Global extinction occurs when there are no surviving individuals of a species or other taxonomic unit (e.g., subspecies, genus, family, etc. - each is known as a taxon). Extinction of any species results in the irreversible loss of a portion of the Earth's biological richness. Extinction can occur naturally as a result of an unforeseeable disaster, chronic environmental stress, or ecological interactions such as competition, disease, or predation. However, extinction rates have increased dramatically since humans became the dominant large animal on Earth and the cause of global environmental change. In this article, we will discuss Species Extinction which will be helpful for UPSC exam preparation.

Causes of Species Extinction

Overexploitation

• In comparison to terrestrial organisms, intensive exploitation of marine organisms has only begun in the last few hundred years.
• Initially, marine animals were not clearly threatened by the extinction wave that affected land species. However, marine species have come under intense pressure since humans developed the ability to travel across the sea.
• Human exploitation of marine resources has been a major cause of extinction in this short time, both through direct mortality of target species and multiple collateral effects on non-target species (bycatch).
• Fisheries are also indirectly responsible for biodiversity loss and ecosystem disruption by dumping massive amounts of derelict fishing gear into the ocean, which kills many marine top predator species.

Disturbance in Habitat

• In most ecosystems, biological, physical, and chemical factors are inextricably linked. As a result, changes in one of these factors can cause changes in others.
• Habitat exploitation can have a significant impact on many components of a system.
• Following are some examples of habitat destruction:
  • Physical changes include:
    • Marine aggregate dredging
    • Trawl Fishing
    • Economic redevelopment of coastal wetlands (mangroves, salt marshes)
    • Structures for coastal protection
  • Chemical alterations include:
    • Chemical (industrial and agricultural) and oil pollution
    • Plastics and non-biodegradable litter
    • Eutrophication
    • Acidification of oceans
• Biological changes include the introduction of non-native species.

Climate Change

• Recent climate change, such as global warming, has increased local water temperatures beyond the range of many species.
• Because of changes in the food web, previously productive areas, such as upwelling regions, have become less productive.
• Lower primary production leads to lower primary consumer biomass. Krill are important primary consumers in the oceans, supporting many important ecosystems.
• As a result, climate change will inevitably have an impact on krill-based food webs, resulting in a decrease in top-level consumers such as large plankton-grazing fish and sea mammals.

Process of Extinction

• Deterministic processes have a cause and effect. For example, glaciation and human interference such as deforestation.
• Stochastic processes (chance and random events) that affect individual survival and reproduction.
• For example, unexpected changes in weather patterns, decreased food supply, disease, an increase in competitors, predators, or parasites, and so on, which may act independently or in conjunction with deterministic effects.
• The impact of these processes will, of course, be determined by the size, genetic diversity, and resilience of populations.

Natural and Artificial Extinction

Natural Extinction

• Factors that contribute to natural extinction are:
  • Continent drifting
  • Climate change
  • Tectonic activity
  • Increased volcanic activity
  • Global glaciations in the late Ordovician period
  • An extraterrestrial impact is thought to have caused the late Cretaceous extinction.
• In comparison to animal extinction, vascular plant extinction has been more gradual.
  • It is thought that extinction in this group was caused by competitive displacement by more advanced plant forms, or by gradual climate change, rather than by a sudden catastrophic event.

Artificial Extinction

• Even though species extinction is a natural process that can occur without human intervention, extinctions caused by humans are now exceeding reasonable estimates of natural extinction rates.
• Human intervention threatens the extinction of species due to:
  • Direct causes - such as hunting, collection or capture, and persecution
  • Indirect causes - such as habitat loss, modification, and fragmentation, as well as the introduction of invasive species.

Traits of Extinction

• Traits that negatively affect or increase a species' vulnerability to extinction as a result of habitat fragmentation have been identified. These are:
  • scarcity of resources
  • poor dispersal ability
  • ecological specialization
  • unstable populations
  • high trophic status - animals at higher trophic levels (i.e. the position of a species in a food chain) typically have smaller populations than those at lower levels (e.g. carnivores are fewer in number than herbivores)
  • adult survival rates are low
  • population growth at a low intrinsic rate
  • body size, fecundity, and dietary specialization

Vulnerability of Species

Although all species contribute to the function of the ecosystem, some are more vulnerable to extinction and have a greater impact than others. Following are some examples:

Large carnivores and other top-of-the-food-chain species

• Top predators (also known as 'apex predators') play an important role in ecosystems by regulating all underlying trophic levels both directly and indirectly.
• They require a large territory to catch enough prey, and their abundance is low.
• Reproduction and growth are slower in larger species, as is recovery after partial depletion. They are a popular fishing target and thus subject to overfishing.
• Top predators are thus a vulnerable group, with most species declining dramatically, in some cases by more than 90%.
• Even light fishing pressure, for example, is enough to cause significant population declines in many large shark species.
• Because of the critical role that apex predators can play in ecosystem functioning, disease regulation, and biodiversity maintenance, this 'trophic downgrading' has sparked widespread concern.

