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We provide photographic evidence for eight fish species from five families, not previously seen within the Galápagos Marine Reserve. Four species are native to the Central Tropical Pacific and likely arrived during recent El Niño phenomena: Acanthurus leucocheilus Herre, 1927, Acanthurus olivaceus Bloch & Schneider, 1801, Naso hexacanthus (Bleeker, 1855), and Chaetodon punctatofasciatus Cuvier, 1831. One is a pantropical species: Kyphosus sectatrix (Linnaeus, 1758). The remaining species likely originated within the Eastern Tropical Pacific: Ctenochaetus marginatus (Valenciennes, 1835), Halichoeres malpelo Allen & Robertson, 1992, and Gymnothorax porphyreus (Guichenot, 1848).

We investigated the globally distributed red algal genus Pterocladiella , comprising 24 described species, many of which are economically important sources of agar and agarose. We used DNA-based species delimitation approaches, phylogenetic, and historical biogeographical analyses to uncover cryptic diversity and infer the drivers of biogeographic patterns. We delimited 43 species in Pterocladiella , of which 19 are undescribed. Our multigene time-calibrated phylogeny and ancestral area reconstruction indicated that Pterocladiella most likely originated during the Early Cretaceous in the Tethys Sea. Ancient Tethyan vicariance and long-distance dispersal have shaped current distribution patterns. The ancestor of Eastern Pacific species likely arose before the formation of the formidable Eastern Pacific Barrier—a first confirmation using molecular data in red algae. Divergences of Northeast and Southeast Pacific species have been driven by the Central American Seaway barrier, which, paradoxically, served as a dispersal pathway for Atlantic species. Both long- and short-distance dispersal scenarios are supported by genetic relationships within cosmopolitan species based on haplotype analysis. Asymmetrical distributions and the predominance of peripatry and sympatry between sister species suggest the importance of budding speciation in Pterocladiella . Our study highlights the underestimation of global diversity in these crucial components of coastal ecosystems and provides evidence for the complex evolution of current species distributions.

To understand how allopatric speciation proceeds, we need information on barriers to gene flow, their antiquity, and their efficacy. For marine organisms with planktonic larvae, much of this information can only be obtained through the determination of divergence between populations. We evaluated the importance of ocean barriers by studying the mitochondrial DNA phylogeography of Tripneustes, a pantropical genus of shallow water sea urchin. A region of cytochrome oxidase I (COI) was sequenced in 187 individuals from locations around the globe. The COI phylogeny agreed with a previously published phylogeny of bindin that barriers important to the evolution of Tripneustes are: (1) the cold water upwelling close to the tip of South Africa, (2) the Isthmus of Panama, (3) the long stretch of deep water separating the eastern from the western Atlantic, and (4) the freshwater plume of the Orinoco and the Amazon rivers between the Caribbean and the coast of Brazil. These barriers have previously been shown to be important in at least a subset of the shallow water marine organisms in which phylogeography has been studied. In contrast, the Eastern Pacific Barrier, 5000 km of deep water between the central and the eastern Pacific that has caused the deepest splits in other genera of sea urchins, is remarkably unimportant as a cause of genetic subdivision in Tripneustes. There is also no discernible subdivision between the Pacific and Indian Ocean populations of this genus. The most common COI haplotype is found in the eastern, central, and western Pacific as well as the Indian Ocean. Morphology, COI, and bindin data agree that T. depressus from the eastern Pacific and T. gratilla from the western Pacific are, in fact, the same species. The distribution of haplotype differences in the Indo‐Pacific exhibits characteristics expected from a sea urchin genus with ephemeral local populations, but with high fecundity, dispersal, and growth: there is little phylogenetic structure, and mismatch distributions conform to models of recent population expansion on a nearly global scale. Yet, comparisons between local populations produce large and significant FST values, indicating nonrandom haplotype distribution. This apparent local differentiation is only weakly reflected in regional divergence, and there is no evidence of isolation by distance in correlations between FST values and either geographical or current distance. Thus, Tripneustes in the Indo‐Pacific (but not in the Atlantic) seems to be one large metapopulation spanning two oceans and containing chaotic, nonequilibrium local variation, produced by the haphazard arrival of larvae or by unpredictable local extinction.

