The Hawaiian Archipelago is a stepping stone for dispersal in the Pacific: an example from the plant genus Melicope (Rutaceae)

Aim Pacific biogeographical patterns in the widespread plant genus Melicope J.R. Forst. & G. Forst. (Rutaceae) were examined by generating phylogenetic hypotheses based on chloroplast and nuclear ribosomal sequence data. The aims of the study were to identify the number of colonization events of Melicope to the Hawaiian Islands and to reveal the relationship of Hawaiian Melicope to the Hawaiian endemic genus Platydesma H. Mann. The ultimate goal was to determine if the Hawaiian Islands served as a source area for the colonization of Polynesia. Location Nineteen accessions were sampled in this study, namely eight Melicope species from the Hawaiian Islands, four from the Marquesas Islands, one species each from Tahiti, Australia and Lord Howe Island, two Australian outgroups and two species of the Hawaiian endemic genus Platydesma. To place our results in a broader context, 19 sequences obtained from GenBank were included in an additional analysis, including samples from Australia, Papua New Guinea, New Zealand, Southeast Polynesia and Asia. Methods DNA sequences were generated across 19 accessions for one nuclear ribosomal and three chloroplast gene regions. Maximum parsimony analyses were conducted on separate and combined data sets, and a maximum likelihood analysis was conducted on the combined nuclear ribosomal and chloroplast data set. A broader nuclear ribosomal maximum parsimony analysis using sequences obtained from GenBank was also performed. Geographic areas were mapped onto the combined chloroplast and nuclear ribosomal tree, as well as onto the broader tree, using the parsimony criterion to determine the dispersal patterns. Results Phylogenetic analyses revealed that Platydesma is nested within Melicope and is sister to the Hawaiian members of Melicope. The Hawaiian Melicope + Platydesma lineage was a result of a single colonization event, probably from the Austral region. Finally, Marquesan Melicope descended from at least one, and possibly two, colonization events from the Hawaiian Islands. Main conclusions These data demonstrate a shifting paradigm of Pacific oceanic island biogeography, in which the patterns of long‐distance dispersal and colonization in the Pacific are more dynamic than previously thought, and suggest that the Hawaiian Islands may act as a stepping stone for dispersal throughout the Pacific.     

The origin and number of introductions of the Hawaiian endemic Silene species (Caryophyllaceae)

The Hawaiian endemic Silene are a small group of woody or semiwoody representatives from a large, predominantly herbaceous, species-rich genus. We here investigated the origin and number of introductions of the endemic Hawaiian Silene based on phylogenetic relationships inferred from DNA sequences from both the plastid (the rps16 intron) and the nuclear (ribosomal internal transcribed sequences, ITS, and intron 23 of the RPB2 gene) genomes. Silene antirrhina, a widespread weedy American annual, is strongly supported as sister to a monophyletic group consisting of the Hawaiian Silene, indicating a single colonization event. There are no obvious morphological similarities between S. antirrhina and any of the species of Hawaiian Silene. Our results suggest an American origin for the Hawaiian endemics because that would require only a single trans-ocean dispersal. Two of the Hawaiian endemics (S. struthioloides and S. hawaiiensis) that form a subclade in the analyses have evolved woodiness after introduction to the Hawaiian Islands. Our results contribute to other recent results based on molecular phylogenetics that emphasize the American continent as a source area for the Hawaiian flora and support a striking morphological radiation and evolution of woodiness from a single introduction to the archipelago.     

Radiation following long‐distance dispersal: the contributions of time,opportunity and diaspore morphology in Sicyos (Cucurbitaceae)

Aim  To infer the most plausible explanations for the presence of 14 species of the Neotropical cucurbit genus Sicyos on the Hawaiian Islands, two on the Galápagos Islands, two in Australia, and one in New Zealand. Location  Neotropics, the Hawaiian and Galápagos archipelagos, Australia and New Zealand. Methods  We tested long‐problematic generic boundaries in the tribe Sicyoeae and reconstructed the history of Sicyos using plastid and nuclear DNA sequences from 87 species (many with multiple accessions) representing the group’s generic and geographic diversity. Maximum likelihood and Bayesian approaches were used to infer relationships, divergence times, biogeographic history and ancestral traits. Results  Thirteen smaller genera, including Sechium, are embedded in Sicyos, which when re‐circumscribed as a monophyletic group comprises 75 species. The 14 Hawaiian species of Sicyos descended from a single ancestor that arrived c. 3 million years ago (Ma), Galápagos was reached twice at c. 4.5 and 1 Ma, the species in Australia descended from a Neotropical ancestor (c. 2 Ma), and New Zealand was reached from Australia. Time since arrival thus does not correlate with Sicyos species numbers on the two archipelagos. Main conclusions  A plausible mechanism for the four trans‐Pacific dispersal events is adherence to birds of the tiny hard fruit with retrorsely barbed spines found in those lineages that underwent long‐distance migrations. The Hawaiian clade has lost these spines, resulting in a lower dispersal ability compared with the Galápagos and Australian lineages, and perhaps favouring allopatric speciation.     

