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- de Boer, Agatha M., et al.
(författare)
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Interconnectivity Between Volume Transports Through Arctic Straits
- 2018
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Ingår i: Journal of Geophysical Research - Oceans. - 2169-9275 .- 2169-9291. ; 123:12, s. 8714-8729
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Tidskriftsartikel (refereegranskat)abstract
- Arctic heat and freshwater budgets are highly sensitive to volume transports through the Arctic-Subarctic straits. Here we study the interconnectivity of volume transports through Arctic straits in three models; two coupled global climate models, one with a third-degree horizontal ocean resolution (High Resolution Global Environmental Model version 1.1 [HiGEM1.1]) and one with a twelfth-degree horizontal ocean resolution (Hadley Centre Global Environment Model 3 [HadGEM3]), and one ocean-only model with an idealized polar basin (tenth-degree horizontal resolution). The two global climate models indicate that there is a strong anticorrelation between the Bering Strait throughflow and the transport through the Nordic Seas, a second strong anticorrelation between the transport through the Canadian Arctic Archipelago and the Nordic Seas transport, and a third strong anticorrelation is found between the Fram Strait and the Barents Sea throughflows. We find that part of the strait correlations is due to the strait transports being coincidentally driven by large-scale atmospheric forcing patterns. However, there is also a role for fast wave adjustments of some straits flows to perturbations in other straits since atmospheric forcing of individual strait flows alone cannot lead to near mass balance fortuitously every year. Idealized experiments with an ocean model (Nucleus for European Modelling of the Ocean version 3.6) that investigate such causal strait relations suggest that perturbations in the Bering Strait are compensated preferentially in the Fram Strait due to the narrowness of the western Arctic shelf and the deeper depth of the Fram Strait. Plain Language Summary The Arctic is one of the most fragile places on the Earth, facing double the rate of warming as the rest of the globe. This warming is partly due to melting of sea ice because open water reflects less sunlight than ice. One of the major controls on Arctic sea ice concentration is the heat flowing into the Arctic through its straits. However, due to the harsh conditions in the Arctic, there are limited long-term observations of the currents flowing through these straits. Here we turn to climate models to investigate these Arctic straits flows and in particular focus on how flows into and out of the Arctic balance each other. We find that in some instances specific pairs of strait flows are simultaneously affected by large-scale atmospheric. In other instances, the inflow through one strait flows out through another distant strait because of the way the ocean floor guides the currents. Traditionally, the flows through Arctic straits are studied in relation to local forces such as wind and sea level. Our work suggests value in a more holistic approach; one that also accounts for flow changes in a strait as a response to flow changes in other straits.
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| 2. |
- Garzón-Orduña, Ivonne J., et al.
(författare)
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Wing pattern diversity in Eunica butterflies (Nymphalidae: Biblidinae) : phylogenetic analysis implies decoupled adaptive trends in dorsal sexual dimorphism and ventral eyespot evolution
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Ingår i: Cladistics. - 0748-3007.
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Tidskriftsartikel (refereegranskat)abstract
- Butterfly eyespots are wing patterns reminiscent of vertebrate eyes, formed by concentric rings of contrastingly coloured scales. Eyespots are usually located close to the wing margin and often regarded as the single most conspicuous pattern element of butterfly wing colour displays. Recent efforts to understand the processes involved in the formation of eyespots have been driven mainly by evo-devo approaches focused on model species. However, patterns of change implied by phylogenetic relationships can also inform hypotheses about the underlying developmental mechanisms associated with the formation or disappearance of eyespots, and the limits of phenotypic diversity occurring in nature. Here we present a combined evidence phylogenetic hypothesis for the genus Eunica, a prominent member of diverse Neotropical butterfly communities, that features notable variation among species in eyespot patterns on the ventral hind wing surface. The data matrix consists of one mitochondrial gene region (COI), four nuclear gene regions (GAPDH, RPS5, EF1a and Wingless) and 68 morphological characters. A combined cladistic analysis with all the characters concatenated produced a single most parsimonious tree that, although fully resolved, includes many nodes with modest branch support. The phylogenetic hypothesis presented corroborates a previously proposed morphological trend leading to the loss of eyespots, together with an increase in the size of the conserved eyespots, relative to outgroup taxa. Furthermore, wing colour pattern dimorphism and the presence of androconia suggest that the most remarkable instances of sexual dimorphism are present in the species of Eunica with the most derived eyespot patterns, and are in most cases accompanied by autapomorphic combinations of scent scales and “hair pencils”. We discuss natural and sexual selection as potential adaptive explanations for dorsal and ventral wing patterns.
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