First record of Randall's snapper Randallichthys filamentosus (Perciformes: Lujanidae) from the eastern Indian Ocean (north-western Australia)

The rare Randall's snapper Randallichthys filamentosus is recorded here for the first time in the eastern Indian Ocean from Scott Reef, north-western Australia. A single specimen of R. filamentosus , measuring 495 mm fork length, was captured on 9 July 2006 at a depth of 211 m on the outer reef slopes of Scott Reef. The capture of this specimen indicates that this deepwater fish is more widely distributed than was previously acknowledged and further implies that this species has a dispersal capacity that extends across ocean boundaries.     

Worldwide phylogeography of the blacktip shark (Carcharhinus limbatus) inferred from mitochondrial DNA reveals isolation of western Atlantic populations coupled with recent Pacific dispersal

Although many coastal shark species have widespread distributions, the genetic relatedness of worldwide populations has been examined for few species. The blacktip shark, (Carcharhinus limbatus), inhabits tropical and subtropical coastal waters throughout the world. In this study, we examined the genetic relationships of blacktip shark populations (n = 364 sharks) throughout the majority of the species' range using the entire mitochondrial control region (1067-1070 nucleotides). Two geographically distinct maternal lineages (western Atlantic, Gulf of Mexico, and Caribbean Sea clades, and eastern Atlantic, Indian, and Pacific Ocean clades) were identified and shallow population structure was detected throughout their geographic ranges. These findings indicate that a major population subdivision exists across the Atlantic Ocean, but not the Pacific Ocean. The historical dispersal of this widespread, coastal species may have been interrupted by the rise of the Isthmus of Panama. This scenario implies historical dispersal across the Pacific Ocean (supported by the recovery of the same common haplotype from the Philippines, Hawaii, and the Gulf of California reflecting recent/contemporary dispersal abilities) and an oceanic barrier to recent migration across the Atlantic. Genetic structure within the eastern Atlantic/Indo-Pacific (Phi(ST) = 0.612, P < 0.001) supports maternal philopatry throughout this area, expanding previous western Atlantic findings. Eastern Atlantic/Indo-Pacific C. limbatus control region haplotypes were paraphyletic to Carcharhinus tilstoni haplotypes in our maximum-parsimony analysis. The greater divergence of western Atlantic C. limbatus than C. tilstoni from eastern Atlantic/Indo-Pacific C. limbatus reflects the taxonomic uncertainty of western Atlantic C. limbatus.     

Shallow mtDNA coalescence in Atlantic pygmy angelfishes (genus Centropyge) indicates a recent invasion from the Indian Ocean

Pygmy angelfishes (genus Centropyge) are widespread and species-rich in the Indo-Pacific, but only three species are recognized in the Atlantic: Centropyge resplendens on the Mid-Atlantic Ridge, Centropyge argi in the Caribbean, and Centropyge aurantonotus in Brazil and the southern Caribbean. Atlantic species are distinguished only by color patterns and are very similar to Centropyge acanthops (Cac) in the western Indian Ocean, raising the possibility that pygmy angelfish recently invaded the Atlantic Ocean via southern Africa. To test this zoogeographic hypothesis, we compared a 454-bp segment of the mitochondrial DNA (mtDNA) control region among pygmy angelfishes of the subgenus Xiphypops, which includes the three Atlantic species, the Indian Ocean species, and an Indo-Pacific species [Centropyge fisheri (Cfi)]. The Indian Ocean species Cac is closest to the Atlantic species (d = 0.059) relative to Cfi (d = 0.077). The mtDNA genealogy indicates a colonization pathway from the Indian Ocean directly to the West Atlantic, followed by at least two waves of dispersal to the Mid-Atlantic Ridge. The gene tree for the three Atlantic species is polyphyletic, raising questions about taxonomic assignments based on color pattern. Mismatch distributions place Atlantic founder events and population expansions at about 250,000-500,000 years ago. Estimates of effective female population sizes from mismatch and coalescence analyses are consistent with founder events by tens of individuals in the western Atlantic, followed by expansions to several million individuals.     