Diversity despite dispersal: colonization history and phylogeography of Hawaiian crab spiders inferred from multilocus genetic data

The Hawaiian archipelago is often cited as the premier setting to study biological diversification, yet the evolution and phylogeography of much of its biota remain poorly understood. We investigated crab spiders (Thomisidae, Mecaphesa ) that demonstrate contradictory tendencies: (i) dramatic ecological diversity within the Hawaiian Islands, and (ii) accompanying widespread distribution of many species across the archipelago. We used mitochondrial and nuclear genetic data sampled across six islands to generate phylogenetic hypotheses for Mecaphesa species and populations, and included penalized likelihood molecular clock analyses to estimate arrival times on the different islands. We found that 17 of 18 Hawaiian Mecaphesa species were monophyletic and most closely related to thomisids from the Marquesas and Society Islands. Our results indicate that the Hawaiian species evolved from either one or two colonization events to the archipelago. Estimated divergence dates suggested that thomisids may have colonized the Hawaiian Islands as early as ~10 million years ago, but biogeographic analyses implied that the initial diversification of this group was restricted to the younger island of Oahu, followed by back-colonizations to older islands. Within the Hawaiian radiation, our data revealed several well-supported genetically distinct terminal clades corresponding to species previously delimited by morphological taxonomy. Many of these species are codistributed across multiple Hawaiian Islands and some exhibit genetic structure consistent with stepwise colonization of islands following their formation. These results indicate that dispersal has been sufficiently limited to allow extensive ecological diversification, yet frequent enough that interisland migration is more common than speciation.     

Biogeographic mirages? Molecular evidence for dispersal‐driven evolution in Hydrobiusini water scavenger beetles

Water beetles of the tribe Hydrobiusini are globally distributed in the northern hemisphere and all austral continents except Antarctica. A remarkable clade also occurs in the Hawaiian Islands. The phylogenetic relationships among genera were recently investigated using a combination of molecules and morphology. Here, we use this phylogenetic framework to address the biogeographic evolution of this group using Bayesian fossil‐based divergence times, and model‐based maximum likelihood ancestral range estimations. We recover an origin of the tribe in the Cretaceous ca. 100 Ma. Our biogeographic analyses support an origin of the tribe in Laurasia followed by the colonization of Australia. However, a Gondwanan origin of the group cannot be ruled out when considering the fossil record. The timeframe of the tribe's evolution as well as the model‐based approach of ancestral range estimation favour a scenario invoking multiple transoceanic dispersal events over a Gondwana vicariance hypothesis. The Hawaiian radiation originated from long‐distance dispersal to now‐submerged islands, paired with dispersal to new islands as they formed.     

Phylogenetic position and biogeography of Hillebrandia sandwicensis (Begoniaceae): a rare Hawaiian relict

The Begoniaceae consist of two genera, Begonia, with approximately 1400 species that are widely distributed in the tropics, and Hillebrandia, with one species that is endemic to the Hawaiian Islands and the only member of the family native to those islands. To help explain the history of Hillebrandia on the Hawaiian Archipelago, phylogenetic relationships of the Begoniaceae and the Cucurbitales were inferred using sequence data from 18S, rbcL, and ITS, and the minimal age of both Begonia and the Begoniaceae were indirectly estimated. The analyses strongly support the placement of Hillebrandia as the sister group to the rest of the Begoniaceae and indicate that the Hillebrandia lineage is at least 51-65 million years old, an age that predates the current Hawaiian Islands by about 20 million years. Evidence that Hillebrandia sandwicensis has survived on the Hawaiian Archipelago by island hopping from older, now denuded islands to younger, more mountainous islands is presented. Various scenarios for the origin of ancestor to Hillebrandia are considered. The geographic origin of source populations unfortunately remains obscure; however, we suggest a boreotropic or a Malesian-Pacific origin is most likely. Hillebrandia represents the first example in the well-studied Hawaiian flora of a relict genus.     

