| 1. |
- Dessborn, Lisa, 1976-, et al.
(författare)
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Pike predation affects breeding success and habitat selection of ducks
- 2011
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Ingår i: Freshwater Biology. - : Wiley: 12 months. - 0046-5070 .- 1365-2427. ; 56:3, s. 579-589
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Tidskriftsartikel (refereegranskat)abstract
- 1. Fish and ducks often belong to the same local food web, and several studies indicate that there is a general negative effect of fish on breeding ducks. This pattern has so far been addressed mainly within the framework of competition for common invertebrate prey, while predation by large fish as a force behind settlement and abundance patterns in ducks remains largely unknown. This is the first study to address the effect of fish predation on breeding ducks, isolated from that of competition, and the first experiment to explore the ability of ducks to identify and avoid lakes with high risk of fish predation. 2. We used a before-after control-impact design and 11 naturally fishless lakes. Waterfowl on the lakes were surveyed during the breeding season of 2005. Large adult pike (Esox lucius) were added to two lakes in early spring 2008, and waterfowl surveys were repeated on all 11 lakes. 3. Pike introduction did not affect the number of pairs on lakes during the nesting season in any of three focal duck species (mallard Anas platyrhynchos, teal Anas crecca, and goldeneye Bucephala clangula). During the brood-rearing season, however, there was a decrease in duck days in teal and goldeneye in lakes with pike, with similar trends observed in mallard. The number of goldeneye ducklings was also significantly lower in lakes with pike. We were unable to determine whether the response was attributable to direct pike predation or to broods leaving experimental lakes, but in either case, our study demonstrates high fitness costs for ducks breeding on lakes with pike. 4. The apparent inability of nesting ducks to detect pike and the clear fitness implications may influence the annual recruitment of ducks on a larger scale as pike are both common and widespread. Vegetation complexity and food abundance are likely to be of overriding importance when breeding ducks are choosing a nesting site. As pike have a strong influence on breeding birds, relying on vegetation and cues of food abundance, while ignoring indicators of predation risk from fish, could lead to lakes with pike acting as an ecological trap.
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| 2. |
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| 3. |
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| 4. |
- Barclay, C J, et al.
(författare)
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Efficiency of cross-bridges and mitochondria in mouse cardiac muscle
- 2010
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Ingår i: Muscle biophysics. - : Springer Berlin/Heidelberg. - 9781441963659 - 9781441963666 ; , s. 267-278
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Bokkapitel (refereegranskat)abstract
- The aim of this study was to make cellular-level measurements of the mechanical efficiency of mouse cardiac muscle and to use these measurements to determine (1) the work performed by a cross-bridge in one ATP-splitting cycle and (2) the fraction of the free energy available in metabolic substrates that is transferred by oxidative phosphorylation to free energy in ATP (i.e. mitochondrial thermodynamic efficiency). Experiments were performed using isolated left ventricular mouse papillary muscles (n = 9; studied at 27°C) and the myothermic technique. The production of work and heat was measured during and after 40 contractions at a contraction frequency of 2 Hz. Each contraction consisted of a brief isometric period followed by isovelocity shortening. Work output, heat output and enthalpy output were all independent of shortening velocity. Maximum initial mechanical efficiency (mean ± SEM) was 31.1 ± 1.3% and maximum net mechanical efficiency 16.9 ± 1.5%. It was calculated that the maximum work per cross-bridge cycle was 20 zJ, comparable to values for mouse skeletal muscle, and that mitochondrial thermodynamic efficiency was 72%. Analysis of data in the literature suggests that mitochondrial efficiency of cardiac muscle from other species is also likely to be between 70 and 80%.
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| 5. |
- Bengtsson, Daniel, et al.
(författare)
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Änders rörelser kartlagda
- 2014
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Ingår i: Vår fågelvärld. - 0042-2649. ; 73:5, s. 46-48
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 6. |
- Champagnon, Jocelyn, et al.
