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Extinction is definitively confirmed only after the absolute last individual of a species has died.
Answer: True
Extinction is definitively confirmed only upon the death of the last individual of a species, marking the irreversible cessation of that lineage.
A species is considered 'functionally extinct' only when all its members are deceased.
Answer: False
A species is considered 'functionally extinct' when its remaining population can no longer sustain itself or reproduce effectively, even if some individuals are still alive. This is distinct from absolute extinction, which requires the death of the last individual.
Lazarus taxa are species that have been successfully reintroduced into the wild after being declared extinct.
Answer: False
Lazarus taxa are species that were presumed extinct but were later rediscovered, or whose fossil record reappears after a significant gap. They are not species reintroduced after being declared extinct, but rather those that persisted undetected or reappeared in the fossil record.
The coelacanth is a well-known example of a Lazarus taxon, rediscovered in the 20th century.
Answer: True
The coelacanth, a fish previously known only from fossils dating back millions of years, serves as a prominent example of a Lazarus taxon, having been rediscovered alive in the 20th century.
Pseudoextinction involves the complete disappearance of a lineage, with no evolutionary continuation.
Answer: False
Pseudoextinction occurs when a lineage evolves into a new form or species, meaning the original classification ceases to exist but the lineage persists. True extinction involves the complete termination of a lineage.
The obelisk symbol (obelus) is used to denote extinct species.
Answer: False
The dagger symbol (†), not the obelisk (obelus), is conventionally used in scientific literature to indicate that a species or taxon is extinct.
Chains of extinction are most common when a species goes extinct in isolation with no ecological dependencies.
Answer: False
Chains of extinction, where the loss of one species precipitates the extinction of others reliant upon it, are most prevalent when species have significant ecological dependencies, such as predator-prey or host-parasite relationships, not when they go extinct in isolation.
Coextinction occurs when a species goes extinct independently of any other species.
Answer: False
Coextinction is defined as the loss of a species that occurs as a consequence of the extinction of another species upon which it depends.
Extinction debt refers to species that go extinct very rapidly after environmental changes.
Answer: False
The 'extinction debt' phenomenon describes the temporal lag between environmental changes that doom a species and its eventual extinction, implying that current extinctions are often consequences of past habitat alterations or environmental shifts.
What is the fundamental definition of extinction?
Answer: The termination of a species through the death of its very last individual member.
The fundamental definition of extinction denotes the irreversible cessation of a species or organismal lineage, occurring upon the death of its final individual member.
Which condition might lead to a species being considered 'functionally extinct'?
Answer: The remaining individuals are too old or unhealthy to reproduce successfully.
A species may be considered 'functionally extinct' when its remaining population is unable to reproduce effectively or recover, often due to factors like advanced age, poor health, or insufficient numbers of viable breeding pairs, even if some individuals persist.
What are Lazarus taxa?
Answer: Species believed extinct but later rediscovered, or fossils reappearing after a gap.
Lazarus taxa are defined as species that were previously thought to be extinct but were subsequently rediscovered, or those whose fossilized remains reappear in the geological record after a prolonged absence, underscoring the challenges in definitively assessing extinction.
How does pseudoextinction differ from true extinction?
Answer: Pseudoextinction occurs when a lineage evolves into a new form, while true extinction is a complete lineage termination.
Pseudoextinction signifies the evolutionary transformation of a lineage into a new form or species, meaning the original classification ceases to exist but the lineage persists. True extinction, conversely, represents the complete termination of a lineage with no evolutionary continuation.
What does the dagger symbol (\u2020) typically indicate next to a species name?
Answer: The species is extinct.
The dagger symbol (†) is the conventional notation used in scientific literature to signify that a species or taxon is extinct.
The extinction of one species causing the extinction of others dependent on it is known as:
Answer: Coextinction
The phenomenon where the extinction of one species leads to the extinction of other species dependent upon it is termed coextinction, often occurring with keystone species or obligate mutualists.
The Haast's eagle going extinct because its prey (the moa) disappeared is an example of:
Answer: Coextinction
The extinction of the Haast's eagle due to the disappearance of its primary prey, the moa, exemplifies coextinction, where the loss of one species directly causes the extinction of another dependent species.
What does the 'extinction debt' phenomenon imply?
