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Browsing Artikler, rapporter og annet (arktisk og marin biologi) by Author
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Rabindranath, Ananda; Daase, Malin; Falk-Petersen, Stig; Wold, Anette; Wallace, M.I.; Berge, Jørgen; Brierley, A. S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: The diel vertical migration (DVM) of Calanus (Calanus finmarchicus, Calanus glacialis and Calanus hyperboreus) and Metridia longa was investigated in August 2008 at six locations to the north and northwest of Svalbard (Rijpfjorden, Ice, Marginal Ice Zone, Shelf break, Shelf and Kongsfjorden). Despite midnight sun conditions, a diel light cycle was clearly observed at all stations. We collected data on zooplankton vertical distribution using a Multi Plankton Sampler (200-μm mesh size) and an EK60 echosounder system (38, 120 and 200 kHz). These were supplemented by environmental data collected using a standard conductivity, temperature and depth (CTD) profiler. The sea ice had recently opened in Rijpfjorden, Ice and Shelf stations, and these stations exhibited phytoplankton bloom conditions with pronounced fluorescence maxima at approximately 30 m. In contrast, Kongsfjorden was more representative of autumn conditions, with the Arctic bloom having culminated 2–3 months prior to sampling. All three Calanus species were found shallower than 50 m on average at Rijpfjorden and the Ice station, while C. glacialis and C. hyperboreus were found deeper than 200 m on average at Kongsfjorden. Shallow water DVM behaviour (<50 m) was observed at Rijpfjorden and the Shelf station, especially among the C. finmarchicus CI-CIII population, which was particularly abundant at the Shelf (>5,000 individuals/m3). A bimodal depth distribution was observed among C. finmarchicus at the Shelf break station, with CI-CIII copepodites dominating at depths shallower than 100 m and CIV-adult stages dominating at depths exceeding 600 m. Statistical analyses revealed significant differences between the day and night 200-kHz data, particularly at specified depth strata (25–50 m) where backscatter intensity was higher during the day, especially in Rijpfjorden and at the Ice station. We conclude that DVM signals exist in the Arctic during late summer/autumn, when a need to feed and an abundant food source exists, and these signals are primarily due to mesozooplankton. Description: This article is part of Anette Wold's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/4152 URI: http://hdl.handle.net/10037/4036 File(s) in this item: 1
article.pdf (1.103Mb) -
Ravolainen, Virve; Bråthen, Kari Anne; Ims, Rolf Anker; Yoccoz, Nigel; Henden, John-André; Killengreen, Siw Turid (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: Productive tundra plant communities composed of a variety of fast growing herbaceous and woody plants are likely to attract mammalian herbivores. Such vegetation is likely to respond to different-sized herbivores more rapidly than currently acknowledged from the tundra. Accentuated by currently changing populations of arctic mammals there is a need to understand impacts of different-sized herbivores on the dynamics of productive tundra plant communities. Here we assess the differential effects of ungulate (reindeer) and small rodent herbivores (voles and lemmings) on high productive tundra vegetation. A spatially extensive exclosure experiment was run for three years on river sediment plains along two river catchments in low-arctic Norway. The river catchments were similar in species pools but differed in species abundance composition of both plants and vertebrate herbivores. Biomass of forbs, deciduous shrubs and silica-poor grasses increased by 40–50% in response to release from herbivory, whereas biomass of silica-rich grasses decreased by 50–75%. Hence both additive and compensatory effects of small rodents and reindeer exclusion caused these significant changes in abundance composition of the plant communities. Changes were also rapid, evident after only one growing season, and are among the fastest and strongest ever documented in Arctic vegetation. The rate of changes indicates a tight link between the dynamics of productive tundra vegetation and both small and large herbivores. Responses were however not spatially consistent, being highly different between the catchments. We conclude that despite similar species pools, variation in plant species abundance and herbivore species dynamics give different prerequisites for change. URI: http://hdl.handle.net/10037/4097 File(s) in this item: 1
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Rikardsen, Audun H.; Hansen, L. P.; Jensen, A. J.; Vollen, Tone; Finstad, Bengt (Journal article; Tidsskriftartikkel; Peer reviewed, 13-Jan-2008)[+][-]
