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Title |
Exposing the structure of an Arctic food web |
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Journal |
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Year |
2015 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
5 |
Issue |
17 |
Pages |
3842-3856 |
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Keywords |
Calidris DNA barcoding generalism Greenland Hymenoptera molecular diet analysis Pardosa Plectrophenax specialism Xysticus |
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Abstract |
Abstract How food webs are structured has major implications for their stability and dynamics. While poorly studied to date, arctic food webs are commonly assumed to be simple in structure, with few links per species. If this is the case, then different parts of the web may be weakly connected to each other, with populations and species united by only a low number of links. We provide the first highly resolved description of trophic link structure for a large part of a high-arctic food web. For this purpose, we apply a combination of recent techniques to describing the links between three predator guilds (insectivorous birds, spiders, and lepidopteran parasitoids) and their two dominant prey orders (Diptera and Lepidoptera). The resultant web shows a dense link structure and no compartmentalization or modularity across the three predator guilds. Thus, both individual predators and predator guilds tap heavily into the prey community of each other, offering versatile scope for indirect interactions across different parts of the web. The current description of a first but single arctic web may serve as a benchmark toward which to gauge future webs resolved by similar techniques. Targeting an unusual breadth of predator guilds, and relying on techniques with a high resolution, it suggests that species in this web are closely connected. Thus, our findings call for similar explorations of link structure across multiple guilds in both arctic and other webs. From an applied perspective, our description of an arctic web suggests new avenues for understanding how arctic food webs are built and function and of how they respond to current climate change. It suggests that to comprehend the community-level consequences of rapid arctic warming, we should turn from analyses of populations, population pairs, and isolated predator?prey interactions to considering the full set of interacting species. |
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1036 |
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2045-7758 |
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2045-7758 |
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yes |
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7282 |
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Title |
Effects of food abundance and early clutch predation on reproductive timing in a high Arctic shorebird exposed to advancements in arthropod abundance |
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Journal |
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Year |
2016 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
6 |
Issue |
20 |
Pages |
7375-7386 |
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Keywords |
Bird migration Calidris alba chick growth climate change nest survival phenology timing trophic interactions trophic mismatch |
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Abstract |
Climate change may influence the phenology of organisms unequally across trophic levels and thus lead to phenological mismatches between predators and prey. In cases where prey availability peaks before reproducing predators reach maximal prey demand, any negative fitness consequences would selectively favor resynchronization by earlier starts of the reproductive activities of the predators. At a study site in northeast Greenland, over a period of 17 years, the median emergence of the invertebrate prey of Sanderling Calidris alba advanced with 1.27 days per year. Yet, over the same period Sanderling did not advance hatching date. Thus, Sanderlings increasingly hatched after their prey was maximally abundant. Surprisingly, the phenological mismatches did not affect chick growth, but the interaction of the annual width and height of the peak in food abundance did. Chicks grew especially better in years when the food peak was broad. Sanderling clutches were most likely to be depredated early in the season, which should delay reproduction. We propose that high early clutch predation may favor a later reproductive timing. Additionally, our data suggest that in most years food was still abundant after the median date of emergence, which may explain why Sanderlings did not advance breeding along with the advances in arthropod phenology. |
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2045-7758 |
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2045-7758 |
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yes |
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7306 |
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Title |
Experimental stress during molt suggests the evolution of condition-dependent and condition-independent ornaments in the king penguin |
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Year |
2018 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
8 |
Issue |
2 |
Pages |
1084-1095 |
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Keywords |
Corticosterone honest signal Immunity sexual selection social selection |
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Abstract |
