The Impact of Invasive Species

Question 1

How can invasive species be introduced?

Answer 1

• Colonisation - bring organisms to recreate their previous home
• Horticulture botanic gardens
• Accidental transportation - polynesian rat, ballast on ships - North Pacific Sea Star, Chickens from China spread Avian Pox - led to extinction of some native Hawaiian species
• Deliberate introduction - Cane toad added to deter sugar cane pests because they are poisonous, prey on native fauna, compete with vertebrate insectivores (skinks) , spread disease to native fish and frogs.

Question 2

Why are invasions more likely on islands than in continental areas?

Answer 2

• Species poor
• more disturbed
• species are less resistant
• propagule pressures higher on islands
• endemics
• isolation.

Question 3

What are the characteristics of invaders?

Answer 3

• High rates of reproduction
• Long-lived
• High dispersal rates
• Single-parent reproduction
• Vegetative or clonal reproduction
• High genetic variability
• Broad diet (polyphagous)
• Broad native range
• Habitat generalists
• Human commensal.