What is the fundamental definition of extinction for an organism or species?

Extinction is defined as the termination of an organism or species through the death of its final member. Once the very last individual of a species dies, that species is considered extinct. This marks the irreversible end of that lineage.

Under what circumstances might a species be considered 'functionally extinct' before the death of its last individual?

A species can be deemed functionally extinct if its remaining individuals lose the capacity to reproduce and recover their population. This can occur due to various factors such as poor health, advanced age, sparse distribution, or a lack of individuals of both sexes, even if some members are still alive.

What are Lazarus taxa, and why are they significant in the study of extinction?

Lazarus taxa refer to species or groups that were believed to be extinct but were later rediscovered, or species whose fossils reappear in the record after a long absence. They are significant because they highlight the difficulty in definitively declaring a species extinct and the potential for species to persist undetected for long periods.

Can you provide an example of a Lazarus taxon and explain its rediscovery?

A notable example of a Lazarus taxon is the coelacanth, a fish previously known only from fossils dating back to the Cretaceous Period. In 1938, a living specimen was discovered off the coast of South Africa, demonstrating that species thought lost can still exist.

What is pseudoextinction, and how does it differ from true extinction?

Pseudoextinction, also known as phyletic extinction, occurs when a parent species transforms into a successor species or splits into multiple daughter species, effectively causing the original species' classification to vanish. Unlike true extinction, where the last member dies, pseudoextinction involves evolutionary change where the lineage continues in a modified form.

What is the estimated number of species that have gone extinct throughout Earth's history?

It is estimated that over five billion species have gone extinct throughout the history of life on Earth. This vast number underscores that extinction is a natural and pervasive process in the planet's biological past.

Approximately how many species of eukaryotes are estimated to exist globally today?

There are approximately 8.7 million species of eukaryotes estimated to exist globally. This figure may be significantly higher if microorganisms are included, highlighting the vastness of known and unknown biodiversity.

What are some notable examples of extinct animal species mentioned in the text?

Notable examples of extinct animal species include non-avian dinosaurs, saber-toothed cats, and mammoths. These iconic creatures represent just a fraction of the species that have disappeared over geological time.

What is the typical lifespan of a species before it goes extinct?

On average, a species typically becomes extinct within 1 to 10 million years of its first appearance. However, this lifespan can vary widely among different taxonomic groups.

What are mass extinctions, and how frequently do they occur?

Mass extinctions are relatively rare but significant events where a large proportion of species disappear in a short period of geological time. While isolated extinctions are common, mass extinctions represent major disruptions to the biosphere.

What is the current status of extinction rates, according to the provided text?

The text indicates that extinctions have begun to be recorded more systematically, and there is an ongoing mass extinction event caused by human activity. Many species that become extinct are never scientifically documented.

What percentage of plant and animal species are currently threatened with extinction?

According to a 2019 report, twenty-five percent of plant and animal species are currently threatened with extinction. This highlights the severe impact of human activities on global biodiversity.

What symbol is typically used next to the name of an extinct species?

A dagger symbol (†) is typically placed next to the name of a species or other taxon to indicate its status as extinct.

What does the conservation status 'Extinct in the Wild (EW)' signify?

The 'Extinct in the Wild (EW)' conservation status, as defined by the IUCN, means that a species is only known to exist in captivity or in other artificial environments. There are no living specimens known in the wild, and the species may be functionally extinct if restoration efforts are unlikely.

What are 'chains of extinction,' and when are they particularly common?

Chains of extinction refer to the phenomenon where the extinction of one species can trigger the extinction of other species that depend on it, such as its parasites, predators, or pollinators. This is especially common when a keystone species goes extinct.

What are the primary drivers of the current global extinction crisis, according to IPBES?

According to IPBES, unsustainable fishing, hunting, and logging are identified as some of the primary drivers of the global extinction crisis. These activities, along with habitat destruction, significantly contribute to biodiversity loss.

What is the estimated impact of human activities on wild mammal biomass?

Human activities have led to a significant decline in the biomass of wild mammals, which has fallen by 82%. This statistic underscores the profound impact of human actions on the planet's fauna.

What is considered the main anthropogenic cause of species extinctions today?

Habitat degradation, primarily driven by agriculture, is considered the main anthropogenic cause of species extinctions. Urban sprawl, logging, mining, and certain fishing practices also contribute significantly.

How can habitat degradation lead to species extinction?

