Genetic tests of rapid parallel speciation of flightless birds from an extant volant ancestor

Prior to the extinction wave that followed the human colonization of Oceania, flightless rails (Aves: Rallidae) were among the largest radiations of island birds, and perhaps the most species-rich example of convergent evolution in vertebrates. Insular flightless species are thought to have evolved from extant, volant species that colonized from continental sources and rapidly followed parallel adaptive pathways to flightlessness. The present study provides the first test of this model of speciation using genetic data sampled throughout the range of a putative ancestral species. Mitochondrial control region sequences from 71 individuals of the Gallirallus philippensis species complex reveal essentially no geographic structure within archipelagos and only weak structure among archipelagos, with no major genetic breaks except for birds sampled in the Philippines. Demographic tests of coalescent models support a recent rapid expansion into Oceania (including Australia) out of the Philippines approximately 20 000 years ago. The estimated coalescence of G. philippensis mitochondrial alleles approximately 33 000 years ago closely corresponds to the expansion of humans into the archipelagoes of Near Oceania, suggesting that humans may have facilitated its colonization by exterminating flightless competitors and clearing lowland forests. Phylogenetic analyses that included all G. philippensis haplotypes and samples from 11 single-island endemic flightless species of Gallirallus indicate that G. philippensis is polyphyletic, but is not the ancestor of most of its flightless congeners, as previously thought. Nuclear gene sequences (β-actin inron 3) suggest that G. philippensis polyphyly is at least partly due to hybridization. The flightless condition evolves in rails before reproductive isolation is complete.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 601–616.     

Nestedness in island faunas: novel insights into island biogeography through butterfly community profiles of colonization ability and migration capacity

Aim To relate variation in the migration capacity and colonization ability of island communities to island geography and species island occupancy. Location Islands off mainland Britain and Ireland. Methods Mean migration (transfer) capacity and colonization (establishment) ability (ecological indices), indexed from 12 ecological variables for 56 butterfly species living on 103 islands, were related to species nestedness, island and mainland source geography and indices using linear regression models, RLQ analysis and fourth‐corner analysis. Random creation of faunas from source species, rank correlation and rank regression were used to examine differences between island and source ecological indices, and relationships to island geography. Results Island butterfly faunas are highly nested. The two ecological indices related closely to island occupancy, nestedness rank of species, island richness and geography. The key variables related to migration capacity were island area and isolation; for colonization ability they were area, isolation and longitude. Compared with colonization ability, migration capacity was found to correlate more strongly with island species occupancy and species richness. For island faunas, the means for both ecological indices decreased, and variation increased, with increasing island species richness. Mean colonization ability and migration capacity values were significantly higher for island faunas than for mainland source faunas, but these differences decreased with island latitude. Main conclusions The nested pattern of butterfly species on islands off mainland Britain and Ireland relates strongly to colonization ability but especially to migration capacity. Differences in colonization ability among species are most obvious for large, topographically varied islands. Generalists with abundant multiple resources and greater migration capacity are found on all islands, whereas specialists are restricted to large islands with varied and long‐lived biotopes, and islands close to shore. The inference is that source–sink dynamics dominate butterfly distributions on British and Irish islands; species are capable of dispersing to new areas, but, with the exception of large and northern islands, facilities (resources) for permanent colonization are limited. The pattern of colonization ability and migration capacity is likely to be repeated for mainland areas, where such indices should provide useful independent measures for assessing the conservation status of faunas within spatial units.     

When snails inform about geology: Pliocene emergence of islands of Vanuatu indicated by a radiation of truncatelloidean freshwater gastropods (Caenogastropoda: Tateidae)

The South Pacific archipelago Vanuatu has a very complex geological history including three major phases of volcanism creating island belts and phases of repeated submergence and re‐emergence. An important issue for the evolution of the biota of Vanuatu ambiguously discussed in the geological literature is the question whether the entire archipelago has been submerged until the early Pleistocene or if at least parts of the island of Espiritu Santo have remained subaerial throughout the Pliocene. We used a time‐calibrated phylogenetic analysis of freshwater gastropods of the family Tateidae based on COI, 16S rRNA and ITS2 to infer the colonization history of Vanuatu. Our analyses suggested that Espiritu Santo was colonized c. 3 Mya. Espiritu Santo was probably the place of origin for the subsequent colonization of the island of Erromango (2 Mya) and the Pleistocene radiation across the remaining archipelago. We describe 10 new species largely based on morphological and anatomical data. The genetic data in particular of the species from the young islands are taxonomically incongruent probably due to incomplete lineage sorting typical for young radiations. In contrast, the paraphyly of Fluviopupa espiritusantoana appearing in three distant clades indicates either the existence of cryptic species or the long survival of the stem species of almost the entire radiation.     