We provide photographic evidence for eight fish species from five families, not previously seen within the Galápagos Marine Reserve. Four species are native to the Central Tropical Pacific and likely arrived during recent El Niño phenomena: Acanthurus leucocheilus Herre, 1927, Acanthurus olivaceus Bloch & Schneider, 1801, Naso hexacanthus (Bleeker, 1855), and Chaetodon punctatofasciatus Cuvier, 1831. One is a pantropical species: Kyphosus sectatrix (Linnaeus, 1758). The remaining species likely originated within the Eastern Tropical Pacific: Ctenochaetus marginatus (Valenciennes, 1835), Halichoeres malpelo Allen & Robertson, 1992, and Gymnothorax porphyreus (Guichenot, 1848).

Aim: To infer species identity, population isolation, and geographical variation in inter-specific hybridization among corals of the genus Pontes from the central and eastern tropical Pacific, with a focus on the timing of separation between populations of P. evermanni and P. lobata divided by the Eastern Pacific Barrier. Location: Hawaii, American Samoa, Panama and the Galapagos Islands of Ecuador. Methods: Maximum likelihood gene trees were obtained for mitochondrial DNA (COI), the internal transcribed spacer (ITS), and 5 single-copy nuclear (SCN) gene regions. Allelic networks were used to group multi-locus sen data into species clusters despite some alíele sharing. Coalescent analyses (IMa2) of the 5 sen markers were used to estimate the time of population divergence and test for introgression between P. evermanni and P. lobata. Results: Allelic networks based on sen gene sequences agreed with mtCOI and ITS designations. Divergence times between Hawaiian and eastern Pacific populations are consistent with an early Pleistocene recolonization of the eastern Pacific by P. evermanni followed by a more recent arrival of P. lobata. The two species were fully isolated in Hawaii/American Samoa populations, but introgression from P. evermanni into P. lobata was evident in the eastern Pacific. Main conclusions: These results are consistent with a scenario where a bout of introgression with P. evermanni> an early-arriving colonizer of the eastern Pacific suited to marginal environmental conditions, facilitated the later colonization of the more sensitive P. lobata.

To understand how allopatric speciation proceeds, we need information on barriers to gene flow, their antiquity, and their efficacy. For marine organisms with planktonic larvae, much of this information can only be obtained through the determination of divergence between populations. We evaluated the importance of ocean barriers by studying the mitochondrial DNA phylogeography of Tripneustes, a pantropical genus of shallow water sea urchin. A region of cytochrome oxidase I (COI) was sequenced in 187 individuals from locations around the globe. The COI phylogeny agreed with a previously published phylogeny of bindin that barriers important to the evolution of Tripneustes are: (1) the cold water upwelling close to the tip of South Africa, (2) the Isthmus of Panama, (3) the long stretch of deep water separating the eastern from the western Atlantic, and (4) the freshwater plume of the Orinoco and the Amazon rivers between the Caribbean and the coast of Brazil. These barriers have previously been shown to be important in at least a subset of the shallow water marine organisms in which phylogeography has been studied. In contrast, the Eastern Pacific Barrier, 5000 km of deep water between the central and the eastern Pacific that has caused the deepest splits in other genera of sea urchins, is remarkably unimportant as a cause of genetic subdivision in Tripneustes. There is also no discernible subdivision between the Pacific and Indian Ocean populations of this genus. The most common COI haplotype is found in the eastern, central, and western Pacific as well as the Indian Ocean. Morphology, COI, and bindin data agree that T. depressus from the eastern Pacific and T. gratilla from the western Pacific are, in fact, the same species. The distribution of haplotype differences in the Indo-Pacific exhibits characteristics expected from a sea urchin genus with ephemeral local populations, but with high fecundity, dispersal, and growth: there is little phylogenetic structure, and mismatch distributions conform to models of recent population expansion on a nearly global scale. Yet, comparisons between local populations produce large and significant FST values, indicating nonrandom haplotype distribution. This apparent local differentiation is only weakly reflected in regional divergence, and there is no evidence of isolation by distance in correlations between FST values and either geographical or current distance. Thus, Tripneustes in the Indo-Pacific (but not in the Atlantic) seems to be one large metapopulation spanning two oceans and containing chaotic, nonequilibrium local variation, produced by the haphazard arrival of larvae or by unpredictable local extinction.

