Island Gigantism

  A keystone species is an organism that helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether.  Keystone species have low functional redundancy. This means that if the species were to disappear from the ecosystem, no other species would be able to fill its ecological niche. The ecosystem would be forced to radically change, allowing new and possibly invasive species to populate the habitat. Any organism, from plants to fungi, may be a keystone species; they are not always the largest or most abundant species in an ecosystem. However, almost all examples of keystone species are animals that have a huge influence on food webs. The way these animals influence food webs varies from habitat to habitat.  Their consumption of plants helps control the physical and biological aspects of an ecosystem. In African savannas such as the Serengeti plains in Tanzania, elephants are a keystone species. Elephants eat s

The productive west coast of North America holds one of the greatest spectacles known to nature. During fall, dormant water bodies pulsate with millions of migrating Pacific salmon and the events that follow create the ‘salmon run.’ Mature Pacific salmon migrate from the Pacific Ocean to rivers to spawn and their annual arrival is of immense importance to Grizzly bears, Bald eagles, wolves, local fisherman, etc. Each year, these salmon provide a bountiful supply of fresh food to other creatures, therefore it is regarded as a keystone species. Pacific salmon are born in freshwater and as they mature, they undergo physiological changes so that they can adapt to saltwater conditions. During these changes, they spend time in the brackish waters of river estuaries and once they are 15 to 20 centimetres long, they swim out to sea. The salmon spend around 4 years at sea, where they grow strength and mass to prepare for their strenuous migration back to freshwater systems, to spawn. Salmon are