Cryptic diversity and population genetic structure in the rare, endemic, forest-obligate, slender geckos of the Philippines.

Recent studies of forest lizards in Southeast Asia have highlighted spectacular morphological and cryptic genetic diversity in several poorly known clades. Unfortunately, many of the included species have microhabitat preferences for forested environments, and therefore they are threatened by extensive forest destruction throughout the region. This is particularly true in the Philippines, an archipelago with a strikingly high proportion (84%) of endemic geckos. Abundances inferred from historical museum collections suggests that we are in a critical period where apparent declines in population viability and species' abundance have taken place faster than the growth in our understanding of alpha diversity. This phenomenon is exemplified in the exceedingly rare Philippine slender forest geckos of the genus Pseudogekko. Most of the known species are rarely encountered by field biologists, and species boundaries are unclear; this poor state of knowledge impedes effective conservation measures. Using the first multilocus phylogeny for these taxa, and phylogenetic and population genetic approaches, we elucidate evolutionary lineages and delimit species-level conservation targets in this unique radiation of endemic Philippine geckos. The results support the presence of widespread cryptic diversity in the genus, providing a framework for the re-evaluation of conservation priorities aimed at protecting these rare, forest-obligate species.