Download Keystone Species

Review of Population Topics
Biodiversity:
 Species diversity:
combination of:
 species richness - the number of different
species it contains
 species evenness - abundance of
individuals within each of those species
 Biggest threat to Biodiversity is
habitat loss
Biodiversity
Species richness: Equal – both have 10 species
But clearly B is far less diverse….because 1
species is dominant – have to look at evenness
Species evenness:
For A: 10 species
with 10 indiv each
For B: 1 species has 82 indiv
9 species have 2 indiv
Invasive species
Nonnative (Introduced)
• They lower biodiversity
– The can outcompete the native species
– This displaces / kills native species
• The can adapt very quickly to local habitats
• They have no/few natural predators
• They can reproduce very quickly
Importation of Species
• Ex. The Chinese chestnut had a fungus that
spread & virtually eliminated the American
chestnut.
• Kudzu
Keystone Species: Major Players
• Keystone species help determine the types and
numbers of other species in a community
thereby helping to sustain it.
Figures 7-4 and 7-5
Keystone Species
• Keystone species- a species that plays a role in
its community that is far more important than
its relative abundance might suggest.
Succession
• Succession is a series of changes that occur as an
ecosystem develops
– Initial species are called pioneer species – they set the
stage for the appearance of other species
– eventually resulting in a climax or mature community.
• Primary
– Starts with bare rock
– ex.: volcanic flows, glacier movement
• Secondary
– Soil already there, after a major ecological disruption
– Ex: post mining, post fire, post flood
Tragedy of the Commons
Be prepared to explain
& give examples