Lecture 6, Chapter 55 - Conservation Biology

3 Broad Threats to Biodiversity

1. the clearing of forests

2. the commercial exploitation of marine populations

3. hydrologic alterations of freshwater ecosystems

When large lands in subtropical forest are cleared and overused, the land goes often undergoes desertification. Define desertification.

the groundwater table recedes to deeper levels, less surface water is available for plants (fertile land turns into a desert)

Desertification speeds the loss of biodiversity locally, sometimes eliminating entire ecosystems

Overexploitation

the excessive harvesting of an animal or plant species

can foster evolutionary changes in the exploited population

Hydrologic alterations

changes to the pathways through which water moves in the water cycle

(human-made/nature changes that disrupt the water cycle)

Habitat Fragmentation

the process where large, continuous natural ecosystems are broken down into smaller, isolated patches separated by human-altered or unnatural landscape (i.e. - lakes)

caused by human activities

Edge Effects

changes in plant and animal communities that happen at the boundary where two different habitats meet

Invasive Species

nonnative organisms pose a serious threat to biodiversity

Endangered

danger of extinction throughout of all or a significant portion of their ranges

Biodiversity Hotspots

areas where biodiversity is both concentrated and endangered by human encroachment
must meet requirements:

• lost at least 70% of its original natural vegetation

• must have at least 1,500 species of vascular plants that are endemic (only found in that one area) to the area

Population Bottleneck

a sharp, sudden reduction in the size of a population caused by environmental disasters, disease, or human activities

Landscape Ecology

analyzes how large-scale ecological factors influence local populations and communities

Ecotourism

visitors, often from wealthier countries, pay a fee to visit a natural preserve

Benefits of Biodiversity

• instrumental value: economic value that species provide (i.e. - lumber, crops, medicine, ecosystem services)

• intrinsic value: species have inherent value not tied to any economic benefit

Provisioning Services

tangible material goods, resources taken from ecosystems for human use

• lumber, fur, meat, crops, cotton

• many of these plants have been artificially selected to enhance their human benefit

Biodiversity: Regulating & Supporting & Cultural Services

• Regulating: biodiversity benefits such as climate regulation, flood control, water purification

• Supporting: benefits of biodiversity that allows ecosystems to exist, such as primary production, soil formation, nutrient cycling

• Cultural: aesthetic, spiritual, ecotourism (very important for economies of tropical countries

Ecosystem Services

a function performed by an ecosystem that directly or indirectly benefits humans

• pollination services

• productivity

• water filtration

• storm mitigation

• prevention invasive species

Biodiversity can increase ecosystem services

How does biodiversity influence ecosystem services?

more biodiversity leads to more ecosystem services because more species have more types of supportive systems

Describe the Monoculture Case Study of Coffee

• coffee grew in tropical forests → monoculture (high yield plant; only one type) plantations vs shade grown coffee

• in the monoculture plantations, they are exposed to sunlight and there are a lot of them while for shade-grown coffee, there are trees in a forest and there is less exposure to sunlight

• however, the monoculture coffee grows faster (but shorter because there is no competition and uses chemical inputs to push growth to the maximum) and if exposed to disease/natural disaster, it would wipe out the entire ecosystem

• shade-grown coffee is grown in longer periods of time, can be more expensive because it’s grown organically

Background Extinction Rates

extinction is natural; species occasionally go extinct and historical climate change also caused mass extinctions

Historical mass extinction events

over past 500 million years, we’ve had 5 mass extinction events

caused by volcanic activity, climate change, and asteroids

Mass extinction

the loss of at least 75% of species within a short period of time (geologically, this is around 2 million years)

Half Earth by Edward O. Wilson - What does it argue?

the situation facing us is too large to be solved and says we should fully dedicate half of the Earth to nature and the other half to human populations

Extinct

species was known in the wild in the year 1500 but no individuals remain alive today

Extinct in the wild

only individual remaining are in captivity (zoos)

Threatened

populations face high risk of extinction in the future

Near-threatened

will likely be threatened in the future

Least concern

abundant populations will not likely become threatened in the future

How Do Humans Affect Extinction?

1. overharvesting (advanced techniques us to log trees, plow grasslands, capture animals → decreases population size → increases extinction

   • islands (animals have not evolved defenses against humans)

   • government involvement (they regulate the harvest of plants/animals)

2. Invasive Species (can affect native prey because prey have not evolved with predator)

   • cats

3. Global Climate Change

   • sea level rise

   • ocean acidification

When humans break up large areas of nature into smaller pieces (habitat fragmentation), seven major things happen:

1. total amount of habitat decreases

2. number of patches increases

3. average patch size decrease

4. patch isolation increase

5. amount of edge habitat increases

6. each patch can support lower populations (K)

7. each patch can support fewer species

T/F: When a habitat patch gets smaller, the safe, intact center shrinks much faster than the outside edge

True

Edge habitat (purple) supports different species than intact habitat. When a habitat patch gets smaller, you lose more “edge habitat” and that is dangerous because more wildlife gets exposed to harm.

Allopatric Speciation

new species form because of a physical, geographic barrier (like a mountain range, river, or ocean) that divides a single population into two or more isolated groups

(groups adapt to their different local environments through natural selection and mutations and they eventually become so genetically different they can no longer interbreed)

Sympatric Speciation

new species form from a single ancestral population while living in the same geographic location, without any physical barriers separating them

(reproductive isolation happens through genetic change)

Corridors (Optimizing Nature Reserve Design)

small strips of habitat that increase connectivity between habitat fragments (i.e. - bridges)

example: buckeye butterfly; butterflies were recaptured in a more connected patch

Important for organisms that require continuous connection to move between patches (i.e. - nonflying)

Negative Impacts: can facilitate the movement of predators to target species we are trying to protect. You want to maximize connectivity and minimize extinction

Preservation

access and use of land space is highly restricted and expensive, resulting in conflict with local people → successful long-term conservation must also include benefits to local residents

Example: local residents support conservation efforts at National Park and the residents in the area receive a percentage of park revenue

High Endemism (Hotspot)

a large number of species are unique to the region and cannot be found anywhere else in the world

Significant Habitat Loss (Hotspots)

the region has experienced severe destruction in its natural habitat → urgent need for protection

Name 2 Conservation Winners

1. bald eagle in U.S. → after legal protection (ban of DDT), population went from endangered to thriving

2. humpback whales → protecting of marine habitats let the population grow more

Umbrella Species

a species's conservation indirectly protects many other species that share a similar habitat

Example: conservation of the humpback whales also help the regulation of the fish population in the ocean, etc