APES Unit 2

Species Area Curve

The number of species on an island increases with the area of the island

Island Biogeography

how species are distributed and interact on islands

The number of species depends on

colonization and extinction rates

Model of Island Biogeography

Equilibrium occurs when the rate of colonization is offset by the rate of extinction

When an island contains very few species, rate of colonization

by new species is high

When an island contains very few species, rate of extinction

is low due to less competition and predation

Number of species and rate of colonization is

inverse

Number of species and rate of extinction is

direct

Species on islands are specialists, leaving them

vulnerable to invasive species

Islands with greater area

contain more species

Number of species on an island depends on

area of island and distance from mainland

Range of Ecological Tolerance

Abiotic Conditions under which a species can survive, grow, and reproduce

Fundamental Niche is

Abiotic Conditions

Realized Niche

Abiotic and Biotic conditions under which a species lives

Geographic Range

Areas of the world a species lives

Environmental change beyond a species’ tolerance can cause

species extinctions

Global Mass Extinctions

Many species go extinct over short periods of time

6th Mass Extinction

Anthropogenic Causes

Periodic Disruption

Occurs regularly and predictably

Periodic Example

Moon Cycles

Episodic Disruption

Somewhat regular

Episodic example

high rain

Random Disruption

no regular pattern

Random example

volcanic eruption

Disruptions with a small spatial extent also

occur over a short duration

Resistance

How much a disruption affects the flow of energy and matter in an ecosystem

Resilience

Rate at which an ecosystem returns to its pre-disruption state

Disruptions can cause

large habitat changes and animal migrations

Intermediate Disturbance Hypothesis

Ecosystems with intermediate levels of disturbance will have higher diversity

Large, Rare Disruption

Wildfire

Seasonal Disruptions can favor

Migration

Most rapid shifts in temperature occurred during

the onset of the Ice Age

Indirect evidence showing that Earth’s atmosphere has changed historically

Foraminifera and ice bubbles

Evolution

change in the genetic composition of a population over time

Microevolution

Evolution at the population level

Macroevolution

Evolution giving rise to new classification

Evolution by Artificial Selection

humans determine which traits to breed out

Evolution by Natural Selection

Environment determines which individuals survive and reproduce

Evolution by Random Processes

are not related to fitness (mutations, gene flow)

Mutations

favored if it improves fitness

Gene Flow

process by which individuals move from one population to another

Genetic Drift

Change in genetic composition due to random mating, especially in small populations

Bottleneck Effect

Drastic reduction in population reduces genetic variation

Founder Effect

Founders’ genetic composition is different from that of original population

Artificial Selection causes

rapid evolution

Allopatric Speciation

Occurs through geographic isolation

Sympatric Speciation

Evolution without geographic isolation

GMO

produced by copying and inserting genes from a species with desirable traits

Ecological Succession

predictable replacement of one group of species by another over time

Primary Succession

occurs on bare rock with no soil

Pioneer Species

Can survive with little or no soil

Pioneer examples

moss and lichen

Secondary Succession

occurs after disturbance in an area with soil

Climax community

final stage of succession

Succession in lakes and ponds leads to

terrestrial habitats

Succession initially increases

species richness, biomass, productivity

Keystone Species

not abundant but has large effects on a community

Indicator Species

demonstrates characteristic of an ecosystem

Bioremediation

using living organisms to clean up environmental pollutants.