New and noteworthy plant records from Palau: an annotated checklist

A total of 37 new or notable records of vascular plants are listed here for Palau. Most of these have not been included in previous checklists and/or floras of Palau. If so the names have been revised or new information is presented here. The majority were discovered through herbarium and database inventory and are records that have been overlooked. A few of them have been collected or published more recently which would account for their absence from any checklist. Additionally, five records are listed as doubtfully recorded or likely mistakes. Approximately 12 (32%) of the records are introduced species, or suspected to be so. The remaining 68%, approximately 25, are likely to be native species. Two of these are endemic to Palau or suspected to be so. Many of these are entirely new records for Palau. These are mostly flowering plants but also include two ferns and even one new cycad record. Some of the records require further revisions and/or collections. All known data of these records is presented to assist in this effort. Although most of the annotated specimens contain descriptive information about the habitat they were collected in, distribution data for the majority of records is not well known. Some of these new native records are likely to be uncommon or rare. Clearly this new information demonstrates the need for further floristic work and taxonomic revision in Micronesia

DNA barcodes confirm the taxonomic and conservation status of a species of tree on the brink of extinction in the Pacific

The taxonomic status of a single island, narrow range endemic plant species from Palau, Micronesia (Timonius salsedoi) was assessed using DNA barcode markers, additional plastid loci, and morphology in order to verify its conservation status. DNA barcode loci distinguished T. salsedoi from all other Timonius species sampled from Palau, and were supported by sequence data from the atpB-rbcL intergenic spacer region. Timonius salsedoi was only known from two mature individual trees in 2012. Due to its extremely narrow range and population size, it had previously been recommended to be listed as Critically Endangered Status under three separate IUCN Criteria. In 2014 a second survey of the population following a typhoon revealed that the only two known trees had died suggesting that this species may now be extinct. Comprehensive follow up surveys of suitable habitat for this species are urgently required

Plant DNA Barcodes Can Accurately Estimate Species Richness in Poorly Known Floras

Extent: 9p.BACKGROUND: Widespread uptake of DNA barcoding technology for vascular plants has been slow due to the relatively poor resolution of species discrimination (~70%) and low sequencing and amplification success of one of the two official barcoding loci, matK. Studies to date have mostly focused on finding a solution to these intrinsic limitations of the markers, rather than posing questions that can maximize the utility of DNA barcodes for plants with the current technology. METHODOLOGY/PRINCIPAL FINDINGS: Here we test the ability of plant DNA barcodes using the two official barcoding loci, rbcLa and matK, plus an alternative barcoding locus, trnH-psbA, to estimate the species diversity of trees in a tropical rainforest plot. Species discrimination accuracy was similar to findings from previous studies but species richness estimation accuracy proved higher, up to 89%. All combinations which included the trnH-psbA locus performed better at both species discrimination and richness estimation than matK, which showed little enhanced species discriminatory power when concatenated with rbcLa. The utility of the trnH-psbA locus is limited however, by the occurrence of intraspecific variation observed in some angiosperm families to occur as an inversion that obscures the monophyly of species. CONCLUSIONS/SIGNIFICANCE: We demonstrate for the first time, using a case study, the potential of plant DNA barcodes for the rapid estimation of species richness in taxonomically poorly known areas or cryptic populations revealing a powerful new tool for rapid biodiversity assessment. The combination of the rbcLa and trnH-psbA loci performed better for this purpose than any two-locus combination that included matK. We show that although DNA barcodes fail to discriminate all species of plants, new perspectives and methods on biodiversity value and quantification may overshadow some of these shortcomings by applying barcode data in new ways.Craig Costion, Andrew Ford, Hugh Cross, Darren Crayn, Mark Harrington and Andrew Low

Building a Plant DNA Barcode Reference Library for a Diverse Tropical Flora: An Example from Queensland, Australia

A foundation for a DNA barcode reference library for the tropical plants of Australia is presented here. A total of 1572 DNA barcode sequences are compiled from 848 tropical Queensland species. The dataset represents 35% of the total flora of Queensland’s Wet Tropics Bioregion, 57% of its tree species and 28% of the shrub species. For approximately half of the sampled species, we investigated the occurrence of infraspecific molecular variation in DNA barcode loci rbcLa, matK, and the trnH-psbA intergenic spacer region across previously recognized biogeographic barriers. We found preliminary support for the notion that DNA barcode reference libraries can be used as a tool for inferring biogeographic patterns at regional scales. It is expected that this dataset will find applications in taxonomic, ecological, and applied conservation research

Plant biodiversity science, discovery, and conservation : case studies from Australasia and the Pacific.

