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. (2004). A new proposal for spherical cap harmonic modelling. Geophysical journal international, 159(2), 83–103.
Abstract: The geomagnetic field above the surface of the Earth in the current-free region may be expressed as the gradient of a scalar potential solving Laplace's equation. For regions with a fairly dense coverage of data at different altitudes, a regional model ought to offer a better spatial resolution of the regional field over the volume under study than a global field expanded in spherical harmonics (SH). The spherical cap harmonics analysis (SCHA) is an attractive regional modelling tool having close relationship with global SH. With the SCHA adopted so far, difficulties arise in upward continuation and in establishing a relationship between global and local Gauss coefficients. Such a relationship would be useful, for instance, for introducing prior constraint on an inverse problem dealing with the estimation of local Gauss coefficients based upon a local data set. In this paper, we show that these difficulties are overcome if the SCHA modelling is formulated as a boundary value (BV) problem in a cone bounded radially by the surface of the Earth and an upper surface suitable for satellite data, and bounded laterally in order to encompass a specific region of study. Although the example worked out here applies only to a limited class of fields, which verifies some special flux condition, the ideas behind this formalism are quite general and should offer a new way of processing data in a bounded region of space.
Keywords: magnetic field, regional modelling, spherical cap harmonic analysis
Programme: 139;905
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. (2011). Development of fasting abilities in subantarctic fur seal pups: balancing the demands of growth under extreme nutritional restrictions
. 0269-8463, 25(3), 704–717.
Keywords: body fat, energy conservation, fuel partitioning, growth strategy, maternal care, offspring survival, pinnipeds, protein sparing,
Programme: 109;119
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. (2018). Sex identification in King Penguins Aptenodytes patagonicus through morphological and acoustic cues (Vol. 160). Bachelor's thesis, , .
Abstract: In the context of sexual selection, animals have developed a variety of cues conveying information about the sex of an individual to conspecifics. In many colonial seabird species, where females and males are monomorphic and do not show obvious differences in external morphology, acoustic cues are an important signal for individual and sex recognition. Here, we study the vocal and morphological sex dimorphism in the King Penguin Aptenodytes patagonicus, a colonial, monomorphic seabird for which our knowledge about the role of vocalizations and morphology in mate choice is very limited. Data were collected at Possession Island, Crozet Archipelago, in a breeding colony consisting of about 16 000 breeding pairs. Using measurements of six morphological features and analysing acoustic parameters of call recordings of adult individuals, we show that King Penguins can be sexed based on a single morphological measurement of the beak with an accuracy of 79%. We found a sex-specific syntax in adult King Penguin calls that provided a 100% accurate method to distinguish between the sexes in our study population. To confirm the method at the species level, we analysed calls recorded from King Penguin adults in Kerguelen Island, 1300 km away from our study population and found the same accuracy of the sex-specific syntax. This sex-specific syllable arrangement is rare in non-passerines and is a first step in understanding the mate choice process in this species. Furthermore, it offers a cost-effective, non-invasive technique for researchers to sex King Penguins in the field.
Keywords: morphology penguins seabird sexing methods sexual selection vocal sex recognition
Programme: 137,354
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. (2018). Discriminating uniparental and biparental breeding strategies by monitoring nest temperature (Vol. 160). Bachelor's thesis, , .
Keywords: arctic Calidris alba discriminant function incubation strategy nest attendance nest temperature parental care shorebirds
Programme: 1036
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. (2019). Large birds travel farther in homogeneous environments (Vol. 28). Bachelor's thesis, , .
Keywords: enhanced vegetation index landscape complementation movement ecology productivity spatial behaviour terrestrial birds waterbirds
Programme: 388,1091
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. (2021). Meeting Paris agreement objectives will temper seabird winter distribution shifts in the North Atlantic Ocean (Vol. 27). Bachelor's thesis, , .
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. (2018). (Vol. 24). Bachelor's thesis, , .
Keywords: Antarctic breeding success diving activity foraging strategies Pygoscelis adeliae sea ice
Programme: 109,394,1091
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D. B. Green, S. Bestley, R. Trebilco, S. P. Corney, P. Lehodey, C. R. McMahon, C. Guinet, Mark A. Hindell. (2020). Modelled mid-trophic pelagic prey fields improve understanding of marine predator foraging behaviour (Vol. 43). Bachelor's thesis, , .
Keywords: ecosystem modelling kerguelen plateau micronekton predators prey interaction southern elephant seal Southern Indian Ocean
Programme: 109,1201
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. (2022). Classic or hybrid? The performance of next generation ecological models to study the response of Southern Ocean species to changing environmental conditions (Vol. 28). Bachelor's thesis, , .
Keywords: Bayesian inference data-poor systems integrated approaches Kerguelen Islands sea urchin species distribution modelling
Programme: 688,1044
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. (2020). Cryptic speciation in gentoo penguins is driven by geographic isolation and regional marine conditions: Unforeseen vulnerabilities to global change (Vol. 26). Bachelor's thesis, , .
Abstract: Aim The conservation of biodiversity is hampered by data deficiencies, with many new species and subspecies awaiting description or reclassification. Population genomics and ecological niche modelling offer complementary new tools for uncovering functional units of phylogenetic diversity. We hypothesize that phylogenetically delineated lineages of gentoo penguins (Pygoscelis papua) distributed across Antarctica and sub-Antarctic Islands are subject to spatially explicit ecological conditions that have limited gene flow, facilitating genetic differentiation, and thereby speciation processes. Location Antarctica and sub-Antarctic area. Methods We identify divergent lineages for gentoo penguins using ddRAD-seq and mtDNA, and generated species distribution models (SDMs) based on terrestrial and marine parameters. Results Analyses of our genomic data supports the existence of four major lineages of gentoo penguin: (i) spanning the sub-Antarctic archipelagos north of the Antarctic Polar Front (APF); (ii) Kerguelen Island; (iii) South America; and (iv) across maritime Antarctic and the Scotia Arc archipelagos. The APF, a major current system around Antarctica, acts as the most important barrier separating regional sister lineages. Our ecological analyses spanning both the terrestrial (breeding sites) and marine (feeding sites) realms recover limited niche overlap among the major lineages of gentoo penguin. We observe this pattern to correspond more closely with regional differentiation of marine conditions than to terrestrial macroenvironmental features. Main conclusions Recognition of regional genetic lineages as discrete evolutionary entities that occupy distinct ecological niches and also differ morphologically should be considered a priority for conservation. Gentoo penguins provide a good example of how conservation policy can be directly impacted by new insights obtained through the integration of larger genomic datasets with novel approaches to ecological modelling. This is particularly pertinent to polar environments that are among the most rapidly changing environments on earth.
Keywords: diversification ecological niche overlap gentoo penguin subspecies
Programme: 137,354
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