Apolipoprotein E variation at the sequence haplotype level: implications for the origin and maintenance of a major human polymorphism

Three common protein isoforms of apolipoprotein E (apoE), encoded by the epsilon2, epsilon3, and epsilon4 alleles of the APOE gene, differ in their association with cardiovascular and Alzheimer's disease risk. To gain a better understanding of the genetic variation underlying this important polymorphism, we identified sequence haplotype variation in 5.5 kb of genomic DNA encompassing the whole of the APOE locus and adjoining flanking regions in 96 individuals from four populations: blacks from Jackson, MS (n=48 chromosomes), Mayans from Campeche, Mexico (n=48), Finns from North Karelia, Finland (n=48), and non-Hispanic whites from Rochester, MN (n=48). In the region sequenced, 23 sites varied (21 single nucleotide polymorphisms, or SNPs, 1 diallelic indel, and 1 multiallelic indel). The 22 diallelic sites defined 31 distinct haplotypes in the sample. The estimate of nucleotide diversity (site-specific heterozygosity) for the locus was 0.0005+/-0.0003. Sequence analysis of the chimpanzee APOE gene showed that it was most closely related to human epsilon4-type haplotypes, differing from the human consensus sequence at 67 synonymous (54 substitutions and 13 indels) and 9 nonsynonymous fixed positions. The evolutionary history of allelic divergence within humans was inferred from the pattern of haplotype relationships. This analysis suggests that haplotypes defining the epsilon3 and epsilon2 alleles are derived from the ancestral epsilon4s and that the epsilon3 group of haplotypes have increased in frequency, relative to epsilon4s, in the past 200,000 years. Substantial heterogeneity exists within all three classes of sequence haplotypes, and there are important interpopulation differences in the sequence variation underlying the protein isoforms that may be relevant to interpreting conflicting reports of phenotypic associations with variation in the common protein isoforms.     

Phylogeography of the introduced species Rattus rattus in the western Indian Ocean,with special emphasis on the colonization history of Madagascar

Aim To describe the phylogeographic patterns of the black rat, Rattus rattus, from islands in the western Indian Ocean where the species has been introduced (Madagascar and the neighbouring islands of Réunion, Mayotte and Grande Comore), in comparison with the postulated source area (India). Location Western Indian Ocean: India, Arabian Peninsula, East Africa and the islands of Madagascar, Réunion, Grande Comore and Mayotte. Methods Mitochondrial DNA (cytochrome b, tRNA and D‐loop, 1762 bp) was sequenced for 71 individuals from 11 countries in the western Indian Ocean. A partial D‐loop (419 bp) was also sequenced for eight populations from Madagascar (97 individuals), which were analysed in addition to six previously published populations from southern Madagascar. Results Haplotypes from India and the Arabian Peninsula occupied a basal position in the phylogenetic tree, whereas those from islands were distributed in different monophyletic clusters: Madagascar grouped with Mayotte, while Réunion and Grand Comore were present in two other separate groups. The only exception was one individual from Madagascar (out of 190) carrying a haplotype that clustered with those from Réunion and South Africa. ‘Isolation with migration’ simulations favoured a model with no recurrent migration between Oman and Madagascar. Mismatch distribution analyses dated the expansion of Malagasy populations on a time‐scale compatible with human colonization history. Higher haplotype diversity and older expansion times were found on the east coast of Madagascar compared with the central highlands. Main conclusions Phylogeographic patterns supported the hypothesis of human‐mediated colonization of R. rattus from source populations in either the native area (India) or anciently colonized regions (the Arabian Peninsula) to islands of the western Indian Ocean. Despite their proximity, each island has a distinct colonization history. Independent colonization events may have occurred simultaneously in Madagascar and Grande Comore, whereas Mayotte would have been colonized from Madagascar. Réunion was colonized independently, presumably from Europe. Malagasy populations may have originated from a single successful colonization event, followed by rapid expansion, first in coastal zones and then in the central highlands. The congruence of the observed phylogeographic pattern with human colonization events and pathways supports the potential relevance of the black rat in tracing human history.     

