Optimal DNA extractions from blood on preservation paper limits conservation genomic but not conservation genetic applications

Abstract

The acquisition and preservation of biological samples from rare and elusive wildlife species poses many challenges. Opportunities for collection are often limited and valuable DNA samples can degrade in unfavorable field conditions. Blood samples on preservation paper are commonly used across a wide range of taxa as a convenient and non-destructive method to obtain and store DNA. Preserved blood samples have been successfully used in a variety of genetic applications, primarily using traditional genetic markers and sequencing methods such as microsatellites and DNA barcoding. However, genomic methods are increasingly used for species of conservation concern. Genomic methods require large quantities of high-quality DNA and paper preservation methods can limit DNA availability, especially for mammals which have non-nucleated blood cells. Thus, high-yield DNA extraction methods are required to providing adequate unfragmented DNA for downstream genomic applications. Using a nested experimental design, we tested multiple DNA extraction methods and method modifications on mammalian blood stored on three common types of preservation paper. Whatman FTA classic cards with a modified extraction protocol using Qiagen QIAamp kits yielded the most DNA. We further tested the DNA extracted from FTA cards in microsatellite and genomic sequencing and found that FTA card samples were not adequate for genomic applications. For future mammalian blood collection efforts and genetic studies, researchers should weigh the need for high quantity, unfragmented DNA against the convenience of preservation paper. We recommend that researchers optimize their extraction methods and consider collecting fresh blood or tissue for genomic applications.