7.1 Extinction Rates and the Extinction Crisis
3 min read•july 30, 2024
Extinction rates are skyrocketing, way beyond natural levels. We're in the middle of a crisis, with species disappearing faster than ever. It's not just about losing cute animals – it's messing up entire ecosystems and could seriously impact our lives.
Humans are the main culprits here. We're destroying habitats, polluting, overfishing, and changing the climate. It's a perfect storm for wiping out species. The consequences? Unstable ecosystems, loss of important services nature provides, and potential ripple effects we can't even predict yet.
Extinction: Background vs Mass
Defining Extinction and Its Types
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Top images from around the web for Defining Extinction and Its Types
Earth's five mass extinction events View original
Is this image relevant?
Big 5 Mass Extinctions Poster by BudCharles on DeviantArt View original
Is this image relevant?
Charting Earth’s (Many) Mass Extinctions — Blog of the Long Now View original
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Earth's five mass extinction events View original
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Big 5 Mass Extinctions Poster by BudCharles on DeviantArt View original
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- Extinction signifies complete, permanent loss of a species from Earth without surviving individuals or viable populations
- represents natural, ongoing species loss over geological time scales
- Caused by environmental changes or competition
- Estimated rate of 1-5 species per year per million species
- events exhibit significantly increased extinction rates
- Far exceed background levels
- Affect large proportion of species across diverse taxonomic groups
- Result in loss of over 75% of species within relatively short time frame
- Earth experienced five major mass extinction events in geological history
Current Extinction Crisis
- Often referred to as the sixth mass extinction
- Characterized by extinction rates 100 to 1000 times higher than background levels
- Driven by human activities and their far-reaching impacts on global ecosystems
- Poses significant threats to biodiversity and ecosystem functioning
Drivers of Extinction Crisis
Habitat Alteration and Loss
- Habitat loss and fragmentation lead causes of species extinctions
- Primarily due to human activities (deforestation, urbanization, agricultural expansion)
- alters ecosystems and species distributions
- Causes mismatches in ecological relationships
- Pushes species beyond physiological tolerances
- Land-use changes reduce available habitat and fragment remaining populations
- Agricultural intensification
- Urbanization
Resource Exploitation and Pollution
- Overexploitation of natural resources directly threatens many species
- Particularly impacts species with high economic value or slow reproductive rates
- Examples include overfishing, hunting, and poaching
- Pollution degrades habitats and impacts species health and survival
- Chemical contaminants
- Plastic waste
- Excess nutrients
Biological Threats
- Invasive species introductions disrupt native ecosystems
- Outcompete or prey upon native species
- Alter ecological processes
- Emerging infectious diseases cause rapid population declines and extinctions
- Often exacerbated by human activities and global trade
- Particularly affects vulnerable or isolated populations
Human Impact on Extinction Rates
Population Growth and Resource Consumption
- Human population growth drives unprecedented rates of
- Increasing per capita resource consumption leads to resource depletion
- Technological advancements amplify human impacts on ecosystems
- Enable large-scale habitat modifications
- Allow more efficient resource extraction
Globalization and Climate Change
- Globalization and international trade facilitate spread of invasive species and pathogens
- Increases extinction risks for native species
- Anthropogenic climate change alters species distributions, phenology, and interactions
- Exceeds many species' adaptive capacities
- Indirect effects of human activities create additional stressors for species
- Ocean acidification
- Desertification
Consequences of Species Extinction
Ecosystem Disruption and Instability
- Species extinctions disrupt food webs and
- Can lead to secondary extinctions and altered ecosystem dynamics
- Loss of keystone species or ecosystem engineers has disproportionate effects
- Potentially leads to regime shifts in ecosystem structure and function
- Reduced biodiversity decreases ecosystem resilience and stability
- Makes ecosystems more vulnerable to disturbances and environmental changes
Impacts on Ecosystem Services
- Species extinctions impact crucial
- Pollination
- Seed dispersal
- Nutrient cycling
- Consequences extend to human well-being and economic systems
- Loss of genetic diversity through extinctions reduces potential for future evolutionary adaptations
- Limits options for biotechnology and medical research
Cultural and Cumulative Effects
- Extinctions of culturally significant species lead to loss of traditional knowledge and practices
- Impacts human cultural diversity and indigenous communities
- Cumulative effects of multiple species extinctions can lead to ecosystem simplification
- Potentially reduces capacity of ecosystems to provide essential services
- May impact ability of ecosystems to support human populations
Key Terms to Review (18)
Background Extinction: Background extinction refers to the natural, gradual process through which species become extinct at a relatively constant rate over geological time scales. This phenomenon contrasts with mass extinctions, which occur in short, dramatic bursts and result in the loss of a large number of species. Understanding background extinction is crucial for assessing current extinction rates and the ongoing extinction crisis caused by human activities, as it provides a baseline against which to measure these rapid declines in biodiversity.
Biodiversity hotspot: A biodiversity hotspot is a biogeographic region that is both rich in endemic species and experiencing significant habitat loss. These areas are crucial for conservation efforts because they harbor a large number of unique species that are not found anywhere else on Earth, making them important for maintaining global biodiversity. The urgent need to protect these regions arises from the ongoing threats they face, such as habitat destruction, climate change, and overexploitation, which can lead to increased extinction rates.
