To do this, the fur covering their bodies is arranged so that it points outward from a point near the middle of the back, allowing water to run off the fur while they are sleeping. Living in high rainfall areas, tree-kangaroos need to be able to stay dry. Tree-kangaroos are nocturnal and they spend the daylight hours sleeping hunched over in a sitting position high in tree canopies. Lumholtz’s tree-kangaroos are found in the rainforest of tropical Queensland, centred on the Atherton Tablelands, extending north as far as the Carbine Tableland. They're primarily leaf-eaters, but also feed on many fruits and has been known to take cultivated maize from farms adjacent to its rainforest habitat. Lumholtz’s Tree-kangaroo is one of the two Australian species wonderfully adapted for life high up in the trees, the other is Bennett's Tree-kangaroo. Evolved from regular, ground dwelling kangaroos, there are a dozen different species of tree-kangaroos found mostly in New Guinea. "So, although cane toads are unlikely to drive themselves extinct, these cannibalistic behaviors may help to regulate their abundance post-invasion.Kangaroos in trees!? Yes indeed. "The good news is that cannibalism can control population growth," DeVore tells Live Science. The find may give researchers an understanding of how competition within a species ignites an evolutionary arms race and drives rapid evolution. "We found that cane toad clutches from Australia developed more quickly they reached the invulnerable tadpole stage in about four days, whereas native range clutches took about five days," says study author Jayna Devore, a University of Sydney herpetologist, to Live Science. While South American toads spent five days at the hatchling stage, Australian toads only spend three days in this stage, suggesting that the pressures from being cannibalized cut their development time by half, per Ars Technica. Similarly, older tadpoles did not have an appetite for other tadpoles their size and age. But once hatchlings were too big to be cannibalized, the older tadpoles left them alone. The team discovered Australian tadpoles were 2.6 times more likely to cannibalize hatchlings than South American tadpoles, Nature reports. Then, they introduced one large tadpole to a group of ten tiny hatchlings just emerged from their eggs. To see if the behavior results in differences between native and invasive species populations, researchers gathered toads from South America and Australia and bred them. However, cannibalistic behavior occurs more often in Australia. In the species' native South American habitat, cane toad tadpoles have previously been observed eating their peers. The study was published this week in the peer-reviewed journal Proceedings of the National Academy of Sciences. However, researchers at the University of Sydney have found that tadpoles are evolving ways to avoid becoming a snack, such as developing at faster rates to reduce the amount of time they are vulnerable to other ravenous tadpoles, reports Laura Geggel for Live Science. The cannibalistic behavior appears to be an evolutionary response to the toad not having another competing species, causing the toads to turn on the only species competing for resources: themselves. Without predation to keep population numbers low, cane toad tadpoles began to eat their peers, reports Ars Technica's John Timmer. The invasive species has since expanded its reach across large areas of Northern and Eastern Australia with more that 200 million cane toads hopping around the country, reports Nature 's Max Kozlov. When the toads became established in the country, the species had no natural predators. The warty amphibian with thick ridges above their eyes and highly poisonous olive-brown skin devours anything it can fit in its mouth from tiny rodents to birds. Australian sugarcane farmers began using cane toads ( Bufo marinus) as a form of pest control in their fields in 1935-but soon enough, they became a pest themselves.
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