Answer: Extinctions can occur long after the environmental changes that caused them.
The 'extinction debt' phenomenon describes the temporal lag between environmental changes that doom a species and its eventual extinction, implying that current extinctions are often consequences of past habitat alterations or environmental shifts.
Before the 19th century, scientists widely accepted that species could become extinct.
Answer: False
Prior to the 19th century, prevailing scientific and theological views generally held that species were immutable and incapable of extinction, as their disappearance would disrupt a divinely ordered natural hierarchy.
Georges Cuvier argued that fossils represented species that had ceased to exist.
Answer: True
Georges Cuvier challenged prevailing beliefs by presenting empirical evidence, derived from comparative anatomy of fossil remains, that distinct species had indeed ceased to exist, thereby establishing the modern concept of extinction.
Jean-Baptiste Lamarck believed extinction was a frequent and expected outcome of evolution.
Answer: False
Jean-Baptiste Lamarck viewed species change as a gradual process in response to the environment and considered extinction to be an exceptional and rare occurrence, rather than a frequent outcome of evolution.
Charles Darwin viewed extinction primarily as a result of catastrophic geological events.
Answer: False
Charles Darwin integrated extinction into his theory of evolution by positing it as a natural consequence of interspecific competition, whereby less adapted lineages are gradually eliminated, a process often termed background extinction.
The 'great chain of being' concept supported the idea that species extinction was a natural process.
Answer: False
The 'great chain of being' concept proposed a fixed, hierarchical structure of life, implying that species were immutable and incapable of extinction, as their disappearance would create gaps in this divinely ordered system.
Robert Hooke proposed that fossils of unknown species might exist in unexplored regions.
Answer: True
Robert Hooke proposed that fossils of species unknown to his time might simply inhabit unexplored regions of the Earth, such as the deep oceans, rather than indicating complete extinction.
How did Georges Cuvier challenge previous beliefs about species?
Answer: He presented evidence that distinct species had ceased to exist.
Georges Cuvier challenged prevailing beliefs by presenting empirical evidence, derived from comparative anatomy of fossil remains, that distinct species had indeed ceased to exist, thereby establishing the modern concept of extinction.
What was Charles Darwin's view on extinction within his theory of evolution?
Answer: Extinction was a natural consequence of competition, eliminating less fit lineages.
Charles Darwin integrated extinction into his theory of evolution by positing it as a natural consequence of interspecific competition, whereby less adapted lineages are gradually eliminated, a process often termed background extinction.
What was the prevailing belief about species before the 19th century regarding extinction?
Answer: Species were believed incapable of going extinct.
Prior to the 19th century, prevailing scientific and theological views generally held that species were immutable and incapable of extinction, as their disappearance would disrupt a divinely ordered natural hierarchy.
Robert Hooke suggested an alternative explanation for fossils of unknown species, proposing they:
Answer: Lived in unexplored regions of the Earth.
Robert Hooke proposed that fossils of unknown species represented organisms that inhabited unexplored regions of the Earth, such as the deep oceans, rather than indicating complete extinction.
It is estimated that fewer than one billion species have gone extinct throughout Earth's history.
Answer: False
Paleontological estimates indicate that over five billion species have become extinct throughout Earth's history, a number far exceeding one billion.
The estimated number of living eukaryotic species globally is around 8.7 million.
Answer: True
Current scientific estimations posit the existence of approximately 8.7 million eukaryotic species globally, representing a substantial portion of Earth's biodiversity.
Mammoths and saber-toothed cats are examples of species that are still alive today.
Answer: False
Mammoths and saber-toothed cats are cited as iconic examples of extinct animal species, representing taxa that have long since disappeared from the planet.
The average lifespan of a species before extinction is typically between 100,000 and 500,000 years.
Answer: False
The typical lifespan of a species before extinction is considerably longer than suggested, generally ranging from 1 to 10 million years from its evolutionary origin.
The Living Planet Index tracks the rate of human population growth.
Answer: False
The Living Planet Index monitors the abundance of global wildlife populations, not human population growth. Declines in this index serve as indicators of a biodiversity crisis.
What is the estimated number of species that have gone extinct throughout Earth's history?
