What is Wallace Line?
[[Image:Map of Sunda and Sahul.png|thumb|right|300px|Wallace's line delineates Australian and Southeast Asian fauna. The land in the last [[ice age]] when the sea level was more over 100 m lower than today, is shown in grey.]] The '''Wallace Line''' (or 'Wallace's Line') is a [[boundary]] that separates the [[ecozone]] of [[Asia]] and the [[Australasian ecozone]]. The [[transitional zone]] is sometimes called ''Wallacea''. Plants and animals related to [[Asia]]n species are found to the north-west. [[Australasia]]n species are found mainly to the south-east, with some Asian species. The line is named after [[Alfred Russel Wallace]], who noticed this clear dividing line during his travels through the [[East Indies]] in the 19th century. The line runs through [[Indonesia]], between [[Borneo]] and [[Sulawesi]] (Celebes); and through the Lombok Strait between [[Bali]] (in the west) and [[Lombok]] (in the east). The distance between Bali and Lombok is only about 35 kilometers. Surprisingly, the [[distribution]]<nowiki/>s of many [[bird]] species observe the line, because many birds do not cross even the smallest stretches of open ocean water. Some [[bat]]s have distributions that cross the Wallace Line, but other mammals are generally limited to one side or the other; an exception is the [[Crab-eating Macaque]]. Other groups of plants and animals show differing patterns, but the overall pattern is striking and reasonably consistent. The term 'Wallace's Line' was first used by [[Thomas Henry Huxley|Huxley]] in 1868.<ref name=Mayr44/> == Cause == The root cause of Wallace's line is that the ancient [[supercontinent]] [[Gondwana]] was separated entirely from other parts of the world after [[Pangaea]] broke up. [[Australasia]] and its smaller islands were part of Gondwana, and that is why their fauna is so different from that of south-east Asia. Wallace's line marks where part of the old Gondwana [[plate tectonics|plate]] touches part of the old [[Laurasia]] plate. == Ice age == During [[Quaternary]] [[ice age]]