Conservation Biology and Extinction Practice Flashcards

The Reality of Species Extinction vs. Speciation

• A common misconception, exemplified by Former Rep. Helen Chenoweth (ID), suggests that if a species goes extinct every $6$ seconds, another must come into existence just as often. This statement is inaccurate because current extinction rates occur significantly faster than speciation rates.

• Extinction is an inevitable part of biological history. More than $99\%$ of all species that have ever existed are now extinct.

• A primary societal goal in the modern era is to prevent extinctions, though it is acknowledged that this effort will fail to some extent.

• The current extinction rate is approximately $114$ times higher than the geologic background rate.

• The geologic background rate is estimated at $2$ species per $100$ years, or roughly one extinction every $5,000$ to $10,000$ years.

Geologic Mass Extinctions of Species

• Quaternary Period ($0.01$ Million Years Ago): The Pleistocene extinction saw the loss of large mammals and birds.

• Cretaceous Extinction ($65$ Million Years Ago): Affected reptiles and many marine species, including many foraminiferans and mollusks.

• Triassic Extinction ($180$ Million Years Ago): Resulted in the loss of $35\%$ of animal families, including many reptiles and marine mollusks.

• Permian Extinction ($250$ Million Years Ago): This was a massive event where $50\%$ of animal families, including over $95\%$ of marine species, were lost. It also affected many trees, amphibians, most bryozoans and brachiopods, and all trilobites.

• Devonian Extinction ($345$ Million Years Ago): Resulted in the loss of $30\%$ of animal families, including agnathan and placoderm fishes and many trilobites.

• Ordovician Extinction ($500$ Million Years Ago): Resulted in the loss of $50\%$ of animal families, including many trilobites.

Historical Human Impact on Species

• Humans have a long history of causing extinctions, dating back to the Post-Pleistocene era.

• North America ($13,000$ years before present): Extinctions included large mammals such as the woolly mammoth, saber-toothed cats, $500\,lb$ armadillos, cheetahs, lions, and giant sloths.

• South Pacific ($8,000$ years before present to the present): Significant losses occurred in New Zealand, Hawaii, and the Pacific Islands.

• Pacific Islands: Approximately $2,000$ flightless rail species have been lost.

• Hawaii: By the year $1778$, native Hawaiians had already wiped out $50$ species of birds. This includes a massive reduction in flightless birds, forest birds, water birds, and sea birds since approximately $300$ C.E.

Case Studies in Hawaii

• Hawaiian Honeycreepers: Out of $52$ original species, over $20$ are extinct, and $9$ have gone extinct in the last $100$ years.

• Species Last Seen (1984–2004):

  • Kaua'i 'Ō'ō (Last seen $1987$; endemic to Kaua'i; important to immigrant Polynesians for feathers).

  • Kaua'i Nukupu'u

  • Kāma'o

  • 'Ō'ū

  • O'ahu 'Alauahio

  • Moloka'i 'Oloma'o

  • Po'o-uli (Discovered in $1973$, endemic to Maui high-elevation forests, extinct in the wild in $2004$ due to multiple causes).

  • Maui Akepa

  • Maui Nukupu'u

  • 'Alalā

  • `Akialoa

• Critically Endangered Hawaiian Birds:

  • Nihoa Finch

  • Nihoa Millerbird

  • 'Akikiki

  • Puaiohi

  • O'ahu 'Elepaio

  • 'Ākohekohe

  • Maui Parrotbill

  • 'Alalā

Global Extinction Trends and Current Data

• Mammalian megafaunal genera ($>44\,kg$) typically went extinct shortly after human immigration into various regions.

• Approximately $20\%$ of all bird species have gone extinct in the past $2,000$ years.

• In Europe, $50\%$ of fungi species may have become extinct in the past $60$ years.

• IUCN Data Comparison (2025 vs. 2026):

  • 2025 Estimates: $2,139,242$ estimated species; $169,420$ evaluated; $47,187$ ($28\%$) threatened.

  • 2026 Estimates: $2,121,262$ estimated species; $175,909$ evaluated; $49,505$ ($28\%$) threatened.

• Threatened Status by Group (2025–2026):

  • Amphibians: $41\%$

  • Cycads: $71\%$

  • Mammals: $26\%$

  • Conifers: $34\%$

  • Birds: $11\%$

  • Sharks & Rays: $38\%$

  • Reef Corals: $44\%$

  • Selected Crustaceans: $28\%$

  • Reptiles: $21\%$

• Recent Specific Extinctions or Declarations:

  • Thylacine (Tasmanian tiger): The largest carnivorous marsupial ($up to 27\,kg$), endemic to Australia and New Guinea with its last population in Tasmania. Extinct in the wild ~$1933$; last captive died in $1936$ due to persecution (overkill).

