Red squirrels and gray squirrels have been the native species on an island for many years. A few years ago, black squirrels entered this island. The black squirrel is an invasive species. Invasive species aren’t native to the ecosystem. They move into an ecosystem because of natural changes or human intervention. Red squirrels and black squirrels have identical food requirements, but gray squirrels have a different diet. What three effects will these events have on the island’s squirrel population?

Which of the following observation darwin shape his concept of descent with modification? a) species diversity declines farther from the equator. b) fewer species live on islands than on the nearest continents. c) birds live on islands located farther from the mainland than the bird's maximum nonstop flight distance. d) south american temperate plants are more similar to the tropical plants of south america than to the temperate plants of europe. e) earthquakes reshape life by causing mass extinctions.