Phylogenetics of the genus Scaevola (Goodeniaceae): implication for dispersal patterns across the Pacific Basin and colonization of the Hawaiian Islands

Scaevola, the only genus of Goodeniaceae that has extensively radiated outside of Australia, has dispersed throughout the Pacific Basin, with a few species reaching the tropical coastal areas of the Atlantic and Indian Oceans. Five Australian and most of the non-Australian species are placed in Scaevola section Scaevola based on their fleshy fruits, indeterminate inflorescences, and more arborescent habits. Analyses of ITS sequence data demonstrate that Scaevola is a monophyletic group if S. collaris is excluded and Diaspasis filifolia is included. The genus is Australian in origin, but there have been at least six separate dispersal events from Australia. Four of these dispersals each resulted in single extra-Australian species. The remaining two were followed by radiations that gave rise to large groups, each including one of the widespread strand species, S. taccada and S. plumieri. Remarkably, three of the six dispersals established species on the remote Hawaiian Archipelago, representing at present the largest number of colonizations by any flowering plant genus to these islands.     

Molecular phylogenetics of the Macaronesian-endemic genus Bystropogon (Lamiaceae): palaeo-islands, ecological shifts and interisland colonizations

Abstract A molecular phylogenetic study of Bystropogon L'Her. (Lamiaceae) is presented. We performed a cladistic analysis of nucleotide sequences of the internal transcribed spacers (ITS), of the nuclear ribosomal DNA, and of the trnL gene and trnL-trnF intergenic spacer of the chloroplast DNA. Bystropogon odoratissimus is the only species endemic to the Canary Islands that occurs in the three palaeo-islands of Tenerife. This species is not part of an early diverging lineage of Bystropogon and we suggest that it has a recent origin. This phylogenetic pattern is followed by most of the species endemic to the palaeo-islands of Tenerife. The two sections currently recognized in Bystropogon form two monophyletic groups. Taxa belonging to the section Bystropogon clade show interisland colonization limited to the Canary Islands with ecological shifts among three ecological zones. Taxa from the section Canariense clade show interisland colonization both within the Canary Islands and between the Canary Islands and Madeira. Speciation events within this clade are mostly limited to the laurel forest. The genus has followed a colonization route from the Canaries towards Madeira. This route has also been followed by at least five other plant genera with species endemic to Macaronesia. Major incongruences were found between the current infrasectional classification and the molecular phylogeny, because the varieties of Bystropogon origanifolius and Bystropogon canariensis do not form two monophyletic groups. The widespread B. origanifolius appears as progenitor of the other species in section Bystropogon with a more restricted distribution.     

Phylogeny and age of diversification of the planitibia species group of the Hawaiian Drosophila

The Hawaiian Drosophila offer a unique opportunity to examine evolutionary questions because of the known ages of the Hawaiian Islands and the large number of species endemic to this archipelago. One of the more well studied groups of Hawaiian Drosophila is the planitibia species group, a long-standing population genetic model system. Here we present a molecular phylogenetic hypothesis of all 17 taxa in the planitibia group based on nucleotide sequences from two mitochondrial (16S and COII) and four nuclear (Adh, Gpdh, Yp1, and Yp2) loci, accounting for over 4kb of sequence per taxon. We use these data to estimate major divergence times within this group. Our results suggest that the basal diversification within this group, calculated at 6.1 +/- 0.47 MY, predates the oldest high island of Kauai. The older diversifications in this group took place on Kauai, with subsequent colonization and speciation events occurring as new islands became available to Drosophila. Understanding of the phylogenetic relationships of this important group will place the existing population genetic work in a macroevolutionary context and stimulate additional work, particularly on those taxa endemic to the Maui Nui complex of islands.     

Phylogenetic utility of the internal transcribed spacers of nuclear ribosomal DNA in plants: an example from the compositae.

