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  3. Spot the differenceA Taxonomic history has been ma

Spot the differenceA Taxonomic history has been ma

游客2024-01-09  22
问题                             Spot the difference
A  Taxonomic history has been made this week, at least according to the World Wildlife Fund (WWF), a conservation group. Scientists have described a new species of clouded leopard from the tropical forests of Indonesia with spots (or "clouds", as they are poetically known) smaller than those of other clouded leopards, with fur a little darker and with a double, as opposed to a "partial double"—stripe down its back.
B  However, no previously unknown beast has suddenly leapt out from the forest. Instead, some scientists have proposed a change In the official taxonomic accounting system of clouded leopards. Where there were four subspecies there will likely now be two species. A genetic analysis and a closer Inspection of museum specimens’ coats published in Current Biology has found no relevant difference between three subspecies described 50 years ago from continental Asia and from the Halnan and Taiwan islands. The 5000-11000 clouded leopards on Borneo, the 3000-7000 on Sumatra, and the remaining few on the nearby Batu Islands can now, the authors say, claim a more elevated distinction as a species.
C  What this actually means is fuzzy and whether it is scientifically important is questionable. In any case, biologists do not agree what species and subspecies are. Creatures are given Latin first and second names (corresponding to a genus and species) according to the convention of Carl yon Llnné, who was born 300 years ago this May. But Linnaeus, as he Is more commonly known, thought of species as perfectly discrete units created by God. Darwinism has them as mutable things, generated gradually over time by natural selection. So delineating when enough variation has evolved to justify a new category is largely a matter of taste.
D  Take ants and butterflies. Ant experts have recently been waging a war against all types of species subdivision. Lepidopterists, on the other hand, cling to the double barrel second names from their discipline’s 19th century tradition, and categorise many local subclasses within species found over wide areas. Thus it would be futile if one were so inclined—to attempt to compare the diversity of ant and butterfly populations.
E  The traditional way around the problem is to call a species all members of a group that share the same gene pool. They can mate together and produce fertile offspring. Whether Indonesian clouded leopards can make cubs with continental ones remains unknown but seems probable. Instead, the claim this week is that genetics and slight differences In fur patterning are enough to justify re-branding the clouded leopard as two significant types. Genetically, that makes sense if many DNA variations correlate perfectly between members of the two groups. The authors did find some correlation, but they looked for it in only three Indonesian animals. A larger sample would have been more difficult.
F  One thing Is abundantly clear: conservationists who are flying to stop the destruction of the leopards’ habitat in Borneo and Sumatra see the announcement of a new species of big cat as a means to gain publicity and political capital. Upgrading subspecies to species is a strategy which James Mallet, of University College London, likes to call species inflation. It is a common by-product of genetic analysis, which can reveal differences between populations that the eye cannot, Creating ever more detailed genetic categories means creating smaller and increasingly restricted populations of more species. The trouble is that risks devaluing the importance of the term species.
G The problem of redefining species by genetics is the creation of taxonomic confusion, a potentially serious difficulty for conservationists and others, Take for example the recent proposal to add the polar bear to the list of animals protected under America’s Endangered Species Act. That seems all well and good. However, study the genetics and it transpires that polar bears are closer to some brown bears, than some brown bears are to each other. Go by the genes and it seems that the polar bear would not count as a species in its own right (and thus might not enjoy the protection afforded to species) but should be labelled a sub-species of the brown bear. [br] *
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