Barcoding of Arrow Worms (Phylum Chaetognatha) from Three Oceans: Genetic Diversity and Evolution within an Enigmatic Phylum

Arrow worms (Phylum Chaetognatha) are abundant planktonic organisms and important predators in many food webs; yet, the classification and evolutionary relationships among chaetognath species remain poorly understood. A seemingly simple body plan is underlain by subtle variation in morphological details, obscuring the affinities of species within the phylum. Many species achieve near global distributions, spanning the same latitudinal bands in all ocean basins, while others present disjunct ranges, in some cases with the same species apparently found at both poles. To better understand how these complex evolutionary and geographic variables are reflected in the species makeup of chaetognaths, we analyze DNA barcodes of the mitochondrial cytochrome oxidase c subunit I (COI) gene, from 52 specimens of 14 species of chaetognaths collected mainly from the Atlantic Ocean. Barcoding analysis was highly successful at discriminating described species of chaetognaths across the phylum, and revealed little geographical structure. This barcode analysis reveals hitherto unseen genetic variation among species of arrow worms, and provides insight into some species relationships of this enigmatic group

SNAGA, TEORIJA I PRAKSA (Kraft, Theorie und Praxis)

We have developed a global biogeographic classification of the mesopelagic zone to reflect the regional scales over which the ocean interior varies in terms of biodiversity and function. An integrated approach was necessary, as global gaps in information and variable sampling methods preclude strictly statistical approaches. A panel combining expertise in oceanography, geospatial mapping, and deep-sea biology convened to collate expert opinion on the distributional patterns of pelagic fauna relative to environmental proxies (temperature, salinity, and dissolved oxygen at mesopelagic depths). An iterative Delphi Method integrating additional biological and physical data was used to classify biogeographic ecoregions and to identify the location of ecoregion boundaries or inter-regions gradients. We define 33 global mesopelagic ecoregions. Of these, 20 are oceanic while 13 are ‘distant neritic.’ While each is driven by a complex of controlling factors, the putative primary driver of each ecoregion was identified. While work remains to be done to produce a comprehensive and robust mesopelagic biogeography (i.e., reflecting temporal variation), we believe that the classification set forth in this study will prove to be a useful and timely input to policy planning and management for conservation of deep-pelagic marine resources. In particular, it gives an indication of the spatial scale at which faunal communities are expected to be broadly similar in composition, and hence can inform application of ecosystem-based management approaches, marine spatial planning and the distribution and spacing of networks of representative protected areas

Pelagic Biodiversity and Biogeography around the SouthAmerican continent Biodiversidad pelagica y biogeografIa en torno del continente sudamericano

Biogeography around South America is well documented on the Atlantic side and less well documented on the Pacific side especially south of about 30º S. The South Pacific oceanic areas are the least known of all pelagic areas. The different approaches to determine biogeographic provinces (e.g. the classical one showing mainly latitudinal and watermass distribution patterns based on presence/absence of species; and the biogeochemical approach based on productivity regimes and modelling) are discussed. The latter shows more east-west division. Testing of these concepts will probably reveal more coastal provinces in the Pacific area. The transitional area in the South Pacific is also an interesting area for molecular species research because there are some joint species with the Atlantic Ocean species that are not often found in the southern Indian Ocean.<br>La biogeografía en torno de América del Sur está bien documentada en el lado Atlántico y menos documentada en el Pacífico, especialmente al sur de los 30º S. Las áreas oceánicas del Pacífico Sur son las menos conocidas de todas las áreas pelágicas. Se discute los diversos intentos para determinar las provincias biogeográficas, e.g. el clásico que muestra los principales patrones de distribución latitudinal y de masas de agua basados en la presencia/ausencia de especies, y del método biogeoquímico basado en regímenes de productividad y modelamiento. El último muestra una división más este-oeste. La prueba de estos conceptos revelará probablemente más provincias costeras en el área del Pacífico. El área de transición en el Pacífico Sur, también es un área interesante para la investigación molecular de las especies porque hay un número de especies comunes con el Océano Atlántico, especies que no se presentan a menudo en el Océano Índico del Sur

Gene tree for COI, showing topology and branch lengths from Bayesian analysis.

<p>Pairs of numbers in parentheses are support values, given as (Bayesian posterior probabilities, approximate Likelihood Ratio Test support), with asterisks indicating maximum support of (1.00, 1.00), and blanks indicating topologies not recovered in that analysis. Scale bar denotes distance along branches. Underlined sequences were obtained from GenBank. Symbols following species names depict sampling location.</p

Species identity and collection information for barcoded chaetognaths.

<p>Species identity and collection information for barcoded chaetognaths.</p

Map showing locations of cruises and material collected in this study.

<p>Map showing locations of cruises and material collected in this study.</p

Photographs of pteropod specimens.

Photographs of pteropod specimens used for phylogenetic analyses in this study