Understanding the colonization history of the Galápagos flycatcher (Myiarchus magnirostris)

The Galápagos archipelago has never been connected to any continental land masses, so it is of interest to know the colonization and diversification history of its endemic species. We analyzed the phylogenetic placement of the endemic Galápagos flycatcher, M. magnirostris, within Myiarchus by using the genes ND2 and cytb (1970 bp) to compare 16 of the 22 species that comprise this genus. We also analyzed variability in cytb sequences from 154 M. magnirostris individuals captured on seven Galápagos islands. Our phylogenetic analyses recovered the two main Myiarchus clades that had been described by previous genetic, morphological, and vocal analyses. M. magnirostris is monophyletic and its closest living relative is M. tyrannulus from Mexico and Central America. The average age for the split node between these two groups was approximately 850,000 years (95% C.I. 630,735-1,087,557). M. tyrannulus, M. nugator, M. nuttingi, M. sagrae, and M. stolidus are not monophyletic species. Within M. magnirostris itself, we found low nucleotide and haplotype diversities (π=0.0009 and h=0.4913, respectively) and a high genetic structure among populations. We also detected a star-shaped haplotype network and significantly negative values for Tajima's D and Fu's Fs for this species. Our results suggest that M. magnirostris originated from a single colonization event and had a recent population expansion in the Galápagos archipelago.     

Diversification,Biogeographic Pattern,and Demographic History of Taiwanese Scutellaria Species Inferred from Nuclear and Chloroplast DNA

The ragged topography created by orogenesis generates diversified habitats for plants in Taiwan. In addition to colonization from nearby mainland China, high species diversity and endemism of plants is also present in Taiwan. Five of the seven Scutellaria species (Lamiaceae) in Taiwan, for example, are endemic to the island. Hypotheses of multiple sources or in situ radiation have arisen to explain the high endemism of Taiwanese species. In this study, phylogenetic analyses using both nuclear and chloroplast markers revealed the multiple sources of Taiwanese Scutellaria species and confirmed the rapid and recent speciation of endemic species, especially those of the “indica group” composed of S. indica, S. austrotaiwanensis, S. tashiroi, and S. playfairii. The common ancestors of the indica group colonized first in northern Taiwan and dispersed regionally southward and eastward. Climate changes during glacial/interglacial cycles led to gradual colonization and variance events in the ancestors of these species, resulting in the present distribution and genetic differentiation of extant populations. Population decline was also detected in S. indica, which might reflect a bottleneck effect from the glacials. In contrast, the recently speciated endemic members of the indica group have not had enough time to accumulate much genetic variation and are thus genetically insensitive to demographic fluctuations, but the extant lineages were spatially expanded in the coalescent process. This study integrated phylogenetic and population genetic analyses to illustrate the evolutionary history of Taiwanese Scutellaria of high endemism and may be indicative of the diversification mechanism of plants on continental islands.     

Molecular phylogeny and dating of an insular endemic moth radiation inferred from mitochondrial and nuclear genes: the genus Galagete (Lepidoptera: Autostichidae) of the Galapagos Islands

Galagete is a genus of microlepidoptera including 12 nominate species endemic to the Galapagos Islands. In order to better understand the diversification of this endemic insular radiation, to unravel relationships among species and populations, and to get insight into the early stages of speciation, we developed a phylogenetic reconstruction based on the combined mitochondrial cytochrome oxidase I (555bp) and II (453bp), and the nuclear elongation factor-1alpha (711bp) and wingless (351bp) genes. Monophyly of the genus is strongly supported in the Bayesian and maximum likelihood analyses suggesting a single colonization event by a common ancestor. Two cases of paraphyly observed between species are hypothesized to represent imperfect species limits for G. espanolaensis nested within the G. turritella clade, and introgressive hybridization or lineage sorting in the case of the population of G. protozona from Santa Fe nested within the G. gnathodoxa clade. A geologically calibrated, relaxed molecular clock model was used for the first time to unravel the chronological sequence of an insular radiation. The first split occurring within the Galagete lineage on the archipelago is estimated at 3.3+/-0.4million years ago. The genus radiated relatively quickly in about 1.8million years, and gives an estimated speciation rate of 0.8 species per million years. Although the colonization scenario shows a stochastic dispersal pattern, the arrival of the ancestor and the diversification of the radiation coincide with the chronological emergence of the major islands.     