Answer: Over 5 billion
Paleontological estimates indicate that more than five billion species have become extinct throughout Earth's history, highlighting extinction as a fundamental and pervasive process in the evolution of life.
According to the text, approximately how many species of eukaryotes are estimated to exist globally?
Answer: Approximately 8.7 million
Current scientific estimations posit the existence of approximately 8.7 million eukaryotic species globally. This figure represents a substantial portion of Earth's biodiversity, though it may be conservative if microbial diversity is fully accounted for.
Which of the following is NOT mentioned as an example of an extinct animal species?
Answer: Giant Sloths
While non-avian dinosaurs, saber-toothed cats, and mammoths are cited as examples of extinct species, Giant Sloths are not explicitly mentioned in the provided text as such.
What is the typical average lifespan of a species before it goes extinct?
Answer: 1 to 10 million years
The average duration of a species' existence before extinction is typically estimated to be between 1 and 10 million years, although this figure exhibits considerable variation across different taxonomic groups.
Mass extinctions are common events, occurring roughly every few thousand years.
Answer: False
Mass extinctions, characterized by the relatively rapid disappearance of a significant fraction of global species, are infrequent occurrences in geological history, contrasting with the more common background extinction rate.
The current extinction rate is significantly higher than historical background rates due to human activities.
Answer: True
There is widespread scientific consensus that the current extinction rate is dramatically elevated compared to historical background rates, primarily driven by anthropogenic factors.
A 2019 report indicated that approximately half of all plant and animal species are threatened with extinction.
Answer: False
A 2019 report indicated that approximately one-quarter (25%) of plant and animal species are currently threatened with extinction, not half. This figure highlights the severity of the contemporary biodiversity crisis.
Climate change has been identified as a cause of past extinctions, such as the one affecting amphibians 305 million years ago.
Answer: True
The text explicitly links climate change to the extinction of amphibians during the Carboniferous Rainforest Collapse approximately 305 million years ago.
The Permian-Triassic event, which eliminated non-avian dinosaurs, is one of the 'Big Five' mass extinctions.
Answer: False
The Permian-Triassic event is one of the 'Big Five' mass extinctions, but it occurred approximately 250 million years ago and is known for eliminating a vast majority of species, not specifically non-avian dinosaurs, which went extinct later in the Cretaceous-Paleogene event.
The current extinction rate is estimated to be roughly similar to the natural background rate.
Answer: False
Current estimates indicate that the global species extinction rate is 100 to 1,000 times greater than the historical background rate, with projections suggesting even higher rates in the future.
The Raup and Sepkoski paper (1982) supported the idea that extinction events could be catastrophic.
Answer: True
The 1982 paper by Raup and Sepkoski provided significant evidence supporting the concept of catastrophic mass extinction events, contributing to their acceptance in scientific discourse.
What characterizes a mass extinction event?
Answer: A relatively rare event where a large proportion of species disappear quickly.
Mass extinction events are distinguished by the relatively rapid disappearance of a significant fraction of Earth's species, representing major disruptions to the biosphere, and occur infrequently in geological time.
Which past extinction event is explicitly linked to climate change in the text?
Answer: The extinction of amphibians during the Carboniferous Rainforest Collapse
The text explicitly links climate change to the extinction of amphibians during the Carboniferous Rainforest Collapse approximately 305 million years ago.
What is the estimated current rate of species extinction compared to background rates?
Answer: 100 to 1,000 times higher
Current estimates indicate that the global species extinction rate is 100 to 1,000 times greater than the historical background rate, with projections suggesting even higher rates in the future.
According to IPBES, unsustainable logging and hunting are minor contributors to the extinction crisis.
Answer: False
Contrary to the assertion, IPBES identifies unsustainable fishing, hunting, and logging as primary drivers, not minor contributors, to the global extinction crisis, alongside habitat destruction.
Wild mammal biomass has increased significantly due to human activities.
Answer: False
Human activities have resulted in a substantial decrease, estimated at 82%, in the biomass of wild mammals, rather than an increase. This reflects the profound impact of human actions on global fauna.
Agriculture is identified as the leading human-driven cause of species extinctions today.
Answer: True
Habitat degradation, predominantly driven by agricultural expansion, is identified as the principal anthropogenic factor contributing to contemporary species extinctions.
