Keystone Species

Question 1

Keystone species

Answer 1

-could be any organism
- exert very strong control over environment of other species in a community and changes in their numbers have many effect on food chains and webs

Question 2

Biodiversity

Answer 2

describes the variety and variability of all living organisms within a given ecological area
-vital to maintaining life on earth and to ensuring a clean, safe, and sustainable environment

Question 3

Species richness

Answer 3

-measure of the number of different types of species in an area
- a large number of different species in a habitat represents a higher species richness

Question 4

Species evenness

Answer 4

• measure of the relative abundance of each species in an area
• describes how even the species are distributed in a particular ecological area
• more evenly represented species (evidenced by similar population size) illustrate a higher species evenness

Question 5

List 3 organisms that are keystone species
explain why

Answer 5

Grey wolves
Beavers
Bumble Bees
Prairie dogs
Sea otters
Saguaro cactus

Question 6

Why are Grey wolves keystone species

Answer 6

• top level predator, whose presence has a ripple effect on the rest of its ecosystem
• help keep deer and elk pop. in check, preventing them from overgrazing on tree saplings
• allows development of saplings into large trees, whose root systems prevent riverbank erosion
• benefit to other predator populations, their uneaten food scraps help strengthen the food supply for bears, coyotes, and eagles

Question 7

Explain what a higher index value represents

Answer 7

corresponds to a greater degree of biodiversity (high richness and evenness)
suggests a stable site

Question 8

Explain what a lower index value represents

Answer 8

corresponds to a lesser degree of biodiversity (low richness and evenness)

Question 9

Why are bumble bees keystone species

Answer 9

• bees support the reproduction of as much as 90% of the worlds flowering plants
• create seeds and fruits that feed wildlife such as songbirds and grizzly bears
• without bees, many plant species would become extinct, as would the animals that feed on those plants, soon after carnivores would have nothing to eat

Question 10

Why are prairie dogs keystone species

Answer 10

• support many other species
• serve as a food source for coyotes, eagles, foxes, hawks, and black-footed ferrets
• they maintain the health of arid grasslands by churning, aerating, and fertilizing soil as they create vast and intricate underground colonies
• their burrows provide shelter for animals like rattlesnakes, burrowing owls, and jackrabbits