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MODULE 1

MODULE 1. Introduction to Invasive Alien Species. Introduction. Invasive alien species harm: the environment the economy people. Definition. Introduction The movement by human action of a species outside its native range. This movement can be either within or between countries.

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MODULE 1

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  1. MODULE 1 Introduction to Invasive Alien Species

  2. Introduction • Invasive alien species harm: • the environment • the economy • people

  3. Definition • Introduction • The movement by human action of a species outside its native range. This movement can be either within or between countries.

  4. Definition • Alien species • A species that has been intentionally or unintentionally introduced to a location, area, or region where it does not occur naturally

  5. Definition • Invasive alien species • An alien species that causes, or has the potential to cause, harm to the environment, economies, or human health

  6. Key Point • An alien species will be considered invasive only if it has adverse effects on: • the environment, • the economy, or • human health

  7. Mammals Birds Fish Viruses Amphibians Invasive Species are found in ALLtaxonomic groups Fungi Plants Invertebrates Reptiles

  8. Types of introductions Alien Species Introductions Intentional Unintentional Legal Unauthorised Directly released into the wild Introduced into captivity Escaped or intentionally released

  9. Indian House Crow • Accidental introduction • Competes with native birds • Disease vector • A nuisance in urban areas

  10. Salvinia molesta • A serious aquatic weed • Forms thick mats • Prevents boat traffic • Ruins fish habitat

  11. Intentional introductions • Legal • directly released into the wild • introduced into captivity • Illegal / Unauthorised • smuggling

  12. Unintentional introductions • ‘Hitchhikers’ and stowaways • Trade • Travel • Transport

  13. Key Point • Most of the known invasive invertebrates have been introduced unintentionally

  14. Key Point • Natural dispersal tends to play a major role in the subsequent regional spreading once a species has been introduced into a country or region

  15. Process of invasion 1. Introduction 2. Establishment 3. Spread

  16. Explosion phase Carrying capacity Population size Lag phase Time Process of invasion

  17. Can we predict species invasiveness? • Difficult to identify invasive from harmless species • Some characteristics: • invasive elsewhere • adaptable • lack of predators

  18. Key Point • Precautionary approach • Every alien species must be considered invasive • until proven otherwise

  19. Key Point • Human alteration of the environment increases the likelihood of IAS establishing

  20. Land-use changes • IAS thrive in disturbed areas

  21. Globalisation • Increasing trade, travel & transport = increasing IAS introductions World shipping routes

  22. Summary • IAS affect the environment, economy and human health • Species invasiveness cannot be easily predicted • IAS thrive in disturbed areas • The rate of IAS introductions is increasing

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