Larval spatial distributions and other early life-history characteristics predict genetic differentiation in eastern Pacific blennioid fishes

In marine organisms, a pelagic larval stage increases the opportunities for long-distance dispersal and is often associated with little genetic differentiation over large geographical distances. Here we test the hypothesis that early life-history characteristics, including larval spatial distributions, affect the rates of dispersal and, therefore, the levels of genetic partitioning among three Gulf of California reef fishes: Axoclinus nigricaudus, Malacoctenus hubbsi and Ophioblennius steindachneri. These three blennioid fishes have markedly different early life histories: A. nigricaudus has a short larval duration (18 days) and develops inshore, M. hubbsi has an intermediate larval duration (24 days) and most individuals develop inshore and O. steindachneri has a long larval life (50 days) and disperses offshore. Estimates of genetic partitioning from mtDNA control region sequences differed greatly between these species and were in the same rank order as predicted by their early life-history characteristics (A. nigricaudus N(ST)=0.536, M. hubbsi N(ST)=0.261 and O. steindachneri N(ST)=0.000). These results indicate that larval strategies may be good predictors of population genetic structure in some marine fishes.     

Oceanic dispersal in a sedentary reef shark (Triaenodon obesus): genetic evidence for extensive connectivity without a pelagic larval stage

Aim Most reef fishes are site‐attached, but can maintain a broad distribution through their highly dispersive larval stage. The whitetip reef shark (Triaenodon obesus) is site‐attached, yet maintains the largest Indo‐Pacific distribution of any reef shark while lacking the larval stage of bony (teleost) fishes. Here we use mitochondrial DNA (mtDNA) sequence data to evaluate the enigma of the sedentary reef shark that maintains a distribution across two‐thirds of the planet. Location Tropical Pacific and Indian Oceans. Methods We analysed 1025 base pairs of the mtDNA control region in 310 individuals from 25 locations across the Indian and Pacific Oceans. Phylogeographic and population genetic analyses were used to reveal the dispersal and recent evolutionary history of the species. Results We resolved 15 mtDNA control region haplotypes, but two comprised 87% of the specimens and were detected at nearly every location. Similar to other sharks, genetic diversity was low (h = 0.550 ± 0.0254 and π = 0.00213 ± 0.00131). Spatial analyses of genetic variation demonstrated strong isolation across the Indo‐Pacific Barrier and between western and central Pacific locations. Pairwise Φ_ST comparisons indicated high connectivity among archipelagos of the central Pacific but isolation across short distances of contiguous habitat (Great Barrier Reef) and intermittent habitat (Hawaiian Archipelago). In the eastern Pacific only a single haplotype (the most common one in the central Pacific) was observed, indicating recent dispersal (or colonization) across the East Pacific Barrier. Main conclusions The shallow haplotype network indicates recent expansion of modern populations within the last half million years from a common ancestor. Based on the distribution of mtDNA diversity, this began with an Indo‐West Pacific centre of origin, with subsequent dispersal to the Central Pacific and East Pacific. Genetic differences between Indian and Pacific Ocean populations are consistent with Pleistocene closures of the Indo‐Pacific Barrier associated with glacial cycles. Pairwise population comparisons reveal weak but significant isolation by distance, and notably do not indicate the high coastal connectivity observed in other shark species. The finding of population structure among semi‐contiguous habitats, but population connectivity among archipelagos, may indicate a previously unsuspected oceanic dispersal behaviour in whitetip reef sharks.     

Vicariance and dispersal across an intermittent barrier: population genetic structure of marine animals across the Torres Strait land bridge

Biogeographic barriers, some transitory in duration, are likely to have been important contributing factors to modern marine biodiversity in the Indo-Pacific region. One such barrier was the Torres Strait land bridge between continental Australia and New Guinea that persisted through much of the late Pleistocene and separated Indian and Pacific Ocean taxa. Here, we examine the patterns of mitochondrial DNA diversity for marine animals with present-day distributions spanning the Torres Strait. Specifically, we investigate whether there are concordant signatures across species, consistent with either vicariance or recent colonization from either ocean basin. We survey four species of reef fishes (Apogon doederleini, Pomacentrus coelestis, Dascyllus trimaculatus, and Acanthurus triostegus) for mtDNA cytochrome oxidase 1 and control region variation and contrast these results to previous mtDNA studies in diverse marine animals with similar distributions. We find substantial genetic partitioning (estimated from F-statistics and coalescent approaches) between Indian and Pacific Ocean populations for many species, consistent with regional persistence through the late Pleistocene in both ocean basins. The species-specific estimates of genetic divergence, however, vary greatly and for reef fishes we estimate substantially different divergence times among species. It is likely that Indian and Pacific Ocean populations have been isolated for multiple glacial cycles for some species, whereas for other species genetic connections have been more recent. Regional estimates of genetic diversity and directionality of gene flow also vary among species. Thus, there is no apparent consistency among historical patterns across the Torres Strait for these co-distributed marine animals.     