Abstract: Three tagged Atlantic salmon Salmo salar were recaptured as subadults/adults (1.4 - 3 kg) between 70.5º - 78º N in the western Barents Sea; two of the fish originated from the Alta Fjord region in northern Norway and one from the Drammen River, south-eastern Norway. An additional tag was recovered from the stomach of a Greenland halibut captured south-west of Bear Island at >600m depth; this tag was from a smolt released in the River Alta one month earlier. These are the northernmost tag recoveries reported for Atlantic salmon, and indicate that Norwegian salmon, especially the fish from northern populations, may use the northern Barents Sea as a feeding area during part of their life cycle. Description: Dette er forfatternes aksepterte versjon. This is the author’s final accepted manuscript. URI: http://hdl.handle.net/10037/2234 File(s) in this item: 1
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Rodnikova, Anna; Ims, Rolf Anker; Sokolov, Alexander; Skogstad, Gunhild; Sokolov, Vasily; Shtro, Victor; Fuglei, Eva (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: Here, we report from the first direct observation of a red fox (Vulpes vulpes) intrusion on an arctic fox (Vulpes lagopus) breeding den from the southern Arctic tundra of Yamal Peninsula, Russia in 2007. At the same time, as a current range retraction of the original inhabitant of the circumpolar tundra zone the arctic fox is going on, the red fox is expanding their range from the south into arctic habitats. Thus, within large parts of the northern tundra areas the two species are sympatric which gives opportunities for direct interactions including interference competition. However, direct first-hand observations of such interactions are rare, especially in the Russian Arctic. In the present study, we observed one red fox taking over an arctic fox breeding den which resulted in den abandonment by the arctic fox. On July 19, eight arctic fox pups were observed on the den before the red fox was observed on the same den July 22. The pups were never seen at the den or elsewhere after the red fox was observed on the den for as long as we stayed in the area (until August 10). Our observation supports the view that direct interference with red fox on breeding dens may contribute to the range retraction of arctic foxes from the southern limits of the Arctic tundra in Russia. URI: http://hdl.handle.net/10037/4052 File(s) in this item: 1
article.pdf (2.015Mb) -
Rædergård, V.B.; Mathiesen, S.D.; Vader, M.A.; Haga, Ø.E.; Norberg, H.J.; Sørmo, W.; Tyler, N.J.C. (Journal article; Peer reviewed, 1999)[+][-]
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Wiig, Øystein; Rødven, Rolf; Yoccoz, Nigel Gilles; Ims, Rolf Anker (Journal article; Peer reviewed, 2006)[+][-]
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Santos, Jorge (Research report; Forskningsrapport, May-2008)[+][-]
Abstract: Gerir pescarias artesanais é tarefa muito complexa em qualquer parte do mundo, e não existem receitas prontas de como o fazer. Os objectivos do presente trabalho são fazer uma ordenação sistemática dos principais conflitos endógenos e exógenos da pesca artesanal, incluindo uma análise do estado das pescarias, da interacção entre frotas, e da relação das pescas com assuntos de conservação e outras actividades humanas junto ao litoral; segundo, fazer uma classificação geral das pescarias tomando em conta o seu presumível estado de desenvolvimento e maturidade; e, por fim, sugerir modelos de intervenção e participação na gestão integrada das diversas pescarias face ao estado dos recursos, ambiente e o nível da concertação social local. O trabalho dirige-se à administração pesqueira central e provincial, sendo feitas dezenas de sugestões para possíveis linhas de trabalho, com um horizonte de 5-10 anos. URI: http://hdl.handle.net/10037/1704 File(s) in this item: 1
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Seuthe, Lena; Iversen, Kriss Wenche Rokkan (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: The composition and ecological role of ciliates and dinoflagellates were investigated at one station in Kongsfjorden, Svalbard, during six consecutive field campaigns between March and December 2006. Total ciliate and dinoflagellate abundance mirrored the seasonal progression of phytoplankton, peaking with 5.8 9 104 cells l-1 in April at an average chlorophyll a concentration of 10 lg l-1. Dinoflagellates were more abundant than ciliates, dominated by small athecates. Among ciliates, aloricate oligotrichs dominated the assemblage. A large fraction ([60%) of ciliates and dinoflagellates contained chloroplasts in spring and summer. The biomass of the purely heterotrophic fraction of the ciliate and dinoflagellate community (protozooplankton) was with 14 lg C l-1 highest in conjunction with the phytoplankton spring bloom in April. Growth experiments revealed similar