Specialized Endemic Species

• Specialized species with a limited geographic range are particularly vulnerable to invasive species and human intervention.
• These species can perform critical functions for the local ecosystem that are lost when they are replaced by non-native generalist species that compete more effectively on a larger scale.

Migratory Species

• Migratory species require suitable habitats in widely separated locations to feed and rest.
• Dugong (Dugong dugon), Loggerhead turtle (Caretta caretta), Hawksbill turtle (Eretmochelys imbricata), and Mediterranean Monk Seal (Monachus monachus) are all threatened if one of their habitats is lost.

Species with complicated life cycles

• Tunicates (Ciona intestinalis) and Brown bryozoans (Bugula neritina) require several different elements to be present at very specific times to complete their life cycles, making them vulnerable if any single element in the cycle is disrupted.

Consequences of Species Extinction at Local and Regional Scales

• Species extinction at the local or regional level implies a decrease in species richness (number of species) and biodiversity.
• There is compelling evidence that species richness improves ecosystem productivity and stability. The extinction of any species can have a negative impact on the ecosystem.
• This is especially true for the loss of species at higher trophic levels, which face the greatest risk of (local) extinction as a result of human hunting, habitat loss, or toxic bioaccumulation.
• The extinction of top predators can cause a trophic cascade, or a complete reorganisation of the ecosystem and food web relationships.
• Reintroduction of extinct species is not always possible because species that have taken their place in the food web prevent their return.
• In some cases, alien species invasion can compensate for a decline in species diversity.
• However, the majority of alien invasions are caused by species at lower trophic levels.

Mitigation Strategies for Species Extinction

• The most widely used method of protecting marine ecosystems is the establishment of Marine Protected Areas (MPAs).
  • These designated areas aid in the protection of depleted, threatened, rare, or endangered species and populations, as well as the preservation of critical species' habitats.
  • The fully protected MPAs, where all resource extraction is prohibited, are commonly referred to as Marine Reserves.
  • MPAs protect various habitats (e.g., sandbanks, mudflats, lagoons, mangroves, and reefs) and thus different assemblages of species (e.g., Lamprey, Bottlenose Dolphin, and Loggerhead Turtle), depending on the needs and natural states of different countries.
• Conservation and ecologically sound management of critical habitats, particularly coastal wetlands.
• Preventing or reducing marine pollution through integrated coastal and river basin planning to limit the passage of nutrients and other pollutants to the marine environment.
• Implementing the FAO code of conduct for responsible fisheries will help to ensure sustainable fisheries and mariculture.
• Non-native species invasion prevention.
• Above all, substantial efforts should be made to raise public awareness of the critical need for action.
• People all over the world should be aware of the causes and consequences of extinctions, as well as the fact that biodiversity loss is occurring everywhere.

Species Extinction from India

Flora

• According to the BSI, 18 plant species — four non-flowering and 14 flowering — have become extinct.
• Lastreopsis wattii, a fern discovered in Manipur by George Watt in 1882, and three species from the genus Ophiorrhiza (Ophiorrhiza brunonis, Ophiorrhiza caudate, and Ophiorrhiza radican), all discovered in peninsular India, are among the most notable.
• Corypha taliera Roxb, a palm species discovered by William Roxburgh in Myanmar and the Bengal region, is also extinct.

Fauna

• Cheetah (Acionyx jubatus).
• In India, the Sumatran rhinoceros (Dicerorhinus sumatrensisi) is considered extinct.
• Since 1950, the pink-headed duck (Rhodonessa caryophyllaceai) has been considered extinct.
• The Himalayan quail (Ophrysia supercililios) was last seen in 1876.

Conclusion

A mass extinction is a global, catastrophic event that results in the extinction of more than 65% of all species. Our planet is currently experiencing its sixth mass extinction of plants and animals — the sixth wave of extinctions over the last half-billion years. We are currently witnessing the worst mass extinction since the dinosaurs died out 65 million years ago. Although extinction is a natural occurrence, it happens at a "background" rate of one to five species per year. Scientists estimate that we are now losing species at up to 1,000 times the natural rate, with dozens becoming extinct every day.

FAQs

Question: What is species extinction?

Question: What are the major causes of species extinction?

Question: How does species extinction impact ecosystems?

Question: What is the current status of species extinction globally?

Question: How can species extinction be prevented?

