Comment Evolutionary Reductionists Go Home (Score 1) 175
Not the case. Of course all ecosystems are somewhat isolated, but to imagine that this renders there inhabitants "weak" is a distortion of the process of evolution. In a nutshell: ecosystems evolve not just the individual species within them. Any ecosystem is a large and complex solution to an unique set of problems. Within any such large and complex solution there will be points that are easily exploited by aggressive newcomers. This is not to say there is something wrong with the ecosystem.
In any case, one of the interesting points about the Australian ecosystem is that it has not been isolated from all placental mammals. This is not the reason (as the poster suggests) for low energy use marsupials and reptiles predominating. The standout example is the bat. Given pig like animals evolved into whales and apes into humans, over the past few million years, it is implausible that "superior" placental mammals such as bats would not have evolved into niches in the Australian ecosystem unless the marsupials had some advantage.
In the Australian ecosystem energy efficient marsupials have proven to be the superior solution over _evolutionary time_. In the short term placental mammals will disturb the balance of the system, but there is already evidence that these animals are adapting to Australian conditions. In particular, rabbits with smaller litters. How long before they are competing directly with the more highly atuned marsupial reproductive system?
In any case, one of the interesting points about the Australian ecosystem is that it has not been isolated from all placental mammals. This is not the reason (as the poster suggests) for low energy use marsupials and reptiles predominating. The standout example is the bat. Given pig like animals evolved into whales and apes into humans, over the past few million years, it is implausible that "superior" placental mammals such as bats would not have evolved into niches in the Australian ecosystem unless the marsupials had some advantage.
In the Australian ecosystem energy efficient marsupials have proven to be the superior solution over _evolutionary time_. In the short term placental mammals will disturb the balance of the system, but there is already evidence that these animals are adapting to Australian conditions. In particular, rabbits with smaller litters. How long before they are competing directly with the more highly atuned marsupial reproductive system?