(författare)
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Assessing the genetic impact of massive restocking on wild mallard
- 2013
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Ingår i: Animal Conservation. - : Wiley: 12 months. - 1367-9430 .- 1469-1795. ; 16:3, s. 295-305
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Tidskriftsartikel (refereegranskat)abstract
- Captive-bred mallards Anas platyrhynchos have been released for hunting purposes at a very large scale in Europe since the mid-1970s. In spite of a potential genetic impact, the actual contribution of restocked mallards to the genome of the target population has received little attention. The genetic structure of modern wild mallards in the Camargue, Southern France, was assessed from two samples: one originating from shot birds in hunting bags and one from presumed wild ducks captured alive in a hunting-free reserve. Reference samples originated from five mallard farms, as well as from museum samples collected before the mid-1970s (i.e. before massive mallard releases started). Our results revealed that the genetic signature of wild wintering mallards has not changed significantly because museum and presumed wild samples from the Camargue hunting-free nature reserve were genetically similar, and clearly differentiated from the farm mallards. This suggests that mallard releases in the Camargue or elsewhere in France, although massive, have not actually translated into complete admixture of wild and captive genomes, most likely due to low survival of released birds once in the wild. Nevertheless, although genetic introgression of the wild population by captive-bred was contained, we found significant rates of hybridization between wild and captive-bred mallards in modern samples. This result suggests that long-term releases of captive-bred mallards, if carried on at such large scale, could compromise irreversibly the genetic structure and composition of European mallards. This work contributes to fill in the gap on the monitoring of the genetic consequences of large-scale game releases for exploitation.
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| 7. |
- Dalby, Lars, et al.
(författare)
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The status of the Nordic populations of the Mallard (Anas platyrhynchos) in a changing world
- 2013
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Ingår i: Ornis Fennica. - : Finnish Omithological Soc. - 0030-5685. ; 90:1, s. 2-15
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Tidskriftsartikel (refereegranskat)abstract
- Dabbling ducks (Anas spp.) are importantmigratory quarry species, protected as a shared resource under international legislation. However, there is a lack of sufficient high-quality data on vital demographic rates and long-term trends in numbers to judge the conservation status of many duck populations at the flyway level. In response to reported declines in the North-West European flyway population of theMallard, we compiled available data on this species in the Nordic countries up to 2010. Generally, national breeding numbers showed increasing trends, wintering abundance showed variable trends, and productivitymeasures indicated stable or increasing trends.Major knowledge gaps were identified, namely the size of hunting bags, the influence of the released Mallards and the role of short-stopping in explaining changing patterns of wintering abundance across the North-West European flyway. Numerically the Nordic breeding population appears in “good condition”, and the wintering numbers have been either stable or increasing in the last two decades. The annual number of releases needs to be determined in order to judge the sustainability of the current levels of exploitation. Overall, none of the indicators showed alarming signs for the Mallard population in the Nordic countries when considered in isolation. However, the widespread decline in wintering numbers elsewhere across North-western Europe requires urgent pan-European action.
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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Dessborn, Lisa, 1976-, et al.
(författare)
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Innate responses of mallard ducklings towards aerial, aquatic and terrestrial predators
- 2012
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Ingår i: Behaviour. - Leiden, Netherlands : Brill Academic Publishers. - 0005-7959 .- 1568-539X. ; 149:13-14, s. 1299-1317
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Tidskriftsartikel (refereegranskat)abstract
- Reproductive success in ducks is strongly influenced by predation on the breeding grounds. Ducklings are targeted by a range of terrestrial, aerial and aquatic predators, giving a strong selective advantage to individuals and broods that have effective ways to avoid predation. In experiments on naive mallard (Anas platyrhynchos) ducklings without an accompanying adult female we investigated the innate ability to identify and avoid threats at varying intensity from aerial, aquatic and terrestrial predators. Ducklings displayed increased vigilance in response to pre-recorded calls of predatory birds, representing a low level of threat. They did not react to visual and olfactory stimuli generated by motionless northern pike (Esox lucius). Neither did they show a strong response to caged American mink (Neovison vison) (visual and olfactory stimuli), although they avoided the area with the mink, indicating a certain level of recognition. High intensity threats were simulated by staging attacks from aerial (goshawk, Accipiter gentilis) and aquatic predators (northern pike). The aerial attack made ducklings dive and scatter under water, whereas the response to attack by pike was to run on the water and scatter in different directions. The lack of response to a ‘passive’ pike and the rather weak avoidance of mink indicate that olfactory cues are not as important in identifying a potential predatory threat by ducklings as are auditory cues. Visual cues appear to be of little importance unless they are combined with movement, and a clear response is only triggered when the intensity of predator threat is high. Mallard ducklings, thus, show an innate capacity to adjust anti-predator behaviour to different predator types and to threat intensity. Our study highlights the general trade-off between foraging needs and predator avoidance, but also second-order trade-offs in which innate avoidance behaviour towards one type of predator may increase predation risk from another.