MCQs

1. What is meant by species extinction?

A) Temporary disappearance of a species

B) Complete and permanent disappearance of a species

C) Migration of species to other regions

D) Loss of genetic diversity within a species

2. Which of the following is a major cause of species extinction in the modern era?

A) Solar flares

B) Habitat loss and degradation

C) Genetic mutation

D) Geological shifts

3. What is the primary focus of conservation efforts to prevent species extinction?

A) Ignoring climate change

B) Protecting and restoring habitats

C) Increasing hunting practices

D) Introducing more invasive species

4. What is the IUCN Red List?

A) A list of extinct languages

B) A list of species facing varying levels of extinction risk

C) A record of ancient civilizations

D) A global database of geological formations

5. How does species extinction impact human society?

A) It only affects remote ecosystems

B) It has no measurable impact

C) It reduces ecosystem services like pollination and water purification

D) It leads to immediate climate change

GS Mains Questions and Model Answers

Q1: Discuss the causes and consequences of species extinction in modern times. 

Answer: Species extinction in modern times is primarily driven by human-induced factors such as habitat loss, deforestation, urbanization, pollution, overexploitation, introduction of invasive species, and climate change. These activities degrade natural habitats, reduce genetic diversity, and make species more vulnerable to extinction. Overhunting and illegal poaching further contribute to the decline of many species. The consequences of species extinction are profound, impacting ecosystems and human societies. The loss of biodiversity can disrupt food chains, reduce ecosystem resilience, and diminish services like pollination, water purification, and carbon sequestration. Economically, extinction can affect livelihoods dependent on natural resources, such as agriculture and ecotourism. Social and cultural values associated with certain species may also be lost. Addressing species extinction requires global cooperation and comprehensive conservation efforts, including habitat protection, sustainable resource use, anti-poaching laws, and community-based conservation initiatives.

Q2: Evaluate the role of international agreements in addressing species extinction. 

Answer: International agreements play a crucial role in addressing species extinction by fostering global cooperation, setting conservation targets, and providing frameworks for collective action. Treaties like the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) regulate trade to prevent overexploitation of threatened species. The Convention on Biological Diversity (CBD) promotes the conservation and sustainable use of biodiversity, encouraging countries to develop national strategies for biodiversity preservation. Additionally, agreements like the Paris Agreement indirectly contribute by addressing climate change, which poses a significant threat to species survival. While international agreements have led to positive outcomes, such as the recovery of certain endangered species, challenges remain in implementation, enforcement, and funding. Effective collaboration between governments, NGOs, and local communities is essential to ensure that the commitments made under these agreements translate into tangible conservation actions and outcomes.

Q3: Explain the importance of habitat conservation in preventing species extinction.

Answer: Habitat conservation is vital in preventing species extinction, as it provides the necessary conditions for species to survive, reproduce, and thrive. Habitats serve as natural ecosystems that offer food, shelter, and breeding grounds for diverse plant and animal species. Protecting and restoring habitats helps maintain ecological balance, supports biodiversity, and ensures the resilience of ecosystems in the face of environmental changes. Habitat loss due to deforestation, urbanization, and industrial activities is one of the primary causes of species decline, making conservation efforts critical. By establishing protected areas, wildlife corridors, and nature reserves, and by promoting sustainable land-use practices, we can reduce human pressures on ecosystems and create safe havens for endangered species. Effective habitat conservation not only safeguards biodiversity but also contributes to ecosystem services such as carbon storage, climate regulation, and water purification, benefiting human societies and the planet as a whole.

Previous Year Questions on  Species Extinction

1. UPSC CSE 2019

Question: Examine the factors contributing to species extinction and suggest measures to mitigate this issue. 

Answer: Species extinction is driven by factors such as habitat loss, climate change, overexploitation of natural resources, pollution, introduction of invasive species, and disease outbreaks. Human activities like deforestation, industrialization, and urbanization have led to the degradation and fragmentation of habitats, leaving species vulnerable to extinction. Climate change exacerbates the problem by altering ecosystems and making it difficult for species to adapt. Overhunting and poaching, driven by commercial demand, threaten many species, particularly in the wild. To mitigate species extinction, conservation measures must focus on protecting and restoring habitats, combating climate change through emission reductions, and enforcing anti-poaching laws. Establishing protected areas, promoting sustainable resource use, and community-based conservation initiatives can enhance species survival. Raising public awareness and fostering international cooperation through agreements like CITES and the Convention on Biological Diversity are also crucial in addressing this pressing issue.

2. UPSC CSE 2020

Question: Describe the role of biodiversity conservation in mitigating species extinction. 

Answer: Biodiversity conservation plays a key role in mitigating species extinction by maintaining and enhancing the variety of life on Earth. By preserving diverse ecosystems and protecting threatened species, conservation efforts help sustain ecological balance and resilience. Biodiversity conservation ensures the availability of genetic resources that enable species to adapt to changing environments and resist diseases. Efforts such as habitat restoration, the establishment of protected areas, and the implementation of sustainable resource management practices reduce human pressures on ecosystems. Conservation programs focused on specific species, captive breeding, and reintroduction initiatives also contribute to their survival. Additionally, biodiversity conservation supports ecosystem services such as pollination, water purification, and climate regulation, which are essential for human well-being. Through international treaties, community involvement, and education, biodiversity conservation addresses both immediate and long-term threats to species, helping mitigate the global extinction crisis.