  • Eastern Cougar: Declared extinct by USFWS in $2015$, though debate continues regarding its taxonomy and whether it was ever a distinct subspecies.

Conservation Biology as a Discipline

• Conservation biology was established as a scientific discipline to identify species and ecosystems at risk, understand the causes of those risks, and reduce them through protection and restoration.

• History:

  • The first international conference was held in $1978$, leading to a foundational book in $1980$.

  • The Society for Conservation Biology was formed in $1986$, with the journal starting in $1987$.

  • Michael Soulé is known as the "Father of Conservation Biology."

• Evolution of the Field: Prior to being a formal discipline, work was done by groups like the American Committee for International Wildlife Protection (est. $1929$), which was later subsumed by the IUCN. Earlier efforts were often ad hoc and species-specific, while the modern discipline originated from zoos and universities.

• Characteristics of the Field:

  • It is an applied, multi-disciplinary, and "crisis" discipline.

  • It incorporates core fields: Ecology, Genetics, Taxonomy, and Geography.

  • It is influenced by societal values, including Economics, Politics, and Aesthetics.

  • It involves logistical constraints such as time, money, and ethics.

Modern Environmental Crises and Impacts

• South Sudan: Conservation is hindered by well-armed poachers and rebel militia in a "lawless terrain" and a tattered economy. Decades of conflict led to the harvesting of ivory and the extinction of many animals, specifically Sudanese elephants.

• Ukraine "Ecocide": The environment ministry recorded approximately $2,300$ instances of environmental damage. The collapse of the Nova Kakhovka dam (Europe's largest reservoir) resulted in catastrophic flooding of $40$ towns, spilled tons of oil, flooded $50,000$ hectares of forest, and killed an estimated $30,000$ animals.

• Maui Fires: Recent environmental catastrophes affecting local biodiversity.

• Psychological Impacts:

  • Ecological Grief: Sadness experienced from losing parts of the natural environment and ways of life due to climate change.

  • Eco-anxiety: Chronic fear of environmental cataclysm and concern for future generations.

Guiding Principles and Philosophy

• Foundational Axioms:

  1. Evolution is the basic axiom that unites all of biology.

  2. The ecological world is dynamic and largely non-equilibrial.

  3. Human presence must be included in conservation planning.

• Precautionary Principle: In the context of human actions and the environment, avoid actions that could lead to irrevocable harm. When uncertain, err on the side of caution.

• Aldo Leopold (1949): "To keep every cog & wheel is the first precaution of intelligent tinkering."

Rationales for Conserving Biodiversity

• Aesthetics: People value nature and wildlife watching. In the U.S. ($2022$), $148,280,092$ people ($57.2\%$ of residents) participated in wildlife watching, spending over $250$ billion dollars.

• Morality and Ethics: Includes the concept of intrinsic value and intergenerational debt.

• Economics: Resources like crop stock and forestry, recreation, and medicine (e.g., Digitalis derived from plants).

• Ecological Services: Processes such as cleaning water and air, flood and erosion prevention, and agricultural aids like Nitrogen fixation and pollination.

• Ecological Integrity: Often discussed via the "rivet-popping" metaphor (Ehrlich & Ehrlich $1981$), which suggests that losing individual species is like losing rivets from an airplane wing; eventually, the system collapses.

Recent Conservation Successes

• Turkey: Local efforts succeeded in tripling protected seascapes along $300$ miles of coastline (August $6$, $2026$).

• Pacific Islands: The longest predator exclusion fence protects thousands of ground-nesting seabirds (August $4$, $2026$).

• Sunda Clouded Leopard: New images captured an $8$-year-old huntress, providing vital data for the species (August $4$, $2026$).

• Conservation Canines: Dogs are being utilized to fight invasive mussels (August $3$, $2026$).

Questions & Discussion

• Question: How do we know (or how might we know) the current extinction rate?

• Question: What do we need to know in order to determine the answer?

• Question: If extinctions are natural (even inevitable), why are we so concerned about current extinctions?

• Context for Concerns: The primary concern is that the current rate of extinction might reach levels equivalent to previous geologic mass extinctions.