Ch 1.9 Keystone Species

Ch 1 9 Keystone Species Ch 1 9 Keystone Species What is a Keystone? ● A keystone is the wedge shaped stone in the middle of a arch or vault ● It is the final piece placed during construction and locks[.]

Ch 1.9 Keystone Species

What is a Keystone?

● A keystone is the wedge-shaped stone in the middle of a arch or vault

● It is the final piece placed during construction and locks all the stones into position, allowing the arch or vault to bear weight

● Draw this model:

Keyston in Ecosystems

● In any type of ecosystem, a

keystone species is an

organism that helps hold the

system together.

● A keystone species helps

define an entire ecosystem

○ If the species were to

disappear from the

ecosystem, no other

species would be able to fill its ecological niche.

Importance of Keystone Species

● Without its keystone species, ecosystems would look very different

● Some ecosystems might not be able to adapt to environmental changes if

their keystone species disappeared

● That could spell the end of the ecosystem, or it could allow an invasive

species to take over and dramatically shift the ecosystem in a new direction

Let’s

remember the case of twin islands:

Amchitka & Shemya

Three types of keystone species: Predators, Ecosystem Engineers & Mutualist

populations of prey species, which in

turn affects the quantity of plants and

animals further along the food web.

upon old or sick fish, leaving healthier animals to flourish

animals from overgrazing and wiping out the grass

grass beds, the sea turtles were forced to graze across a much wider region.

Ecosystem Engineers 2 Ecosystem engineer: an organism

that creates, changes, or destroys a

habitat

● For example of a beaver River

ecosystems rely on beavers to take down old or dead trees along

riverbanks to use for their dams

This allows new, healthier trees to grow in abundance The dams divert water in rivers, creating wetlands that allow a variety of animals and plants to thrive

Mutualist

3 Mutualists: When two or more

species in an ecosystem interact for each other’s benefit, they are

called mutualists

● Bees are a primary example of this As bees take the nectar from flowers, they collect

pollen and spread it from one flower to the next, enhancing the odds of fertilization and greater flower growth