15.3 Invasive species and their ecological impacts
3 min read•august 7, 2024
Invasive species are non-native organisms that harm ecosystems and economies in new environments. They spread rapidly due to lack of natural controls, outcompeting native species and disrupting . This topic explores their impacts on biodiversity and .
Human-mediated pathways like global trade and travel increase the spread of invasive species. Understanding these pathways and the ecological consequences of invasions is crucial for developing effective conservation strategies and protecting native ecosystems from further damage.
Invasive Species and Native Ecosystems
Defining Invasive, Native, and Exotic Species
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Top images from around the web for Defining Invasive, Native, and Exotic Species
Environmental Impacts of Invasive Alien Plant Species on the Biodiversity of the Nyika National ... View original
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Figure 11.13 Baseline2010 eps View original
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- Invasive species are non-native organisms that cause ecological or economic harm in a new environment
- Tend to spread rapidly due to lack of natural predators or other controls (, )
- Native species are organisms that have evolved and adapted to a particular ecosystem over a long period of time
- Play essential roles in maintaining the balance and function of their native habitats (monarch butterflies, saguaro cactus)
- Exotic species, also known as introduced or non-native species, are organisms that have been transported to a new environment outside their natural range
- Not all exotic species become invasive, but those that do can cause significant damage (, )
Ecological Niches and Competitive Exclusion
- An ecological niche refers to the specific role an organism plays within its ecosystem, including its habitat, food sources, and interactions with other species
- Invasive species often outcompete native species for resources and disrupt established niches (, )
- occurs when two species compete for the same limited resources, and one species ultimately displaces the other
- Invasive species can drive native species to extinction through competitive exclusion (, )
Ecosystem Impacts
Biotic Homogenization and Biodiversity Loss
- is the process by which invasive species replace native species, leading to a decrease in biodiversity and a more uniform ecosystem composition across different regions
- Invasive species can cause the loss of unique, locally adapted species and reduce overall genetic diversity (, )
- Invasive species are a major driver of , second only to habitat destruction
- They can alter ecosystem structure, disrupt food webs, and modify nutrient cycles (, )
Disruption of Predator-Prey Relationships and Disease Transmission
- Invasive species can disrupt predator-prey relationships by either preying on native species or competing with native predators for prey
- This can lead to cascading effects throughout the ecosystem (, )
- Invasive species can also act as vectors, carrying and transmitting diseases to native species that have not evolved defenses against these pathogens
- This can lead to devastating population declines and extinctions (, )
Pathways of Introduction
Human-Mediated Spread of Invasive Species
- Many invasive species are introduced to new environments through human activities, either intentionally or unintentionally
- Examples include the pet trade, horticulture, and agriculture (Burmese pythons, )
- Ballast water, used to maintain stability in cargo ships, is a major pathway for the introduction of aquatic invasive species
- When ships take on ballast water in one port and release it in another, they can transport invasive species across vast distances (zebra mussels, European green crab)
- Other pathways include the release of unwanted pets, escape from cultivation, and accidental transport on vehicles or in shipping materials (red-eared slider turtles, kudzu)
- As global trade and travel increase, so does the risk of introducing new invasive species to vulnerable ecosystems
Key Terms to Review (34)
Asian carp: Asian carp refers to several species of fish, including the bighead carp, silver carp, grass carp, and black carp, that are native to East Asia. These fish have been introduced to North America and have become invasive species, posing significant ecological threats to aquatic ecosystems by outcompeting native species for resources and disrupting food webs.
Avian malaria in Hawaiian honeycreepers: Avian malaria in Hawaiian honeycreepers refers to a parasitic disease caused by the protozoan Plasmodium that significantly impacts these endemic bird species in Hawaii. The introduction of non-native mosquito species has facilitated the spread of avian malaria, posing a severe threat to the already vulnerable Hawaiian honeycreepers, which have evolved in isolation and lack immunity to this disease. The interaction between invasive mosquitoes and native birds highlights the ecological consequences of introduced species and their role in disease transmission.
Biodiversity loss: Biodiversity loss refers to the decline in the variety and variability of life forms within a given ecosystem, impacting species richness and the balance of ecological processes. This phenomenon is critical as it not only threatens individual species but also disrupts the functions that ecosystems provide, such as carbon storage, nutrient cycling, and habitat stability, making it essential to understand its connections to various environmental issues.
Biological control: Biological control is the use of natural predators, parasites, or pathogens to manage and reduce populations of invasive species. This method leverages the relationships within ecosystems to create a balance and diminish the negative impacts of non-native species on local environments. By harnessing these natural mechanisms, biological control aims to restore ecological integrity and enhance biodiversity.
Biotic homogenization: Biotic homogenization is the process by which local biological communities become more similar to one another due to the spread of invasive species and the decline of native species. This phenomenon often leads to a reduction in biodiversity as native species are replaced or outcompeted, resulting in ecosystems that are less distinct and more uniform across different regions. As invasive species thrive, they can alter habitat structures, resource availability, and ecological interactions, further contributing to this loss of biological diversity.
