Final answer:
Australian snakes have evolved through natural selection from burrowing or aquatic lizards into various species with adaptations to different environmental niches. Invasive species like the cane toad have introduced new selective pressures, leading to rapid evolutionary responses among native predators, including snakes.
Step-by-step explanation:
Through evolution by natural selection, Australian snakes have adapted to a variety of environmental niches over millions of years. From their descent from either burrowing or aquatic lizards, snakes have diversified into around 3,600 species with various adaptations. Natural selection has also played a critical role in shaping the behavior and physical characteristics of invasive species such as the cane toad and the brown tree snake in new environments. Notably, the cane toad was introduced to Australia in 1935 and has since caused significant ecological disruption, which has been particularly detrimental to native predators such as snakes. In newly colonized areas, this invasive species often has a major impact when naive predators attempt to consume the toxic toads, resulting in poisoning and often death.
Snakes are carnivorous reptiles that eat a range of prey including small animals, birds, eggs, fish, and insects. Over time, they have developed specialized features such as their jaw structure to accommodate feeding habits. For example, in response to the cane toad invasion, snakes and other predators have had to rapidly evolve strategies to deal with this new, poisonous prey. This includes both adaptations in behavior to avoid eating the toads and potentially physical changes as a result of selective pressures. These evolutionary dynamics are not just limited to the snakes but also affect the entire ecosystem where these exchanges occur.