Answer :
If an ecosystem lost a keystone species, option C: a new keystone species would replace the old keystone species.
An ecosystem would suffer greatly if one of its keystone species disappeared. Other species' population sizes would fluctuate drastically. Ecosystems would look extremely different without their keystone species. However, their oxygen level would not be affected because of the replacements.
If a keystone species vanished, some ecosystems might not be able to adjust to environmental changes. That can lead to the ecosystem's demise or might open the door for an invading species to take control and drastically change the environment.
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Complete question:
If an ecosystem lost a keystone species, which outcome would be expected? responses
the oxygen supply in the ecosystem would be depleted.
the population numbers of other species would change dramatically.
a new keystone species would replace the old keystone species.
the temperature of the ecosystem would increase.