Sexual selection and social selection are two important theories proposed for explaining the evolution of colorful ornamental traits in animals. Understanding signal honesty requires studying how environmental and physiological factors during development influence the showy nature of sexual and social ornaments. We experimentally manipulated physiological stress and immunity status during the molt in adult king penguins (Aptenodytes patagonicus), and studied the consequences of our treatments on colourful ornaments (yellow-orange and UV beak spots and yellow-orange auricular feather patches) known to be used in sexual and social contexts in this species. Whereas some ornamental features showed strong condition-dependence (yellow auricular feather chroma, yellow and UV chroma of the beak), others were condition-independent and remained highly correlated before and after the molt (auricular patch size and beak UV hue). Our study provides a rare examination of the links between ornament determinism and selection processes in the wild. We highlight the coexistence of ornaments costly to produce that may be honest signals used in mate choice, and ornaments for which honesty may be enforced by social mediation or rely on genetic constraints. |
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119 |
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2045-7758 |
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2045-7758 |
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yes |
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Call Number |
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Serial |
7370 |
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Author |
Florian Orgeret, Sam L. Cox, Henri Weimerskirch, Christophe Guinet |
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Title |
Body condition influences ontogeny of foraging behavior in juvenile southern elephant seals |
Type |
Journal |
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Year |
2019 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
9 |
Issue |
1 |
Pages |
223-236 |
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Keywords |
accelerometers diving behavior early-life first-year juveniles foraging behavior ontogeny satellite relay tags southern elephant seals |
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Abstract |
Ontogeny of diving and foraging behavior in marine top predators is poorly understood despite its importance in population recruitment. This lack of knowledge is partly due to the difficulties of monitoring juveniles in the wild, which is linked to high mortality early in life. Pinnipeds are good models for studying the development of foraging behaviors because juveniles are large enough to robustly carry tracking devices for many months. Moreover, parental assistance is absent after a juvenile departs for its first foraging trip, minimizing confounding effects of parental input on the development of foraging skills. In this study, we tracked 20 newly weaned juvenile southern elephant seals from Kerguelen Islands for up to 338 days during their first trip at sea following weaning. We used a new generation of satellite relay tags, which allow for the transmission of dive, accelerometer, and location data. We also monitored, at the same time, nine adult females from the colony during their post-breeding trips, in order to compare diving and foraging behaviors. Juveniles showed a gradual improvement through time in their foraging skills. Like adults females, they remarkably adjusted their swimming effort according to temporal changes in buoyancy (i.e., a proxy of their body condition). They also did not appear to exceed their aerobic physiological diving limits, although dives were constrained by their smaller size compared to adults. Changes in buoyancy appeared to also influence their decision to either keep foraging or return to land, alongside the duration of their haul outs and choice of foraging habitat (oceanic vs. plateau). Further studies are thus needed to better understand how patterns in juveniles survival, and therefore elephant seal populations, might be affected by their changes in foraging skills and changes in their environmental conditions. |
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109,1201 |
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Thesis |
Bachelor's thesis |
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2045-7758 |
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2045-7758 |
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yes |
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Call Number |
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Serial |
7463 |
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Author |
Sam L. Cox, Matthieu Authier, Florian Orgeret, Henri Weimerskirch, Christophe Guinet |
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Title |
High mortality rates in a juvenile free-ranging marine predator and links to dive and forage ability |
Type |
Journal |
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Year |
2020 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
10 |
Issue |
1 |
Pages |
410-430 |
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Keywords |
bio-logging early life foraging ecology juvenile mortality Mirounga leonina southern elephant seal survival analyses |
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Abstract |
High juvenile mortality rates are typical of many long-lived marine vertebrate predators. Insufficient development in dive and forage ability is considered a key driver of this. However, direct links to survival outcome are sparse, particularly in free-ranging marine animals that may not return to land. In this study, we conduct exploratory investigations toward early mortality in juvenile southern elephant seals Mirounga leonina. Twenty postweaning pups were equipped with (a) a new-generation satellite relay data tag, capable of remotely transmitting fine-scale behavioral movements from accelerometers, and (b) a location transmitting only tag (so that mortality events could be distinguished from device failures). Individuals were followed during their first trip at sea (until mortality or return to land). Two analyses were conducted. First, the behavioral movements and encountered environmental conditions of nonsurviving pups were individually compared to temporally concurrent observations from grouped survivors. Second, common causes of mortality were investigated using Cox's proportional hazard regression and penalized shrinkage techniques. Nine individuals died (two females and seven males) and 11 survived (eight females and three males). All but one individual died before the return phase of their first trip at sea, and all but one were negatively buoyant. Causes of death were variable, although common factors included increased horizontal travel speeds and distances, decreased development in dive and forage ability, and habitat type visited (lower sea surface temperatures and decreased total [eddy] kinetic energy). For long-lived marine vertebrate predators, such as the southern elephant seal, the first few months of life following independence represent a critical period, when small deviations in behavior from the norm appear sufficient to increase mortality risk. Survival rates may subsequently be particularly vulnerable to changes in climate and environment, which will have concomitant consequences on the demography and dynamics of populations. |