The complex biogeographic history of a widespread tropical tree species

Many tropical forest tree species have broad geographic ranges, and fossil records indicate that population disjunctions in some species were established millions of years ago. Here we relate biogeographic history to patterns of population differentiation, mutational and demographic processes in the widespread rainforest tree Symphonia globulifera using ribosomal (ITS) and chloroplast DNA sequences and nuclear microsatellite (nSSR) loci. Fossil records document sweepstakes dispersal origins of Neotropical S. globulifera populations from Africa during the Miocene. Despite historical long-distance gene flow, nSSR differentiation across 13 populations from Costa Rica, Panama, Ecuador (east and west of Andes) and French Guiana was pronounced (F(ST)= 0.14, R(ST)= 0.39, P < 0.001) and allele-size mutations contributed significantly (R(ST) > F(ST)) to the divergences between cis- and trans-Andean populations. Both DNA sequence and nSSR data reflect contrasting demographic histories in lower Mesoamerica and Amazonia. Amazon populations show weak phylogeographic structure and deviation from drift-mutation equilibrium indicating recent population expansion. In Mesoamerica, genetic drift was strong and contributed to marked differentiation among populations. The genetic structure of S. globulifera contains fingerprints of drift-dispersal processes and phylogeographic footprints of geological uplifts and sweepstakes dispersal.     

Microsatellite and mitochondrial haplotype diversity reveals population differentiation in the tiger shrimp (Penaeus monodon) in the Indo-Pacific region

The black tiger shrimp (Penaeus monodon) is an ecologically and economically important penaeid species and is widely distributed in the Indo-Pacific region. Here we investigated the genetic diversity of P. monodon (n = 355) from eight geographical regions by genotyping at 10 microsatellite loci. The average observed heterozygosity at various loci ranged from 0.638 to 0.743, indicating a high level of genetic variability in this region. Significant departures from Hardy-Weinberg equilibrium caused by heterozygote deficiency were recorded for most loci and populations. Pairwise F(ST) and R(ST) values revealed genetic differentiation among the populations. Evidence from the assignment test showed that the populations in the West Indian Ocean were unique, whereas other populations examined were partially admixed. In addition, the non-metric multidimensional scaling analysis indicated the presence of three geographic groups in the Indo-Pacific region, i.e. the African populations, a population from western Thailand and the remaining populations as a whole. We also sequenced and analysed the mitochondrial control region (mtCR) in these shrimp stocks to determine whether the nuclear and mitochondrial genomes show a similar pattern of genetic differentiation. A total of 262 haplotypes were identified, and nucleotide divergence among haplotypes ranged from 0.2% to 16.3%. Haplotype diversity was high in all populations, with a range from 0.969 to 1. Phylogenetic analysis using the mtCR data revealed that the West Indian Ocean populations were genetically differentiated from the West Pacific populations, consistent with the microsatellite data. These results should have implications for aquaculture management and conservation of aquatic diversity.     

