17 research outputs found
Feeding associations between Guiana dolphins, Sotalia guianensis (Van BĂ©nĂšden, 1864) and seabirds in the Lagamar estuary, Brazil
Thermodiffused vanadium carbide interface for diamond films on steel and cemented carbides substrates
Genomics detects population structure within and between ocean basins in a circumpolar seabird: the whiteâchinned petrel
The Southern Ocean represents a continuous stretch of circumpolar marine habitat, but the potential physical and ecological drivers of evolutionary genetic differentiation across this vast ecosystem remain unclear. We tested for genetic structure across the full circumpolar range of the whiteâchinned petrel (Procellaria aequinoctialis) to unravel the potential drivers of population differentiation and test alternative population differentiation hypotheses. Following rangeâwide comprehensive sampling, we applied genomic (genotypingâbyâsequencing or GBS; 60,709 loci) and standard mitochondrialâmarker approaches (cytochrome b and 1st domain of control region) to quantify genetic diversity within and among island populations, test for isolation by distance, and quantify the number of genetic clusters using neutral and outlier (nonâneutral) loci. Our results supported the multiâregion hypothesis, with a range of analyses showing clear threeâregion genetic population structure, split by ocean basin, within two evolutionary units. The most significant differentiation between these regions confirmed previous work distinguishing New Zealand and nominate subspecies. Although there was little evidence of structure within the island groups of the Indian or Atlantic oceans, a small set of highlyâdiscriminatory outlier loci could assign petrels to ocean basin and potentially to island group, though the latter needs further verification. Genomic data hold the key to revealing substantial regional genetic structure within wideâranging circumpolar species previously assumed to be panmictic
Which trophic discrimination factors fit the best? A combined dietary study of a coastal seabird
The use of combined conventional and stable isotope analyses to study the diet of seabirds has become very frequent. Unfortunately species and tissue-specific Trophic Discrimination Factors (TDF), necessary to run stable isotope mixing models in the most performing way, are lacking for a wide number of seabird species. We assessed the process of inspecting and selecting the most adequate TDFs by running mixing region simulations with three different TDFs scenarios. This was carried out in a combined dietary study of a widespread but poorly studied seabird from the Americas: the Neotropic Cormorant (Phalacrocorax brasilianus), at a breeding colony from coastal Patagonia. The mixing models were run with the best fitting carbon and nitrogen TDFs (whole blood), which were those obtained with R package SIDER, a Bayesian inference-based model predicting the TDFs of consumers considering their ecology and phylogenetic relatedness. We found that cormorants fed on rather mobile fish of a fairly variable ecological spectrum, both benthic and pelagic, and showed low prey diversity. Our results coincide with the overall generalist and opportunistic piscivorous habit found at different coastal areas along its broad distribution range. Despite some differences found in the proportion estimates of the main prey between the two methods, their combination through the incorporation of prior information into the mixing models provides a comprehensive trophic profile. Finally, the use of SIDER, alongside the inspection and comparison of different potential TDF values, offered a simple and effective framework to calculate and select the most adequate specific TDFs to be employed in stable isotope mixing models.Bei ErnĂ€hrungsuntersuchungen an Seevögeln wird immer hĂ€ufger eine Kombination von konventionellen Analysen mit solchen mit Stabilen Isotopen angewandt. Leider aber fehlen uns fĂŒr eine groĂe Anzahl von Seevogelarten die art- und gewebespezifschen trophischen Unterscheidungsfaktoren (TDF), die notwendig sind, um Stabile Isotopenmischungs-Modelle mit höchstmöglicher Aussagekraft anzuwenden. Wir bewerteten das Verfahren zur PrĂŒfung und Auswahl der bestgeeigneten TDFs, indem wir Simulationen von Mischregionen mit drei unterschiedlichen TDF-Szenarien laufen lieĂen. Diese Untersuchung wurde als kombinierte ErnĂ€hrungsstudie an einer weitverbreiteten, aber nur wenig untersuchten amerikanischen Seevogelart, der neotropischen Humboldtscharbe (Phalacrocorax brasilianus) aus der Familie der Kormorane, in einer Brutkolonie an der KĂŒste Patagoniens durchgefĂŒhrt. Die Misch-Modelle wurden mit den am besten passenden Kohlenstofund Stickstof-TDFs (aus dem Blut) gerechnet, die wiederum mit SIDER (Stable Isotope Discrimination Estimation in R), einem Bayesâschen Inferenz-basierten Modell zur Vorhersage der TDFs von Konsumenten unter BerĂŒcksichtigung ihrer Ăkologie und phylogenetischen Verwandtschaft, erstellt wurden. Wir fanden heraus, dass sich die Kormorane von Fischen aus einem breiten ökologischen Spektrum, benthisch und auch pelagisch, ernĂ€hrten und eine geringe Beutevielfalt zeigten. Unsere Ergebnisse passen gut zu den an unterschiedlichen KĂŒsten mit groĂen Verbreitungsgebieten gefundenen generellen Angewohnheiten von Fischfressern. Trotz einiger Unterschiede, die wir in den SchĂ€tzungen der Anteile der Hauptnahrung zwischen den beiden Methoden fanden, ergibt deren Kombination durch das Einbeziehen frĂŒher gewonnener Informationen in die Misch-Modelle doch ein umfassendes trophisches Profl. SchlieĂlich bietet die Anwendung von SIDER zusammen mit der PrĂŒfung und dem Vergleich unterschiedlicher potentieller TDF-Werte einen einfachen und efektiven Rahmen fĂŒr die Berechnung und Auswahl der am besten passenden, spezifschen TDFs fĂŒr die Anwendung in Modellen mit gemischten Stabilen Isotopen.Fil: Morgenthaler, Annick. Universidad Nacional de la Patagonia Austral. Unidad AcadĂ©mica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Millones, Ana. Universidad Nacional de la Patagonia Austral. Unidad AcadĂ©mica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Gandini, Patricia Alejandra. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad AcadĂ©mica Caleta Olivia. Centro de Investigaciones Puerto Deseado; ArgentinaFil: Frere, Esteban. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de la Patagonia Austral. Unidad AcadĂ©mica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentin