Base your answer on the information below. A decade after the Exxon Valdez oil tanker spilled millions of gallons of crude [oil] off Prince William Sound in Alaska, most of the fish and wildlife species that were injured have not fully recovered. Only two out of the 28 species, the river otter and the bald eagle, listed as being injured from the 1989 spill are considered to be recovered said a new report, which was released by a coalition of federal and Alaska agencies working to help restore the oil spill region. Eight species are considered to have made little or no progress toward recovery since the spill, including killer whales, harbor seals, and common loons [a type of bird]. Several other species, including sea otters and Pacific herring, have made significant progress toward recovery, but are still not at levels seen before the accident the report said. More than 10.8 million gallons of crude oil spilled into the water when the tanker Exxon Valdez ran aground 25 miles south of Valdez on March 24, 1989. The spill killed an estimated 250,000 seabirds, 2,800 sea otters, 300 harbor seals, 250 bald eagles, and up to 22 killer whales. Billions of salmon and herring eggs, as well as tidal plants and animals, were also smothered in oil. Reuters The oil spilled by the Exxon Valdez tanker is an example of .

Explanation: The Exxon Valdez oil spill was a manmade disaster that occurred when Exxon Valdez, an oil tanker owned by the Exxon Shipping Company, spilled 11 million gallons of crude oil into Alaska’s Prince William Sound on March 24, 1989. It was the worst oil spill in U.S. history until the Deepwater Horizon oil spill in 2010. The Exxon Valdez oil slick covered 1,300 miles of coastline and killed hundreds of thousands of seabirds, otters, seals and whales. Nearly 30 years later, pockets of crude oil remain in some locations. After the spill, Exxon Valdez returned to service under a different name, operating for more than two decades as an oil tanker and ore carrier.

On the evening of March 23, 1989, Exxon Valdez left the port of Valdez, Alaska, bound for Long Beach, California, with 53 million gallons of Prudhoe Bay crude oil onboard.

At four minutes after midnight on March 24, the ship struck Bligh Reef, a well-known navigation hazard in Alaska’s Prince William Sound.

The impact of the collision tore open the ship’s hull, causing some 11 million gallons of crude oil to spill into the water.

At the time, it was the largest single oil spill in U.S. waters. Initial attempts to contain the oil failed, and in the months that followed, the oil slick spread, eventually covering about 1,300 miles of coastline.

Investigators later learned that Joseph Hazelwood, the captain of Exxon Valdez, had been drinking at the time and had allowed an unlicensed third mate to steer the massive ship.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).