Multiple population structure of the giant mottled eel, Anguilla marmorata

The population structure of the giant mottled eel, Anguilla marmorata, was investigated with mitochondrial and microsatellite DNA analyses using 449 specimens from 13 localities throughout the species range. Control region F-statistics indicated the North Pacific (Japan, Taiwan, Philippines, Sulawesi), South Pacific (Tahiti, Fiji, New Caledonia, Papua New Guinea), eastern Indian Ocean (Sumatra), western Indian Ocean (Réunion, Madagascar), Ambon, and Guam regions were significantly different (Phi(ST) = 0.131-0.698, P < 0.05) while only a few differences were observed between localities within the South Pacific. These regions were roughly clustered in the neighbour-joining tree, although Ambon individuals were mainly divided into North and South Pacific groups. Analysis with eight microsatellite loci showed almost identical results to those of the control region, except no genetic difference was observed between the western and eastern Indian Ocean (F(ST) = 0.009, P > 0.05). The Bayesian cluster analysis of the microsatellite data detected two genetic groups. One included four North Pacific localities, and the other included eight localities in the South Pacific, Indian Ocean, and Guam, but Ambon individuals were evenly assigned to these two groups. These results showed that A. marmorata has four genetically different populations (North Pacific, South Pacific, Indian Ocean, Guam region). The North Pacific population is fully panmictic whereas the South Pacific and Indian Ocean populations have a metapopulation structure. Interestingly, Guam was suggested to be inhabited by a reproductive population restricted to that region, and the individuals from the North and South Pacific populations co-exist in Ambon.     

Indo-Pacific population structure and evolutionary history of the coconut crab Birgus latro

Mitochondrial DNA variation was used to examine population structure in a widespread, marine-dispersed species, Birgus latro . Crabs were collected from eight locations throughout the species' Indo-Pacific distribution. Purified mtDNA from 160 individuals was cut with five restriction enzymes, revealing high haplotype diversity (0.96) and moderate nucleotide diversity (0.75%). Island populations from the Indian Ocean (Christmas I.) and Pacific Ocean were significantly different ( G _ST= 0.37) and had distinct mtDNA lineages with a net sequence divergence of 1.4%. Pacific island populations had diverged in a manner consistent with isolation by distance, with only the most peripheral populations being significantly different. The results for mtDNA are largely concordant with those from allozymes, although estimates of gene flow between the Indian and Pacific Oceans were much lower when based on mtDNA. The mtDNA phylogeny also permitted a deeper examination of the evolutionary and demographic history of Birgus latro . Long-term separation of populations is evident in the complete phylogenetic subdivision of mtDNA lineages between the Indian and Pacific Ocean populations sampled. The starlike phylogeny of alleles from the Pacific suggests a rapid population expansion in the Pacific during the Pleistocene. Including information about allele phylogeny, as well as distribution and frequency, obscured contemporary population structure, but provided unique insights into the evolutionary history of the species.     

Phylogeography, intraspecific structure and sex-biased dispersal of Dall's porpoise, Phocoenoides dalli, revealed by mitochondrial and microsatellite DNA analyses

Mitochondrial DNA (mtDNA) control-region sequences and microsatellite loci length polymorphisms were used to estimate phylogeographical patterns (historical patterns underlying contemporary distribution), intraspecific population structure and gender-biased dispersal of Phocoenoides dalli dalli across its entire range. One-hundred and thirteen animals from several geographical strata were sequenced over 379 bp of mtDNA, resulting in 58 mtDNA haplotypes. Analysis using F(ST) values (based on haplotype frequencies) and phi(ST) values (based on frequencies and genetic distances between haplotypes) yielded statistically significant separation (bootstrap values P < 0.05) among most of the stocks currently used for management purposes. A minimum spanning network of haplotypes showed two very distinctive clusters, differentially occupied by western and eastern populations, with some common widespread haplotypes. This suggests some degree of phyletic radiation from west to east, superimposed on gene flow. Highly male-biased migration was detected for several population comparisons. Nuclear microsatellite DNA markers (119 individuals and six loci) provided additional support for population subdivision and gender-biased dispersal detected in the mtDNA sequences. Analysis using F(ST) values (based on allelic frequencies) yielded statistically significant separation between some, but not all, populations distinguished by mtDNA analysis. R(ST) values (based on frequencies of and genetic distance between alleles) showed no statistically significant subdivision. Again, highly male-biased dispersal was detected for all population comparisons, suggesting, together with morphological and reproductive data, the existence of sexual selection. Our molecular results argue for nine distinct dalli-type populations that should be treated as separate units for management purposes.     

