The Magnitude of Global Marine Species Diversity

Background: The question of how many marine species exist is important because it provides a metric for how much we do and do not know about life in the oceans. We have compiled the first register of the marine species of the world and used this baseline to estimate how many more species, partitioned among all major eukaryotic groups, may be discovered. Results: There are ∼226,000 eukaryotic marine species described. More species were described in the past decade (∼20,000) than in any previous one. The number of authors describing new species has been increasing at a faster rate than the number of new species described in the past six decades. We report that there are ∼170,000 synonyms, that 58,000–72,000 species are collected but not yet described, and that 482,000–741,000 more species have yet to be sampled. Molecular methods may add tens of thousands of cryptic species. Thus, there may be 0.7–1.0 million marine species. Past rates of description of new species indicate there may be 0.5 ± 0.2 million marine species. On average 37% (median 31%) of species in over 100 recent field studies around the world might be new to science. Conclusions: Currently, between one-third and two-thirds of marine species may be undescribed, and previous estimates of there being well over one million marine species appear highly unlikely. More species than ever before are being described annually by an increasing number of authors. If the current trend continues, most species will be discovered this century

Systematics and phylogeography of shallow water jellyfish (Scyphozoa, Discomedusae) in the Tropical Eastern Pacific

Species diversity is declining, due to habitat loss, over-exploitation, pollution, and climate change. It is imperative that biodiversity and distributions be accounted for immediately, to understand the impacts of anthropogenic change, and to sustain natural resources. Biodiversity in the seas, and geographic variation, have been underestimated—due to challenges in (1) the delimitation of species, (2) a preponderance of cryptic species, (3) uneven sampling effort, and (4) limited systematic framework. As a consequence, the mechanisms that govern species richness in the seas are poorly understood. The magnitude of these issues varies by taxon and by region, leaving open questions such as: Are estimates of species richness accurate? What are the tempo and mode of evolution in marine species? What mechanisms determine species’ distributions in the ocean?Here, we tackle the first question, using the example of jellyfishes in the Tropical Eastern Pacific (TEP). The TEP is known as a ‘hotspot’ for its generally high biodiversity, but it harbors only five scyphozoan jellyfishes. To redress the four known challenges facing estimates of marine biodiversity, we increased sampling effort, combined molecular and morphological characters, and applied phylogenetic, barcoding, and morphospecies analyses to estimate species richness of scyphomedusae in the TEP. We found a total of 25 species; of which 22 are new to science, two are non-indigenous, and one is a previous record. Thus, by overcoming known challenges, we found that, as for other more well-known taxa, the TEP also is a hotspot for scyphozoans. To answer the second question, above, we test the hypotheses about the origins of the Discomedusae by synthesizing molecular and morphological phylogenies. We calibrate a scyphozoan molecular clock using geologic events and fossil records. We demonstrate that Coronatae is sister taxon to Discomedusae; we find evidence for geographic radiations in the genus Stomolophus and Family Pelagiidae, which are the most species rich taxa in the TEP. Their diversification rates confirm a rapid genetic radiation in the genera Chysaora, but the morphological characters mapped in the phylogeny did not show any shift in the rates of morphological evolution. To address the last question, we took advantage of a comparative phylogenetic approach. A multi-taxon comparison—including five species of Stomolophus and four Chrysaora species—demonstrates that biological factors play the more important role in shaping species’ distributions and assemblages, compared to abiotic factors. The vicariance model of speciation is not the only process though which the biodiversity in the TEP could have originated. Peripatric and sympatric models of speciation also can define many of the diversification patterns in the TEP

Sistemática de los Balanomorfos (Cirripedia , thoracica) de la región Sur de la Península de Baja California, México.

impreso y digita

Systematics and phylogeography of shallow water jellyfish (Scyphozoa, Discomedusae) in the Tropical Eastern Pacific

Species diversity is declining, due to habitat loss, over-exploitation, pollution, and climate change. It is imperative that biodiversity and distributions be accounted for immediately, to understand the impacts of anthropogenic change, and to sustain natural resources. Biodiversity in the seas, and geographic variation, have been underestimated—due to challenges in (1) the delimitation of species, (2) a preponderance of cryptic species, (3) uneven sampling effort, and (4) limited systematic framework. As a consequence, the mechanisms that govern species richness in the seas are poorly understood. The magnitude of these issues varies by taxon and by region, leaving open questions such as: Are estimates of species richness accurate? What are the tempo and mode of evolution in marine species? What mechanisms determine species’ distributions in the ocean?Here, we tackle the first question, using the example of jellyfishes in the Tropical Eastern Pacific (TEP). The TEP is known as a ‘hotspot’ for its generally high biodiversity, but it harbors only five scyphozoan jellyfishes. To redress the four known challenges facing estimates of marine biodiversity, we increased sampling effort, combined molecular and morphological characters, and applied phylogenetic, barcoding, and morphospecies analyses to estimate species richness of scyphomedusae in the TEP. We found a total of 25 species; of which 22 are new to science, two are non-indigenous, and one is a previous record. Thus, by overcoming known challenges, we found that, as for other more well-known taxa, the TEP also is a hotspot for scyphozoans. To answer the second question, above, we test the hypotheses about the origins of the Discomedusae by synthesizing molecular and morphological phylogenies. We calibrate a scyphozoan molecular clock using geologic events and fossil records. We demonstrate that Coronatae is sister taxon to Discomedusae; we find evidence for geographic radiations in the genus Stomolophus and Family Pelagiidae, which are the most species rich taxa in the TEP. Their diversification rates confirm a rapid genetic radiation in the genera Chysaora, but the morphological characters mapped in the phylogeny did not show any shift in the rates of morphological evolution. To address the last question, we took advantage of a comparative phylogenetic approach. A multi-taxon comparison—including five species of Stomolophus and four Chrysaora species—demonstrates that biological factors play the more important role in shaping species’ distributions and assemblages, compared to abiotic factors. The vicariance model of speciation is not the only process though which the biodiversity in the TEP could have originated. Peripatric and sympatric models of speciation also can define many of the diversification patterns in the TEP