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Programme |
109,1201 |
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Bachelor's thesis |
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2045-7758 |
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Approved |
yes |
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Call Number |
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Serial |
7667 |
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Title |
Underwater photogrammetry for close-range 3D imaging of dry-sensitive objects: The case study of cephalopod beaks |
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Journal |
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Year |
2021 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
11 |
Issue |
12 |
Pages |
7730-7742 |
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Keywords |
3D models cephalopod beaks dry-sensitive material micro-CT scanning micro-photogrammetry underwater photogrammetry |
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Abstract |
Technical advances in 3D imaging have contributed to quantifying and understanding biological variability and complexity. However, small, dry-sensitive objects are not easy to reconstruct using common and easily available techniques such as photogrammetry, surface scanning, or micro-CT scanning. Here, we use cephalopod beaks as an example as their size, thickness, transparency, and dry-sensitive nature make them particularly challenging. We developed a new, underwater, photogrammetry protocol in order to add these types of biological structures to the panel of photogrammetric possibilities. We used a camera with a macrophotography mode in a waterproof housing fixed in a tank with clear water. The beak was painted and fixed on a colored rotating support. Three angles of view, two acquisitions, and around 300 pictures per specimen were taken in order to reconstruct a full 3D model. These models were compared with others obtained with micro-CT scanning to verify their accuracy. The models can be obtained quickly and cheaply compared with micro-CT scanning and have sufficient precision for quantitative interspecific morphological analyses. Our work shows that underwater photogrammetry is a fast, noninvasive, efficient, and accurate way to reconstruct 3D models of dry-sensitive objects while conserving their shape. While the reconstruction of the shape is accurate, some internal parts cannot be reconstructed with photogrammetry as they are not visible. In contrast, these structures are visible using reconstructions based on micro-CT scanning. The mean difference between both methods is very small (10?5 to 10?4 mm) and is significantly lower than differences between meshes of different individuals. This photogrammetry protocol is portable, easy-to-use, fast, and reproducible. Micro-CT scanning, in contrast, is time-consuming, expensive, and nonportable. This protocol can be applied to reconstruct the 3D shape of many other dry-sensitive objects such as shells of shellfish, cartilage, plants, and other chitinous materials. |
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109 |
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2045-7758 |
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yes |
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8092 |
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Title |
Divergent ecological histories of two sister Antarctic krill species led to contrasted patterns of genetic diversity in their heat-shock protein (hsp70) arsenal |
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Year |
2016 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
6 |
Issue |
5 |
Pages |
1555-1575 |
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Keywords |
Balancing selection duplication heat-shock proteins krill sweep thermal adaptation |
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Abstract |
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Programme |
1039 |
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2045-7758 |
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yes |
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Serial |
8175 |
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Author |
Mark A. Hindell, Clive R. McMahon, Ian Jonsen, Robert Harcourt, Fernando Arce, Christophe Guinet |
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Title |
Inter- and intrasex habitat partitioning in the highly dimorphic southern elephant seal |
Type |
Journal |
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Year |
2021 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
11 |
Issue |
4 |
Pages |
1620-1633 |
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Keywords |
Antarctic Shelf foraging and diving behavior Kerguelen Plateau mid-year haul out predation risk Southern Ocean |
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Abstract |