Extreme mtDNA divergences in a terrestrial slug (Gastropoda, Pulmonata, Arionidae): accelerated evolution, allopatric divergence and secondary contact

Extremely high levels of intraspecific mtDNA differences in pulmonate gastropods have been reported repeatedly and several hypotheses to explain them have been postulated. We studied the phylogeny and phylogeography of 51 populations (n = 843) of the highly polymorphic terrestrial slug Arion subfuscus (Draparnaud, 1805) across its native distribution range in Western Europe. By combining the analysis of single stranded conformation polymorphisms (SSCP) and nucleotide sequencing, we obtained individual sequence data for a fragment of the mitochondrial 16S rDNA and a fragment of the nuclear ITS1. Additionally, five polymorphic allozyme loci were scored. Based on the 16S rDNA phylogeny, five monophyletic haplotype groups with sequence divergences of 9-21% were found. Despite this deep mitochondrial divergence, the haplotype groups were not monophyletic for the nuclear ITS1 fragment and haplotype group-specific allozyme alleles were not found. Although there is evidence for an accelerated mtDNA clock, the divergence among the haplotype groups is older than the Pleistocene and their current allopatric ranges probably reflect allopatric divergence and glacial survival in separate refugia from which different post-glacial colonization routes were established. A range-overlap of two mtDNA groups (S1 and S2, 21% sequence divergence) stretched from Central France and Belgium up to the North of the British Isles. The nuclear data suggest that this secondary contact resulted in hybridization between the allopatrically diverged groups. Therefore, it seems that, at least for two of the groups, the deep mtDNA divergence was only partially accompanied by the formation of reproductive isolation.     

High levels of genetic diversity in island populations of the island endemic Suzukia luchuensis (Labiatae)

Genetic diversity and genetic differentiation within and among island populations was examined by allozyme electrophoresis in Suzukia luchuensis (Labiatae), which is endemic to four of the Ryukyu Islands, southern Japan, and one island near Taiwan. Intrapopulation allozyme diversity was very low in all the four Ryukyu Islands, probably due to the effects of random drift in small populations. In contrast, genetic diversity at the species level was high, possibly because of an ancient origin of populations and/or multiple colonization of the species on different islands. Genetic differentiation among the overall populations was high (G(ST)=0.863), while gene flow (Nm) as estimated from allozyme frequency data was 0.041, suggesting that its occurrence among populations is highly restricted. Hierarchical analysis of genetic differentiation indicated that a high proportion of the total allelic variance is attributed to variation among islands, corresponding to the fact that several alleles were fixed on only one island. However, intraisland genetic differentiation was small on all islands except Yonaguni Island, where S. luchuensis is relatively widely distributed. Most diversity was thus due to differences among islands.     

Isolation and differentiation of Rivulus hartii across Trinidad and neighboring islands

Diversification of freshwater fishes on islands is considered unlikely because the traits that enable successful colonization—specifically, broad salinity tolerances and the potential for oceanic dispersal—may also constrain post‐colonization genetic differentiation. Some secondary freshwater fish, however, exhibit pronounced genetic differentiation and geographic structure on islands, whereas others do not. It is unclear what conditions give rise to contrasting patterns of differentiation because few comparative reconstructions of population history have been carried out for insular freshwater fishes. In this study, we examined the phylogeography of Hart’s killifish (Rivulus hartii) across Trinidad, with reference to neighboring islands and northern South America, to test hypotheses of colonization and differentiation derived from comparable work on co‐occurring guppies (Poecilia reticulata). Geographic patterns of mitochondrial DNA haplotype variation and microsatellite genotype variation provide evidence of genetic differentiation of R. hartii among islands and across Trinidad. Our findings are largely consistent with patterns of geographically structured ancestry and admixture found in Trinidadian guppies, which suggests that both species share a history of colonization and differentiation and that post‐colonization diversification may be more common among members of insular freshwater fish assemblages than has been previously thought.     