Biogeography of Old World emballonurine bats (Chiroptera: Emballonuridae) inferred with mitochondrial and nuclear DNA

Extant bats of the genus Emballonura have a trans-Indian Ocean distribution, with two endemic species restricted to Madagascar, and eight species occurring in mainland southeast Asia and islands in the western Pacific Ocean. Ancestral Emballonura may have been more widespread on continental areas, but no fossil identified to this genus is known from the Old World. Emballonura belongs to the subfamily Emballonurinae, which occurs in the New and Old World. Relationships of all Old World genera of this subfamily, including Emballonura and members of the genera Coleura from Africa and western Indian Ocean islands and Mosia nigrescens from the western Pacific region, are previously unresolved. Using 1833 bp of nuclear and mitochondrial genes, we reconstructed the phylogenetic history of Old World emballonurine bats. We estimated that these lineages diverged around 30 million years ago into two monophyletic sister groups, one represented by the two taxa of Malagasy Emballonura, Coleura and possibly Mosia, and the other by a radiation of Indo-Pacific Emballonura, hence, rendering the genus Emballonura paraphyletic. The fossil record combined with these phylogenetic relationships suggest at least one long-distance dispersal event across the Indian Ocean, presumably of African origin, giving rise to all Indo-Pacific Emballonura species (and possibly Mosia). Cladogenesis of the extant Malagasy taxa took place during the Quaternary giving rise to two vicariant species, E. atrata in the humid east and E. tiavato in the dry west.     

Conservation implications of complex population structure: lessons from the loggerhead turtle (Caretta caretta)

Complex population structure can result from either sex-biased gene flow or population overlap during migrations. Loggerhead turtles (Caretta caretta) have both traits, providing an instructive case history for wildlife management. Based on surveys of maternally inherited mtDNA, pelagic post-hatchlings show no population structure across the northern Atlantic (phi(ST) < 0.001, P = 0.919), subadults in coastal habitat show low structure among locations (phi(ST) = 0.01, P < 0.005), and nesting colonies along the southeastern coast of the United States have strong structure (phi(ST) = 0.42, P < 0.001). Thus the level of population structure increases through progressive life history stages. In contrast, a survey of biparentally inherited microsatellite DNA shows no significant population structure: R(ST) < 0.001; F(ST) = 0.002 (P > 0.05) across the same nesting colonies. These results indicate that loggerhead females home faithfully to their natal nesting colony, but males provide an avenue of gene flow between regional nesting colonies, probably via opportunistic mating in migratory corridors. As a result, all breeding populations in the southeastern United States have similar levels of microsatellite diversity (H(E) = 0.70-0.89), whereas mtDNA haplotype diversity varies dramatically (h = 0.00-0.66). Under a conventional interpretation of the nuclear DNA data, the entire southeastern United States would be regarded as a single management unit, yet the mtDNA data indicate multiple isolated populations. This complex population structure mandates a different management strategy at each life stage. Perturbations to pelagic juveniles will have a diffuse impact on Atlantic nesting colonies, mortality of subadults will have a more focused impact on nearby breeding populations, and disturbances to adults will have pinpoint impact on corresponding breeding populations. These findings demonstrate that surveys of multiple life stages are desirable to resolve management units in migratory marine species.     

Imprints from genetic drift and mutation imply relative divergence times across marine transition zones in a pan-European small pelagic fish (Sprattus sprattus)

Geographic distributions of most temperate marine fishes are affected by postglacial recolonisation events, which have left complex genetic imprints on populations of marine species. This study investigated population structure and demographic history of European sprat (Sprattus sprattus L.) by combining inference from both mtDNA and microsatellite genetic markers throughout the species' distribution. We compared effects from genetic drift and mutation for both genetic markers in shaping genetic differentiation across four transition zones. Microsatellite markers revealed significant isolation by distance and a complex population structure across the species' distribution (overall θ(ST)=0.038, P<0.01). Across transition zones markers indicated larger effects of genetic drift over mutations in the northern distribution of sprat contrasting a stronger relative impact of mutation in the species' southern distribution in the Mediterranean region. These results were interpreted to reflect more recent divergence times between northern populations in accordance with previous findings. This study demonstrates the usefulness of comparing inference from different markers and estimators of divergence for phylogeographic and population genetic studies in species with weak genetic structure, as is the case in many marine species.     

