Which mechanism of evolution below examples are involves: Natural Selection, Genetic Drift (Founder’s Effect or Bottlenect Effect), Sexual Selection, or Gene Flow.

1- A large hurricane blows a log offshore to an island. A group of beetles that were living on the log arrive on an island and begin to interbreed with the population of beetles that were already living on the island.
2- Cats and dogs are often given flea medications to control flea outbreaks. In one area, the flea medications are no longer working because the fleas have acquired a mutation that makes them resistant to this type of chemical.
3- A volcanic eruption causes lava to flow down the slide of a mountain that is the habitat for a population of sloths. Being slow, the sloths are unable to outrun the approaching lava flow and die. A few sloths were in trees not burned by the lava flow and survived. These sloths are the last of their kind in this region of the rainforest.