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| 12. |
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| 13. |
- Eichholz, Michael W., et al.
(författare)
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Nest site selection by Holarctic waterfowl : a multi-level review
- 2014
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Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special Issue 4, s. 86-130
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Tidskriftsartikel (refereegranskat)abstract
- Because of birds’ mobility, behaviour and many species’ migratory nature, they select repeatedly and spatially among habitats and have been central figures in studies of avian breeding habitat selection during the 20th and 21st centuries. The scientific literature on habitat use by breeding waterfowl has origins dating back to the writings of Charles Darwin in The Voyage of the Beagle, wherein he described the distribution and habitat differences of two species of geese on the Falkland Islands. Since that time, waterfowl ecologists have gone from descriptive studies of nest site characteristics used for planning waterfowl conservation and management to comparing nest site use in relation to potential habitat availability and determining selection for a wide array of ecological correlates. Waterfowl ecologists most recently have been investigating the adaptive significance of nest site selection by associating the latter with individual fitness and demographic measurements to assess the birds’ adaptability under environmental conditions at multiple scales of selection. While little direct assessment of 1st and 2nd order nest site selection has occurred (sensu Johnson 1980), available information is most consistent with the hypothesis that selection at these scales is driven by food availability. At the 3rd and 4th order of selection, data are consistent with hypotheses that both food availability and predator avoidance drive nest site selection, depending on the species and type of nesting aggregation. We also identify understudied areas of nest site selection important for the conservation and management of waterfowl and suggest that the large-scale influence of current anthropogenic and natural effects on the environment indicates that greater emphasis should be directed toward understanding waterfowl nest site selection at the 1st and 2nd orders of selection and how nesting habitat selection interfaces with community ecology of sympatric breeding waterfowl. Moreover, because habitat selection of prefledging waterfowl is inherently linked to breeding habitat selection, we suggest an updated review of brood habitat selection should ensue from our synthesis here.
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| 14. |
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| 15. |
- Elmberg, Johan, 1960-, et al.
(författare)
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Diurnal seabird movements at Cabo Carvoeiro (Peniche, Portugal) : observations in early October 2012
- 2013
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Ingår i: Seabird. - 0267-9310. ; 26, s. 24-30
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Tidskriftsartikel (refereegranskat)abstract
- The ecology and movements of seabirds are still inadequately understood, mainly because they can rarely be studied efficiently from land. The potential of Cabo Carvoeiro (Peniche, Portugal) for monitoring seabird movements from land is poorly known internationally, as few results from this site have been published in English. Here we present data from standardised counts in October 2012 and draw attention to recent organised seabird counts in Portugal. Despite unfavourable weather conditions for concentrating seabirds towards land, we observed a strong passage of Northern Gannet Morus bassanus, Cory’s Shearwater Calonectris diomedea, Great Skua Stercorarius skua, and Balearic Shearwater Puffinus mauretanicus (mean morning passage of 252, 99, 19, and 21 birds / hour, respectively). Manx Shearwater Puffinus puffinus, Sooty Shearwater P. griseus and Great Shearwater P. gravis occurred regularly in low numbers. Extrapolation indicates that thousands of seabirds passed daily within a few kilometres from land. The high counts of some species and the fairly high species diversity observed by us and in the RAM (Rede de observação de Aves e Mamiferos marinhos) initiative show that Cabo Carvoeiro is an outstanding site for monitoring and studying seabirds in the eastern Atlantic, as it is also located further south in the flyway than most other seawatch points. We hope this note will inspire ornithologists from other countries to participate in standardised seabird counts at Cabo Carvoeiro and other Portuguese sites.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Elmberg, Johan, 1960-, et al.