Climate Change: Climate change refers to significant and lasting changes in the Earth's climate, primarily driven by human activities that increase greenhouse gas emissions. This shift impacts ecosystems, biodiversity, and the health of our planet, resulting in various consequences for wildlife and conservation efforts.
Convention on Biological Diversity: The Convention on Biological Diversity (CBD) is an international treaty aimed at promoting sustainable development through the conservation of biological diversity, the sustainable use of its components, and the fair sharing of benefits arising from genetic resources. It recognizes that biodiversity is essential for human well-being and sets out commitments for countries to safeguard ecosystems and species while integrating conservation into their development strategies.
E.O. Wilson: E.O. Wilson is an American biologist, naturalist, and author known for his work on biodiversity, the behavior of ants, and the concept of biophilia. His contributions have profoundly influenced conservation biology, emphasizing the importance of preserving ecosystems and species to maintain global biodiversity and ecological health.
Ecosystem Services: Ecosystem services are the benefits that humans derive from natural ecosystems, including provisioning, regulating, supporting, and cultural services. These services play a crucial role in maintaining the health of the planet and supporting human well-being by providing essential resources, regulating environmental conditions, and offering cultural and recreational benefits.
Endangered Species Act: The Endangered Species Act (ESA) is a key piece of environmental legislation enacted in the United States in 1973 aimed at protecting and recovering imperiled species and the ecosystems upon which they depend. The act provides a framework for the conservation of threatened and endangered species through habitat protection, recovery plans, and regulation of activities that may harm these species.
Endangered species protection: Endangered species protection refers to the legal and conservation measures taken to prevent the extinction of species that are at risk due to various factors such as habitat loss, climate change, and human activities. This protection is crucial for maintaining biodiversity and ecosystem health, as well as ensuring that future generations can enjoy and benefit from a diverse range of wildlife.
Extinction vortex: An extinction vortex is a downward spiral in which small populations experience a decline in genetic diversity, leading to increased vulnerability to environmental changes and ultimately resulting in extinction. This process is driven by factors such as inbreeding, habitat loss, and demographic fluctuations, creating a feedback loop that exacerbates the decline of these populations. Understanding this concept is crucial for conservation efforts aimed at preserving species facing the threat of extinction.
Habitat destruction: Habitat destruction refers to the process through which natural habitats are altered or completely removed, leading to a decline in biodiversity and the loss of ecosystem functions. This issue is a significant driver of species extinction, contributing to an ongoing crisis in conservation biology. Understanding habitat destruction is crucial for developing strategies that address the conservation needs of ecosystems and the species that rely on them.
Habitat Fragmentation: Habitat fragmentation is the process in which large, continuous habitats are divided into smaller, isolated patches, often due to human activities such as agriculture, urban development, and infrastructure expansion. This separation can significantly affect biodiversity, ecosystem function, and species survival by creating edge effects and altering species interactions.
In situ conservation: In situ conservation refers to the practice of protecting and managing species and their habitats in their natural environment. This approach emphasizes the importance of maintaining ecological processes and biodiversity within ecosystems, allowing species to thrive as part of their natural communities. By focusing on preserving species in their native habitats, in situ conservation addresses the root causes of decline and supports long-term sustainability.
Mass extinction: Mass extinction refers to a significant and rapid loss of a large number of species in a relatively short geological timeframe, often due to catastrophic events or drastic changes in the environment. This phenomenon is marked by extinction rates that are significantly higher than the background rate, which is the normal rate of extinction. Mass extinctions can lead to profound ecological changes and can alter the course of evolution by eliminating dominant groups of organisms.
Rachel Carson: Rachel Carson was an influential American marine biologist and conservationist whose work is credited with advancing the global environmental movement. Her book 'Silent Spring' exposed the dangers of pesticide use, particularly DDT, leading to increased public awareness about environmental issues and influencing policy changes regarding chemical regulations. Carson's work highlights the interconnectedness of species and ecosystems, emphasizing the importance of biodiversity and habitat protection.
Red List Index: The Red List Index (RLI) is a numerical measure that reflects the overall status of biodiversity by tracking changes in the conservation status of species over time, based on data from the International Union for Conservation of Nature (IUCN) Red List. It provides insight into whether species are becoming more endangered or recovering, and is calculated by assessing shifts in the categories of threat faced by different species, ultimately contributing to understanding extinction rates and the extinction crisis.
Species extinction rate: Species extinction rate refers to the speed at which species become extinct within a certain timeframe, often expressed as the number of extinctions per unit of time, such as per decade or century. This rate is crucial for understanding the ongoing biodiversity crisis, where many species are disappearing at an unprecedented pace due to human activities, habitat loss, climate change, and other environmental pressures.
Theory of island biogeography: The theory of island biogeography is a scientific concept that explains the diversity and distribution of species on islands based on their size and distance from the mainland. It suggests that larger islands tend to support more species due to greater habitat variety and resources, while closer islands have higher rates of species colonization. This theory is crucial in understanding extinction rates and the extinction crisis, as it illustrates how habitat fragmentation affects biodiversity.
Trophic Cascades: Trophic cascades are ecological phenomena where changes in the population of one species, usually a predator, lead to cascading effects throughout the food web, impacting multiple levels of the ecosystem. These interactions illustrate the interconnectedness of species and highlight how the removal or addition of key species can dramatically alter community structure and biodiversity.