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Genomics at the Wallace line


I just watched Sold for a Song, a documentary on BBC about songbirds in Indonesia. In simplest terms, the songbirds in the wild rainforest of Java are going extinct. It is not that the birds are being hunted for food or feathers; rather, they are being taken for their songs. Traditionally, it is important to possess a songbird, and there are widespread competitions where owners take great pride in showing their bird and the songs the bird produces. The authorities in Java are working hard to bring about reforms to save their birds. Conservation, education and captive breeding will all hopefully contribute to mitigation of this serious problem.

As I watched the show, another thought that occurred to me was that these birds were probably among the species collected by Alfred Russel Wallace prior to the 1860s. Besides being associated with Charles Darwin and the theory of evolution by natural selection, Wallace is also called the father of biogeography after the publication of his 1876 book The Geographical Distribution of Animals. As I thought about the songbirds, I also recalled discussions of the Wallace line. The line is significant in that generally, it demarks a distinction between the flora and fauna of Asia and Australia.

The Wallace line has played roles in supporting models of plate tectonics, glaciation and sea level changes. Even now, there are genomic studies that use the line as a reference point. In genomic research supported by the Natural Sciences and Engineering Research Council of Canada, Ben J. Evans of McMaster University examined the "nature of speciation over the edge of this biogeographic divide", using "genomic data to test for evidence of gene flow between macaque species across Wallace’s Line". The authors indicate that the "Wallace’s Line is an important evolutionary arena for studying speciation because some groups have anomalous distributions that span this barrier."

Because it is a natural laboratory of geographic isolation over time, we can expect many more evolutionary studies coming from the area of the Wallace line which first contributed to the theory of evolution almost 160 years ago.

Links of Interest:
     BBC Sold for a Song
     Speciation over the edge

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Genomics at the Wallace line

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