(författare)
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Hur utsatta är utsatta änder?
- 2012
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Ingår i: Vår fågelvärld. - 0042-2649. ; 71:2, s. 40-42
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Utsättningar av djur och växter har förekommit mycket länge. Slottens svandammar har kommit till av detta skäl, godsen har satt ut jaktbart vilt. Jordbruk och skogsbruk bygger på idén att plantera ut för att sedan skörda, och även naturvården ägnar sig åt ”stödutplanteringar”. Ingen fågelart sätts ut i så stora antal som gräsanden. Men vad är det för änder det handlar om? Vilka blir effekterna?
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| 20. |
- Elmberg, Johan, 1960-
(författare)
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Inköpta ägg hotar gräsanden
- 2012
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Ingår i: Forskning & Framsteg. - 0015-7937. ; :3, s. 26-29
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Vad händer med inhemska arter när de vilda bestånden hela tiden fylls på med individer som är uppfödda i fångenskap och som kanske inte är anpassade till vår miljö?
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| 21. |
- Elmberg, Johan, 1960-, et al.
(författare)
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Knipa och gräsand är goda grannar
- 2012
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Ingår i: Vår fågelvärld. - 0042-2649. ; 71:4, s. 39-
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 22. |
- Elmberg, Johan, 1960-
(författare)
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Lever elfenbensnäbben?
- 2013
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Ingår i: Vår fågelvärld. - 0042-2649. ; 72:2, s. 8-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 23. |
- Elmberg, Johan, 1960-
(författare)
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Nötskrikans vintervanor
- 2012
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Ingår i: Vår fågelvärld. - 0042-2649. ; 71:5, s. 12-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 24. |
- Elmberg, Johan, 1960-, et al.
(författare)
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Snokens barnkammare försvinner
- 2013
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Ingår i: Fauna och flora. - 0014-8903. ; 108:1, s. 10-16
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 25. |
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| 26. |
- Elmberg, Johan, 1960-, et al.
(författare)
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Vad händer med utsatta änder?
- 2012
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Ingår i: Svensk Jakt. - 0039-6583. ; 150:8, s. 88-89
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 27. |
- Elmberg, Johan, 1960-, et al.
(författare)
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Änder klarar sig bättre utan grannar
- 2012
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Ingår i: Anser. - 0347-9595. ; 51:1, s. 22-27
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Häckningen är på många sätt den viktigaste delen av fåglarnas årscykel, men den är också en av de farligaste.Ett bo fullt med ägg är ju en fantastisk måltid för många rovdjur. mFågelekologer vid Högskolan Kristianstad berättar här om nya rön om samspelet mellan gräsänder och de rovdjur som gillar deras bon. Det finns mycket att vinna för de änder som häckar vid rätt tidpunkt och placerar sina bon på rätt ställe!
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| 28. |
- Eriksson, Susanne P., et al.
(författare)
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Stress biology and immunology in Nephrops norvegicus
- 2013
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Ingår i: The ecology and biology of <em>Nephrops norvegicus</em>. - Amsterdam : Academic Press. - 9780124104662 ; , s. 149-200
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Bokkapitel (refereegranskat)abstract
- The Norway lobster Nephrops norvegicus lives at low-light depths, in muddy substrata of high organic content where water salinities are high and fluctuations in temperature are moderate. In this environment, the lobsters are naturally exposed to a number of potential stressors, many of them as a result of the surficial breakdown of organic material in the sediment. This process (early diagenesis) creates a heterogeneous environment with temporal and spatial fluctuations in a number of compounds such as oxygen, ammonia, metals, and hydrogen sulphide. In addition to this, there are anthropogenically generated stressors, such as human-induced climate change (resulting in elevated temperature and ocean acidification), pollution and fishing. The lobsters are thus exposed to several stressors, which are strongly linked to the habitat in which the animals live. Here, the capacity of Nephrops to deal with these stressors is summarised. Eutrophication-induced hypoxia and subsequent metal remobilisation from the sediment is a well-documented effect found in some wild Nephrops populations. Compared to many other crustacean species, Nephrops is well adapted to tolerate periods of hypoxia, but prolonged or severe hypoxia, beyond their tolerance level, is common in some areas. When the oxygen concentration in the environment decreases, the bioavailability of redox-sensitive metals such as manganese increases. Manganese is an essential metal, which, taken up in excess, has a toxic effect on several internal systems such as chemosensitivity, nerve transmission and immune defence. Since sediment contains high concentrations of metals in comparison to sea water, lobsters may accumulate both essential and non-essential metals. Different metals have different target tissues, though the hepatopancreas, in general, accumulates high concentrations of most metals. The future scenario of increasing anthropogenic influences on Nephrops habitats may have adverse effects on the fitness of the animals.
