Ch. 54 Biodiversity and Conservation Ecology

conservation
biology

making progress in
studying, preserving, and restoring
biodiversity.

Genetic diversity

total genetic information
contained within all
individuals of a population,
species, or group of species
– Measured as the number and
relative frequency of all genes
(and their alleles) present in a
species

Species Diversity

The diversity of species is a key feature of
biological communities; it is usually quantified
in two ways

Species richness

a count of the
species present in a defined region

Species evenness

a measure of how
similar the abundances of different
species are in an environment

Species diversity

a weighted
measure that incorporates both species
richness and evenness, the relative
abundance of each species present

horizontal diversity

Communities vary in…

Number of species in each trophic level—and in
vertical diversity—and the number of trophic levels

Ecosystem Diversity

a measure of these complex
factors plus interactions with the abiotic environment

Mutations

create new alleles increase genetic
diversity

Natural selection, genetic drift, and gene flow

may
eliminate certain alleles or change their frequency,
leading to an increase or decrease in overall genetic
diversity
Speciation increases species diversity; extinction
decreases it

Multiple Interacting Threats on
Diversity

Threats can be challenging to categorize because multiple threats can
overlap and interact

Habitat loss

the most important factor in declines

overexploitation

Marine species are threatened mostly by

Climate change

has had a larger impact on marine species than
freshwater and terrestrial species

Habitat destruction

such as forest loss, logging and burning forests,
housing development, grazing livestock

Habitat fragmentation

the breakup of large, contiguous areas of
natural habitat into small, isolated fragments

Habitat fragmentation

can reduce habitats
until they are too small to support some
species like top predators:
– Loss of top predators can cause
trophic cascades
– Fragmentation can force species into
metapopulation structure
– Leads to small, isolated populations
vulnerable to catastrophes
– Isolated populations more likely to
wipe out:
▪ Catastrophic events
▪ Inbreeding depression—loss of
alleles due to genetic drift

Overexploitation

refers to any unsustainable removal of organisms
from the natural environment of use by humans

Overhunting

refers to hunting animals or birds to an excessive and
unsustainable degree

Invasive Species

a nonnative species that is introduced into a
new area
▪ are threats because they compete with
native species, carry disease, or cause other types of
interactions

Pollution

can cause acid rain and contribute to greenhouse
gases or nutrient runoffs can cause eutrophication

Climate Change

refers to climate change refers to long-term
shifts in temperatures and weather patterns

Climate Change

Temperature and precipitation changes cause more
frequent droughts, deep freezes, flood, and heat waves
• Coral reefs are suffering from bleaching induced by high
temperatures
• Ocean acidification—due to increased carbon dioxide
concentrations—inhibits the ability of marine animals to
make calcium carbonate skeletons

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How Will Threats Affect Future
Extinction Rates?

To estimate current extinction rates and predict how they
might change in the near future, biologists use several
approaches from multiple levels, including:
– Effects of evolutionary processes on genetic variation
– Impact of abiotic factors on distribution of organisms
– Behavior of organisms in response to change
– Basic demographic characteristics of populations
– Species interactions at community and ecosystem
levels
– Effect of biodiversity at all these levels

Resource use efficiency

diverse plant assemblages
are more efficient and can thus make more biomass

Facilitation

certain species assist the growth of other
species by providing them with benefits

Chance inclusion of high-productivity species

if one or two species are extremely productive, NPP will
depend on whether those species are in a study plot;
high-species plots will tend to outproduce low-species
plots

ecosystem services

Collectively, all direct and indirect benefits that humans
derive from organisms and ecosystems they compose
are called

Provisioning services

provide raw materials
• Food
• Fuel
• Fiber and other materials
• Medicines
• Genetic resources
• Water

Regulating services

are part of Earth’s life support system
• Climate moderation
• Soil formation
• Erosion control
• O sub 2 and C O sub 2 regulation
• Water capture
• Water purification
• Air cleaning
• Flood control
• Storm mitigation
• Waste decomposition
Muddy looking water covers a wetland, with thin bands of vegetated land reaching above the level of the water2 2O and CO

Cultural services

enrich quality of life
• Aesthetics
• Recreation
• Education
• Spiritual value
• Human mental and physical health

Supporting services

enable all the other ecosystem
services
• Primary productivity
• Nutrient cycling
• Pollination
• Pest control
A bee on a flower

Conservation Strategies to Preserve Genetic
Diversity, Species, and Ecosystem Function

Several successes are currently under way:
– Education campaigns can help raise public
awareness of conservation issues and affect public
demand for unsustainable products

Designing effective protective areas to preserve
biodiversity from various impacts is the most successful
strategy:
– Most species still lack protected areas, but the amount
of globally protected area is increasing

Genetic restoration

can help isolated populations by
creating artificial gene flow in endangered species

Seed banks

provide long-term storage and protection
against loss of genetic diversity

Management plans for invasive species

are being
implemented to prevent introduction and spread of
invasive species

Endangered species

are being carefully managed and
protected by law

Ex situ conservation

and reintroduction of animals:
– Preservation of species in zoos, aquaria, or other
artificial settings

Wildlife corridors

are strips of undeveloped habitat that
connect protected areas; they encourage gene flow and
allow areas to be recolonized

Ecosystem Restoration

Recovery due to restoration projects can be much
slower in forests than in other ecosystems, but it can
occur in a matter of decades, not centuries
• Restoration success is positively correlated with size
of area restored, its connectedness, remoteness, and
intactness of surrounding areas:
– An accumulation of many small changes can also
have a big effect

Quantifying Ecosystem Services

Other strategies rely on ecotourism:
– Assumes country will profit more in long term by
tourism than in short term by activities such as logging
• Regardless of the approach, outcomes that boost
biodiversity and ecosystem function are a boon to humans