Conservation Biology: Human Impact, Extinction, and Ecosystem Dynamics

What is the 6th Great Extinction?

A period characterized by a significant increase in species extinction rates due to human activities.

What are the modern causes of extinction?

1. Habitat loss 2. Overharvesting 3. Climate change 4. Pollution 5. Introduced species

How does habitat loss contribute to extinction?

Habitat loss reduces the living space and resources available for species, leading to population declines.

What role does overharvesting play in species extinction?

Overharvesting depletes populations of species faster than they can reproduce, leading to their decline.

How does climate change affect species survival?

Climate change alters habitats and ecosystems, making it difficult for species to adapt to new conditions.

What is the impact of pollution on biodiversity?

Pollution can harm or kill species directly and disrupt ecosystems, leading to declines in biodiversity.

What are introduced species and how do they affect native species?

Introduced species are non-native organisms that can outcompete, prey on, or bring diseases to native species, disrupting local ecosystems.

What historical event is linked to the extinction of large mammals in North America?

The end of the last glacial period around 10,000-8,000 years ago, which coincided with human migration and overhunting.

What is genetic diversity and why is it important?

Genetic diversity refers to the variation of genes within a population, and it is crucial for a population's ability to adapt to environmental changes.

What is species diversity?

Species diversity refers to the variety of different species within a given ecosystem or on Earth.

What is ecosystem diversity?

Ecosystem diversity is the variety of ecosystems in a given area, which contributes to overall biodiversity.

What is the significance of the IUCN Red List?

The IUCN Red List categorizes species based on their risk of extinction, helping to raise awareness and guide conservation efforts.

What are the categories of threatened species according to the IUCN?

1. CR: Critically Endangered 2. EN: Endangered 3. VU: Vulnerable 4. DD: Data Deficient

What is the current extinction rate compared to historical rates?

The current extinction rate is estimated to be 10 to 100 times higher than the background rate over the past 10 million years.

What is the estimated number of species facing high risk of extinction?

Approximately 1 million species are estimated to face a high risk of extinction.

How have human activities accelerated species extinctions?

Human activities such as habitat destruction, pollution, and introduction of invasive species have significantly increased extinction rates.

What is the relationship between species loss and ecosystem health?

The extinction of one species can negatively impact others and disrupt ecosystem functions, leading to further biodiversity loss.

What historical example illustrates human impact on ecosystems?

Polynesian explorers introduced rats to Oceania, which contributed to the decline of flightless birds and large mammals.

What is the significance of the Bering land bridge in human migration?

The Bering land bridge allowed migration from Siberia to North America, which coincided with the extinction of many large mammals.

What is the greatest threat to biodiversity?

Human alteration of habitat

What percentage of species on IUCN's Red List are threatened by habitat loss?

85%

What is the average annual loss of forest cover over the last decade?

~13 million hectares per year

What are the main causes of terrestrial habitat loss?

Clearing land for farming, grazing, logging, and collection of biomass for fuel

How many people depend on forests for their livelihoods?

~1.6 billion people

What is the estimated value of goods from forests?

US$122 billion

What are the direct and indirect effects of marine habitat loss?

Coastal development, runoff, eutrophication, siltation, and damage from dredging and trawling

What percentage of coral reefs are damaged?

~70%

What is overharvesting?

Harvesting at rates exceeding the ability of populations to rebound

Why are large organisms with low reproductive rates especially vulnerable?

They cannot recover quickly from overharvesting

What has caused the decline in elephant populations?

Harvesting for ivory

What has been the impact of overfishing on North Atlantic bluefin tuna?

Population decreased by 80% in 10 years

What was the peak catch of the cod fishery in the late 1960s?

810,000 tons

What is the role of the atmosphere in keeping Earth warm?

It traps heat, preventing average surface temperature from dropping to -17°C

What gases are known as greenhouse gases (GHGs)?

CO2, water vapor, methane, and refrigerants

What is the Greenhouse Effect?

GHGs reflect infrared radiation back toward Earth

What did Svante Arrhenius hypothesize in 1896?

Burning coal would release enough CO2 to raise Earth's temperature

What are some types of global pollution affecting ecosystems?

Acid rain, nutrient enrichment, accumulation of toxins, and ozone depletion

What causes acid precipitation?

Sulfuric and nitric acid from burning wood and fossil fuels

What was the Acid Rain Accord signed in 1991?

Legislation to reduce sulfur dioxide emissions from coal plants

What are introduced species?

Species moved by humans from native locations to new geographic regions

What can happen when introduced species reproduce and spread quickly?

They can become invasive and disrupt local ecosystems

What is an example of an accidental introduction of a species?

The brown tree snake in Guam

What impact did the brown tree snake have on Guam's wildlife?

It drove over half of bird and lizard species to extinction

What is parasitism in ecology?

A type of symbiotic relationship where one organism (the parasite) benefits at the expense of the other (the host).

What are endoparasites?

Parasites that live inside the host's body.

What are ectoparasites?

Parasites that live on the surface of the host, such as fleas and ticks.

What is co-evolution?

The process in which two or more species influence each other's evolution over time.

How do co-evolutionary relationships explain biodiversity?

They help explain the diversity of life forms and adaptations in ecosystems.

What is a food chain?

A linear sequence showing who eats whom in an ecosystem, tracing the flow of energy from one organism to another.

What is a food web?

A network of interconnected food chains within an ecosystem, illustrating multiple feeding relationships.

What are trophic levels?

Levels in a food chain that categorize organisms based on their feeding relationships.

What role do producers play in an ecosystem?

Producers, usually plants, make food using sunlight through photosynthesis.

What is a keystone species?

A species that has a disproportionately large effect on its ecosystem relative to its abundance.

What is an energy pyramid?

A diagram that shows how energy flows through different trophic levels in an ecosystem.

What happens to energy as it moves up trophic levels?

Energy decreases with each successive level of the food chain, with only about 10% of energy being converted to biomass at the next level.

What is a biomass pyramid?

A representation of the mass of living organisms at each level of a food chain, usually measured in grams or kilograms per square meter.

What is the significance of dominant species in an ecosystem?

They are the most abundant or highest biomass species, influencing community structure.

What are microplastics?

Small plastic pieces less than five millimeters long that can be harmful to ocean and aquatic life.

What is the impact of invasive species?

Invasive species may become dominant in an ecosystem because they lack natural predators or diseases.

What is the role of decomposers in an ecosystem?

Decomposers break down dead material and recycle nutrients back into the ecosystem.

What is the relationship between energy flow and biomass in ecosystems?

Both energy and biomass decrease as you move up trophic levels, although some marine ecosystems can have inverted biomass pyramids.

What are the four main factors that affect population growth rate?

Births + Immigration - Deaths + Emigration.

What is the projected world population by 2050?

About 9.7 billion.

What is the Carboniferous Period known for?

It is known for giant trees due to lignin, which could not be digested by bacteria or fungi for thousands of years.

What is plastic recycling?

The reprocessing of plastic waste into new and useful products to reduce landfill dependence and environmental impact.

What percentage of plastic produced has been recycled?

Less than 10% of all plastic ever produced.