Genetic structuring of Patagonian toothfish populations in the Southwest Atlantic Ocean: the effect of the Antarctic Polar Front and deep-water troughs as barriers to genetic exchange

The environmental and/or life history factors affecting genetic exchange in marine species with potential for high dispersal are of great interest, not only from an evolutionary standpoint but also with regard to effective management. Previous genetic studies have demonstrated substantial differentiation among populations of the Patagonian toothfish around the Southern Ocean, indicating breakdown of gene flow across large distances between inhabited shelf areas. The present study examined genetic structuring through analysis of microsatellite loci and restriction fragment length polymorphism (RFLP) of the mitochondrial ND2 gene and control region of the toothfish population in the SW Atlantic, allowing examination of the relative effects of the Antarctic Polar Front (APF), deep-water troughs and distance between sites. Mitochondrial DNA (mtDNA) data indicated a sharp genetic division between the Patagonian Shelf/North Scotia Ridge and the Shag Rocks/South Georgia samples, whereas microsatellite data showed much less distinct structuring and an intermediate position of the North Scotia Ridge samples. We suggest these data indicate that the APF, as a barrier to larval dispersal, is the major inhibitor of genetic exchange between toothfish populations, with deep-water troughs and distance between sites contributing to genetic differentiation by inhibiting migration of relatively sedentary adults. We also suggest that differences between mtDNA and nuclear DNA population patterns may reflect either genome population size effects or (putative) male-biased dispersal.     

Phylogeography of <Emphasis Type="Italic">Eleotris fusca</Emphasis> (Teleostei: Gobioidei: Eleotridae) in the Indo-Pacific area reveals a cryptic species in the Indian Ocean

Indo-Pacific insular freshwater systems are mainly dominated by amphidromous species. Eleotris fusca is a widespread one, its life cycle is characterised by a marine pelagic larval phase allowing the species to disperse in the ocean and then to recruit to remote island rivers. In the present study, the population structure of E. fusca over its Indo-Pacific distribution range (Western Indian Ocean to French Polynesia, Pacific Ocean) was evaluated. We analysed a section of mitochondrial COI of 557 individuals sampled from 28 islands to visualise the population structure. Haplotypes diversity (Hd) was between 0.458 and 1 and, nucleotide diversity (π) was between 0.001 and 0.02. Two distinct genetic groups appeared, one in the Indian Ocean and the other in the Pacific Ocean (F_ST mean?=?0.901; 5.2% average divergence). Given these results, complete mitogenomes (mtDNA) were sequenced and combined with the nuclear Rhodopsin (Rh) gene for a subset of individuals. The two phylogenetic trees based on each analysis showed the same genetic pattern: two different groups belonging to the Indian and the Pacific oceans (6.6 and 1.6% of divergence for mtDNA and Rh gene respectively), which supported species level differentiation. These analyses revealed the presence of two sister species confounded until present under the name of Eleotris fusca. One of them is cryptic and endemic of the Indian Ocean and the other one is the true E. fusca, which keeps, nevertheless, its status of widespread species.     

Comparative phylogeography of reef fishes from the Gulf of Aden to the Arabian Sea reveals two cryptic lineages

The Arabian Sea is a heterogeneous region with high coral cover and warm stable conditions at the western end (Djibouti), in contrast to sparse coral cover, cooler temperatures, and upwelling at the eastern end (southern Oman). We tested for barriers to dispersal across this region (including the Gulf of Aden and Gulf of Oman), using mitochondrial DNA surveys of 11 reef fishes. Study species included seven taxa from six families with broad distributions across the Indo-Pacific and four species restricted to the Arabian Sea (and adjacent areas). Nine species showed no significant genetic partitions, indicating connectivity among contrasting environments spread across 2000 km. One butterflyfish (Chaetodon melannotus) and a snapper (Lutjanus kasmira) showed phylogenetic divergences of d = 0.008 and 0.048, respectively, possibly indicating cryptic species within these broadly distributed taxa. These genetic partitions at the western periphery of the Indo-Pacific reflect similar partitions recently discovered at the eastern periphery of the Indo-Pacific (the Hawaiian and the Marquesan Archipelagos), indicating that these disjunctive habitats at the ends of the range may serve as evolutionary incubators for coral reef organisms.