Habitat degradation can lead to extinction by making the environment toxic, limiting a species' ability to find resources, or reducing its capacity to compete with new species. The physical destruction of habitats, like rainforests or ocean floors, can eliminate essential niches for survival.

What are some natural causes for species extinction?

Natural causes for species extinction include the extinction of a necessary host, prey, or pollinator; interspecific competition; the inability to adapt to evolving diseases; and changes in environmental conditions, such as sudden climate shifts or the introduction of novel predators.

How have humans contributed to extinction through the introduction of species?

Humans have introduced species to new environments, sometimes intentionally and sometimes accidentally, which can lead to extinction. When these invasive alien species establish themselves, they can prey on, compete with, or degrade the habitat of native species, or introduce pathogens.

What is the 'overkill hypothesis' regarding human-caused extinctions?

The overkill hypothesis suggests that the rapid extinction of megafauna in various regions, such as Australia and the Americas, resulted from the introduction of humans to environments with animals unaccustomed to human predation techniques.

What is coextinction, and how does it manifest?

Coextinction is the loss of a species that occurs as a consequence of the extinction of another species. This commonly happens when a species loses its host, pollinator, or a crucial part of its food chain, such as the Haast's eagle going extinct because its prey, the moa, disappeared.

What role has climate change played in past extinctions?

Climate change has been confirmed as a cause of past extinctions, notably the extinction of amphibians during the Carboniferous Rainforest Collapse approximately 305 million years ago. Studies predict significant future losses due to ongoing climate change.

What is the estimated percentage of land species that could be committed to extinction by 2050 due to climate change?

A 2003 review predicted that 15% to 37% of land species could be committed to extinction by the year 2050 as a direct result of climate change. This indicates a potentially massive loss of biodiversity in the near future.

How might high sexual dimorphism in males increase a species' risk of extinction?

Species exhibiting high sexual dimorphism, particularly males with traits for competing for mates, appear to have a higher risk of extinction. This could be because costly sexually selected ornaments may negatively impact survival, or sexual selection might remove genes that, while neutral for survival, could be crucial for adapting to future environmental changes.

What are the 'Big Five' mass extinction events in Earth's history?

The text mentions at least five mass extinctions in Earth's history. Specific events noted include the Permian-Triassic extinction event (about 250 million years ago), which killed about 90% of species, and the Cretaceous-Paleogene extinction event (66 million years ago), known for eliminating non-avian dinosaurs.

What is the current scientific consensus on human-driven mass extinctions?

There is widespread consensus among biologists that the Earth is currently experiencing the early stages of a human-caused mass extinction event, often referred to as the Holocene extinction. This event is characterized by significantly accelerated extinction rates compared to background levels.

What is the estimated current extinction rate compared to background rates?

The current rate of global species extinctions is estimated to be 100 to 1,000 times higher than the background rates observed over Earth's evolutionary history. Some projections suggest future rates could be 10,000 times higher.

What are considered the main drivers of the modern extinction crisis?

Human population growth and increasing per capita consumption are identified as the main drivers of the modern extinction crisis. These factors exacerbate pressures on ecosystems and resources.

What actions have been proposed by the UN to mitigate the contemporary extinction crisis?

In January 2020, the UN's Convention on Biological Diversity drafted a plan to protect 30% of the Earth's land and oceans by 2030 and reduce pollution by 50%. The goal is to facilitate ecosystem restoration by 2050.

What was the scientific understanding of extinction before the 19th century?

Before the 19th century, prevailing beliefs, influenced by theology and concepts like the 'great chain of being,' generally held that species could not go extinct. It was thought that a species' disappearance would create gaps in the natural order, which was considered impossible in a perfect creation.

How did Georges Cuvier contribute to the modern understanding of extinction?

Georges Cuvier is credited with establishing the modern concept of extinction in the late 18th century. By comparing fossil remains, particularly mammoth skulls, with living species, he argued that distinct species had indeed ceased to exist, challenging prevailing views.

What was Jean-Baptiste Lamarck's view on species change and extinction?

Jean-Baptiste Lamarck, while not denying extinction entirely, believed it was exceptional and rare. He favored a gradualist view, suggesting that species changed over time in response to their environment, rather than disappearing due to catastrophic events.

How did Charles Lyell's concept of uniformitarianism influence the understanding of extinction?

Charles Lyell, a proponent of uniformitarianism, believed that geological processes shaping the Earth were gradual and consistent over time. He argued against catastrophic mass extinctions, suggesting that species disappearances were also gradual processes, contrasting with Cuvier's catastrophic view.