The internal transcribed spacer (ITS) region of 18-26S nuclear ribosomal DNA was sequenced in 12 representatives of the Compositae subtribe Madiinae and two outgroup species to assess its utility for phylogeny reconstruction. High sequence alignability and minimal length variation among ITS 1, 5.8S, and ITS 2 sequences facilitated determination of positional homology of nucleotide sites. In pairwise comparisons among Madiinae DNAs, sequence divergence at unambiguously aligned sites ranged from 0.4 to 19.2% of nucleotides in ITS 1 and from 0 to 12.9% of nucleotides in ITS 2. Phylogenetic relationships among ITS sequences of Hawaiian silversword alliance species (Argyroxiphium, Dubautia, and Wilkesia) and California tarweed taxa in Adenothamnus, Madia, Raillardella, and Raillardiopsis are highly concordant with a chloroplast DNA-based phylogeny of this group. Maximally parsimonious trees from ITS and chloroplast DNA data all suggest (a) origin of the monophyletic Hawaiian silversword alliance from a California tarweed ancestor, (b) closer relationship of the Hawaiian species to Madia and Raillardiopsis than to Adenothamnus or Raillardella, (c) paraphyly of Raillardiopsis, a segregate of Raillardella, and (d) closer relationship of Raillardiopsis to Madia and the silversword alliance than to Raillardella. These findings indicate that the ITS region in plants should be further explored as a promising source of nuclear phylogenetic markers.     

Molecular phylogenetics and historical biogeography of Hawaiian Dryopteris (Dryopteridaceae)

The fern genus Dryopteris (Dryopteridaceae) is represented in the Hawaiian Islands by 18 endemic taxa and one non-endemic, native species. The goals of this study were to determine whether Dryopteris in Hawai'i is monophyletic and to infer the biogeographical origins of Hawaiian Dryopteris by determining the geographical distributions of their closest living relatives. We sequenced two chloroplast DNA fragments, rbcL and the trnL-F intergenic spacer (IGS), for 18 Hawaiian taxa, 45 non-Hawaiian taxa, and two outgroup species. For individual fragments, we estimated phylogenetic relationships using Bayesian inference and maximum parsimony. We performed a combined analysis of both cpDNA fragments employing Bayesian inference, maximum parsimony, and maximum likelihood. These analyses indicate that Hawaiian Dryopteris is not monophyletic, and that there were at least five separate colonizations of the Hawaiian Islands by different species of dryopteroid ferns, with most of the five groups having closest relatives in SE Asia. The results suggest that one colonizing ancestor, perhaps from SE Asia, gave rise to eight endemic taxa (the glabra group). Another colonizing ancestor, also possibly from SE Asia, gave rise to a group of five endemic taxa (the exindusiate group). Dryopteris fusco-atra and its two varieties, which are endemic to Hawai'i, most likely diversified from a SE Asian ancestor. The Hawaiian endemic Nothoperanema rubiginosum has its closest relatives in SE Asia, and while the remaining two species, D. wallichiana and D. subbipinnata, are sister species, their biogeographical origins could not be determined from these analyses due to the widespread distributions of D. wallichiana and its closest non-Hawaiian relative.     

Resolving the native provenance of invasive fireweed (Senecio madagascariensis Poir.) in the Hawaiian Islands as inferred from phylogenetic analysis

Accurate identification of weedy species is critical to the success of biological control programs seeking host-specific control agents. Phylogenetic relationships based on internal transcribed spacer region (ITS1, ITS2) DNA sequence data were used to elucidate the most likely origin and taxonomic placement of Senecio madagascariensis Poir. (fireweed; Asteraceae) in the Hawaiian archipelago. Putative S. madagascariensis populations from Madagascar, South Africa, Swaziland, and Hawaii were included in the analysis. Different phylogenetic models (maximum parsimony and maximum likelihood) were congruent in suggesting that Hawaiian fireweed is most closely related to populations from the KwaZulu-Natal region in South Africa. Phylogenetic divergence and morphological data (achene characteristics) suggest that the S. madagascariensis complex is in need of revised alpha-level taxonomy. Taxonomic identity of invasive fireweed in Hawaii is important for finding effective biological control agents as native range populations constitute different biotypic variants across a wide geographical area. Based on our phylogenetic results, research directed at biological control of Hawaiian infestations should focus on areas in the KwaZulu-Natal region in South Africa where host-specific natural enemies are most likely to be found. Our results show that phylogeographical analysis is a potential powerful and efficient tool to address questions relevant to invasion biology of plants.     

