Basics
Does speciation increase or decrease biodiversity?
Increase
What impact does biodiversity have on ecosystem stability?
The more biodiverse an ecosystem is, the more stable it is.
How many mass extinction events have occurred on Earth?
At least 5
What are the first and second greatest threats to biodiversity loss?
Habitat destruction and invasive species
What is an example of a biodiversity hotspot?
Madagascar (also New Zealand, Japan, the Philippines, the Caribbean Islands, etc.)
Define biodiversity.
The variety of life on Earth or in an ecosystem
What are two examples of keystone species?
Sea otters, coral, honeybees, African elephants
A habitat has recently been cut in half by a road and a new shopping plaza has been built on one side. Which type of species will be better able to adapt: generalist or specialist?
Generalist
Define overharvesting.
A species is used by humans at a faster rate than it can replenish
What is the ultimate goal of captive breeding programs?
Reintroduction of a species into the wild
What are two reasons that measuring biodiversity is difficult?
There are many locations on Earth that we have not explored yet (ex. Deep ocean, parts of the jungle) that may hold new species.
Many species (ex. Bacteria) are microscopic and may not have been found yet.
What is the difference between ecosystem resistance and resilience?
Resistance is an ecosystem’s ability to withstand disturbances as they happen.
Resilience is an ecosystem’s ability to recover, or bounce back, after a disturbance has ended.
Define habitat fragmentation and explain why it decreases biodiversity.
Definition: development (ex. A road) splits a habitat into smaller, isolated patches
This makes it more difficult for organisms to find resources, including genetically diverse mates
What are three examples of invasive species?
Zebra mussels, cane toads, kudzu vine, sea lampreys,
Define the term endemic.
A species that is found only in one location (ex. Galapagos tortoises)
Explain how geographic isolation results in the formation of new species.
When geographic isolation occurs, a barrier (such as a river or mountain) splits one population into smaller isolated populations that reproduce separately from each other. Over time, each of the populations is so different from the other that they are separate species.
Which ecosystem has a more stable food web: one with high species biodiversity or one with low species biodiversity?
An ecosystem with a food web with high biodiversity will be more stable than an ecosystem with lower biodiversity.
If a specific species of producer is eliminated, an ecosystem with low biodiversity will lose a major food source and can collapse (ex. Algae in Antarctica).
If a predator is eliminated in an ecosystem with low biodiversity, prey numbers may increase unchecked, causing overgrazing and reduction of producers.
What is the difference between a species that is endangered, threatened, and extirpated?
Endangered: at high risk of extinction
Threatened: likely to become endangered soon
Extirpated: has disappeared from a specific area, but exists elsewhere
What are two impacts climate change has on habitats and ecosystems?
Melts polar ice caps
Increases drought occurrence
Increases wildfire occurrence
Forces animals to migrate to higher latitudes where it is a suitable temperature
What are the three main parts of the Endangered Species Act?
Bans harm to listed species & their habitats
Bans trade of products made from listed species
Requires recovery plans for protected species
What are the three types of biodiversity?
Genetic diversity includes the variety of genes and variations within one species.
Species diversity includes the variety of species within an ecosystem or area.
Ecosystem diversity includes the variety of ecosystems in an area.
CHALLENGE QUESTION: What are four ecosystem services provided by biodiversity?
Agriculture: The more genetically diverse our crop species are, the more resistant they are to pests and disease. Agriculture also relies heavily on pollinator species, including bees, bats, and butterflies.
Medicine: Nearly half of our modern medicines come from nature. Reducing biodiversity could eliminate current and future cures.
Climate regulation: Healthy forests and wetlands are needed to absorb carbon dioxide from the air and regulate our climate. A loss of plants would lead to an increase in greenhouse gases.
Protection: Certain plants, such as mangroves and marsh plants, protect our shorelines during storms. Other plant species anchor soil in place with their roots.
Recreational benefits: Including tourism, mental health benefits (ex. The peaceful feeling of nature), and physical health benefits (ex. Hiking, kayaking, backpacking)
What are the 5 main causes of population decline and extinction?
Habitat destruction
Invasive species
Pollution
Overexploitation (overharvesting)
Climate change
Tough question! What are three ways invasive species are harmful in their new habitat?
Compete with native species
Hunt or prey on native species
Transmit diseases or parasites
What happens when predators are removed from an ecosystem, such as in the savanna?
Prey populations decline, and plant life increases
Predator species return quickly
Overgrazing occurs, which can lead to desertification
Overgrazing occurs, which can lead to desertification