     

Diversification of sympatric broadcast-spawning limpets (Cellana spp.) within the Hawaiian archipelago

Speciation remains a central enigma in biology, and nowhere is this more apparent than in shallow tropical seas where biodiversity rivals that of tropical rainforests. Obvious barriers to gene flow are few and most marine species have a highly dispersive larval stage, which should greatly decrease opportunities for speciation via geographic isolation. The disparity in the level of geographic isolation for terrestrial and marine species is exemplified in Hawai'i where opportunities for allopatric speciation abound in the terrestrial realm. In contrast, marine colonizers of Hawai'i are believed to produce only a single endemic species or population, due to the lack of isolating barriers. To test the assertion that marine species do not diversify within Hawai'i, we examine the evolutionary origin of three endemic limpets (Cellana exarata, C. sandwicensis and C. talcosa) that are vertically segregated across a steep ecocline on rocky shores. Analyses of three mtDNA loci (12S, 16S, COI; 1565bp) and two nDNA loci (ATPSβ, H3; 709bp) in 26 Indo-Pacific Cellana species (N=414) indicates that Hawai'i was colonized once ～3.4-7.2Ma from the vicinity of Japan. Trait mapping demonstrates that high-shore residence is the ancestral character state, such that mid- and low-shore species are the product of subsequent diversification. The Hawaiian Cellana are the first broadcast-spawners demonstrated to have speciated within any archipelago. The habitat stratification, extensive sympatry, and evolutionary history of these limpets collectively indicate a strong ecological component to speciation and support the growing body of evidence for non-allopatric speciation in the ocean.     

Species-level phylogeography and evolutionary history of the hyperdiverse marine gastropod genus Conus

Phylogenetic and paleontological analyses are combined to reveal patterns of species origination and divergence and to define the significance of potential and actual barriers to dispersal in Conus, a species-rich genus of predatory gastropods distributed throughout the world's tropical oceans. Species-level phylogenetic hypotheses are based on nucleotide sequences from the nuclear calmodulin and mitochondrial 16S rRNA genes of 138 Conus species from the Indo-Pacific, eastern Pacific, and Atlantic Ocean regions. Results indicate that extant species descend from two major lineages that diverged at least 33 mya. Their geographic distributions suggest that one clade originated in the Indo-Pacific and the other in the eastern Pacific + western Atlantic. Impediments to dispersal between the western Atlantic and Indian Oceans and the central and eastern Pacific Ocean may have promoted this early separation of Indo-Pacific and eastern Pacific + western Atlantic lineages of Conus. However, because both clades contain both Indo-Pacific and eastern Pacific + western Atlantic species, migrations must have occurred between these regions; at least four migration events took place between regions at different times. In at least three cases, incursions between regions appear to have crossed the East Pacific Barrier. The paleontological record illustrates that distinct sets of Conus species inhabited the Indo-Pacific, eastern Pacific + western Atlantic, and eastern Atlantic + former Tethys Realm in the Tertiary, as is the case today. The ranges of <1% of fossil species (N=841) spanned more than one of these regions throughout the evolutionary history of this group.     

Gene flow of Acanthaster planci (L.) in relation to ocean currents revealed by microsatellite analysis

Population outbreaks of the coral-eating starfish, Acanthaster planci , are hypothesized to spread to many localities in the Indo-Pacific Ocean through dispersal of planktonic larvae. To elucidate the gene flow of A. planci across the Indo-Pacific in relation to ocean currents and to test the larval dispersal hypothesis, the genetic structure among 23 samples over the Indo-Pacific was analysed using seven highly polymorphic microsatellite loci. The F -statistics and genetic admixture analysis detected genetically distinct groups in accordance with ocean current systems, that is, the Southeast African group (Kenya and Mayotte), the Northwestern Pacific group (the Philippines and Japan), Palau, the North Central Pacific group (Majuro and Pohnpei), the Great Barrier Reef, Fiji, and French Polynesia, with a large genetic break between the Indian and Pacific Oceans. A pattern of significant isolation by distance was observed among all samples ( P =  0.001, r  = 0.88, n  = 253, Mantel test), indicating restricted gene flow among the samples in accordance with geographical distances. The data also indicated strong gene flow within the Southeast African, Northwestern Pacific, and Great Barrier Reef groups. These results suggest that the western boundary currents have strong influence on gene flow of this species and may trigger secondary outbreaks.