The odd one out or a hidden generalist: Hawaiian Melicope (Rutaceae) do not share traits associated with successful island colonization

Oceanic islands are unique in their species composition, which is defined by arrival of colonizers via long distance dispersal followed by establishment of species followed in some cases by adaptive radiation. Evolutionary biologists identified traits facilitating successful colonization of islands as including polyploidy, self‐compatibility, herbaceousness and ability for long‐distance dispersal. Successful establishment and evolutionary diversification of lineages on islands often involves shifts to woodiness and shifts in methods of outcrossing as well as changes in dispersal ability. The genus Melicope colonized numerous archipelagos throughout the Pacific including the Hawaiian Islands, where the lineage comprises currently 54 endemic species and represents the largest radiation of woody plants on the islands. The wide distributional range of the genus illustrates its high dispersibility, most likely due to adaption to bird dispersal. Here we investigate ploidy in the genus using flow cytometry and chromosome counting. We find the genus to be paleopolyploid with 2n = 4x = 36, a ploidy level characterizing the entire subfamily Amyridoideae and dating back to at least the Palaeocene. Therefore Hawaiian Melicope have not undergone recent polyploidization prior to colonization of the islands. Thus Melicope retained colonization success while exhibiting a combination of traits that typically characterize well established island specialists while lacking some traits associated to successful colonizers.     

Phylogeographical patterns and genetic diversity in three species of Eurasian boreal forest beetles

Many species that occur in formerly glaciated areas of Fennoscandia have reached their current ranges from glacial refugial areas in Eurasia. Little is known of the refugia and postglacial colonization routes of insect species that are confined to boreal forests. Here, we investigate the phylogeography of three species of saproxylic beetles distributed across Eurasia: two rare boreal forest specialists, Pytho kolwensis and Pytho abieticola , and a common, less specialized species, Pytho depressus . In all species, there were two well-defined haplotype clades based on 645 bp of cytochrome oxidase subunit I gene sequence. In each species one clade was found only in China. The other clade occurred from China to north-western Europe in both P. kolwensis and P. depressus , but was apparently absent from China in P. abieticola. In spite of common phylogeographical patterns, the distribution of genetic variation differed markedly between the three species. In P. kolwensis , a highly-threatened species in old-growth forests in Fennoscandia, there was an extremely low level of genetic variation throughout Eurasia. One common haplotype, represented by 86% of the samples, dominated in all sampling localities. Levels of genetic variation were higher in both P. abieticola and P. depressus , with 31% and 58%, respectively, of the samples representing a unique haplotype. In each species, relationships between haplotypes were not well resolved, and haplotypes from one sampling locality were generally not clustered in either Neighbour-joining trees or statistical parsimony networks. These patterns in the distribution of genetic variation can be attributed to differences in the species' population sizes, ecologies, glacial refugial areas, and postglacial colonization dynamics.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 267–279.     

Nestedness of Southern Ocean island biotas: ecological perspectives on a biogeographical conundrum

Aim To use patterns of nestedness in the indigenous and non‐indigenous biotas of the Southern Ocean islands to determine the influence of dispersal ability on biogeographical patterns, and the importance of accounting for variation in dispersal ability in their subsequent interpretation, especially in the context of the Insulantarctic and multi‐regional hypotheses proposed to explain the biogeography of these islands. Location Southern Ocean islands. Methods Nestedness was determined using a new metric, d1 (a modification of discrepancy), for the indigenous and introduced seabirds, land birds, insects and vascular plants of 26 Southern Ocean islands. To assess the possible confounding effects of spatial autocorrelation on the results, islands were assigned to 11 major island groups and each group was treated as a single island in a following analysis. In addition, nestedness of the six Southern Ocean islands comprising the South Pacific Province (New Zealand islands) was analysed. All analyses were conducted for species and genera, for each of the taxa on its own, and for the complete data sets. Results Statistically significant nestedness was found in all of the taxa examined, with nestedness declining in the order seabirds > land birds > vascular plants > insects for the indigenous species. Vagility had a marked influence on nestedness and the biogeographical patterns shown by the indigenous species. This influence was borne out by additional analyses of marine taxa and small‐sized terrestrial species, both of which were more nested than the most nested group examined here, the seabirds. Assemblages of non‐indigenous species also showed nestedness, and nestedness was generally more pronounced than in the indigenous species. Surprisingly, vagility had a significant effect on nestedness in these assemblages too. Main conclusions Nestedness analyses provide a quantitative means of comparing biogeographical patterns for groups differing in vagility. These comparisons revealed that vagility has a considerable influence on biogeographical patterns and should be taken into account in analyses. Here, investigations of more vagile taxa support hypotheses for a single origin of the Southern Ocean island biota (the Insulantarctica scenario), whilst those of less mobile taxa support the more commonly held, multi‐regional hypothesis. All biogeographical analyses across the Southern Ocean (and elsewhere) will be influenced by the effects of dispersal ability, with composite analyses dominated by sedentary groups likely to favour multi‐regional scenarios, and those dominated by mobile groups favouring single origins. Mechanisms underlying nestedness in the region range from nested physiological tolerances in more mobile groups to colonization ability and patterns of speciation in less vagile taxa. Considerable nestedness in the non‐indigenous assemblages is largely a consequence of the fact that many of these species are European weedy species.     

