Ecology and Island Biogeography

These flashcards cover key terms and concepts discussed in the lecture on ecology and island biogeography.

Krakatau

A volcanic island in Indonesia, known for its catastrophic eruptions and subsequent ecological recovery.

Immigration Rate

The rate at which new species arrive at an island, influencing species diversity.

Extinction Rate

The rate at which species disappear from an island, affecting species richness.

Equilibrium Point (S*)

The level at which immigration and extinction rates balance, stabilizing species diversity.

Niche Partitioning

A concept illustrated by Robert MacArthur, where species coexist by utilizing different resources.

Ecological Truncation

The phenomenon where larger and specialized species are the first to go extinct in fragmented habitats.

Habitat Fragmentation

The process of breaking up large habitats into smaller, isolated patches, affecting biodiversity.

Corridors

Paths that connect habitat fragments, facilitating species movement and immigration.

Theory of Island Biogeography

A theory developed by Robert MacArthur and E.O. Wilson that explains how the number of species on an island results from a balance between immigration of new species and extinction of existing species.

Immigration decreases over time

In the context of island biogeography, immigration rates typically decrease over time as the number of species on an island increases, due to fewer new species arriving or suitable niches being filled.

Extinction increases over time

In the context of island biogeography, extinction rates generally increase over time as the number of species on an island grows, due to increased competition, predator pressure, and smaller population sizes.

Time to equilibrium varies by species group

The time it takes for an island's species diversity to reach equilibrium (S*) can vary significantly depending on the specific species group, dispersal abilities, and life history traits.

Island Size (in Island Biogeography)

A key factor influencing species diversity; larger islands generally have lower extinction rates and can support a greater number of species and larger populations.

Island Isolation (in Island Biogeography)

The distance of an island from a mainland source, which primarily affects immigration rates; more isolated islands tend to have lower immigration rates.

Terrestrial Islands

Habitats that become isolated by surrounding inhospitable land or different land uses (e.g., mountaintops, lakes, forest fragments), contrasting with oceanic islands.

Terrestrial vs. Oceanic Islands

Terrestrial islands are formed by habitat fragmentation within a landmass, while oceanic islands are landmasses surrounded by water. They differ in origin, typical initial species pool (oceanic are often colonized from scratch), and persistence of 'relict' species.

Relaxation (in Island Biogeography)

The process by which a newly isolated habitat (e.g., a terrestrial island formed by fragmentation) loses species until it reaches a new, lower equilibrium species number, often experiencing a period of extinctions known as 'extinction debt'.

Immigration must be possible to prevent extinction

For species populations in isolated habitats (islands or fragments), continued immigration from source populations is essential to counteract local extinctions and maintain genetic diversity, preventing overall species loss.

Reserve Design

The application of ecological principles, including island biogeography, to strategically plan and create protected areas to maximize biodiversity conservation, considering factors like size, shape, and connectivity (e.g., through corridors).

Charismatic Megafauna

Large, popular animal species (e.g., pandas, tigers, elephants) that attract significant public attention and support, often serving as 'flagship species' for broader conservation efforts.

Specialists (Ecology)

Species that have very specific requirements for habitat, diet, or other ecological factors, making them particularly vulnerable to environmental changes, habitat loss, and fragmentation compared to generalists.

Robert MacArthur and E.O. Wilson

Two ecologists well-known for their groundbreaking work in developing the Theory of Island Biogeography, which provides a framework for understanding species richness and turnover on islands.

Coconuts (Ecological Dispersal)

An example of a plant species known for its ability to disperse over long distances via ocean currents, effectively colonizing new islands and illustrating a mechanism of immigration.

Spruce Forests (Habitat Fragmentation)

An example of a specific forest type that, when fragmented or isolated, can form 'terrestrial islands' for species dependent on that particular habitat, impacting their populations and diversity.