Final answer:
The factor that allowed non-native rabbits to spread so quickly in Australia was primarily the lack of natural predators. Additional factors like an abundance of food resources, adaptability to the Australian environment, and a rapid reproduction rate also contributed to their rapid proliferation. Option 1 is correct answer.
Step-by-step explanation:
When 10 rabbits were introduced to Australia in the 1800s, they rapidly proliferated across the continent. This rapid spread can be attributed to several factors, but the primary one is the lack of natural predators that could control the rabbit population. In their native habitats, rabbits are kept in check by predators, but in Australia, these predators were either absent or not effective against the rabbits. Consequently, there were few natural controls to prevent their spread and population growth.
Furthermore, the rabbits also had an abundance of food resources and displayed remarkable adaptability to the Australian environment, but perhaps the most significant factor that allowed them to spread so quickly was their rapid reproduction rate. Rabbits have a high fecundity rate, meaning they breed prolifically; this characteristic enabled the rabbit population to grow exponentially.
Moreover, rabbits moved into the nests of native burrowing animals and outcompeted them for resources. The introduced species, including rabbits, often lack the same diseases or parasites that regulate their populations in their home ranges, which facilitated their spread. Invasive species like rabbits and cane toads have demonstrated that they can disperse quickly, covering large distances annually, often aided by their own evolved behaviors and changes in morphology that enhance their dispersal capabilities.
Based on the information and the options provided, option 1) Lack of natural predators is the correct answer that allowed the non-native rabbits to spread so quickly in Australia.