Genetically depauperate in the continent but rich in oceanic islands: Cistus monspeliensis (Cistaceae) in the Canary Islands

Background

Population genetic theory holds that oceanic island populations are expected to have lower levels of genetic variation than their mainland counterparts, due to founder effect after island colonization from the continent. Cistus monspeliensis (Cistaceae) is distributed in both the Canary Islands and the Mediterranean region. Numerous phylogenetic results obtained in the last years allow performing further phylogeographic analyses in Cistus.

Methodology/Principal Findings

We analyzed sequences from multiple plastid DNA regions in 47 populations of Cistus monspeliensis from the Canary Islands (21 populations) and the Mediterranean basin (26 populations). The time-calibrated phylogeny and phylogeographic analyses yielded the following results: (1) a single, ancestral haplotype is distributed across the Mediterranean, whereas 10 haplotypes in the Canary Islands; (2) four haplotype lineages are present in the Canarian Islands; (3) multiple colonization events across the archipelago are inferred; (4) the earliest split of intraspecific lineages occurred in the Early to Middle Pleistocene (<930,000 years BP).

Conclusions/Significance

The contrasting pattern of cpDNA variation is best explained by genetic bottlenecks in the Mediterranean during Quaternary glaciations, while the Canarian archipelago acted as a refugium of high levels of genetic diversity. Active colonization across the Canarian islands is supported not only by the distribution of C. monspeliensis in five of the seven islands, but also by our phylogeographic reconstruction in which unrelated haplotypes are present on the same island. Widespread distribution of thermophilous habitats on every island, as those found throughout the Mediterranean, has likely been responsible for the successful colonization of C. monspeliensis, despite the absence of a long-distance dispersal mechanism. This is the first example of a plant species with higher genetic variation among oceanic island populations than among those of the continent.     

Population history of Berthelot's pipit: colonization, gene flow and morphological divergence in Macaronesia

The fauna of oceanic islands provide exceptional models with which to examine patterns of dispersal, isolation and diversification, from incipient speciation to species level radiations. Here, we investigate recent differentiation and microevolutionary change in Berthelot's pipit (Anthus berthelotii), an endemic bird species inhabiting three Atlantic archipelagos. Mitochondrial DNA sequence data and microsatellite markers were used to deduce probable colonization pathway, genetic differentiation, and gene flow among the 12 island populations. Phenotypic differentiation was investigated based on eight biologically important morphological traits. We found little mitochondrial DNA variability, with only one and four haplotypes for the control region and cytochrome b, respectively. However, microsatellite data indicated moderate population differentiation (FST=0.069) between the three archipelagos that were identified as genetically distinct units with limited gene flow. Both results, combined with the estimated time of divergence (2.5 millions years ago) from the Anthus campestris (the sister species), suggest that this species has only recently dispersed throughout these islands. The genetic relationships, patterns of allelic richness and exclusive alleles among populations suggest the species originally colonized the Canary Islands and only later spread from there to the Madeiran archipelago and Selvagen Islands. Differentiation has also occurred within archipelagos, although to a lesser degree. Gene flow was observed more among the eastern and central islands of the Canaries than between these and the western islands or the Madeiran Islands. Morphological differences were also more important between than within archipelagos. Concordance between morphological and genetic differentiation provided ambiguous results suggesting that genetic drift alone was not sufficient to explain phenotypic differentiation. The observed genetic and morphological differences may therefore be the result of differing patterns of selection pressures between populations, with Berthelot's pipit undergoing a process of incipient differentiation.     

