[ 307 ] Life Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Wolves crossed an ice bridge from Canada to the Isle Royale, Michigan, and established a population. Moose were native to the island. Since the 1950s, ecologists have studied the moose and wolf populations on the island. The population data are shown in the graph. The Isle Royale Moose and Wolf Populations 45 3,000 40 35 30 25 20 15 10 5 2,500 2,000 1,500 1,000 500 Number of Wolves Number of Moose 0 0 1950 1960 1970 1980 1990 2000 2010 Years Ecologists noted several events, which are summarized in the table. Year Event 1964–1972 Mild winters 1972–1980 Severe winters 1981–1984 Humans inadvertently introduce canine parvovirus to the island 1997 Severe winter, outbreak of moose ticks, new wolf emigrates from Canada Does this relationship hold after 1995?