Whose work has contributed to the development of the Theory of Natural Selection?
Thomas Malthus
Malthus was an economist that claimed that populations increase or decrease based on the amount of available resources. However, if a population gets too big, a "superior" power (war, disease, disaster, etc.) will decrease it.
Things out of our control will decrease the population of those not immune.
Georges Cuvier
Cuvier was a French naturalist and zoologist who claimed that the earth was older than 6,000 years and that extinction was a factor in life.
Those not strong enough will become extinct and unable to pass on genes.
Charles Lyell
Lyell was a British lawyer and geologist who claimed that those processes which changed animals in the past were still in effect during their time.
Species never stop evolving and adapting.
Jean-Baptiste Lamarck
Lamarck was a French naturalist who believed that animals had the drive to change themselves to adapt. This was in contrast to Charles Darwin's idea of Natural Selection.
Acquired traits are passed on to offspring.
Charles Darwin
Darwin was an English naturalist and geologist who is best known for his contributions to evolutionary theory and the theory of Natural Selection. In his book, On the Origin of Species, Darwin explained his observations of the Galapagos finches and tortoises and presented his ideas on the theory of evolution.
All species of life have descended over time from common ancestors.
What is natural selection?
Natural selection is the gradual process by which heritable biological traits become either more or less common in a population as a function of the effect of inherited traits on the differential reproductive success of organisms interacting with their environment.
Darwin claimed that organisms with the highest fitness, or the ability to survive and reproduce, would be favored in the struggle for life. Eventually these organisms would be favored in a population and the average population phenotype would evolve to look and act like the favored one.
There are six features that affect natural selection.
Overproduction of Offspring
When there are more organisms in an environment than can be provided for, those that do not have enough fitness will not be able to survive.
Variation Among Individuals
Without variation in a population, there would be no other phenotype for evolution to select for which would cause the organisms to be greatly affected by natural selection and eventually become extinct.
Limited Resources
Only those chosen by natural selection to be the fittest in a population will be able to get to the limited resources needed to survive. There are not enough resources in an environment to provide for all organisms.
Competition
Because there are limited resources in an environment, organisms must compete against one another to get through fitness to get those resources. Those who are best fit to compete for the limited resources will survive and eventually reproduce.
Differential Reproductive Success (Fitness)
Those who are the best equipped to survive and reproduce in an environment are considered to have a high amount of fitness and overtime the population will evolve to replicate the fittest organism.
Adaptation
The ability to adapt, or adjust to new conditions, creates a higher fitness level in an organism and will allow it to survive a constantly changing environment.
How does all of this affect us today?
Artificial selection through humans kills unwanted bacteria but ones with resistance live and reproduce creating a stronger bacteria that can't be killed. This can also happen if a patient stops taking antibiotics before they are told to do so or if antibiotics are prescribed when they are not needed.
One example of this is the treatment of gonorrhea with Penicillin. Penicillin was able to treat gonorrhea when the treatments first started in the 1960s, but today 24% of gonorrheal bacteria is resistant to Penicillin in the US and 98% is resistant in Southeast Asia.