specific growth rates for heterotrophic ciliates and dinoflagellates (\0–0.8 d-1). Food availability may have controlled the protozooplankton assemblage in winter, while copepods may have exerted a strong control during the post-bloom period. Calculations of the potential grazing rates of the protozooplankton indicated its ability to control or heavily impact the phytoplankton stocks at most times. The results show that ciliates and dinoflagellates were an important component of the pelagic food web in Kongsfjorden and need to be taken into account when discussing the fate of phytoplankton and biogeochemical cycling in Arctic marine ecosystems. Description: This paper is part of Lena Seuthe's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3777 URI: http://hdl.handle.net/10037/3778 File(s) in this item: 1
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Siwertsson, Anna; Knudsen, Rune; Kahilainen, Kimmo; Præbel, Kim; Primicerio, Raul; Amundsen, Per-Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2010)[+][-]
Abstract: In adaptive radiations, ecological opportunity (i.e. niche availability) is considered to be an important driver to increase phenotypic variation, but diversity may also be constrained by historical factors related to colonization events. How do ecological opportunity and post-glacial colonization history affect the phenotypic diversity in a young species lineage? We quantified phenotypic diversity by the number of co-existing morphs and a heritable morphological trait (gill raker number) in 39 European whitefish (Coregonus lavaretus) populations. Level of diversity was compared within and between three sub-arctic watercourses, and explored in relation to ecological opportunity (habitat availability and lake productivity) and colonization history (lake elevation and position). We found three main distribution patterns of gill raker number: unimodal (approximate range 20–30), bimodal (20–30 vs. 30–40), and trimodal (15–20 vs. 20–30 vs. 30–40), representing monomorphic, dimorphic, and trimorphic populations respectively. In addition, a pattern intermediate to the monomorphic and dimorphic populations was recorded in all watercourses. Polymorphism increased from west to east among watercourses, which can mainly be explained by post-glacial colonization history. Higher diversity was also observed in downstream sites within each watercourse, and increased with lake size and productivity. Our findings confirm that both ecological opportunity and historical constraints related to post-glacial colonization influence phenotypic patterns in a diverging lineage. Description: This article is part of Anna Siwertsons' doctoral thesis. Available in Munin at http://hdl.handle.net/10037/4566 URI: http://hdl.handle.net/10037/4754 File(s) in this item: 1
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Sokolov, Vasily; Ehrich, Dorothee; Yoccoz, Nigel; Sokolov, Alexander; Lecomte, Nicolas (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: The ratio of habitat generalists to specialists in birds has been suggested as a good indicator of ecosystem changes due to e.g. climate change and other anthropogenic perturbations. Most studies focusing on this functional component of biodiversity originate, however, from temperate regions. The Eurasian Arctic tundra is currently experiencing an unprecedented combination of climate change, change in grazing pressure by domestic reindeer and growing human activity. Here we monitored bird communities in a tundra landscape harbouring shrub and open habitats in order to analyse bird habitat relationships and quantify habitat specialization. We used ordination methods to analyse habitat associations and estimated the proportions of specialists in each of the main habitats. Correspondence Analysis identified three main bird communities, inhabiting upland, lowland and dense willow shrubs. We documented a stable structure of communities despite large multiannual variations of bird density (from 90 to 175 pairs/km2). Willow shrub thickets were a hotspot for bird density, but not for species richness. The thickets hosted many specialized species whose main distribution area was south of the tundra. If current arctic changes result in a shrubification of the landscape as many studies suggested, we would expect an increase in the overall bird abundance together with an increase of local specialists, since they are associated with willow thickets. The majority of these species have a southern origin and their increase in abundance would represent a strengthening of the boreal component in the southern tundra, perhaps at the expense of species typical of the subarctic zone, which appear to be generalists within this zone. URI: http://hdl.handle.net/10037/4970 File(s) in this item: 1
article.pdf (1.158Mb) -