Brown tree snakes: Brown tree snakes are nonvenomous constrictor snakes native to Australia, New Guinea, and the Solomon Islands. They are notorious as an invasive species in Guam, where they have caused significant ecological disruptions by preying on native birds and small mammals, leading to severe declines in local biodiversity.
Burmese pythons: Burmese pythons are large, non-venomous constrictor snakes native to Southeast Asia, known for their impressive size and distinctive coloration. In recent years, they have become a significant concern in ecosystems outside their natural habitat due to their status as an invasive species, particularly in the Florida Everglades. Their introduction has resulted in severe consequences for local wildlife, leading to declines in biodiversity and disruption of ecological balance.
Cane Toads: Cane toads are large, terrestrial amphibians native to Central and South America, known scientifically as Rhinella marina. They were introduced to various countries, including Australia, for agricultural pest control, but have since become a notorious invasive species. Their introduction has led to significant ecological impacts, disrupting local ecosystems and threatening native wildlife due to their rapid reproduction and toxic defense mechanisms.
Chytrid fungus in amphibians: Chytrid fungus, specifically Batrachochytrium dendrobatidis, is a pathogenic fungus that infects the skin of amphibians, leading to significant declines in their populations worldwide. This fungus disrupts the ability of amphibians to regulate water and electrolytes, ultimately causing a disease known as chytridiomycosis, which has been linked to mass extinctions in various amphibian species. Its role as an invasive species underscores the ecological impacts it has on amphibian biodiversity and the ecosystems they inhabit.
Competitive Exclusion: Competitive exclusion is an ecological principle stating that two species competing for the same limited resources cannot coexist indefinitely. One species will outcompete the other, leading to the latter's extinction or displacement from the habitat. This concept highlights the importance of resource availability and niche differentiation in shaping community structures, especially in the context of invasive species that disrupt existing ecosystems.
Ecological balance: Ecological balance refers to the state of equilibrium between living organisms and their environment, ensuring the sustainability of ecosystems. This balance is crucial for maintaining biodiversity, as it allows different species to coexist and thrive while relying on one another for resources. When this balance is disrupted, often due to human activities or invasive species, it can lead to negative impacts on ecosystems, such as species extinction and habitat degradation.
Ecosystem disruption: Ecosystem disruption refers to significant alterations in the structure or function of an ecosystem, often caused by external factors such as invasive species, natural disasters, or human activities. These disruptions can lead to changes in species composition, loss of biodiversity, and altered ecosystem services, ultimately affecting the balance of natural systems. Understanding how these disruptions occur and their consequences is crucial for maintaining ecosystem health and resilience.
Ecosystem Function: Ecosystem function refers to the natural processes and interactions that occur within an ecosystem, contributing to its overall health and sustainability. These functions include energy flow, nutrient cycling, and species interactions, which work together to support biodiversity and maintain ecological balance. Understanding ecosystem function is vital for assessing the impact of changes, such as those brought about by invasive species, on environmental stability.
Eradication programs: Eradication programs are organized efforts aimed at completely eliminating invasive species from a specific environment or ecosystem. These programs are crucial in preventing the ecological, economic, and social impacts that invasive species can cause by outcompeting native species, altering habitats, and disrupting food webs.
European Starlings: European starlings are small to medium-sized passerine birds, scientifically known as Sturnus vulgaris, originally native to Europe, Asia, and North Africa. They are well-known for their iridescent plumage and remarkable social behavior, often seen in large flocks. As an invasive species in North America, European starlings have significant ecological impacts, affecting local bird populations and disrupting ecosystems.
Feral pigs: Feral pigs are domesticated swine that have escaped or been released into the wild and have adapted to living independently. They are often considered an invasive species due to their rapid population growth and their ability to thrive in diverse environments, which can lead to significant ecological impacts on native ecosystems and agricultural areas.
Galapagos Islands: The Galapagos Islands are an archipelago located in the Pacific Ocean, known for their unique biodiversity and as a living laboratory of evolution. They are famous for their role in Charles Darwin's theory of natural selection, but the islands also face serious ecological challenges due to invasive species that threaten native wildlife and ecosystems.
Garlic Mustard: Garlic mustard (Alliaria petiolata) is an invasive plant species native to Europe and Asia, characterized by its heart-shaped leaves and small white flowers. This plant has a significant ecological impact, as it outcompetes native vegetation for resources, disrupts local ecosystems, and alters soil chemistry, making it a prime example of how invasive species can reshape habitats and threaten biodiversity.
Great Lakes: The Great Lakes are a group of five interconnected freshwater lakes located in North America, comprising Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario. These lakes form the largest system of freshwater lakes in the world by total area and play a crucial role in the ecology and economy of the surrounding regions. The Great Lakes are also significant in terms of their biodiversity and are affected by various ecological challenges, including invasive species that threaten native ecosystems.
