Cane toads Flashcards
Why were they first introduced?
To control insect pests in sugar cane
Why are cane toads so good at surviving?
They eat almost anything
High reproduction rates
Ecological impacts of cane toads in Australia
Many Australian predators eat frogs and are killed by the toads poisons (Australia has no native toad species)
Some predators don’t eat toads - so are less affected
Some predators can eat toads and are not affected by the toads poisons
And some predators learn to recognise toads and not eat them because they make them fill ill
Indirect effects - because many larger predators are killed, many smaller species benefit from toad arrival
How might a vulnerable snake predator adapt to toad invasion?
- Behaviour (feeding responses)
- Physiology (toxin resistance)
- Body shape (relative head size)
How have can toads evolved in Australia?
Toads are moving faster and faster
- Offspring inherit the dispersal rate of their parents
- Offspring inherit the path straightness of their parents
Invasion front toads are better at climbing and move by scurrying not giant leaps
Invasion front toads are slender, with large forelimbs
Invasion front toads are bolder and more active
Invasion front toads have high endurance, invert less energy into immune responses
At the invasion front, a toad has more access to food and is exposed to fewer predators
Invasion front toads breed together as others are too slow - future generations are bred to be faster
The cost of a weaker immune system in invasion front cane toads
Develop spinal arthritis and are vulnerable to harmless soil bacteria
What can we do to reduce toad numbers?
Toad-proof the native species
Reduce toad numbers
Teach native predators to avoid toads (to learn you need to ingest smaller non-lethal toads- these doesn’t occur in the wild as invasion toads are always large due to spatial sorting)
Toad tadpoles eat toad eggs
Attractant chemicals can be used to trap tadpoles
Exposing toad eggs to tadpole chemicals that suppress development of younger tadpoles