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| 29. |
- Guillemain, Matthieu, et al.
(författare)
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The teal
- 2014
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Bok (refereegranskat)abstract
- Small, noisy and colourful, the Teal is a familiar duck throughout the wetlands and waterways Europe and Asia. Once hunted extensively for the pot, its numbers have recovered and it is now one of our commonest species of waterfowl.A flagship species for wetland conservation, the Teal is also an excellent model species for ecological research, and this forms the spine of this new Poyser monograph.The Teal looks at distribution and trends in numbers, foraging ecology, breeding behaviour), population dynamics, management and conservation of teal, looking at both the Eurasian Common Teal and its North American equivalent, the Green-winged Teal (which until relatively recently was considered to be the same species). The book provides a scientifically robust account on which wetland managers, research scientists and the ornithological community may rely, with wider implicatons for the conservation and management of other waterfowl, and for ecological research in general.
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| 30. |
- Gunnarsson, Gunnar, 1976-, et al.
(författare)
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Bristande födotillgång och torrare vårar på strandängarna i Kristianstads Vattenrike : möjliga orsaker till vadarnas tillbakagång?
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Strandängsvadarna har minskat påtagligt i antal längs nedre Helgeån i Kristianstads Vattenrike. Orsaken till minskningarna är inte uppenbara, men ett antal möjliga faktorer har lyfts fram. I den här rapporten presenteras studier som genomfördes 2012 med målet att undersöka två av dessa faktorer, nämligen (1) vadarnas födotillgång (dvs. förekomst av ryggradslösa djur) och hur den kan ha påverkats av sommaröversvämningen 2007, samt (2) om det finns stöd i väder- och hydrologiska data att vårarna har blivit torrare.Tillgången på föda var överlag god på själva strandängarna. I våtmarkerna (vätor, Helge å, Hammarsjön) var det däremot stora skillnader mellan lokaler i Vattenriket, med högre förekomster av ryggradslösa djur längre ner i Helge å-systemet (dvs. närmare utloppet i Hanöbukten) än högre upp. Detta kan vara en kvarvarande effekt av sommaröversvämningen 2007.Några tydliga tendenser till torrare vårar under perioden 1990–2012 kunde inte skönjas vid analyser av väder- och hydrologiska data. Möjligen kan man säga att vårarna i början av 1990-talet var relativt torra för att följas av våtare vårar under andra halvan av 1990-talet och att 2000-talet har dominerats av torra vårar. Det är emellertid inte möjligt att utifrån befintliga data göra några säkra uttalanden om eventuella långtgående förändringar som kan ha påverkat vadarnas livsmiljöer eller häckningsframgång.För att vända den negativa trenden med sviktande populationer av strandängsvadare behövs drastiska och omedelbara åtgärder. Dessa inbegriper främst att få bukt med alltför kortsnaggade och ensartade ängar, för hög predation, och vätor som torkar ut för snabbt.
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| 31. |
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| 32. |
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| 33. |
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| 34. |
- Jönsson, K. Ingemar, 1959-, et al.
