Genetic Drift: Northern elephant seals have reduced genetic variation due to overhunting by humans which reduced their population size to as few as 20 individuals at the end of the 19th century., Mount St. Helen eruption in 1980 kills over 40% of the red deer population, Isolated plant undergoes self-fertilization due to the absence of pollinator species, In the state of Pennsylvania, there is an Amish population of about 12,000 people who have a unique lifestyle and marry other members of their community. Because of their small gene pool, many individuals have inherited a rare genetic disorder, Adult lion arriving to a new pride kills all cubs from previous male. Millions of greater prairie chickens once lived on the prairies of Illinois. As these prairies were converted to farmland, the numbers of greater prairie chickens plummeted. By 1993, there were fewer than 50 birds, Natural Selection: After volcanic eruption, black mice become more common on the slopes of Mount St. Helen because they camouflaged against the dark rock, After treatment with antibiotics, biologists discover a new strain of bacteria with resistance to antibiotics, Guppies can be found in pools below waterfalls with high predation risk, or pools above waterfalls with low predation risk. In high predation areas, males exhibit very little coloration and tend to be relatively small. In low predation environments, males display bright coloration and a larger number of spots., The widespread use and misuse of antibiotics has resulted in increased microbial resistance to antibiotics in clinical use, to the point that some microbes have been described as a "superbugs" because of the threat they pose to health and their relative invulnerability to existing drugs, Peppered moth populations show different allele frequencies depending on what part of the forest they are collected, Gene Flow: Adult lion kicks out male offspring forcing them to find another pride,  Ecologists fear that genetically modified plants may transfer some of their genes to their wild relatives through the help of pollinators, After the Florida panther population was reduced to very small numbers, biologists brought new individuals from southwestern United States, Wind and many animals carry pollen and seeds away from a forest to other areas, Mutation: A white mouse is born to in a population of typically black mice, About 9000 years ago, two parents were surprised to discover their teenage daughters’ ability to drink milk and not get sick like everyone else, Nonrandom mating: In the Hercules beetle population, larger males have larger weapons in respect to their body length and win more often in direct encounters. A smaller male losing in competition is not able to contribute genetic information to the population’s gene pool, The Great Sage Grouse congregates in large groups of male and females in areas called “leks.” Only one or two males are chosen by the females, while the other males watch enviously,

Mechanisms of Evolution

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