How did Charles Darwin incorporate extinction into his theory of evolution?

Charles Darwin viewed extinction as a constant side effect of competition in his theory of evolution. He proposed that less fit lineages would naturally disappear over time, a concept often referred to as background extinction.

What is the significance of the Raup and Sepkoski paper from 1982 regarding extinction?

The 1982 paper by David Raup and Jack Sepkoski on mass extinctions was significant because it provided evidence supporting the idea of catastrophic extinction events. This work helped vindicate Georges Cuvier's earlier theories and established catastrophic extinction as an important mechanism alongside background extinction.

What are some reasons for scientific interest in preserving species?

Scientists are interested in preserving species for several key reasons: they represent valuable genetic resources, they are crucial for maintaining ecosystem stability, and there are ethical considerations regarding the intrinsic value of biodiversity.

How have corporations engaged with conservation efforts?

While some corporations may label environmental concerns as exaggerated and cause significant damage, others find it beneficial to adopt good conservation practices. Some even engage in preservation efforts that exceed those undertaken by national parks, recognizing the value of biodiversity.

What is 'planned extinction,' and what are examples of completed planned extinctions?

Planned extinction refers to the deliberate eradication of certain species, often for human benefit. Examples of completed planned extinctions include the smallpox virus and the rinderpest virus, both of which are now extinct in the wild, though samples may be retained in labs.

What is the concept of 'de-extinction,' and what are potential targets?

De-extinction is the theoretical possibility of bringing extinct species back to life, typically through cloning using DNA from preserved remains. Potential targets mentioned include the mammoth, the thylacine, and the Pyrenean ibex.

What challenges exist in the process of de-extinction through cloning?

Successfully bringing back an extinct species via cloning faces significant challenges. These include obtaining viable DNA, cloning enough individuals to form a healthy population, and overcoming potential physical defects in cloned offspring, as seen in the failed Pyrenean ibex cloning attempts.

What is the 'extinction debt' phenomenon?

Extinction debt refers to the phenomenon where extinctions occur a long time after the events that set them in motion. This means that species may be doomed to extinction due to past environmental changes, even if the environment appears stable in the present.

How can genetic pollution contribute to species extinction?

Genetic pollution, resulting from uncontrolled hybridization, introgression, and genetic swamping, can lead to the homogenization or out-competition of native species. This process can deplete the unique gene pool of rarer species, increasing their risk of extinction, sometimes without obvious morphological changes.

What is the significance of genetic diversity for a species' survival?

A large gene pool, meaning extensive genetic diversity, is associated with robust populations that have a higher chance of adapting to and surviving adverse environmental changes. Conversely, low genetic diversity, often caused by bottlenecks or inbreeding, reduces a species' adaptability and increases its extinction risk.

What role do invasive species play in extinction?

Invasive alien species can cause extinction by directly preying on native species, competing with them for resources, introducing diseases or parasites, or degrading their habitat. This can have catastrophic consequences for native ecosystems.

What is the 'extinction vortex' model used for in conservation biology?

The extinction vortex model is used in conservation biology to classify extinctions by their causes. It describes a positive feedback loop where small population size leads to reduced genetic diversity and lower fitness, which further reduces population size, potentially leading to extinction.

What are the main concerns regarding human extinction, as discussed in the text?

Concerns about human extinction, as raised by figures like Martin Rees, often focus on the potential impacts of climate change or technological disasters. These existential risks pose a significant threat to the long-term survival of humanity.

What is the relationship between sexual selection and extinction risk?

Studies suggest that species with high sexual dimorphism, particularly males with elaborate traits for competition, face a higher extinction risk. These traits might hinder survival against natural selection or lead to the loss of genetic diversity important for adaptation.

What is the 'great chain of being,' and how did it relate to the concept of extinction?

The 'great chain of being' was a theological concept popular in the 1700s, proposing a hierarchical structure of all life from the simplest to the divine. Under this model, the extinction of a species was considered impossible, as it would create gaps in this perfect, continuous chain.

What was Robert Hooke's explanation for fossils of unknown species?

Robert Hooke, when presented with fossils of species unknown to him, theorized that they simply lived in unexplored regions, such as the deep ocean. He considered it unlikely that a species could be entirely 'lost' or extinct.