(författare)
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Trehalose in three species of desiccation tolerant tardigrades
- 2010
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Ingår i: Open Zoology Journal. - 1874-3366. ; 3, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- We report a study on the presence of the disaccharide trehalose in three desiccation tolerant tardigrades. This sugar has long been suggested to play a protective role in desiccation tolerant animals. Trehalose was found in all species, with increased levels in dehydrated specimens of Macrobiotus islandicus, and possibly also in Macrobiotus krynauwi, both belonging to the family Macrobiotidae. In the third species, Milnesium tardigradum, very low amounts of trehalose were found, with no increase in the dehydrated state. This species has previously been reported to lack trehalose. Induction of trehalose has been reported only for species in the family Macrobiotidae, where also the highest levels have been found. Although the role of trehalose in the desiccation tolerance of tardigrades remains unclear, the diverging patterns in response to desiccation are interesting. Further studies of higher tardigrade taxa are needed in order to understand the evolutionary history of trehalose in these invertebrates.
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| 35. |
- Kaminski, Richard M., et al.
(författare)
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An introduction to habitat use and selection by waterfowl in the northern hemisphere
- 2014
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Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special Issue 4, s. 9-16
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Tidskriftsartikel (refereegranskat)abstract
- This introductory article aims to provide a theoretical framework to the topics of habitat use and selection by waterfowl (i.e. family Anatidae) in the northern hemisphere during the four stages of their annual cycle: autumn migration and winter, spring migration and pre-breeding, nesting and brood rearing, and postbreeding and moulting. Papers addressing each of these seasonal sectors of the annual cycle, which follow this introduction, were presented at the 6th North American Duck Symposium, “Ecology and Conservation of North American Waterfowl” in Memphis, Tennessee in January 2013. Here, we consider the theory and selected empirical evidence relevant to waterfowl habitat and resource use and selection that may affect individual survival and fitness of waterfowl in Nearctic and Palearctic ecozones. Additionally, where possible, a comparative taxonomic approach is attempted in the following papers to identify and generalise patterns in habitat and resource use and selection across waterfowl taxa that may influence biological outcomes for individuals, populations and species through space and time. Each of the subsequent papers use accumulated science-based information to recommend future opportunities and strategies for research and for habitat and population conservation. Collectively, our goals in synthesising information on waterfowl are to help sustain harvestable populations of waterfowl and to protect rare species amid worldwide changes in climate, landscape, economics, socio-politics and growth of human populations.
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| 36. |
- Nilsson, E J Charlotta, et al.
(författare)
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Evaluation of cryoanalysis as a tool for analyzing elemental distributionin ‘‘live’’ tardigrades using micro-PIXE
- 2014
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - 0168-583X .- 1872-9584. ; 332, s. 181-186
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Tidskriftsartikel (refereegranskat)abstract
- Although heavy on labor and equipment, thus not often applied, cryoanalysis of frozen hydrated biological specimens can provide information that better reflects the living state of the organism, compared with analysis in the freeze-dried state. In this paper we report a study where the cryoanalysis facility with cryosectioning capabilities at Materials Research Department, iThemba LABS, South Africa was employed to evaluate the usefulness of combining three ion beam analytical methods (μPIXE, RBS and STIM) to analyze a biological target where a better elemental compositional description is needed – the tardigrade. Imaging as well as quantification results are of interest.In a previous study, the element composition and redistribution of elements in the desiccated and active states of two tardigrade species was investigated. This study included analysis of both whole and sectioned tardigrades, and the aim was to analyze each specimen twice; first frozen hydrated and later freeze-dried. The combination of the three analytical techniques proved useful: elements from C to Rb in the tardigrades could be determined and certain differences in distribution of elements between the frozen hydrated and the freeze-dried states were observed. RBS on frozen hydrated specimens provided knowledge of matrix elements.
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| 37. |
- Rasmussen, Arne R., et al.
(författare)
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Rediscovery of the rare sea snake Hydrophis parviceps Smith 1935 : identification and conservation status
- 2012
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Ingår i: Copeia. - 0045-8511 .- 1938-5110. ; :2, s. 276-282
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Tidskriftsartikel (refereegranskat)abstract
- Smith's small-headed sea snake, Hydrophis parviceps, was originally described in 1935 from a single type specimen collected in southern Vietnam. Since this time there has been only one further record for the species—a specimen collected near the type locality in 1960 that has since been lost. Through field surveys in southern Vietnam in 2001, we obtained three additional specimens of this poorly known sea snake from fisheries bycatch. In the current paper, we present morphological and molecular data for the three new specimens and the holotype, and redescribe H. parviceps based on data synthesized for all five specimens known to date. We also discuss the conservation status of the species based on its vulnerability to fisheries bycatch mortality and seemingly low abundance within a very restricted geographic distribution.
