By Ethan Low
Background
Cane toads, native to Central and South America, are a dangerous invasive species known for their introduction to Australia in 1935. Cane toads are classified as an invasive species due to being a non-native organism that causes harm to the environment around it. Cane toads were introduced to Australia as an attempt for biocontrol, which is the use of natural predators to manage a population of pests. This caused Cane toads to reproduce quickly, creating competition for other organisms in the environment, and limiting the amount of resources available.
Cane Toads, Source: CNN
Environmental Hazard
In a research study, cane toads in Australia have evolved the ability to spread quickly in an efficient and effective amount of time. Their annual rate of increase has increased by 5 times over 75 years. This is an environmental hazard because invasive species like cane toads tend to outcompete native species, and with a faster dispersal rate, cane toads will be able to cover a larger amount of territory. Cane toads will ultimately require more resources in order to multiply their population, reducing the amount of resources there are for native populations, and reducing their population growth.
The animal survival rate after poison release
Cane toads are also dangerous because they have the ability to secrete poison as a defense mechanism. This harms a lot of the native population, such as predators. Predators who try to eat these cane toads often get poisoned. Toads also majorly impact the population of snakes in Australia. These snakes regularly attack toads and are more likely to be fatally poisoned by the toxins. These events heavily change the environment, making it necessary that native species quickly adapt to their new competitor. However, these adaptations also have drawbacks.The adaptations that native species have to make due to different environmental interactions impact the evolution of that native species. For example, predators that were used to eating all toads but suddenly started being fatally injured by cane toads will develop the instinct to avoid those toads.
Cane toads will also have an impact that will affect the food chain as well. Predators used to eating toads will have to shift their dietary habits. Since cane toads are so abundant and their dispersal rate is so high, many different habitats will be introduced to the cane toad. This could cause a change in habits of predators that usually hunt in that area. Overall, the attempts at biological control over pest invasions have had severe consequences. Biocontrol is the most ecologically beneficial way to control pests, if used correctly, but can have devastating effects on a whole ecosystem if uncontrolled.
References
Jolly, C. J., Shine, R., & Greenlees, M. J. (2015). The impact of invasive cane toads on native wildlife in southern Australia. Ecology and Evolution, 5(18), 3879-3894.
Regan, H. (2023, September 5). Invasive species cost the world $423 billion every year, UN report finds. CNN. https://www.cnn.com/2023/09/05/world/invasive-species-global-threat-report-climate-scn-intl-hnk/index.html
Shine, R. (2012). Invasive species as drivers of evolutionary change: cane toads in tropical Australia. Evolutionary Applications, 5(2), 107-116.
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