PACT in practice: comparative historical biogeographic patterns and species–area relationships of the Greater Antillean and Hawaiian Island terrestrial biotas

Aim To compare the evolutionary and ecological patterns of two extensively studied island biotas with differing geological histories (the Hawaiian Islands and the Greater Antilles). We evaluated the results from PACT (phylogenetic analysis for comparing trees), an innovative approach that has been proposed to reveal general patterns of biotic expansion (between regions) and in situ (within a region) diversification, as well as species–area relationships (SAR) and the taxon pulse dynamic. Location The Hawaiian Islands and Greater Antilles. Methods We used the PACT algorithm to construct general area cladograms and identified biotic expansion and in situ nodes. We analysed the power‐law SAR and relative contribution of biotic expansion and in situ diversification events using power‐law and linear regression analyses. Results Both biotic expansion and in situ nodes were prevalent throughout the PACT general area cladograms (Greater Antilles, 55.9% biotic expansion, 44.1% in situ; Hawaiian Islands, 40.6% biotic expansion, 59.4% in situ). Of the biotic expansion events, both forward and backward events occurred in both regions (Greater Antilles, 85.1% forward, 14.9% backward; Hawaiian Islands, 65% forward, 35% backward). Additionally, there is a power‐law SAR for the Greater Antilles but not for the Hawaiian Islands. However, exclusion of Hawai'i (the youngest, largest Hawaiian Island) produced a power‐law SAR for the Hawaiian Islands. Main conclusions The prevalence of in situ events as well as forward and backward biotic expansion events reveals that both Hawaiian and Greater Antillean biotas have evolved through alternating episodes of biotic expansion and in situ diversification. These patterns are characteristic of the taxon pulse dynamic, for which few data have previously been recorded on islands. Additionally, our analysis revealed that historical influences on the power‐law SARs are pronounced in both assemblages: old, small islands are relatively species rich and young, large islands are relatively species poor. Thus, our PACT results are consistent with hypotheses of geological influence on the evolution of island biotas and also provide greater insight into the role of the taxon pulse dynamic in the formation of island equilibria.     

Reconstructing ancestral patterns of colonization and dispersal in the Hawaiian understory tree genus Psychotria (Rubiaceae): a comparison of parsimony and likelihood approaches

Systematic and biogeographical relationships within the Hawaiian clade of the pantropical understory shrub genus Psychotria (Rubiaceae) were investigated using phylogenetic analysis of 18S-26S ribosomal DNA internal (ITS) and external (ETS) transcribed spacers. Phylogenetic analyses strongly suggest that the Hawaiian Psychotria are monophyletic and the result of a single introduction to the Hawaiian Islands. The results of phylogenetic analyses of ITS and ETS partitions alone give slightly different topologies among basal lineages of the Hawaiian clade; however, such differences are not well supported. Relationships in the section Straussia clade in particular are not well resolved because of few nucleotide changes on internal branches, suggesting extremely rapid radiation in the lineage. Parsimony and likelihood reconstructions of ancestral geographical distributions using the topologies inferred from both parsimony and likelihood analysis of combined data and using different combinations of models and branch lengths gave highly congruent results. However, for one internal node (corresponding to the majority of the "greenwelliae" clade), parsimony reconstructions were unable to distinguish between three possible island states, whereas likelihood reconstructions resulted in clear ordering of possible states, with the island of Oàhu slightly more probable than other islands under all but one model and branch length combination considered (the Jukes-Cantor-like model with branch lengths inferred under parsimony, under which conditions Maui Nui is more probable). A pattern of colonization from oldest to youngest islands was inferred from the phylogeny, using maximum parsimony and maximum likelihood. Additionally, a much higher incidence of intraisland versus interisland speciation was inferred.     

Scrophularia arguta,a widespread annual plant in the Canary Islands: a single recent colonization event or a more complex phylogeographic pattern?