Extinction Wiki: The Great Silence: Understanding Extinction

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Definition

The Finality of Existence

Extinction signifies the termination of an organism or a species, marked by the death of its final member. This process can also occur when a taxon becomes functionally extinct, losing its capacity to reproduce and recover, even if a few individuals persist. Determining the precise moment of extinction is often challenging, leading to phenomena like Lazarus taxa, where species presumed extinct reappear in the fossil record after periods of absence.

Temporal Perspective

The vast majority of species that have ever existed are now extinct, with estimates suggesting over 99.9% of all life forms have perished. The typical lifespan of a species is estimated to be between one and ten million years, though some species, termed "living fossils," have demonstrated remarkable morphological stability over hundreds of millions of years.

Local vs. Global

In ecological contexts, "extinction" can sometimes refer to local extinction, where a species disappears from a specific area but persists elsewhere. Such local losses can be mitigated by reintroduction efforts. Species that are not globally extinct are termed extant, and those facing imminent threats are classified as threatened or endangered.

Causes of Extinction

Natural Processes

Extinction is an intrinsic aspect of evolution. Species typically disappear within ten million years of their first appearance, often due to an inability to adapt to changing environmental conditions or to compete effectively with better-adapted organisms. These gradual declines are part of the natural background extinction rate.

Catastrophic Events

Mass extinctions, characterized by the rapid disappearance of numerous species, have punctuated Earth's history. Events like the Permian-Triassic extinction (approx. 250 million years ago) and the Cretaceous-Paleogene (K-Pg) extinction (66 million years ago) dramatically reshaped biodiversity, often linked to geological or extraterrestrial phenomena.

Anthropogenic Drivers

Human activities are now the primary driver of extinction. Overharvesting, pollution, habitat destruction (especially deforestation), the introduction of invasive species, and climate change are accelerating species loss at unprecedented rates, leading to what is recognized as the Holocene extinction event.

Genetic and Demographic Factors

Small population sizes, reduced genetic diversity, and the accumulation of deleterious mutations can create an "extinction vortex," making populations more vulnerable. Factors that limit a species' evolvability, such as population bottlenecks or loss of genetic variation, increase the likelihood of extinction.

Historical Understanding

Pre-Darwinian Views

Historically, the concept of extinction was often at odds with prevailing worldviews, particularly the theological notion of a perfect, immutable creation. Early naturalists, like Robert Hooke and Thomas Molyneux, grappled with fossil evidence of extinct species, often rationalizing their existence as undiscovered or locally absent rather than entirely vanished.

Cuvier and Catastrophism

Georges Cuvier, in the late 18th century, was pivotal in establishing the modern concept of extinction. Through comparative anatomy and geological strata analysis, he inferred that catastrophic events led to widespread species loss and subsequent repopulation, a view that challenged gradualist perspectives.

Darwin and Gradualism

Charles Darwin integrated extinction into his theory of evolution by natural selection, positing it as a constant side effect of competition. His work popularized the idea of gradual, background extinction, though the significance of catastrophic mass extinctions, as proposed by Cuvier, was later re-emphasized by scientists like David Raup and Jack Sepkoski.

Mass Extinction Events

Geological Eras of Loss

Earth's history is marked by at least five major mass extinction events, periods of rapid, widespread species loss. These events, such as the Permian-Triassic extinction (the "Great Dying") and the Cretaceous-Paleogene (K-Pg) event that eliminated non-avian dinosaurs, have profoundly altered the trajectory of life.

Extinction Intensity

Analysis of the fossil record, particularly marine genera, reveals cyclical patterns of extinction intensity across geological periods. These graphs illustrate the dramatic fluctuations in species survival rates, highlighting the vulnerability of life to major environmental shifts.

The intensity of marine extinctions, often measured as the percentage of readily fossilized genera that disappear, varies significantly across geological time. Major events include:

Capitanian (Cap)
Permian-Triassic (P-Tr)
Triassic-Jurassic (Tr-J)
Cretaceous-Paleogene (K-Pg)
Late Ordovician-Silurian (O-S)
Late Devonian (Late D)

These periods represent significant disruptions to global ecosystems, underscoring the dynamic nature of biodiversity through Earth's history.

The Modern Crisis

The Holocene Extinction

Scientists widely agree that Earth is currently experiencing a human-induced mass extinction event, known as the Holocene extinction. Current extinction rates are estimated to be 100 to 1,000 times higher than background rates, with projections indicating future rates could be exponentially greater.

Biodiversity Decline

Reports indicate a drastic decline in the biomass of wild mammals and natural ecosystems. A significant percentage of plant and animal species are now threatened with extinction, largely due to unsustainable human practices such as habitat destruction, overexploitation, and pollution.