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| 38. |
- Sanders, Kate L., et al.
(författare)
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Aipysurus mosaicus, a new species of egg-eating sea snake (Elapidae: Hydrophiinae), with a redescription of Aipysurus eydouxii (Gray, 1849)
- 2012
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Ingår i: Zootaxa. - 1175-5326 .- 1175-5334. ; :3431, s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- We describe a new species of egg-eating sea snake, Aipysurus mosaicus sp. nov., from northern Australia and southern New Guinea. This species was previously considered to be an allopatric population of A. eydouxii, which occurs throughout the Sunda Shelf and in New Guinea. Molecular analyses reveal these two species to be sister lineages with fixed nucleotide substitutions at three independent mitochondrial and nuclear loci, and a deep phylogenetic divergence exceeding that of all other sampled species pairs in Aipysurus. Aipysurus mosaicus sp. nov. is also distinguished from A. eydouxii by morphological characters relating to scalation (e.g. number of ventral scales), colour pattern (e.g. number and shape of transverse body bands), internal soft anatomy (e.g. position of heart in relation to ventral scales), and skeletal morphology (e.g. shape of nasal and caudal neural spines). Additional sampling is needed to clarify the extent of geographic contact between A. eydouxii and the new species in New Guinea where they appear to be sympatric. It is likely that the boundaries between these taxa will be mirrored in other coastal sea snakes with ranges spanning the deep waters of the Timor Trench; discovery of such cryptic species will have important implications for conservation of this highly diverse but relatively poorly studied group of marine vertebrates.
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| 39. |
- Sanders, Kate L., et al.
(författare)
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Independent innovation in the evolution of paddle-shaped tails in viviparous sea snakes (Elapidae Hydrophiinae)
- 2012
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Ingår i: Integrative and Comparative Biology. - 1540-7063 .- 1557-7023. ; 52:2, s. 311-320
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Tidskriftsartikel (refereegranskat)abstract
- The viviparous sea snakes (Hydrophiinae) comprise ∼90% of living marine reptiles and display many physical and behavioral adaptations for breathing, diving, and achieving osmotic balance in marine habitats. Among the most important innovations found in marine snakes are their paddle-shaped (dorsoventrally expanded) tails, which provide propulsive thrust in the dense aquatic medium. Here, we reconstruct the evolution of caudal paddles in viviparous sea snakes using a dated molecular phylogeny for all major lineages and computed tomography of internal osteological structures. Bayesian ancestral state reconstructions show that extremely large caudal paddles supported by elongated vertebral processes are unlikely to have been present in the most recent common ancestor of extant sea snakes. Instead, these characters appear to have been acquired independently in two highly marine lineages of relatively recent origin. Both the Aipysurus and Hydrophis lineages have elongated neural spines that support the dorsal edge of their large paddles. However, whereas in the Aipysurus lineage the ventral edge of the paddle is supported by elongated haemapophyses, this support is provided by elongated and ventrally directed pleurapophyses in the Hydrophis lineage. Three semi-marine lineages (Hydrelaps, Ephalophis, and Parahydrophis) form the sister group to the Hydrophis clade and have small paddles with poorly developed dorsal and ventral supports, consistent with their amphibious lifestyle. Overall, our results suggest that not only are the viviparous hydrophiines the only lineage of marine snakes to have acquired extremely large, skeletally supported caudal paddles but also that this innovation has occurred twice in the group in the past ∼2–6 million years.
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| 40. |
- Sanders, Kate L., et al.
