科研之友
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摘要
Noninvasive DNA sampling from scats can provide powerful tools for wildlife research depending in large part on how scats are collected in the field. Preservation of scat in 95-100% ethanol can be highly effective, but not always practical. Use of swabs to sample the mucous layer from scats is a popular alternative, but has not been adequately tested in arid environments, where the mucous layer can rapidly desiccate. We conducted a paired comparison of methods, extraction from scats stored in ethanol ("direct method") versus from swabs ("swab method"), for carnivore scats collected under typical field conditions during May-September 2013 and January-February 2015 in northern California, USA. Direct quantification of DNA indicated that the extracts from ethanol-preserved direct-method samples contained, on average, an order of magnitude (14x) more target DNA than extracts from swab method (P < 0.03). For mitochondrial sequencing, which is typically used for species-typing, we obtained slightly higher success for the direct (81%) than the swab (73%) extracts, but not significantly so (P = 0.25, n = 104). Among 62 canid scats, microsatellite genotyping (typically used for individual identification) was much more successful for the direct extracts (74%) than the swab extracts (35%; P < 0.001, n = 62). Together, our findings indicated a substantial advantage of ethanol preservation followed by extraction directly from scats over swabbing in our arid study area. Our results apply most specifically to canids in the arid study environment; swabbing is potentially more effective in humid environments or in other carnivore species. Nevertheless, our findings highlight the importance of conducting pilot studies before committing to swabbing as a means of fecal DNA collection.
- 出版日期2015-12