Habitat Loss and Climate Change

Habitat degradation, driven primarily by agriculture and urban sprawl, is the leading anthropogenic cause of species extinction. Concurrently, climate change exacerbates this crisis by altering ecosystems, driving desertification, and forcing species to adapt or perish.

Scientific Understanding & Future

Scientific Inquiry

The study of extinction spans multiple disciplines, from paleontology and evolutionary biology to ecology and conservation science. Understanding the mechanisms of extinction, both natural and anthropogenic, is crucial for predicting future biodiversity trends and informing conservation strategies.

Conservation Efforts

Efforts to mitigate extinction include establishing nature preserves, enacting protective legislation, and implementing biodiversity action plans. Organizations worldwide work to educate the public and advocate for policies that protect endangered species and their habitats.

De-Extinction and Specicide

Advancements in genetics and cloning technology raise the possibility of "de-extinction," or resurrecting extinct species. Conversely, some scientists advocate for "specicide"—the deliberate extinction of specific species, such as disease vectors like mosquitoes—to prevent human suffering, a concept raising significant ethical considerations.

Human Attitudes and Interests

Ethical and Philosophical Dimensions

Human concern for species extinction often stems from perceived impacts on human wants and needs, rather than an intrinsic value for non-human life. Philosophical perspectives highlight the anthropocentric nature of many conservation motivations and the potential disconnect between human society and the natural world.

Economic and Societal Factors

Commercial and industrial interests frequently clash with conservation goals. While some corporations engage in proactive environmental stewardship, the broader economic system, driven by continuous growth and resource extraction, often exacerbates extinction pressures. Governments balance economic development with ecological preservation, sometimes enacting laws to protect species and their habitats.

Advocacy and Awareness

Public awareness campaigns and advocacy groups play a vital role in highlighting the extinction crisis and pressuring governments for action. The success of conservation efforts often depends on shifting societal priorities to recognize the critical importance of biodiversity for planetary health and human well-being.

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References

J.H.Lawton and R.M.May, Extinction rates, Oxford University Press, Oxford, UK

A full list of references for this article are available at the Extinction Wikipedia page

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This page was generated by an Artificial Intelligence and is intended for informational and educational purposes only. The content is based on a snapshot of publicly available data from Wikipedia and may not be entirely accurate, complete, or up-to-date.

This is not scientific or environmental advice. The information provided on this website is not a substitute for professional consultation regarding conservation, ecology, or evolutionary biology. Always refer to official scientific literature and consult with qualified experts for specific analyses or guidance.

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The Great Silence

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Definition ⚰️

💀 The Finality of Existence

⏳ Temporal Perspective

📍 Local vs. Global

Causes of Extinction 🌍

🌱 Natural Processes

🔥 Catastrophic Events

🚶 Anthropogenic Drivers

🧬 Genetic and Demographic Factors

Historical Understanding 📜

⏳ Pre-Darwinian Views

🔬 Cuvier and Catastrophism

🌿 Darwin and Gradualism

Mass Extinction Events 💥

⏳ Geological Eras of Loss

📊 Extinction Intensity

The Modern Crisis 🚨

📈 The Holocene Extinction

📉 Biodiversity Decline

🌳 Habitat Loss and Climate Change

Scientific Understanding & Future 💡

🔬 Scientific Inquiry

🌱 Conservation Efforts

🧬 De-Extinction and Specicide

Human Attitudes and Interests 🤔

⚖️ Ethical and Philosophical Dimensions

🏢 Economic and Societal Factors

📣 Advocacy and Awareness

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📜 Important Notice

Dive in with Flashcard Learning!

Definition

The Finality of Existence

Temporal Perspective

Local vs. Global

Causes of Extinction

Natural Processes

Catastrophic Events

Anthropogenic Drivers

Genetic and Demographic Factors

Historical Understanding

Pre-Darwinian Views

Cuvier and Catastrophism

Darwin and Gradualism

Mass Extinction Events

Geological Eras of Loss

Extinction Intensity

The Modern Crisis

The Holocene Extinction

Biodiversity Decline

Habitat Loss and Climate Change

Scientific Understanding & Future

Scientific Inquiry

Conservation Efforts

De-Extinction and Specicide

Human Attitudes and Interests

Ethical and Philosophical Dimensions

Economic and Societal Factors

Advocacy and Awareness

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice