Institution
Sea Mammal Research Unit
About: Sea Mammal Research Unit is a based out in . It is known for research contribution in the topics: Population & Foraging. The organization has 84 authors who have published 100 publications receiving 5315 citations.
Topics: Population, Foraging, Whale, Phoca, Cetacea
Papers published on a yearly basis
Papers
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TL;DR: In this article, a hierarchial classification scheme is proposed for stock designations, which is based on a discontinuous genetic divergence pattern where locally adapted and closely related genome assemblages are separated from others geographically and by significant genetic distances.
Abstract: The “stock” is the fundamental population unit of legally mandated conservation efforts, yet its formal definition in the scientific literature and in two U.S. conservation acts is varied and so general that attempts to apply it in practice are arbitrary. Because choice of stocks deserving management protection is sometimes politically contentious, improvement of the working definition is important.
A key element should be the degree to which a population can be considered an evolutionarily significant unit. We propose that a hierarchial classification scheme be applied to stock designations. Category I populations, having the highest probability of being evolutionarily significant units, are characterized by a discontinuous genetic divergence pattern where locally adapted and closely related genome assemblages are separated from others geographically and by significant genetic distances. Category II populations are similarly characterized by significant genetic diversity, but with weak geographic partitioning. Category III populations are the converse of II, having little genetic differentiation between assemblages that are clearly separate and likely to be reproductively isolated. Category IV assemblages have the lowest probability of being evolutionarily significant units and are characterized by extensive gene flow and no subdivision by extrinsic barriers. In addition to phylogeographic designation, the following information is used in the classification, as indicated by single-letter abbreviations: distribution (a), population response (b), phenotypic (c), and genotypic (d) information. Included are evidence both for and against designating population as a separate stock. In the designation “Type II a/bc,” for example, information to the right of the solidus would be evidence for “lumping,” to the left would be for “splitting.” Missing letter abbreviations would signify lack of reliable data. Note that phylogeographic designation depends on the results of selection operating to produce a locally adapted genome (indicated by differences in demographic, phenotypic, and genotypic measures) and on gene flow (indicated by differences in distribution or by movement data).
Hierarchial stock categorization allows resource managers to direct limited resources to the populations most deserving of protection, that is, the populations that are most likely to be evolutionarily significant units. Using this comprehensive classification of stock allows preliminary, conservative splitting of assemblages where data are lacking without the danger that these divisions will become entrenched as biological dogma.
321 citations
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TL;DR: Although grey seals are known to range over very large areas outside the breeding season, site fidelity of adults and philopatry of pups for these breeding colonies must be sufficiently common to have effects, through genetic drift, at the sub‐population level.
Abstract: Eight highly variable microsatellite loci were used to examine the genetic variability and differentiation of grey seals (Halichoerus grypus) at two widely spaced British breeding colonies. Samples were collected from adults and pups on the island of North Rona, off the north-west coast of Scotland, and on the Isle of May, situated at the mouth of the Firth of Forth on the east coast Highly significant differences in allele frequencies between these two sites were found for all eight loci, indicating considerable genetic differentiation. Thus, although grey seals are known to range over very large areas outside the breeding season, site fidelity of adults and philopatry of pups for these breeding colonies must be sufficiently common to have effects, through genetic drift, at the sub-population level. Migration rate was estimated using Wrighf's fixation index (FST), Slatkin's private alleles model and the new statistic, RST, which is analogous to (FST) but which takes into account the process of microsatellite mutation. An almost 8-fold discrepancy between the values we obtained provides cautionary evidence that microsatellite loci may contravene one or more of the assumptions on which these methods are based.
235 citations
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SLAC National Accelerator Laboratory1, Kansas State University2, Istituto Nazionale di Fisica Nucleare3, University of Trieste4, University of Padua5, University of Maryland, College Park6, Goddard Space Flight Center7, University of Turin8, École Polytechnique9, Instituto Politécnico Nacional10, INAF11, Agenzia Spaziale Italiana12, United States Naval Research Laboratory13, University of Montpellier14, University of Bologna15, University of Udine16, Stanford University17, Hiroshima University18, University of London19, École Normale Supérieure20, Paris Diderot University21, University of Tokyo22, University of Iceland23, University of Gothenburg24, Max Planck Society25, University of Botswana26, University of Johannesburg27, Ames Research Center28, Jagiellonian University29, Sea Mammal Research Unit30, Catalan Institution for Research and Advanced Studies31, Spanish National Research Council32
TL;DR: In this article, the authors observed minute-scale variability suggests a very compact emission region at hundreds of Schwarzschild radii from the central engine in conical jet models, where a minimum bulk jet Lorentz factor of 35 is necessary to avoid both internal gamma-ray absorption and super-Eddington jet power.
Abstract: On 2015 June 16, Fermi-LAT observed a giant outburst from the flat spectrum radio quasar 3C 279 with a peak $>100$ MeV flux of $\sim3.6\times10^{-5}\;{\rm photons}\;{\rm cm}^{-2}\;{\rm s}^{-1}$ averaged over orbital period intervals. It is the historically highest $\gamma$-ray flux observed from the source including past EGRET observations, with the $\gamma$-ray isotropic luminosity reaching $\sim10^{49}\;{\rm erg}\;{\rm s}^{-1}$. During the outburst, the Fermi spacecraft, which has an orbital period of 95.4 min, was operated in a special pointing mode to optimize the exposure for 3C 279. For the first time, significant flux variability at sub-orbital timescales was found in blazar observations by Fermi-LAT. The source flux variability was resolved down to 2-min binned timescales, with flux doubling times less than 5 min. The observed minute-scale variability suggests a very compact emission region at hundreds of Schwarzschild radii from the central engine in conical jet models. A minimum bulk jet Lorentz factor ($\Gamma$) of 35 is necessary to avoid both internal $\gamma$-ray absorption and super-Eddington jet power. In the standard external-radiation-Comptonization scenario, $\Gamma$ should be at least 50 to avoid overproducing the synchrotron-self-Compton component. However, this predicts extremely low magnetization ($\sim5\times10^{-4}$). Equipartition requires $\Gamma$ as high as 120, unless the emitting region is a small fraction of the dissipation region. Alternatively, we consider $\gamma$ rays originating as synchrotron radiation of $\gamma_{\rm e}\sim1.6\times10^6$ electrons, in magnetic field $B\sim1.3$ kG, accelerated by strong electric fields $E\sim B$ in the process of magnetoluminescence. At such short distance scales, one cannot immediately exclude production of $\gamma$ rays in hadronic processes.
233 citations
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227 citations
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University of Tokyo1, National Institute of Polar Research2, Sea Mammal Research Unit3, Nagasaki University4, Scripps Institution of Oceanography5, Centre national de la recherche scientifique6, Tokyo Institute of Technology7, University of California, Santa Cruz8, British Antarctic Survey9, Woods Hole Oceanographic Institution10
TL;DR: It is suggested that muscle characteristics may constrain swimming during cruising travel, with convergence among diving specialists in the proportions and contraction rates of propulsive muscles.
Abstract: It is obvious, at least qualitatively, that small animals move their locomotory apparatus faster than large animals: small insects move their wings invisibly fast, while large birds flap their wings slowly. However, quantitative observations have been difficult to obtain from free-ranging swimming animals. We surveyed the swimming behaviour of animals ranging from 0.5 kg seabirds to 30 000 kg sperm whales using animal-borne accelerometers. Dominant stroke cycle frequencies of swimming specialist seabirds and marine mammals were proportional to mass(-0.29) (R(2)= 0.99, n = 17 groups), while propulsive swimming speeds of 1-2 m s(-1) were independent of body size. This scaling relationship, obtained from breath-hold divers expected to swim optimally to conserve oxygen, does not agree with recent theoretical predictions for optimal swimming. Seabirds that use their wings for both swimming and flying stroked at a lower frequency than other swimming specialists of the same size, suggesting a morphological trade-off with wing size and stroke frequency representing a compromise. In contrast, foot-propelled diving birds such as shags had similar stroke frequencies as other swimming specialists. These results suggest that muscle characteristics may constrain swimming during cruising travel, with convergence among diving specialists in the proportions and contraction rates of propulsive muscles.
198 citations
Authors
Showing all 84 results
Name | H-index | Papers | Citations |
---|---|---|---|
Paul M. Thompson | 183 | 2271 | 146736 |
Peter L. Tyack | 75 | 281 | 19108 |
Ian L. Boyd | 68 | 182 | 11838 |
Michael A. Fedak | 66 | 128 | 10968 |
Philip S. Hammond | 54 | 135 | 10066 |
Pejman Rohani | 52 | 192 | 13386 |
Mark Johnson | 46 | 131 | 8383 |
Patrick J. O. Miller | 42 | 142 | 5035 |
Luke Rendell | 39 | 109 | 6400 |
Ailsa J. Hall | 38 | 133 | 4428 |
Bernie J. McConnell | 35 | 77 | 4859 |
Patrick Pomeroy | 27 | 67 | 2576 |
Callan Duck | 25 | 48 | 2384 |
Martin Biuw | 25 | 61 | 2410 |
Lars Boehme | 24 | 64 | 2180 |