AP Biology — Ecology & Evolution

What is **speciation**?

**Speciation** is the evolutionary process where populations evolve to become distinct species, often due to geographic, ecological, or genetic isolation.

Explain **Keystone species**.

A **keystone species** is a species that has a disproportionately large impact on its ecosystem relative to its abundance.

What is **trophic level**?

A **trophic level** refers to the position an organism occupies in a food chain, such as producers, primary consumers, or secondary consumers.

Describe **symbiosis** and list its types.

**Symbiosis** is a close and long-term biological interaction between two different biological organisms, including mutualism, commensalism, and parasitism.

What is **adaptive radiation**?

**Adaptive radiation** is the rapid evolution of diversely adapted species from a common ancestor, often following environmental changes or mass extinctions.

Explain the **Hardy-Weinberg equilibrium**.

The **Hardy-Weinberg equilibrium** describes a non-evolving population where allele and genotype frequencies remain constant, given no mutation, selection, migration, genetic drift, or mating preference.

Define **biome**.

A **biome** is a large area characterized by its vegetation, soil, climate, and wildlife, such as tundras, deserts, and rainforests.

What is **genetic drift**?

**Genetic drift** is a change in the frequency of an allele within a population due to random sampling, affecting small populations more significantly.

Describe the **carbon cycle**.

The **carbon cycle** involves the movement of carbon among the atmosphere, hydrosphere, lithosphere, and biosphere through processes like photosynthesis and respiration.

What is **allopatric speciation**?

**Allopatric speciation** occurs when a population is geographically isolated, leading to the evolution of a new species due to lack of gene flow.

Explain **co-evolution**.

**Co-evolution** is the process where two or more species influence each other's evolutionary pathway, such as predators and their prey.

Define **biomagnification**.

**Biomagnification** is the increasing concentration of toxins in organisms at higher trophic levels in a food chain.

What is **endosymbiotic theory**?

The **endosymbiotic theory** proposes that eukaryotic cells evolved from a symbiotic relationship between early prokaryotes, especially through mitochondria and chloroplasts.

Describe **r-selected species**.

**r-selected species** produce many offspring with low survival rates, thriving in unstable environments; examples include insects and annual plants.

What is **primary succession**?

**Primary succession** is the series of community changes that occur on an entirely new habitat which has never been colonized before, such as lava flows.

Explain the concept of **ecological footprint**.

An **ecological footprint** measures the environmental impact of an individual or community in terms of the amount of land and water needed to produce the resources consumed and to absorb the waste generated.

Define **habitat fragmentation**.

**Habitat fragmentation** is the process where large, continuous habitats are divided into smaller, isolated sections, impacting biodiversity and ecosystem function.

What are **invasive species**?

**Invasive species** are non-native organisms that spread widely in a new habitat, often causing harm to native species and ecosystems.

Describe the **nitrogen cycle**.

The **nitrogen cycle** involves the conversion of nitrogen between its various chemical forms, primarily carried out by nitrogen-fixing bacteria and denitrifying bacteria.

What is **ecological succession**?

**Ecological succession** is the process of change in the species structure of an ecological community over time, leading to a stable climax community.

Explain **gene flow**.

**Gene flow** is the transfer of genetic variation from one population to another, which can help maintain genetic diversity.

What is **secondary succession**?

**Secondary succession** occurs in areas where a community previously existed but has been removed; soil is already present, unlike in primary succession.

Define **mutualism**.

**Mutualism** is a type of symbiotic relationship where both species involved benefit from the interaction.

What is the **bottleneck effect**?

The **bottleneck effect** is a sharp reduction in the size of a population due to environmental events or human activities, leading to decreased genetic diversity.

Describe the **phosphorus cycle**.

The **phosphorus cycle** involves the movement of phosphorus through the lithosphere, hydrosphere, and biosphere, crucial for DNA, RNA, and ATP.