The 'Eastern Pacific Barrier' (EPB), 5400 km of uninterrupted deep water between the central and eastern Pacific, constitutes the greatest marine obstacle to the dispersal of shallow-water organisms. However, some species are found on both sides of the EPB. These 'transpacific' species are considered by 'dispersal' biogeographers as evidence of invasions through the barrier. 'Vicariance' biogeographers, on the other hand, think that transpacific species are morphologically conservative remnants of previously continuous distributions. We compared nucleotide sequences in a 642 bp region of mitochondrial DNA, and electrophoretically detected alleles in 17 enzymatic loci of central and eastern Pacific populations of Echinothrix diadema, an Indo-Pacific sea urchin recently reported from the eastern Pacific. Both types of molecules produced clear evidence of massive, recent gene flow across the EPB. Thus, rather than being isolated relicts of Tethyan distributions, conspecific populations from the eastern and central Pacific are genetically connected. Though the EPB is biogeographically important as a cause of speciation in many groups, it allows genetic connections in others, possibly through larval transport during El Niño events.

AIM: We develop the first global model of connectivity for a generic broadcast spawning coral, and compare the results to connectivity estimates from genetic studies, general biogeographic patterns and theories. We also derive various ‘connectivity indices’ describing relative isolation and source potential between locations. LOCATION: Modelled oceans 47° S–47° N. METHODS: Dispersal of model coral ‘larvae’ was simulated over 8 years using an individual‐based biophysical dispersal model driven by 1/12°‐resolution surface ocean current data and incorporating individual trait variability (e.g. a phased pre‐competency period). Source and arrival locations of modelled larvae on suitable reef habitat gave standardized dispersal paths and relative levels of connectivity. RESULTS: In the model c. 50% of connections occurred within 50–100 km, with rarer dispersal between regions linking entire oceans in a ‘stepping stone’ fashion. The central Pacific was an almost complete barrier to dispersal, only rarely breached westward from the Galapagos to Marquesas Islands. Areas showing strong isolation also included Hawaii, Easter Island, the Red Sea and the eastern Atlantic. The Indo‐West Pacific and Great Barrier Reef showed the highest levels of connectivity, with secondary peaks in the western Indian Ocean, corresponding to areas of enriched coral diversity. The central Indo‐Pacific diversity hotspot was overall a greater source than sink for dispersal. CONCLUSIONS: This study provides a global view of connectivity that complements genetic and biogeographic work as well as providing a number of novel findings relevant to biogeographic theories (e.g. the central Indo‐Pacific as a dispersal source; Johnston Atoll as the sole ‘stepping‐stone’ into Hawaii). Discrepancies with proposed connectivity patterns (e.g. one‐way, westward, connectivity across the central Pacific) present hypotheses for future research. The model represents an effective tool for exploring the factors controlling connectivity on this scale and the effects of climate change on future connectivity, and will also aid predictions of future reef distributions.

Aim: The distribution and genetic composition of marine populations is the result of climatic and oceanographic factors as well as life history strategies. Studying species with wide distributions and high dispersal potential in sites that were differentially affected during the Pleistocene glaciations provides an opportunity to evaluate the genetic and distributional effect of glaciations on marine populations, such as the limpet Siphonaria lesonii. The aim of the present study is to evaluate the differential effects of glaciations on areas covered and not covered by ice sheets during the Pleistocene glaciations. Location: Intertidal zone of the south-eastern Pacific covering approximately 5,000 km of coastline of Peru and Chile. Methods: We performed molecular analyses of mitochondrial and nuclear data jointly, as well as environmental niche modelling (ENM) of populations of the limpet Siphonaria lessonii. Using ENM, we modelled the potential distributional range of the species in the present and its distribution during the Last Glacial Maximum (LGM). Results: Two lineages were found that were separated by a break at 41° S, corresponding to the biogeographical discontinuity previously reported for this region. Both of these lineages experienced genetic and demographical fluctuations that match the Pleistocene glaciations; however, the variability was more intense in the southern lineage. Phylogeography and ENM yielded complementary results for the southern lineage, which experienced loss of genetic diversity and habitat during the LGM, whereas the northern lineage evidenced loss of genetic diversity without distributional changes. Main conclusions: The phylogeographical and ENM approaches suggest a historical scenario involving demographic and distributional contractions of S. lessonii surviving in glacial refugia in the southern portion of the south-eastern Pacific. This study is the first to include both phylogeographical and ENM analyses of marine species from the Southern Hemisphere.