Tuesday, August 27, 2013

Natural history collections

In yesterdays post I had mentioned that there are more examples of initiatives that aim to build reference DNA Barcode libraries by sequencing type specimens and historical material wherever possible. 

Natural history collections would seem an ideal resource for barcode library construction, but they have never seen large-scale analysis because of concerns linked to DNA degradation. The present study examines the strength of this barrier, carrying out a comprehensive analysis of moth and butterfly (Lepidoptera) species in the Australian National Insect Collection (ANIC). 

This is from the abstract of a publication that came out earlier this summer describing protocols that were developed to enable tissue samples, specimen data, and images to be assembled in a short time. The results are quite impressive:
A total of 41,650 specimens were processed over 375 person-days of work, an average of 111 specimens per person-day. These specimens provided coverage for 8245 named species and for 4454 presumptive species for a total of 12,699 taxa. The specimens had an average age of 30.4 years (median = 28.9 years), but ranged from 1 to 112 years.

Some 20,000 species of the order lepidoptera are thought to live in Australia. Only about have of those (10,500) have been described in the last 235 years. Without formal documentation, all the undescribed species contribute nothing towards a deeper understanding of distributional patterns and biodiversity despite the fact that this information is of high importance to both research and conservation. The answer to the problem could be large scale efforts to barcode large collections but before one would do such a thing he would need to find out if it is feasible. It seems it actually is (at least for a collection with largely pinned insects):

The results from analysis of the ANIC specimens indicate that existing collections of museum specimens, especially insects, can enable the construction of a comprehensive DNA barcode reference library. They also establish that progress can be rapid – a team of five individuals can sample tissues, photograph and digitize data from 10,000 species in three months and a matching team with sequencing expertise can barcode these samples in nine months. Three teams of this size could complete barcode libraries for the Lepidoptera of Australia, Europe, and North America in a year. Coverage for Asia, Africa and South America would require more time, but could still be accomplished in less than a decade. If similar teams were established to lead work on each of the other insect orders, progress would be rapid. We conclude that a comprehensive DNA barcode library for insects is not only feasible, but is almost irresistible.

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