Exam 4 pt.3 Flashcards
Dominant species
are those that are most abundant or have the highest biomass
Keystone species
exert strong control on a community by their ecological roles, or niches
-they can have a large effect (starfish
example)
ecosystem _________ influence other species by _________ altering the environment
ecosystem engineers influence other species by physically altering the environment
a general point
food webs, species interactions, trophic cascades, etc. all emphasize connections, networks among species- both direct and indirect (expected and unexpected)
Biodiversity
-the variety of all life forms:
-the different plants, animals, and
micro-organisms, their genes, and
the ecosystems of which they are a
part
Species diversity: Richness
total # of species in a given area
Species diversity: Evenness
distribution of individuals among the different species
Patterns of species diversity: habitat size:
species-area curves
The value of biodiversity
biodiversity is a resource for which there is absolutely no substitute; its loss is irreversible on any time-scale of interest to society
the biodiversity crisis
-current rates of extinction are unusually high
-humans have increased the species
extinction rate by as much as 1,000
times over background rates typical
over the planet’s history
-10-30% of mammal, bird, and
amphibian species are currently
threatened with extinction
causes of modern extinctions:
-habitat destruction
-loss
-fragmentation
-introduced species
-overexploitation
Top-down control
grazing —> algae
Bottom-up control
nutrients—> algae
Introduced/Exotic species
-species introduced to an area outside of their native range
invaders can:
(3 things)
-alter habitat
-reduce or displace native species
-alter ecosystem services
common features of invasive species
-wide environmental tolerances
-large native range
-high rate of population increase (r)
-predator resistance/absence
Rapid spread:
-wide environmental tolerance
-high “r”
-predator resistance
_____ homogenization via _____ or _______ ______ is likely to contribute to establishment of _______ ________
biotic homogenization via trade or intentional transport is likely to contribute to establishment of invasive species
Overexploitation
harvesting of plant, animal populations at higher rates than population growth rates
solutions to overexploitation
-education and awareness
-prevent invasions
-reduce overexploitation
-biodiversity reserves
-reduce overexploitation
-restoration and remediation
reserves: goals- conservation of:
-large, intact, functioning ecosystems
-areas with high biological diversity
-species or groups of species of special interest
-significant natural communities
-important ecosystem services
