2.4.3. Conservation Assessment

The taxonomic impediment [175] is also a significant problem in assessing species diversity and making accurate species determinations for conservation monitoring. This case is especially true in tropical biomes, where biodiversity is poorly known and a greater number of species lack verified scientific names. Species identification by non-taxonomists can be extremely difficult, especially when using non-fertile specimens often only labeled as "morphospecies" [176]. In such cases, DNA barcoding offers a solution for more uniform and accurate identifications, recognizing that some logistical hurdles may still impede the widespread use of DNA barcodes in this fashion [177].

In the relatively poorly known tropical forests of northern Queensland, Australia, it has been demonstrated that plant DNA barcodes can play a key role in estimating species richness and thereby determining conservation priorities [77]. Similarly, in the fragmented rain forest habitats in South Eastern Queensland, Shapcott et al. [61,169] generated plant DNA barcodes for 86% of the flora (770 species in 111 families) and calculated phylogenetic diversity (PD; see Owen [178]) measures for each of the 18 subregions in the area. For these forests, which have lately received renewed conservation attention and are taxonomically rich at the generic-level and less so at the species-level, species richness may not be the most appropriate measure for setting conservation priorities. The phylogenetic diversity estimates calculated from the DNA barcode data were used to prioritize subregions for conservation action and it was concluded that the local floristic patterns were consistent with both ancient ecological refugia and recent lineage range expansions [179].

Even though the Earth may be undergoing its sixth major extinction with extinction rates over one thousand times that of "normal" periods [69], observing an extinction event is rare. For plants the extinction of only 571 species over the last several hundred years has been carefully documented [180]. On the island of Palau in Micronesia, plant DNA barcodes were used to verify that a narrow range endemic tree described in the 1980s

known from only two mature individuals was *Timonius salsedoi* Fosberg and Sachet in the family Rubiaceae [181]. Subsequently, after a typhoon hit the area, a survey of the island revealed that both trees had perished. Although previously assessed as Critically Endangered by IUCN criteria, it is suspected that this species is now extinct [181].

DNA barcodes have significant potential as a tool for understanding and enhancing conservation efforts. Using standardized and comparable genetic information for species across broad geographic regions can have a substantial impact on basic biodiversity research (e.g., Mi et al. [112]; Erickson et al. [45]; Pei et al. [98]), as well as conservation monitoring and priority assessments in threatened habitats, in local communities, and across large geographic regions (e.g., Shapcott et al. [61]).

### **3. Looking Forward: The Expanding Technological Spectrum of DNA Barcodes**
