Natural Selection, Genetic Bottleneck, or Founder Effect
Genetic Bottleneck
A catastrophe kills many individuals in a population, leaving a small number of individuals to interbreed. These individuals may have different genes than the original population.
Natural Selection
Antibiotic resistance occurs when certain bacteria with a mutation that allows them to survive exposure to antibiotic chemicals live on and reproduce. Quickly, a fully resistant generation develops.
Natural Selection
Camouflage allows many species to blind into their environment. Those individuals with the best camouflage are not eaten by predators as often as those with poorer camouflage.
Genetic Bottleneck
During a hike a man accidentally steps on a population of rare beetles that were in the path, leaving just four of the original twenty.
Genetic Bottleneck
In 2013, Typhoon Haiyan is estimated to have killed over 500 water buffalo in the Philippines. Water buffalo are used in the Philippines to plow crops. Many of the water buffalo that perished were concentrated near farms. These animals are more muscular than buffalo allowed to roam free.
Founder Effect
More severe illnesses exist among certain Jewish groups. Ashkenazi Jews, for example, have a particularly high chance of suffering from Tay-Sachs disease, a fatal condition in young children.
Natural Selection
Organisms better adapted to their environment tend to survive and produce more offspring. Their genetic profile becomes more common in the population over time.
Founder Effect
The Afrikaner population of Dutch settlers in South Africa is descended from a few colonists. Today, the Afrikaner population has an unusually high frequency of the gene for Huntington's disease.
Founder Effect
The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors that interbreed.
Founder Effect
When Christopher Columbus came to the Americas, he randomly chose 3 chickens from Spain to bring along. These 3 chickens were the only chickens to breed in the Americas for hundreds of years.
