Conservation Biology and Extinction Practice Flashcards

Flashcards covering species extinction history, IUCN data, theoretical concepts in conservation biology, and the ethical foundations of the field.

Historical Extinction Percentage

More than $99\%$ of all species that have ever existed are now extinct.

Permian Extinction

A mass extinction occurring $250$ million years ago where $50\%$ of animal families, including over $95\%$ of marine species, went extinct.

Cretaceous Extinction

A mass extinction occurring $65$ million years ago affecting reptiles and many marine species.

Human History of Extinction

Humans have a long history of causing extinctions, such as the disappearance of $50$ bird species in Hawaii by $1778$ and ~$2000$ flightless rail species across Pacific Islands.

Kauai 'Ō'ō

A species endemic to Kauai, important for its feathers to immigrant Polynesians, last seen in $1986$.

Mammalian Megafauna

Genera weighing over $44\,kg$ that often went extinct soon after human immigration to various regions.

Thylacine (Tasmanian tiger)

The largest carnivorous marsupial of modern times (up to $27\,kg$), extinct in the wild around $1933$ due to persecution (overkill).

Po`o-uli (Hawaiian Honeycreeper)

A species discovered in $1973$ and endemic to Maui high-elevation forests, declared extinct in the wild by $2004$.

Eastern Cougar

Declared extinct by the USFWS in $2015$, though debate persists regarding its taxonomy and whether it was a unique subspecies.

Geologic Background Rate

The natural rate of extinction, estimated at one extinction every $5,000$ to $10,000$ years, or roughly $2$ species per $100$ years.

Current Extinction Rate

The current rate of extinction for vertebrates is estimated to be $114$ times higher than the geologic background rate.

IUCN Threatened Species Stats (2026)

More than $49,500$ species ($28\%$ of all assessed species) are threatened with extinction.

Amphibians Extinction Risk

According to IUCN data, $41\%$ of this vertebrate group is currently threatened with extinction.

Cycads Extinction Risk

A group of plants with a very high threat level, listed at $71\%$ in $2025$ and $2026$ IUCN data.

Conservation Biology

A scientific discipline aimed at identifying species and ecosystems at risk, understanding causes of risk, and reducing those risks through protection and restoration.

Michael Soulé

Commonly referred to as the "Father of Conservation Biology."

Ecological Grief

The sadness experienced by people due to the loss of natural environments and ways of life caused by climate change.

Eco-anxiety

A chronic fear of environmental cataclysm stemming from the observed impact of climate change.

Precautionary Principle

The approach of avoiding actions that could lead to irrevocable harm, such as extinction, often summarized by Aldo Leopold as keeping "every cog & wheel."

Value-laden Discipline

A characteristic of conservation biology where goals are set based on societal values, including economics, politics, and aesthetics.

Ecological Services

The practical benefits nature provides society, including water and air cleaning, flood prevention, nitrogen fixation, and pollination.

Rivet-popping

A concept by Ehrlich & Ehrlich (1981) used to describe the declining ecological integrity as individual species are lost from an ecosystem.