Habitat alteration: Habitat alteration refers to the change in the natural environment that affects the living conditions for plants and animals. This can result from both natural processes and human activities, leading to a reduction in biodiversity and the disruption of ecosystems. Understanding how habitat alteration interacts with climate regulation and invasive species is crucial to grasping the full impact on ecological balance and resilience.
Japanese beetle: The Japanese beetle (Popillia japonica) is an invasive insect species native to Japan, recognized for its distinctive metallic green and copper coloring. These beetles are notorious for their voracious appetite for a wide range of plants, causing significant damage to gardens, crops, and natural ecosystems. Their introduction to North America in the early 20th century led to profound ecological impacts, as they disrupted local plant communities and affected agriculture.
Japanese Knotweed: Japanese Knotweed is an invasive perennial plant native to East Asia that can cause significant ecological disruption. It is known for its rapid growth and ability to outcompete native flora, leading to negative impacts on biodiversity, soil stability, and local ecosystems. This plant's aggressive growth habits make it a prime example of how invasive species can alter habitats and pose challenges for land management and conservation efforts.
Kudzu: Kudzu is a fast-growing, invasive vine native to East Asia, specifically Japan and China, that has become notorious in the southeastern United States for its ability to rapidly cover and outcompete native vegetation. This plant, often referred to as 'the vine that ate the South,' poses significant ecological challenges by disrupting local ecosystems, altering habitats, and smothering trees and shrubs, which can lead to a decrease in biodiversity.
Lionfish: Lionfish are venomous marine fish belonging to the family Scorpaenidae, characterized by their striking appearance with long, spiky fins and vibrant stripes. They are considered one of the most problematic invasive species in the Atlantic and Caribbean waters, where they disrupt local ecosystems and threaten native fish populations due to their rapid reproduction and lack of natural predators.
Nile Perch: The Nile Perch is a large freshwater fish native to the Nile River and many African lakes, particularly Lake Victoria. It is an example of an invasive species that has significantly altered the ecosystem of Lake Victoria, leading to the decline of native fish populations and impacting local fisheries and communities.
Pollination services: Pollination services refer to the process by which pollinators, like bees, birds, bats, and other insects, transfer pollen from one flower to another, enabling fertilization and the production of fruits and seeds. These services are crucial for maintaining biodiversity, supporting food production, and sustaining ecosystems, particularly in the face of ecological disturbances such as those caused by invasive species.
Predation Pressure: Predation pressure refers to the influence exerted by predators on prey populations and their behaviors, leading to changes in prey dynamics and community structure. This concept is vital in understanding ecological interactions, as it can determine species distribution, abundance, and even the evolution of prey species over time. When predation pressure is high, prey may exhibit adaptive behaviors such as changes in feeding patterns or habitat use to avoid becoming food for predators.
Purple loosestrife: Purple loosestrife is a perennial wetland plant native to Europe and Asia, known for its striking purple flowers and tall, spiky appearance. This species has become a significant invasive plant in North America, where it disrupts local ecosystems, outcompeting native vegetation and altering habitats, particularly in wetland areas.
Red imported fire ants: Red imported fire ants are an invasive species originally from South America, known for their aggressive behavior and painful stings. These ants have spread across the United States and other regions, causing significant ecological impacts by disrupting local ecosystems, outcompeting native species, and posing threats to human health and agriculture.
Transport Pathways: Transport pathways refer to the routes or mechanisms through which organisms, nutrients, and other materials move across ecosystems. These pathways play a critical role in facilitating ecological interactions, influencing species distribution, and shaping community dynamics, especially in the context of invasive species, which can exploit these pathways to spread rapidly into new environments.
Vector: A vector is a mathematical and physical concept that represents a quantity having both magnitude and direction. In ecological studies, particularly concerning invasive species, vectors can refer to the means through which these species are introduced to new environments, such as through human activity or natural processes. Understanding vectors is essential for assessing how invasive species spread and their subsequent ecological impacts.
Water hyacinth: Water hyacinth is an aquatic plant native to South America, known for its striking purple flowers and ability to grow rapidly on the surface of freshwater bodies. This plant is often considered one of the most invasive species in the world due to its capacity to outcompete native flora, disrupt ecosystems, and impact water quality, making it a significant ecological concern.
Water Quality: Water quality refers to the physical, chemical, and biological characteristics of water, which determine its suitability for various uses including drinking, recreation, agriculture, and supporting aquatic life. High water quality means that the water is clean and safe for these uses, while low water quality can lead to health risks and environmental problems. Factors affecting water quality include pollutants from land use changes and the introduction of invasive species that disrupt ecosystems.
Zebra mussels: Zebra mussels are small, freshwater bivalve mollusks native to the Caspian Sea and Black Sea regions. They are considered an invasive species due to their rapid reproduction and ability to outcompete native species for resources, leading to significant ecological impacts in the ecosystems they invade.