Strand, Jo Espen Tau; Davidsen, Jan Grimsrud; Jørgensen, Even Hjalmar; Rikardsen, Audun (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: Two groups of migrating wild Atlantic salmon (Salmo salar) smolts caught within a 1 week interval in the River Alta, northern Norway, were tagged with acoustic transmitters and measured for gill Na+, K+ -ATPase activity in order to compare their smolt status with timing of sea entry. The first group of smolts had low levels of gill Na+, K+ -ATPase activity and resided in the lower part of the river twice as long as the second group that had high levels of gill Na+, K+ -ATPase activity. This indicates that early migrating smolts may not be completely physiologically adapted for salt water and delay their sea entry, thereby also synchronizing their seaward migration with the later migrating smolts.Seaward migrating Atlantic salmon smolts with low levels of gill Na+, K+ -ATPase activity; is sea entry delayed? [Published online: 16 november 2010] URI: http://hdl.handle.net/10037/4003 File(s) in this item: 1
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Sørum, Vidar; Figenschou, Lars; Rudolfsen, Geir; Folstad, Ivar (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: A mismatch in timing between the release of male and female gametes in external fertilizers may lead to failed fertilization or, under sperm competition, reduced paternity. To quantify the actual synchrony of gamete release and the level of sperm competition we placed video cameras on two spawning grounds of a naturally spawning population of Arctic charr ( Salvelinus alpinus). Females release eggs in response to courting (quivering) in less than 1% of the cases, yet to both dominant and sneaker males. That is, females initiated spawning with dominant males in 73.3% of the recorded spawning events. Although the actual spawning seems to be largely under female control, 55.6% of spawning events occur under sperm competition. The average time delay between dominant and sneaker males milt release under sperm competition is 0.68 s. Thus, female reproductive decisions seem to be strongly influenced by male-male competition and this may have set the stage for the evolution and maintenance of the observed plasticity in ejaculate characteristics of male charr. URI: http://hdl.handle.net/10037/4055 File(s) in this item: 1
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Tadesse, Margey; Gulliksen, Bjørn; Strøm, Morten B.; Styrvold, Olaf B.; Haug, Tor (Journal article; Tidsskriftartikkel; Peer reviewed, 18-Jun-2008)[+][-]
Abstract: Benthic marine invertebrates collected from sub-Arctic regions of northern Norway, were found to be a promising source of novel bioactive compounds against human and fish pathogenic bacteria and fungi. Lyophilized material from seven species of ascidians, six sponges and one soft alcyonid coral were extracted with 60% acidified acetonitrile (ACN). After separation into an ACN-rich phase (ACN extract) and an aqueous phase, and subsequent solid phase extraction of the aqueous phase, fractions differing in polarity were obtained and screened for antibacterial and antifungal activities, along with the more lipophilic ACN-extracts. Antimicrobial activity was determined against two Gram-negative, two Gram-positive bacteria, and two strains of fungi. Notably, all the invertebrate species in the study showed activity against all four strains of bacteria and the two strains of fungi. In general, the aqueous fractions displayed highest antimicrobial activity, and the most potent extracts were obtained from the colonial ascidian Synoicum pulmonaria which displayed activity against bacteria and fungi at a concentration of 0.02 mg/ml; the lowest concentration tested. Description: This is the accepted manuscript version of the article. Reprinted with permission. Published version is available at http://dx.doi.org/10.1016/j.jip.2008.06.009
The published version of this article is part of Margey Tasesse's doctoral thesis, which is available at http://hdl.handle.net/10037/2702URI: http://hdl.handle.net/10037/2728 File(s) in this item: 1
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Tamelander, Tobias; Aubert, Anais; Wexels Riser, Christian (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: Sinking of particles is a key mechanism in the transport of organic matter from the ocean’s productive surface layer to the deep sea and sediments, but also constitutes a loss of carbon and growth-limiting nutrients to the pelagic food web. Knowledge on export of particulate phosphorus is limited, particularly in high-latitude regions, in spite of its role as a co-limiting factor in many marine systems. We therefore investigated suspended concentrations and vertical export (by means of sediment traps) of particulate organic carbon (POC), nitrogen (PON) and total particulate phosphorus (TPP) at 3 contrasting