Partitioning resources is a key mechanism for avoiding intraspecific competition and maximizing individual energy gain. However, in sexually dimorphic species it is difficult to discern if partitioning is due to competition or the different resource needs of morphologically distinct individuals. In the highly dimorphic southern elephant seal, there are intersexual differences in habitat use; at Iles Kerguelen, males predominantly use shelf waters, while females use deeper oceanic waters. There are equally marked intrasexual differences, with some males using the nearby Kerguelen Plateau, and others using the much more distant Antarctic continental shelf ( 2,000 km away). We used this combination of inter and intrasexual behavior to test two hypotheses regarding habitat partitioning in highly dimorphic species. (a) that intersexual differences in habitat use will not appear until the seals diverge in body size and (b) that some habitats have higher rates of energy return than others. In particular, that the Antarctic shelf would provide higher energy returns than the Kerguelen Shelf, to offset the greater cost of travel. We quantified the habitat use of 187 southern elephant seals (102 adult females and 85 subadult males). The seals in the two groups were the same size ( 2.4 m) removing the confounding effect of body size. We found that the intersexual differences in habitat use existed before the divergence in body size. Also, we found that the amount of energy gained was the same in all of the major habitats. This suggests that the use of shelf habitats by males is innate, and a trade-off between the need to access the large benthic prey available on shelf waters, against the higher risk of predation there. Intrasexual differences in habitat use are another trade-off; although there are fewer predators on the Antarctic shelf, it is subject to considerable interannual fluctuations in sea-ice extent. In contrast, the Kerguelen Plateau presents more consistent foraging opportunities, but contains higher levels of predation. Habitat partitioning in this highly dimorphic species is therefore the result of complex interplay of life history strategies, environmental conditions and predation pressure. |
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109,1201 |
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Bachelor's thesis |
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2045-7758 |
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yes |
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8243 |
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Title |
Sex, body size, and boldness shape the seasonal foraging habitat selection in southern elephant seals |
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Journal |
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Year |
2022 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
12 |
Issue |
1 |
Pages |
e8457 |
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Abstract |
Selecting foraging habitat is a fundamental behavior in the life of organisms as it directly links resource acquisition to fitness. Differences in habitat selection among individuals may arise from several intrinsic and extrinsic factors, and yet, their interaction has been given little attention in the study of wild populations. We combine sex, body size, and boldness to explain individual differences in the seasonal foraging habitat selection of southern elephant seals (Mirounga leonina) from the Kerguelen Archipelago. We hypothesize that habitat selection is linked to the trade-off between resource acquisition and risk, and that individuals differ in their position along this trade-off because of differences in reproductive strategies, life stages, and metabolic requirements. Before the post-molt foraging trip, we used a novel object approach test to quantify the boldness of 28 subadult and adult females and 42 subadult males and equipped them with data loggers to track their movements at sea. Subadult males selected neritic and oceanic habitats, whereas females mostly selected less productive oceanic habitats. Both sexes showed a seasonal shift from Antarctic habitats in the south in the summer to the free of ice subantarctic and subtropical habitats in the north in the winter. Males avoided oceanic habitats and selected more productive neritic and Antarctic habitats with body size mostly in the winter. Bolder males selected northern warmer waters in winter, while shyer ones selected the Kerguelen plateau and southern colder oceanic waters. Bolder females selected the Kerguelen plateau in the summer when prey profitability is assumed to be the highest. This study not only provides new insights into the spatiotemporal foraging ecology of elephant seals in relation to personality but also emphasizes the relevance of combining several intrinsic and extrinsic factors in understanding among-individual variation in space use essential in wildlife management and conservation. |
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109,1201 |
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Bachelor's thesis |
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2045-7758 |
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yes |
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Serial |
8405 |
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Author |
Dominique A. Cowart, Stefano Schiaparelli, Maria Chiara Alvaro, Matteo Cecchetto, Anne-Sophie Le Port, Didier Jollivet, Stephane Hourdez |
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Title |
Origin, diversity, and biogeography of Antarctic scale worms (Polychaeta: Polynoidae): a wide-scale barcoding approach |
Type |
Journal |
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Year |
2022 |
Publication |
Ecology and Evolution |
Abbreviated Journal |
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Volume |
12 |
Issue |
7 |
Pages |
e9093 |
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Keywords |
Antarctic biogeography benthic invertebrate DNA barcoding gene flow polynoid Southern Ocean species connectivity |
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1044 |
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2045-7758 |
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yes |
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Call Number |
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Serial |
8581 |
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