Determining evolutionary origin and phylogenetic relationships of mallard-like ducks of Oceania, greater Indonesia, and the Philippines with ddRAD-seq data.

AIM: We aim to determine the evolutionary origins and population genetics of mallard-like ducks of Oceania, greater Indonesia, and the Philippines. LOCATION: Oceania, greater Indonesia, and the Philippines. TAXON: Mallard (Anas platyrhynchos), Pacific black duck (A. superciliosa spp.), and Philippine duck (A. luzonica) METHODS: Thousands of nuclear ddRAD-seq loci and the mitochondrial DNA control region were assayed across individuals representative of each species' range. We assessed population structure and phylogenetic relationships, as well as estimated demographic histories to reconstruct the biogeographical history of each species. RESULTS: Philippine and Pacific black ducks represent unique genetic lineages that diverged from the mallard 1-2 million years ago. We find no support for the Philippine duck representing a hybrid species as once posited; however, their low levels of genetic diversity requires further attention. We find a lack of substructure among Philippine ducks. However, we found pronounced differentiation between subspecies of Pacific black ducks, especially between A. s. superciliosa from New Zealand and A. s. rogersi from Australia, Papua New Guinea, and Timor-Leste, Indonesia. Anas superciliosa pelewensis gave mixed results; individuals from the Solomon Islands were differentiated from the other subspecies, but those from the island of Aunu'u, American Samoa, were genetically more similar to A. s. rogersi than A. s. pelewensis samples from the Solomon Islands. Finally, we find limited evidence of interspecific gene flow at evolutionary scales, and mallard introgression among contemporary samples. MAIN CONCLUSIONS: Mallard-like ducks radiated across Oceania, greater Indonesia, and the Philippines within the last 2 million years. Only the Pacific black duck showed unique sub-structuring that largely followed known sub-species ranges, except for A. s. pelewensis. We posit that the high interrelatedness among Solomon Island samples suggests that their genetic distinctiveness may simply be the result of high levels of genetic drift. In contrast, we conclude that mainland Australian Pacific black ducks were the most likely source for the recent colonization of American Samoa. As a result, our findings suggest that either the A. s. pelewensis subspecies designations and/or its geographical range may require re-evaluation. Continued re-evaluation of evolutionary and taxonomic relationships is necessary when attempting to reconstruct and understand biogeographical histories, with important implications towards any attempts to implement conservation strategies.

Beginnings of a plant parasite: early development of Rafflesia consueloae inside its Tetrastigma host.

MAIN CONCLUSION: Extensive histology of host organs revealed the early events in the vegetative growth of Rafflesia consueloae including initial infection site, endophyte distribution, and other developmental events prior to bud emergence. The early events in the vegetative development of the holoparasite Rafflesia have long remained a mystery. Because its entire vegetative growth occurs within the host body, very little is known about the developmental events prior to emergence of the floral shoot. The goal of this study was to describe the events that occur during the vegetative growth of R. consueloae, particularly in the early stages of infection. We performed extensive microtome sectioning of multiple root and stem segments from different Tetrastigma host individuals to examine the cytology, distribution, and development of the R. consueloae endophyte within the host tissues. We found that R. consueloae infection is restricted to the roots of its host. Infection begins within the vascular cambium where the endophyte appears to initially reside prior to their radial spread to the vascular tissues. The tissues obtained from different host individuals had varying degrees of infection alluding to a possible role of host resistance mechanisms and/or varying levels of parasite infectiousness. Endophyte presence in host vines without external manifestations of infection indicates that the parasite may dwell within the host tissues for prolonged periods as small cell clusters without transitioning to the reproductive stage. Furthermore, we found that floral shoots may develop in scarcely infected host tissues indicating that extensive endophyte growth within the host is not a prerequisite to the onset of reproductive development. Overall, our study describes for the first time the developmental events prior to emergence of R. consueloae buds from its host.

Living in small spaces: Forest fragment characterization and its use by Philippine tarsiers (Tarsius syrichta Linnaeus, 1758) in Mindanao Island, Philippines.

The Philippine tarsier (Tarsius syrichta) is a charismatic species that is threatened by illegal hunting and deforestation. Although they occur in forest and disturbed habitats, ecological information about them is still considerably lacking, which consequently hampers our ability to effectively protect tarsiers from further endangerment. Here, we characterized a 36-ha forest fragment in Mindanao Island where a population of tarsiers persist, and assessed the factors that could have influenced their distribution within the area. We sampled trees (> 1 cm DBH) within 10 × 10-m sampling plots (N = 54), which were established within 1-ha grids (N = 32) and locations where tarsiers were captured (N = 22). The habitat was characterized as a regenerating forest over limestone, with a generally homogeneous structure in terms of tree species richness, abundance, mean DBH, and height. In both sampling plots, we found an abundance of trees below 5 cm in DBH (> 50%) and between 2.6 and 5 m in height (> 40%), which, accordingly, the tarsiers appeared to prefer to use when foraging or sleeping. Lianas were among the most important features of the forest, possibly being a keystone structure in such habitats. Community assemblage, species richness, and mean height of trees, as well as distance to the forest edge, were found to be significant factors that influenced tarsier distribution in the fragment. Our study provides basic yet critical information on the habitat and ecology of Philippine tarsiers in Mindanao, and highlights the importance of forest fragments with rich flora diversity to the survival of the species.

Conservation genetics of the Philippine tarsier: cryptic genetic variation restructures conservation priorities for an island archipelago primate.

Establishment of conservation priorities for primates is a particular concern in the island archipelagos of Southeast Asia, where rates of habitat destruction are among the highest in the world. Conservation programs require knowledge of taxonomic diversity to ensure success. The Philippine tarsier is a flagship species that promotes environmental awareness and a thriving ecotourism economy in the Philippines. However, assessment of its conservation status has been impeded by taxonomic uncertainty, a paucity of field studies, and a lack of vouchered specimens and genetic samples available for study in biodiversity repositories. Consequently, conservation priorities are unclear. In this study we use mitochondrial and nuclear DNA to empirically infer geographic partitioning of genetic variation and to identify evolutionarily distinct lineages for conservation action. The distribution of Philippine tarsier genetic diversity is neither congruent with expectations based on biogeographical patterns documented in other Philippine vertebrates, nor does it agree with the most recent Philippine tarsier taxonomic arrangement. We identify three principal evolutionary lineages that do not correspond to the currently recognized subspecies, highlight the discovery of a novel cryptic and range-restricted subcenter of genetic variation in an unanticipated part of the archipelago, and identify additional geographically structured genetic variation that should be the focus of future studies and conservation action. Conservation of this flagship species necessitates establishment of protected areas and targeted conservation programs within the range of each genetically distinct variant of the Philippine tarsier.