High genetic differentiation in the edible cannonball jellyfish (cnidaria: Scyphozoa: Stomolophus spp.) from the Gulf of California, Mexico

Studies of population genetic structure in relation to ecological and evolutionary processes are crucial for conservation genetics and particularly for sustainable management of fisheries. However, such knowledge is not always available for the management of fisheries, as is the case of the edible cannonball jellyfish Stomolophus spp. fishery in the Gulf of California, Mexico. The aim of this study is describe the population genetic structure of cannonball jellyfish in the Gulf of California. We used sequences of cytochrome oxidase I (COI) and microsatellite markers in five locations within the Gulf of California and the southern Pacific coast. Both COI and microsatellite markers corroborated the presence of two differentiated genetic lineages in the fishing areas, which diverged around 1.17 Mya: Stomolophus sp.1, distributed in the Golfo de Santa Clara; and Stomolophus sp.2, in the southern region of the Gulf of California and the Pacific coast of the Baja California peninsula. In addition, significant differentiation between the four locations within the lineage Stomolophus sp.2 was found (mean FST: 0.56 and 0.12 for COI and microsatellites respectively). Our results are consistent with the endemism and phylogeographic break hypotheses proposed for the northern region of the Gulf of California. We proposed that the historical geology and complex oceanography of the Gulf of California might be responsible of this species-level differentiation. Conversely, the population structure within Stomolophus sp.2 could be more related to the life cycle, and particularly due the short larval dispersal stage of cannonball jellyfish in the Gulf of California.Fil: Getino Mamet, Leandro Nicolás. Instituto Politécnico Nacional; . Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gómez Daglio, Liza. University of California; Estados UnidosFil: García De León, Francisco Javier. Instituto Politécnico Nacional

A "shallow phylogeny" of shallow barnacles (chthamalus).

BACKGROUND:We present a multi-locus phylogenetic analysis of the shallow water (high intertidal) barnacle genus Chthamalus, focusing on member species in the western hemisphere. Understanding the phylogeny of this group improves interpretation of classical ecological work on competition, distributional changes associated with climate change, and the morphological evolution of complex cirripede phenotypes. METHODOLOGY AND FINDINGS:We use traditional and Bayesian phylogenetic and 'deep coalescent' approaches to identify a phylogeny that supports the monophyly of the mostly American 'fissus group' of Chthamalus, but that also supports a need for taxonomic revision of Chthamalus and Microeuraphia. Two deep phylogeographic breaks were also found within the range of two tropical American taxa (C. angustitergum and C. southwardorum) as well. CONCLUSIONS:Our data, which include two novel gene regions for phylogenetic analysis of cirripedes, suggest that much more evaluation of the morphological evolutionary history and taxonomy of Chthamalid barnacles is necessary. These data and associated analyses also indicate that the radiation of species in the late Pliocene and Pleistocene was very rapid, and may provide new insights toward speciation via transient allopatry or ecological barriers

Isolation and characterization of 14 tetranucleotide microsatellite loci for the cannonball jellyfish (Stomolophus sp.) by next generation sequencing

The Cannonball jellyfish (Stomolophus sp.) is a species of jellyfish with high relevance in artisanal fishing. Studies of their populations do not extend beyond the morphological descriptions knowing that presents a great morphological variability. However, there are no genetic studies to determine the number of independent populations, so microsatellite markers become a suitable option. Since there are no species-specific microsatellite loci, in this paper, 14 new microsatellite loci are characterized. Microsatellite loci were isolated de novo through next generation sequencing, by two runs on Illumina MiSeq. A total of 506,771,269 base pair were obtained, from which 142,616 were microsatellite loci, and 1546 of them could design primers. We tested 14 primer pairs on 32 individuals from Bahía de La Paz, Gulf of California. We observed low genetic variation among loci (mean number of alleles per locus = 4.33, mean observed heterozygosity 0.381, mean expected heterozygosity 0.501). These loci are the first ones described for the species and will be helpful to carry out genetic diversity and population genetics studies.Fil: Getino Mamet, Leandro Nicolás. Instituto Politécnico Nacional 195; México. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Valdivia Carrillo, Tania. Instituto Politécnico Nacional 195; MéxicoFil: Gómez Daglio, Liza. University of California; Estados UnidosFil: García De León, Francisco Javier. Instituto Politécnico Nacional 195; Méxic

Calibrated rates of molecular evolution per locus.

<p>None of the individual data sets carry an appropriate fit to the standard molecular clock model (rejected at p<0.001). Net nucleotide distance is calculated for both trans-Isthmian taxa as appropriate; for <i>Chthamalus</i>, the mean distance for comparisons among all Pacific ‘<i>fissus</i> group’ species with both <i>C. proteus</i> and <i>C. fragilis</i> was calculated with standard deviations. Rate distributions (and calculations per million years) are estimated using a range of dates 3.0–3.5 mya for the closing of the Panamanian Isthmus. Rate distributions for nLTRS exclude the <i>Microeuraphia</i> comparison as all <i>Chthamalus</i> comparisons were extremely similar with low variance.</p