Many studies have addressed evolution and phylogeography of plant taxa in oceanic islands, but have primarily focused on endemics because of the assumption that in widespread taxa the absence of morphological differentiation between island and mainland populations is due to recent colonization. In this paper, we studied the phylogeography of Scrophularia arguta, a widespread annual species, in an attempt to determine the number and spatiotemporal origins of dispersal events to Canary Islands. Four different regions, ITS and ETS from nDNA and psbA‐trnH and psbJ‐petA from cpDNA, were used to date divergence events within S. arguta lineages and determine the phylogenetic relationships among populations. A haplotype network was obtained to elucidate the phylogenetic relationships among haplotypes. Our results support an ancient origin of S. arguta (Miocene) with expansion and genetic differentiation in the Pliocene coinciding with the aridification of northern Africa and the formation of the Mediterranean climate. Indeed, results indicate for Canary Islands three different events of colonization, including two ancient events that probably happened in the Pliocene and have originated the genetically most divergent populations into this species and, interestingly, a recent third event of colonization of Gran Canaria from mainland instead from the closest islands (Tenerife or Fuerteventura). In spite of the great genetic divergence among populations, it has not implied any morphological variation. Our work highlights the importance of nonendemic species to the genetic richness and conservation of island flora and the significance of the island populations of widespread taxa in the global biodiversity.     

Repeated range expansion and niche shift in a volcanic hotspot archipelago: Radiation of C4 Hawaiian Euphorbia subgenus Chamaesyce (Euphorbiaceae)

Woody perennial plants on islands have repeatedly evolved from herbaceous mainland ancestors. Although the majority of species in Euphorbia subgenus Chamaesyce section Anisophyllum (Euphorbiaceae) are small and herbaceous, a clade of 16 woody species diversified on the Hawaiian Islands. They are found in a broad range of habitats, including the only known C₄ plants adapted to wet forest understories. We investigate the history of island colonization and habitat shift in this group. We sampled 153 individuals in 15 of the 16 native species of Hawaiian Euphorbia on six major Hawaiian Islands, plus 11 New World close relatives, to elucidate the biogeographic movement of this lineage within the Hawaiian island chain. We used a concatenated chloroplast DNA data set of more than eight kilobases in aligned length and applied maximum likelihood and Bayesian inference for phylogenetic reconstruction. Age and phylogeographic patterns were co‐estimated using BEAST. In addition, we used nuclear ribosomal ITS and the low‐copy genes LEAFY and G3pdhC to investigate the reticulate relationships within this radiation. Hawaiian Euphorbia first arrived on Kaua`i or Ni`ihau ca. 5 million years ago and subsequently diverged into 16 named species with extensive reticulation. During this process Hawaiian Euphorbia dispersed from older to younger islands through open vegetation that is disturbance‐prone. Species that occur under closed vegetation evolved in situ from open vegetation of the same island and are only found on the two oldest islands of Kaua`i and O`ahu. The biogeographic history of Hawaiian Euphorbia supports a progression rule with within‐island shifts from open to closed vegetation.     

Multiple origins of Hawaiian drosophilids: Phylogeography of Scaptomyza Hardy (Diptera: Drosophilidae)

Scaptomyza is a highly diversified genus in the family Drosophilidae, having undergone an explosive radiation, along with the Hawaiian‐endemic genus Idiomyia in the Hawaiian Islands: about 60% of 269 Scaptomyza species so far described are endemic to the Hawaiian Islands. Two hypotheses have been proposed for the origin and diversification of Hawaiian drosophilids. One is the “single Hawaiian origin” hypothesis: Scaptomyza and Idiomyia diverged from a single common ancestor that had once colonized the Hawaiian Islands, and then non‐Hawaiian Scaptomyza migrated back to continents. The other is the “multiple origins” hypothesis: Hawaiian Scaptomyza and Idiomyia derived from different ancestors that independently colonized the Hawaiian Islands. A key issue for testing these two hypotheses is to clarify the phylogenetic relationships between Hawaiian and non‐Hawaiian species in Scaptomyza. Toward this goal, we sampled additional non‐Hawaiian Scaptomyza species, particularly in the Old World, and determined the nucleotide sequences of four mitochondrial and seven nuclear genes for these species. Combining these sequence data with published data for 79 species, we reconstructed the phylogeny and estimated ancestral distributions and divergence times. In the resulting phylogenetic trees, non‐Hawaiian Scaptomyza species were interspersed in two Hawaiian clades. From a reconstruction of ancestral biogeography, we inferred that Idiomyia and Scaptomyza diverged outside the Hawaiian Islands and then independently colonized the Hawaiian Islands, twice in Scaptomyza, thus supporting the “multiple origins” hypothesis.     

