AP Environmental Science Unit 2 Review (Everything you Need to Know!)

Summary

Mr. Smeads' AP Environmental Science review covers Unit 2, focusing on biodiversity's three levels: genetic, species, and ecosystem. He explains how biodiversity benefits ecosystems and humans through ecosystem services. The video also discusses island biogeography, ecological tolerance, natural ecosystem disturbances, and adaptations, like Homo habilis' opposable thumbs. It concludes with ecological succession and keystone species, emphasizing their roles in maintaining ecosystem balance.

Takeaways

• 🌿 Biodiversity encompasses three levels: genetic, species, and ecosystem diversity, each nested within the other.
• 🧬 Genetic diversity is crucial for species' adaptability to environmental changes, as it provides a range of traits that may help some individuals survive.
• 🌳 Species diversity, including species richness and evenness, is beneficial for ecosystems' resilience, as it ensures that if one species declines, others can fill the gap.
• 🌍 Ecosystem diversity is important for biomes' health, with higher diversity supporting more species and functions.
• 💰 Ecosystems provide valuable services to humans, known as ecosystem services, which are categorized into provisioning, supporting, regulating, and cultural services.
• 🏝 The theory of Island biogeography suggests that island species richness is influenced by proximity to the mainland and island size.
• 🕊 The dodo bird's extinction illustrates the vulnerability of specialist species on islands to invasive species and environmental changes.
• 🌡 Ecological tolerance refers to the range of conditions an organism can tolerate; genetic diversity can provide a buffer against environmental disturbances.
• 🌪 Natural events, such as seasonal changes, hurricanes, and forest fires, can disrupt ecosystems, but they also drive natural selection and adaptation.
• 🌎 Earth's climate naturally changes over tens of thousands of years due to variations in its orbit, known as Milankovitch Cycles, affecting sea levels and ecosystems.
• 🦍 Adaptations, like opposable thumbs in Homo habilis, provide a survival advantage and can lead to new species' evolution, demonstrating how genetic mutations can be advantageous.
• 🌲 Ecological succession involves the gradual change in species composition over time, with primary succession starting on bare rock and secondary succession following a disturbance.

Q & A

What is the main focus of Unit 2 in the AP Environmental Science course?

Unit 2 focuses on biodiversity, including the three levels of biodiversity and how biodiversity benefits ecosystems.

What are the three levels of biodiversity mentioned in the script?

The three levels of biodiversity are genetic biodiversity, species biodiversity, and ecosystem biodiversity.

How does genetic diversity benefit a species?

Genetic diversity benefits a species by increasing the likelihood that some members will have traits that allow them to adapt to environmental disturbances or changes.

What is species richness and how does it relate to species diversity?

Species richness is a measure of the total number of different species found in a given ecosystem. However, a higher species richness doesn't necessarily mean more species diversity; species evenness, which is the balance of population sizes, is also considered.

How does ecosystem biodiversity benefit biomes?

Ecosystem biodiversity, which refers to the variance in different ecosystems found in a given area, benefits biomes by supporting a greater species richness and providing a wider variety of habitats.

What are ecosystem services and how do they benefit humans?

Ecosystem services are the direct or indirect contributions of ecosystems to human well-being, including provisioning services (like wood for furniture), supporting services (like pollination), regulating services (like carbon sequestration), and cultural services (like tourism and recreation).

What is the theory of Island Biogeography and what are its two simple rules?

The theory of Island Biogeography suggests that the number of species on an island is related to its distance from the mainland and its size. The closer an island is to the mainland and the larger its area, the higher the species richness.

How does ecological tolerance relate to an organism's survival?

Ecological tolerance refers to the range of conditions an organism or species can tolerate before death or serious injury occurs. It's a measure of how much an organism can adapt to changes in its environment.

What are the three main levels of frequency for natural events that disturb ecosystems?

The three main levels of frequency for natural events that disturb ecosystems are periodic events (like seasons), episodic events (like hurricanes), and random events (like asteroid strikes).

How do Malankovic Cycles contribute to natural climate change?

Malankovic Cycles, which include changes in Earth's orbital eccentricity, axial precession, and obliquity, contribute to natural climate change by altering Earth's distance from the Sun and the tilt of the Northern Hemisphere towards the Sun.

What is the difference between primary and secondary ecological succession?

Primary succession occurs on a bare surface like bare rock, starting with pioneer species like moss and lichen, while secondary succession occurs in areas where soil is already present, often following a disturbance that clears out existing vegetation.

What is a keystone species and why is it important?

A keystone species is a species that has a disproportionately large effect on its ecosystem relative to its abundance. Removing a keystone species can cause the ecosystem to undergo dramatic changes or even collapse.