This thesis advances plant biodiversity knowledge in three separate bioregions, Micronesia, the Queensland Wet Tropics, and South Australia. A systematic treatment of the endemic flora of Micronesia is presented for the first time thus advancing alpha taxonomy for the Micronesia-Polynesia biodiversity hotspot region. The recognized species boundaries are used in combination with all known botanical collections as a basis for assessing the degree of threat for the endemic plants of the Palau archipelago located at the western most edge of Micronesia’s Caroline Islands. A preliminary assessment is conducted utilizing the IUCN red list Criteria followed by a new proposed alternative methodology that enables a degree of threat to be established utilizing existing data. Historical records and archaeological evidence are reviewed to establish the minimum extent of deforestation on the islands of Palau since the arrival of humans. This enabled a quantification of population declines of the majority of plants endemic to the archipelago. In the state of South Australia, the importance of establishing concepts of endemism is emphasized even further. A thorough scientific assessment is presented on the state’s proposed biological corridor reserve network. The report highlights the exclusion from the reserve system of one of the state’s most important hotspots of plant endemism that is highly threatened from habitat fragmentation and promotes the use of biodiversity indices to guide conservation priorities in setting up reserve networks. In the Queensland Wet Tropics the thesis achieves two additional outcomes. A localized pilot study test the accuracy of plant DNA barcodes to estimate species richness. Species richness estimations were performed with high accuracy suggesting the suitability of the approach in poorly known floras where the identity of samples is known or from samples in a cryptic life stage that are difficult to identify. The methodology is promising for areas of the world, such as the tropics, that contain a high percentage of undescribed or poorly known taxa. In addition, a large dataset from northeast Queensland was utilized to assess broad scale patterns of phylogenetic diversity. A linear relationship between phylogenetic diversity and genus richness is found to have high statistical support suggesting that taxon richness is an accurate predictor of hot spots of evolutionary history. When the affects of taxon richness are removed through linear regression however, a strong biogeographic pattern is unveiled. Sites with higher phylogenetic diversity than expected based on genus richness are best explained by having a lower percent of Gondwanan or endemic Australian elements of the flora. These sites have a higher percentage of Indomalayan or other foreign lineages that dispersed to Australia and are more frequent in the lowland rainforest areas below 200 meters. Phylogenetic diversity is shown to be effective at unraveling broad scale patterns of evolutionary history at the biome scale, which may prove useful for justifying the preservation of not just species but assemblages of species that represent different epochs of the earth’s evolutionary history.Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 201

A revision of the genus Osmoxylon (Araliaceae) in Palau, including two new species

Osmoxylon Miq. (Araliaceae) is revised for Palau, Micronesia including descriptions of two new taxa Osmoxylon leidichii Costion, sp. nov. and Osmoxylon ngardokense Costion, sp. nov. Full descriptions are provided for all four Palau species, along with diagnostic field keys

Maesa tetrandra (Primulaceae) in Palau: an introduced species mistaken for a single-island endemic

Maesa canfieldiae Fosberg & Sachet was formerly recognized as a single- island endemic in the Palau archipelago with a potentially rare distribution warranting its listing on the IUCN Red List as Vulnerable. Here we synonymize M. canfieldiae into Maesa tetrandra (Roxb.) A. DC., a more widespread species native to Indonesia and New Guinea, and discuss its likely method of recent introduction to the Palau Islands. Because this particular species favors disturbance and is now considered naturalized in the Pacific, we have included a general description of the plant to aid in its identification by nonexperts and to allow monitoring of its invasive potential. We recommend the listing of M. tetrandra as Least Concern on the IUCN Red List

The Sahul–Sunda floristic exchange: dated molecular phylogenies document Cenozoic intercontinental dispersal dynamics

