The process of natural selection causes evolution. what is changing over time?

Evolution is a process that results in changes in the genetic material of a population over time. Evolution reflects the adaptations of organisms to their changing environments and can result in altered genes, novel traits, and new species. Evolutionary processes depend on both changes in genetic variability and changes in allele frequencies over time.

The study of evolution can be performed on different scales. Microevolution reflects changes in DNA sequences and allele frequencies within a species over time. These changes may be due to mutations, which can introduce new alleles into a population. In addition, new alleles can be introduced in a population by gene flow, which occurs during breeding between two populations that carry unique alleles. In contrast with microevolution, macroevolution reflects large-scale changes at the species level, which result from the accumulation of numerous small changes on the microevolutionary scale. An example of macroevolution is the evolution of a new species.

One mechanism that drives evolution is natural selection, which is a process that increases the frequency of advantageous alleles in a population. Natural selection results in organisms that are more likely to survive and reproduce. Another driving force behind evolution is genetic drift, which describes random fluctuations in allele frequencies in a population. Eventually, genetic drift can cause a subpopulation to become genetically distinct from its original population. Indeed, over a long period of time, genetic drift and the accumulation of other genetic changes can result in speciation, which is the evolution of a new species.

Natural selection is Darwin’s most famous theory; it states that evolutionary change comes through the production of variation in each generation and differential survival of individuals with different combinations of these variable characters. Individuals with characteristics which increase their probability of survival will have more opportunities to reproduce and their offspring will also benefit from the heritable, advantageous character. So over time these variants will spread through the population.

Describe the process of evolution by means of natural selection

Natural selection is the process by which species adapt to their environment. Natural selection leads to evolutionary change when individuals with certain characteristics have a greater survival or reproductive rate than other individuals in a population and pass on these inheritable genetic characteristics to their offspring (Survival of the Fittest). Simply put, natural selection is a consistent difference in survival and reproduction between different genotypes, or even different genes, in what we could call reproductive success.

What happens is:

• A mutation occurs
  
• If the mutation is beneficial, the animal will survive longer and reproduce more
  
• Some of its offspring will inherit the mutation
  
• These offspring will also have better chance of survival, meaning they live longer and reproduce more
  
• Over a long period of time this process is repeated and gradually the mutation becomes a common gene in a species and those with the mutation become the only ones, as those without cannot compete with those expressing the mutated gene
  

Describe variation and state that competition leads to differential survival of, and reproduction by, those
organisms best fitted to the environment

Some of the characteristics possessed by an individual in a population can be said to be inherited.  These characteristics are passed on as a result of sexual reproduction. Sexual reproduction also introduces an element of randomness, so that variation is brought about in a population. These two almost contradictory factors - dependable inheritance of characteristics from parents, and variation within the population - are essential to an understanding of the process of evolution.

Assess the importance of natural selection as a possible mechanism for evolution

Natural selection is one of the driving mechanisms of evolution. The compelling logical process of natural selection is clear in producing adaptive changes within a species, such that it evolves to be more competitive in its environment. 


Natural Selection is often used synonymously with Evolution; however, they have very different meanings. Here are some very important points about natural selection and evolution:

1. Natural selection is a mechanism (differential reproductive success due to traits)
   
2. Evolution is a process (change in allele frequencies over time)
   
3. Natural selection is one mechanism that can lead to evolution
   
4. Evolution can also be caused by all of the other forces mentioned here (drift, migration, mutation, nonrandom mating)
   
5. Natural selection may not lead to evolution if the trait under selection is not heritable.  
   

                    No genetic component à no evolution in response to selection

Determine that evolution is the process of biological change within a population over time

Evolution is a change in the gene pool of a population over time. A gene is a hereditary unit that can be passed on unaltered for many generations. The gene pool is the set of all genes in a species or population.

Recognize that the theory of evolution is a scientific explanation based on a large accumulation of evidence

A scientific theory is "a well-substantiated explanation of some aspect of the natural world, based on informational facts that have been repeatedly confirmed through observation and experiment. Theories are formed from hypotheses that have been subjected repeatedly to tests of evidence which attempt to disprove or falsify them. In the case of evolution through natural selection.The "theory of evolution" is actually a network of theories that created the idea of how organisms evolved.  The fossil record is one of the most common evidences given for evolution.

Define natural selection as the greater chance of passing on of genes by the best adapted organisms

Describe the development of strains of antibiotic resistant bacteria as an example of evolution by natural selection

Key Terms:

Antibiotic Resistance

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How does natural selection change over time?

How does evolution change over time?

What are the 4 causes of evolution by natural selection?

What is the process of a species changing over time called?