sites in the Fram Strait and Barents Sea opening and quantified the contribution of zooplankton faecal pellets to POC, PON and TPP export. The TPP fluxes are the first to be reported from this region and probably the first from the entire Arctic Ocean. The suspended and exported C:N ratios were close to the Redfield ratio and did not differ significantly from each other (mean atomic ratios of 6.1 and 6.3, respectively). The mean C:P of suspended particles (91) was below Redfield, whereas the exported mean (117) exceeded Redfield, indicating more efficient retention of phosphorus than of nitrogen in the water column. Copepod faecal pellets had low C:P ratios and contributed a higher proportion to phosphorus export (mean of 17%) than to carbon and nitrogen export (10%). Faecal pellets may therefore be an important loss factor for phosphorus from the water column compared to slower-sinking material, which is retained more efficiently. URI: http://hdl.handle.net/10037/5032 File(s) in this item: 1
article.pdf (892.2Kb) -
Tveit, Alexander Tøsdal; Schwacke, Rainer; Svenning, Mette Marianne; Urich, Tim (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: A substantial part of the Earths’ soil organic carbon (SOC) is stored in Arctic permafrost peatlands, which represent large potential sources for increased emissions of the greenhouse gases CH4 and CO2 in a warming climate. The microbial communities and their genetic repertoire involved in the breakdown and mineralisation of SOC in these soils are, however, poorly understood. In this study, we applied a combined metagenomic and metatranscriptomic approach on two Arctic peat soils to investigate the identity and the gene pool of the microbiota driving the SOC degradation in the seasonally thawed active layers. A large and diverse set of genes encoding plant polymer-degrading enzymes was found, comparable to microbiotas from temperate and subtropical soils. This indicates that the metabolic potential for SOC degradation in Arctic peat is not different from that of other climatic zones. The majority of these genes were assigned to three bacterial phyla, Actinobacteria, Verrucomicrobia and Bacteroidetes. Anaerobic metabolic pathways and the fraction of methanogenic archaea increased with peat depth, evident for a gradual transition from aerobic to anaerobic lifestyles. A population of CH4-oxidising bacteria closely related to Methylobacter tundripaludum was the dominating active group of methanotrophs. Based on the in-depth characterisation of the microbes and their genes, we conclude that these Arctic peat soils will turn into CO2 sources owing to increased active layer depth and prolonged growing season. However, the extent of future CH4 emissions will critically depend on the response of the methanotrophic bacteria. URI: http://hdl.handle.net/10037/5033 File(s) in this item: 1
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Ulvevadet, Birgitte (Journal article; Tidsskriftartikkel; Peer reviewed, 2008)[+][-]
Abstract: Many governments have come to realize that the best way to manage natural resources is to include the resource users in order to increase legitimacy for governance. For the Sami reindeer industry, the Norwegian government has implemented two different management models in order to meet this challenge. On the one hand, there is a corporative management model where a few democratically elected reindeer owners represent the whole industry in the annual negotiations with the government. On the other hand, there is a co-management model where reindeer owners are represented in boards at the local, regional and national levels where the government has delegated a number of management functions. In addition, there is also a hierarchical administrative management system, with only public officials as employees. Nevertheless, through media, surveys and interviews, there has been observed some dissatisfaction among reindeer owners; they claim that the system is not inclusive. I argue that the election of reindeer owners to the different co-management boards and the election of reindeer owners to the corporative units have been challenging because it is difficult to establish systems of representation that are fair for everyone. I also argue that it is complicated to make such comprehensive systems work in practice, as initially planned on paper. URI: http://hdl.handle.net/10037/1705 File(s) in this item: 1
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Ursvik, Anita; Breines, Ragna; Christiansen, Jørgen Schou; Fevolden, Jan-Erik; Coucheron, Dag H.; Johansen, Steinar D. (Journal article; Tidsskriftartikkel; Peer reviewed, 07-Jun-2007)[+][-]