Aim: The aim was to characterize the temporal dynamics of the Sahul–Sunda floristic exchange using published dated molecular phylogenies. Location: The Sahul and Sunda shelves in Australasia and Southeast Asia. Methods: Dated molecular phylogenies were compiled from the literature for plant clades that contained at least one node representing a biogeographical disjunction between the Sahul and Sunda shelves. For these nodes the age, ancestral geographical area and propagule type were determined. Results: We analysed 49 clades from 21 published phylogenies representing a diverse set of angiosperm lineages. The inferred age of the disjunctions ranged from c. 33 Ma to c. 1 Ma; the earliest age marked the onset of the Sahul–Sunda floristic exchange. Disjunctions (resulting from dispersal/migration events) occurred at the rate of 0.41 per 2 Myr between 34 and 12 Ma. Thereafter the rate sharply increased, coincident with the shelves effectively merging. For nearly two-thirds (63%) of the nodes Sunda was the ancestral area, and for 90% the ancestral species possessed zoochorous propagules. Main conclusions: There is strong support for a dynamic model of floristic exchange between Sahul and Sunda. Fewer (18%) disjunctions occurred prior to Sahul and Sunda merging around 12 Ma, which we attribute to a combination of the effect of overwater dispersal barriers and relatively stable, saturated species assemblages resistant to the establishment of newly arrived lineages. The exchange, once underway, was strongly asymmetrical; eastwards migration into Sahul predominated over the reverse by a factor of c. 2.4. As zoochorous lineages were overrepresented among the successful dispersers, we infer a strong role for localized animal dispersal across narrow water barriers

Plant endemism, rarity, and threat in Palau, Micronesia: a geographical checklist and preliminary Red List assessment

An official checklist of the endemic plant species of Palau has been long awaited, and is presented here for the first time. For each species a substrate limitation, growth form, and relative abundance is listed. In addition an IUCN red list assessment was conducted using all available data. For over half of the endemic species there is insufficient data to provide a red listing status however an expected minimum number of threatened plants out of the total is inferred. Approximately 15% of Palau's endemic plants are believed to be only known from the type collection and many more only known from a few collections. These taxa however may now be prioritized and targeted for future inventory and research. The taxonomic robustness of several of these taxa is questionable and it is expected that more endemic species will be lost to synonymy in the future. Previous estimations have significantly over-estimated the rate of plant endemism in Palau (e.g., 194). Here it is established that the rate of plant endemism (130) is comparable to some of its neighboring Micronesian islands to the east, notably Guam and Pohnpei. Several species are known to be restricted to isolated disjunct populations however the causes for their rarity are poorly known and have never been intensively studied. Palau although notable for its high percentage of remaining primary forest compared to other oceanic islands faces increasing threat from development making these small populations highly vulnerable. Nothing is known about how these rare species will respond to the imminent threat of climate change. There is no current legislation protecting specific plant species as their rarity has never been systematically quantified. This paper represents a step towards plant conservation in Micronesia and it aims to stimulate further studies to address the data deficiencies documented here

The Malesian floristic interchange: plant migration patterns across Wallace's Line

[Extract] The convergence of formerly disconnected land masses presents opportunities for plant and animal dispersal and their possible subsequent diversification in new terrain. Examples include the closure of the Isthmus of Panama in the Pliocene, the collision of India with continental Asia and the convergence of the Australian and Eurasian Plates. Perhaps the most widely discussed example of biotic migration is that of the Great American Interchange between the Laurasian North American Plate and the Gondwanan South American Plate that was the subject of George Gaylord Simpson's 'Splendid Isolation' (1980) that focused on migration patterns of animals. Prior to the development of phylogenetic methods, the primary mode of interpreting patterns in migration relied on analysis of fossil and extant distributions. Molecular phylogenetic methods that incorporate the dimension of time are a relatively new and powerful tool in the study of biogeographic history. In an analysis of plant and animal dated phylogenies of taxa that are distributed across the Isthmus of Panama, Cody et al. (2010) demonstrated that plants have a greater capacity for dispersal than animals because they had been dispersing between these areas since the Eocene whereas animals only began to disperse in the mid Miocene. Interestingly, this study indicated that many animals also had the capacity for over-water dispersal prior to closure of the Isthmus of Panama but in general they were more reliant on the formation of a direct land connection. One difference between the Panamanian and Indian convergences and that between the Australian and Eurasian Plates is that the former two both culminated in the formation of a direct land bridge, but the latter has not. Wallace (l869) noted the strong faunistic divide around the area of convergence between Australian and Eurasian Plates that would come to be known as 'Wallace's Line', Wallace was less forthcoming when describing floristic differences and determination of the significance of Wallace's Line for plants has proven far more complex than for the fauna. Any study of biotic interchange between the Eurasian and Australian Plates will ultimately enable better assessment of the capability of over water dispersal of different groups of organisms