mutations quickly disappear, as they are less likely to be passed on to the next generation.
A classic example of selection pressure in action is the case of the peppered moth. Until the middle of the 19th century, almost all specimens of this insect were light colored. It spent a lot of its time resting on tree trunks, and blended in well with the light colored lichens that grew there. In urban areas, however, industrial pollution began to kill off the lichens, and darken the tree trunks with soot. A dark form of the moth that was better camouflaged rapidly became more common, until almost all specimens collected in urban areas were dark.
Attempts by humans to control undesirable organisms can sometimes result in a selection pressure that leads to new forms that are resistant to the methods used. For example, insect pests that are resistant to insecticides, and weeds that are unaffected by herbicides have been seen to emerge. Some other examples of man’s influence are more worrying. The widespread use of antibiotics has resulted in some disease-causing bacteria to evolve into strains that are resistant to many of these compounds.
'Survival of the Fittest'
The 'Survival of the Fittest' means the continued existence of organisms which are best adapted to their environment, with the extinction of others, as a concept in the Darwinian theory of evolution.
The term 'Survival of the Fittest' is similar to Natural Selection, it's just a phrase used. Natural selection is more of an evolutionary process, where living things change over generations to adapt to their environment. For example, some birds live where they have no natural enemies, so over time they lose their ability to fly and ultimately their wings diminish or even disappear. Survival of the fittest is the process of weeding out the weak of a breed of animal by predators killing them since they are easier targets. Ultimately, in theory, animals in a herd that are genetically least healthy will be eliminated, leaving the herd as a whole genetically stronger. These are simple answers, but hopefully it help you distinguish between the two terms.
The term 'Survival of the Fittest' is similar to Natural Selection, it's just a phrase used. Natural selection is more of an evolutionary process, where living things change over generations to adapt to their environment. For example, some birds live where they have no natural enemies, so over time they lose their ability to fly and ultimately their wings diminish or even disappear. Survival of the fittest is the process of weeding out the weak of a breed of animal by predators killing them since they are easier targets. Ultimately, in theory, animals in a herd that are genetically least healthy will be eliminated, leaving the herd as a whole genetically stronger. These are simple answers, but hopefully it help you distinguish between the two terms.