Historical Isolation of the Galápagos Carpenter Bee (Xylocopa darwini) despite Strong Flight Capability and Ecological Amplitude

Colonization across the Galápagos Islands by the carpenter bee (Xylocopa darwini) was reconstructed based on distribution of mitochondrial haplotypes (cytochrome oxidase II (COII) sequences) and haplotype lineages. A total of 12 haplotypes were found in 118 individuals of X. darwini. Distributional, phylogenetic and phylogeographic analyses suggest early colonization of most islands followed by historical isolation in two main groups: eastern and central-western islands. Evidence of recurrent inter-island colonization of haplotypes is largely lacking, despite strong flight capability and ecological amplitude of the species. Recent palaeogeographic data suggest that several of the current islands were connected in the past and thus the isolation pattern may have been even more pronounced. A contrast analysis was also carried out on 10 animal groups of the Galápagos Islands, and on haplotype colonization of seven animal and plant species from several oceanic archipelagos (the Galápagos, Azores, Canary Islands). New colonization metrics on the number of potential vs. inferred colonization events revealed that the Galápagos carpenter bee shows one of the most significant examples of geographic isolation.     

Beyond barcodes: complex DNA taxonomy of a South Pacific Island radiation

DNA barcodes can provide rapid species identification and aid species inventories in taxonomically unstudied groups. However, the approach may fail in recently diverged groups with complex gene histories, such as those typically found on oceanic islands. We produced a DNA-based inventory of taxonomically little known diving beetles (genus Copelatus) in the Fiji archipelago, where they are a dominant component of the aquatic invertebrate fauna. Sampling from 25 localities on five islands and analysis of sequences from one nuclear (328bp histone 3) and three mitochondrial (492bp rrnL, 786bp cox1, 333bp cob) gene regions revealed high haplotype diversity, mainly originated since the Pleistocene, and subdivided into three major phylogenetic lineages and 22 statistical parsimony networks. A traditional taxonomic study delineated 25 morphologically defined species that were largely incongruent with the DNA-based groups. Haplotype diversity and their spatial arrangement demonstrated a continuum of relatedness in Fijian Copelatus, with evidence for introgression at various hierarchical levels. The study illustrates the difficulties for formal classification in evolutionarily complex lineages, and the potentially misleading conclusions obtained from either DNA barcodes or morphological traits alone. However, the sequence profile of Fijian Copelatus provides an evolutionary framework for the group and a DNA-based reference system for the integration of ecological and other biodiversity data, independent of the Linnaean naming system.     

Limited recombination events in merozoite surface protein-1 alleles of Plasmodium falciparum on islands.

Intragenic recombination is a principal mechanism for the generation of allelic variation in the merozoite surface protein-1 gene (Msp-1) of the human malaria parasite Plasmodium falciparum. In the present study, linkage disequilibrium between the 5'- and 3'-polymorphic sites was analyzed to determine the frequency of recombination events in Msp-1 in parasite populations on four islands in Vanuatu, the southwestern Pacific, where malaria transmission is moderate and comparable to other mesoendemic areas. Of 141 isolates, whose 5'-haplotypes (Msp-1 blocks 2-6) were determined by PCR-based typing, 138 were successfully sequenced for the 3'-polymorphism (block 17). A total of four distinct 5'-haplotypes and three distinct 3'-sequence types were identified with apparently different frequency distribution among islands. The number of 5'-haplotypes in each island was one to four, far smaller than in other previously studied geographic areas (ten to 21). Associations between the 5'- and 3'-polymorphisms (here termed Msp-1 gene types) were subjected to the R(2) linkage disequilibrium test. The test revealed complete or very strong linkage disequilibrium in all four islands. Mixed infection was unusually rare (2.1%) and the mean number of Msp-1 alleles per person was nearly 1.0. The heterozygosity of the Msp-1 gene type calculated for each island (h=0.41-0.65) was significantly lower than that in other areas of comparable endemicity (h=0.81-0.89) (P<0.01). These results indicate that recombination events in Msp-1 would be extremely limited in Vanuatu, and stress that the frequency of recombination in Msp-1 is determined by not only the intensity of malaria transmission but the frequency of mixed clone infections, the mean number of clones per person and a repertoire of clones in a local area.