Habitat degradation can lead to extinction by making environments toxic or limiting resources.
Answer: True
Habitat degradation contributes to extinction by rendering environments toxic, diminishing resource availability, or hindering a species' competitive capacity, thereby eliminating essential ecological niches.
Inability to adapt to diseases and competition from other species are solely natural causes of extinction.
Answer: False
While inability to adapt to diseases and interspecific competition can be natural drivers of extinction, they are not *solely* natural. Human activities, such as habitat alteration or the introduction of novel pathogens and competitors, can exacerbate these factors, making them significant anthropogenic contributors as well.
The introduction of invasive alien species by humans can contribute to native species extinction.
Answer: True
Humans introduce species to new environments, often leading to the establishment of invasive alien species that can prey on, compete with, or degrade the habitat of native species, thereby contributing to their extinction.
The 'overkill hypothesis' suggests megafauna extinction was primarily due to climate shifts.
Answer: False
The 'overkill hypothesis' posits that the extinction of large fauna (megafauna), particularly in regions like the Americas and Australia, was primarily caused by the introduction of human hunting pressures to which these animals were not adapted.
Human population growth and consumption patterns are identified as key drivers of the modern extinction crisis.
Answer: True
The primary drivers of the contemporary extinction crisis are identified as human population growth and escalating per capita consumption, which intensify pressures on global ecosystems and resources.
Genetic pollution can lead to extinction by homogenizing or out-competing native species.
Answer: True
The primary risk of genetic pollution lies in its potential to homogenize or out-compete native species through uncontrolled hybridization and introgression, thereby eroding unique gene pools and increasing extinction vulnerability.
Invasive species primarily contribute to extinction by improving native habitats.
Answer: False
Invasive species primarily contribute to extinction by disrupting ecosystems through predation, competition for resources, disease introduction, or habitat degradation, rather than by improving native habitats.
According to IPBES, which activities are primary drivers of the global extinction crisis?
Answer: Unsustainable fishing, hunting, and logging
The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) identifies unsustainable fishing, hunting, and logging, alongside habitat destruction, as principal drivers of the current global extinction crisis.
What has been the estimated impact of human activities on the biomass of wild mammals?
Answer: A decrease of 82%
Human activities are estimated to have caused an 82% reduction in the global biomass of wild mammals, reflecting a profound impact on terrestrial fauna.
What is identified as the main anthropogenic cause of species extinctions today?
Answer: Habitat degradation, primarily driven by agriculture
Habitat degradation, predominantly driven by agricultural expansion, is identified as the principal anthropogenic factor contributing to contemporary species extinctions, with other factors like urbanization and resource extraction also playing significant roles.
How can habitat degradation contribute to extinction?
Answer: By making the environment toxic or limiting resource availability.
Habitat degradation contributes to extinction by rendering environments toxic, diminishing resource availability, or hindering a species' competitive capacity, thereby eliminating essential ecological niches.
Which of the following is listed as a natural cause for species extinction?
Answer: Interspecific competition
Interspecific competition is listed among the natural factors that can lead to species extinction, alongside environmental changes and the inability to adapt to diseases.
What is the 'overkill hypothesis' related to?
Answer: The extinction of megafauna caused by human hunting techniques.
The 'overkill hypothesis' posits that the extinction of large fauna (megafauna), particularly in regions like the Americas and Australia, was primarily caused by the introduction of human hunting pressures to which these animals were not adapted.
What are identified as the main drivers of the modern extinction crisis?
Answer: Human population growth and increased consumption
The primary drivers of the contemporary extinction crisis are identified as human population growth and escalating per capita consumption, which intensify pressures on global ecosystems and resources.
What is the primary risk associated with genetic pollution?
Answer: It leads to the homogenization or out-competition of native species.
The primary risk of genetic pollution lies in its potential to homogenize or out-compete native species through uncontrolled hybridization and introgression, thereby eroding unique gene pools and increasing extinction vulnerability.
The conservation status 'Extinct in the Wild (EW)' means a species survives only in zoos or botanical gardens.
Answer: True
The conservation status 'Extinct in the Wild (EW)' denotes species known to exist solely in captivity or in artificial environments, with no wild populations remaining.