Molecular phylogenetic relationships reveal taxonomic and biogeographic clades in Dianella (flax lilies; Asphodelaceae,Hemerocallidoideae)

A phylogeny of Dianella is presented based on Bayesian and maximum parsimony analyses of a combined molecular data set using three chloroplast markers (trnQ^UUG–5'rps16, 3'rps16–5'trnK^(UUU) and rpl14–rps8–infA–rpl36) and two nuclear markers (ITS and ETS). Accessions included most Dianella species, including all species from Australia, the centre of diversity for the genus, and related outgroup genera Eccremis, Stypandra, Thelionema and Herpolirion. The phylogeny showed Stypandra sister to Herpolirion + Thelionema, and confirmed the monophyly of Dianella. Within Dianella, a number of clades were resolved that revealed biogeographic relationships. Accessions from south-western Australia (extending into South Australia) formed the earliest diverging clade, followed by D. serrulata from New Guinea, sister to all other clades of Dianella from Australia and other regions. Tropical North Queensland species, including the D. pavopennacea complex, were related to a clade of accessions from New Caledonia and the Hawaiian Islands in the Pacific, and a clade that included samples of D. carolinensis (Caroline Islands) and the widespread D. ensifolia from South-East Asia and across the Indian Ocean to Mauritius and Madagascar. However, D. ensifolia is not monophyletic, with accessions from Japan and Taiwan related to a clade of Queensland samples that are part of the D. revoluta complex. Three New Zealand species (diploid, 2n?=?16) were found to be related to Norfolk Island D. intermedia (type locality; octoploid, 2n?=?64). In contrast ‘D. intermedia’ from Lord Howe Island was resolved as sister to the eastern Australian D. caerulea complex. The phylogenetic results indicate the need for taxonomic revision, particularly revision of the species ‘complexes’ D. longifolia and D. caerulea in Australia, and recognition of more than one species within D. ensifolia and within D. sandwicensis on the Hawaiian Islands.     

Molecular insights into the phylogenetic structure of the spider genus Theridion (Araneae, Theridiidae) and the origin of the Hawaiian Theridion-like fauna

The Hawaiian happy face spider ( Theridion grallator Simon, 1900), named for a remarkable abdominal colour pattern resembling a smiling face, has served as a model organism for understanding the generation of genetic diversity. Theridion grallator is one of 11 endemic Hawaiian species of the genus reported to date. Asserting the origin of island endemics informs on the evolutionary context of diversification, and how diversity has arisen on the islands. Studies on the genus Theridion in Hawaii, as elsewhere, have long been hampered by its large size (> 600 species) and poor definition. Here we report results of phylogenetic analyses based on DNA sequences of five genes conducted on five diverse species of Hawaiian Theridion , along with the most intensive sampling of Theridiinae analysed to date. Results indicate that the Hawaiian Islands were colonised by two independent Theridiinae lineages, one of which originated in the Americas. Both lineages have undergone local diversification in the archipelago and have convergently evolved similar bizarre morphs. Our findings confirm para- or polyphyletic status of the largest Theridiinae genera: Theridion , Achaearanea and Chrysso . Convergent simplification of the palpal organ has occurred in the Hawaiian Islands and in two continental lineages. The results confirm the convergent evolution of social behaviour and web structure, both already documented within the Theridiidae. Greater understanding of phylogenetic relationships within the Theridiinae is key to understanding of behavioural and morphological evolution in this highly diverse group.     

RADseq resolves the phylogeny of Hawaiian Myrsine (Primulaceae) and provides evidence for hybridization

The Hawaiian radiation of Myrsine (primrose family, Primulaceae) is the only one among the ten most species‐rich Hawaiian plant lineages that has never been included in a phylogenetic analysis. Our study is based on a RADseq dataset of nearly all Hawaiian Myrsine species and a Sanger sequencing dataset based on a worldwide sampling of Myrsine and related genera. Myrsine as a whole might be paraphyletic with respect to the monotypic Macaronesian genera Heberdenia and Pleiomeris, whereas Hawaiian Myrsine is resolved as monophyletic. The Sanger sequencing proved to be insufficient to resolve the Hawaiian lineage, whereas RADseq fully resolved the relationships with high support. Hawaiian Myrsine consists of three main lineages, of which one contains the majority of species and is mainly confined to Kauaʻi, and the other two lineages primarily consist of few widespread species. Although phylogenetic reconstructions delivered fully resolved and supported tree topologies, Quartet Sampling and HyDe analyses reveal phylogenetic incongruence throughout the phylogeny and provide the first molecular evidence of extensive hybridization in the lineage.