Threats and Invasive Species

Native species

A species that occurs naturally in a specified geographic area.

Nonnative species

A species that does not occur naturally in a specified geographic area.

Introduced species

A species brought to a new geographic area intentionally or unintentionally by humans.

Established species

A species having a self-sustaining and reproducing population in a specified geographic area without the need for human intervention. Applies to both native and nonnative species.

Invasive species

A species that is nonnative to a specified geographic area, was introduced by humans (intentionally or unintentionally), and does or can cause environmental or economic harm to humans.

Nuisance species

An individual or group of individuals of a species that causes management issues or property damage, presents a threat to public safety, or is an annoyance. Can apply to both native and nonnative species.

Food provision, protection against predators, ecosystem engineering.

Invasive species positive impact on species.

Predation, competition for resources, disease transmission.

Invasive species negative impact on species.

Modification of sedimentation, bioturbation, creation of novel habitat.

Invasive species positive impact of ecosystem processes/function.

Reduction of light penetration, overgrazing, filter-feeding.

Invasive species negative impact of ecosystem processes/function.

Structural, chemical, and light engineers.

Invasive species impact on ecosystem engineering.

Principles and framworks, strategies, approaches, tactics.

Management process of invasive species.

Climate change, pollution, invasive species and disease, species overexploitation, changes in land and sea use.

The biggest threats to Earth's biodiversity.

Extinction

turnover of individuals, a natural process.

Fossils

determins the background or natural extinction rate.

Mass extinction

a statistically signficiant increase above background extinction rates. When over 3/4 of species becomes extinct in a short period of time.

Landscape ecology

the study of the relationship between spatial patterns and ecological processes over a range of temporal and spatial scales, includes human infleucnes.

Dispersal

the movement of individuals from their birth site to a different location (either natal or adult movement); emigration and immigration; often unidirectional; might be related to quality and size of habitat, population size and degree of competition.

Genetic benefits, reduced competition for resources/mates, avoids extinction in unpredictable environments.

Benefits of dispersal

Energetic cost, uncertainty in habitat, predation and competition risk.

Costs of dispersal

Active movement

movement by the organism itself; often gender and age bias

Passive movement

transport facilitated by other means because the organism lacks mobility.

Immigration decreases

What happens to immigration as the number of species increases?

There are fewer niches to occupy

What happens as more species colonize an island?

Smaller distances

Where does migrate occur more often?

Extinction increases

What happens to the extinction rate when there are more species present?

Immigration slows

What happens to the net immigration rate when there are more species present?

Higher immigration, lower extinction rates, and more species.

Characteristics of near islands

Extinction rates increase

What happens to the extinction rate as isolation increases?

When immigration is balanced by extinction

When does species equilibrium occur?

Large islands

What types of islands have higher immigration rates?

Small islands

What types of islands have higher extinction rates?

Immigration is positvely correlated with island size.

Relationship between immigration rates and island size.

Extinction is negatively correlated with island size.

Relationship between extinction rates and island size.

Larger islands

What types of islands are more likely to have more species?

Number of species is positively correlated with habitat size.

Relationship between number of species and habitat size.

Fragmentation

habitat loss resulting in division of larger contiguous habitat into smaller isolated patches.

Patch size, number and shapes of patches, quality of habitat.

Factors influencing how habitat patches are created.

Habitat connectivity

degree to which the landscape facilitiates wildlife movement and other ecological processes.