Abstract: Background: The walleye pollock (Theragra chalcogramma) and Norwegian pollock (T. finnmarchica) are confined to the North Pacific and North Atlantic Oceans, respectively, and considered as distinct species within the family Gadidae. We have determined the complete mtDNA nucleotide sequence of two specimens of Norwegian pollock and compared the sequences to that of 10 specimens of walleye pollock representing stocks from the Sea of Japan and the Bering Sea, 2 specimens of Atlantic cod (Gadus morhua), and 2 specimens of haddock (Melanogrammus aeglefinus). Results: A total number of 204 variable positions were identified among the 12 pollock specimens, but no specific substitution pattern could be identified between the walleye and Norwegian pollocks. Phylogenetic analysis using 16.500 homologous mtDNA nucleotide positions clearly identify the Norwegian pollock within the walleye pollock species cluster. Furthermore, the Norwegian pollock sequences were most similar to mitochondrial genotypes present in walleye pollock specimens from the Sea of Japan, an observation supported both by neighbor-joining, maximum parsimony, and maximum likelihood analyses. Conclusion: We infer that walleye pollock and Norwegian pollock represent one single species and that Norwegian pollock has been recently introduced from the Pacific to the Atlantic Oceans. URI: http://hdl.handle.net/10037/1155 File(s) in this item: 1
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Valentini, Alice; Soininen, Eeva Marjatta; Coissac, Eric; Ims, Rolf Anker; Miquel, Christian; Yoccoz, Nigel Gilles; Gielly, Ludovic; Brochmann, Christian; Brysting, Anne K.; Sønstebø, Jørn H.; Taberlet, Pierre (Journal article; Tidsskriftartikkel; Peer reviewed, 20-Aug-2009)[+][-]
Abstract: Background: In order to understand the role of herbivores in trophic webs, it is essential to know what they feed on. Diet analysis is, however, a challenge in many small herbivores with a secretive life style. In this paper, we compare novel (high-throughput pyrosequencing) DNA barcoding technology for plant mixture with traditional microhistological method. We analysed stomach contents of two ecologically important subarctic vole species, Microtus oeconomus and Myodes rufocanus, with the two methods. DNA barcoding was conducted using the P6-loop of the chloroplast trnL (UAA) intron.
Results: Although the identified plant taxa in the diets matched relatively well between the two methods, DNA barcoding gave by far taxonomically more detailed results. Quantitative comparison of results was difficult, mainly due to low taxonomic resolution of the microhistological method, which also in part explained discrepancies between the methods. Other discrepancies were likely due to biases mostly in the microhistological analysis.
Conclusion: We conclude that DNA barcoding opens up for new possibilities in the study of plant-herbivore interactions, giving a detailed and relatively unbiased picture of food utilization of herbivores.URI: http://hdl.handle.net/10037/2195 File(s) in this item: 1
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Van Oort, B.E.H.; Tyler, N.J.C.; Reierth, E.; Stokkan, K.-A. (Journal article; Peer reviewed, 2000)[+][-]
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Vaz Serrano, Jonathan; Folstad, Ivar; Rudolfsen, Geir; Figenschou, Lars (Journal article; Tidsskriftartikkel; Peer reviewed, 2006)[+][-]
Abstract: Theoretical models predict that subordinate males should have higher sperm velocity to compensate for their disadvantaged mating role and because they experience sperm competition more frequently than dominant males. Differences in mean velocity between sperm of dominants and subordinates in the predicted direction are also documented for a few species, including the Arctic char, Salvelinus alpinus (L., 1758). Yet, this difference in mean velocity does not imply that the fastest sperm within an ejaculate, which are those most likely to fertilize eggs, swim faster in subordinates than in dominants. We studied the 5% and 10% fastest sperm cells in ejaculates of dominant and subordinate Arctic char. Before individuals attained their status, there were no differences in velocity between the fastest sperm of males that later became dominant or subordinate. Yet, after establishment of social position, subordinates showed significantly higher sperm swimming speed of the fastest cells in the first 30s post activation (i.e., at 15, 20, and 30s post activation). Males that became subordinates showed no change in sperm speed of the fast cells compared with those at pre-trial levels, whereas males that became dominant reduced the speed of their sperm (15s post activation) compared with those at pre-trial levels. Our results suggest that males which attain social dominance are unable to maintain high sperm velocity, even among the small fraction of the fastest cells. URI: http://hdl.handle.net/10037/4789 File(s) in this item: 1
article.pdf (141.2Kb)
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