By 2050, climate change is predicted to commit less than 10% of land species to extinction.
Answer: False
A 2003 review projected that climate change could commit between 15% and 37% of land species to extinction by 2050, indicating a substantial potential loss of biodiversity.
Species with high sexual dimorphism, especially in males, are less likely to face extinction.
Answer: False
Species with pronounced sexual dimorphism in males may face elevated extinction risk because elaborate traits selected for mate competition can compromise survival or deplete genetic diversity essential for adaptation to environmental shifts.
A UN plan aims to protect 30% of Earth's land and oceans by 2030 to mitigate extinction.
Answer: True
A key objective of the UN's Convention on Biological Diversity plan is to conserve 30% of the Earth's land and oceans by the year 2030, alongside efforts to reduce pollution and restore ecosystems.
Scientists advocate for species preservation mainly for their aesthetic value.
Answer: False
Scientists advocate for species preservation based on multiple factors, including their value as genetic resources, their role in maintaining ecosystem stability, and ethical considerations regarding intrinsic biodiversity value, not solely aesthetic appeal.
The smallpox virus is an example of a successfully completed planned extinction.
Answer: True
The smallpox virus is cited as an example of a successfully completed planned extinction, eradicated globally through deliberate human intervention.
De-extinction aims to clone extinct species using genetic material from living relatives.
Answer: False
De-extinction typically involves using genetic material from preserved remains of extinct species, not solely from living relatives, to attempt cloning or genetic reconstruction.
The Pyrenean ibex cloning attempts were fully successful in establishing a viable population.
Answer: False
Cloning attempts of the Pyrenean ibex faced significant challenges and were not fully successful in establishing a viable population, highlighting the difficulties inherent in de-extinction efforts.
A large gene pool is associated with reduced adaptability and higher extinction risk.
Answer: False
A large gene pool, indicative of high genetic diversity, is associated with increased adaptability and a lower extinction risk. Conversely, reduced genetic diversity can impair a species' ability to cope with environmental changes.
The extinction vortex model describes a positive feedback loop leading to extinction.
Answer: True
The 'extinction vortex' model illustrates a positive feedback mechanism wherein declining population size leads to reduced genetic diversity and fitness, further exacerbating population decline and increasing the probability of extinction.
Concerns about human extinction often relate to natural disasters like asteroid impacts.
Answer: False
While natural disasters like asteroid impacts are potential existential threats, concerns regarding human extinction, as articulated by thinkers like Martin Rees, more frequently focus on anthropogenic factors such as climate change and technological risks, which pose significant threats to long-term human survival.
Which conservation status signifies that a species is known only to exist in captivity?
Answer: Extinct in the Wild (EW)
The conservation status 'Extinct in the Wild (EW)' denotes species known to exist solely in captivity or in artificial environments, with no wild populations remaining.
What percentage range of land species might be committed to extinction by 2050 due to climate change, according to a 2003 review?
Answer: 15% to 37%
A 2003 review projected that climate change could commit between 15% and 37% of land species to extinction by 2050, indicating a substantial potential loss of biodiversity.
Why might species with high sexual dimorphism in males face a higher extinction risk?
Answer: Elaborate male traits may negatively impact survival or reduce adaptive genetic diversity.
Species with pronounced sexual dimorphism in males may face elevated extinction risk because elaborate traits selected for mate competition can compromise survival or deplete genetic diversity essential for adaptation to environmental shifts.
What is a key goal of the UN's Convention on Biological Diversity plan mentioned?
Answer: To protect 30% of Earth's land and oceans by 2030.
A key objective of the UN's Convention on Biological Diversity plan is to conserve 30% of the Earth's land and oceans by the year 2030, alongside efforts to reduce pollution and restore ecosystems.
What is 'de-extinction'?
Answer: The theoretical possibility of bringing extinct species back to life.
De-extinction refers to the theoretical concept and potential scientific endeavor of reviving extinct species, often through advanced genetic and cloning techniques utilizing preserved biological material.
The 'extinction vortex' model illustrates:
Answer: A positive feedback loop where small populations decline towards extinction.
The 'extinction vortex' model illustrates a positive feedback mechanism wherein declining population size leads to reduced genetic diversity and fitness, further exacerbating population decline and increasing the probability of extinction.