(författare)
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Recent rapid speciation and ecomorph divergence in Indo-Australian sea snakes
- 2013
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 22:10, s. 2742-2759
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Tidskriftsartikel (refereegranskat)abstract
- The viviparous sea snakes (Hydrophiinae) are a young radiation of at least 62 species that display spectacular morphological diversity and high levels of local sympatry. To shed light on the mechanisms underlying sea snake diversification, we investigated recent speciation and eco-morphological differentiation in a clade of four nominal species with overlapping ranges in Southeast Asia and Australia. Analyses of morphology and stomach contents identified the presence of two distinct ecomorphs: a ‘macrocephalic’ ecomorph that reaches >2 m in length, has a large head and feeds on crevice-dwelling eels and gobies; and a ‘microcephalic’ ecomorph that rarely exceeds 1 m in length, has a small head and narrow fore-body and hunts snake eels in burrows. Mitochondrial sequences show a lack of reciprocal monophyly between ecomorphs and among putative species. However, individual assignment based on newly developed microsatellites separated co-distributed specimens into four significantly differentiated clusters corresponding to morphological species designations, indicating limited recent gene flow and progress towards speciation. A coalescent species tree (based on mitochondrial and nuclear sequences) and isolation-migration model (mitochondrial and microsatellite markers) suggest between one and three transitions between ecomorphs within the last approximately 1.2 million to approximately 840 000 years. In particular, the macrocephalic ‘eastern’ population of Hydrophis cyanocinctus and microcephalic H. melanocephalus appear to have diverged very recently and rapidly, resulting in major phenotypic differences and restriction of gene flow in sympatry. These results highlight the viviparous sea snakes as a promising system for speciation studies in the marine environment.
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| 41. |
- Stafford, Joshua D., et al.
(författare)
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Spring migration of waterfowl in the northern hemisphere : a conservation perspective
- 2014
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Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special Issue 4, s. 70-85
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Tidskriftsartikel (refereegranskat)abstract
- Spring migration is a key part of the annual cycle for waterfowl populations in the northern hemisphere, due to its temporal proximity to the breeding season and because resources may be limited at one or more staging sites. Research based on field observations during spring lags behind other periods of the year, despite the potential for fitness consequences through diminished survival or cross-seasonal effects of conditions experienced during migration. Consequently, conservation strategies for waterfowl on spring migration are often only refined versions of practices used during autumn and winter. Here we discuss the current state of knowledge of habitat requirements for waterfowl at their spring migratory sites and the intrinsic and extrinsic factors that lead to variability in those requirements. The provision of plant foods has become the main conservation strategy during spring because of the birds’ energy requirements at this time, not only to fuel migration but to facilitate early clutch formation on arrival at the breeding grounds. Although energy sources are important to migrants, there is little evidence on the extent to which the availability of carbohydrate-based food is limiting for many migratory waterfowl populations. Such limitation is relatively unlikely among populations that exploit agricultural grain during migration (e.g. arctic-nesting geese), suggesting that conservation strategies for these populations may be misplaced. In general, however, we found few cases in which an ecological understanding of spring-migrating waterfowl was sufficient to indicate true resource limitation during migration, and still fewer cases where conservation efforts ameliorated these limitations. We propose a framework that aims to address knowledge gaps and apply empirical research results to conservation strategies based on documented limitations and associated fitness impacts on migrating waterfowl. Such a strategy would improve allocation of scarce conservation resources during spring migration and greatly improve ecological understanding of migratory waterfowl and their habitats in the northern hemisphere.
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| 42. |
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| 43. |
- Söderquist, Pär, et al.
(författare)
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Longevity and migration distance differ between wild and hand-reared mallards Anas platyrhynchos in Northern Europe
- 2013
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Ingår i: European Journal of Wildlife Research. - : Springer Verlag (Germany). - 1612-4642 .- 1439-0574. ; 59:2, s. 150-166
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Tidskriftsartikel (refereegranskat)abstract
- The mallard Anas platyrhynchos is the world’s most widespread and numerous dabbling duck. It is also farmed and released to the wild by the millions each year, but the effects of this on wild populations remain little studied. By using historical national ringing–recovery data from Sweden and Finland, we here address three predictions based on previous studies: (1) longevity is higher in wild than in hand-reared mallards, (2) wild mallards migrate longer than hand-reared, and (3) migration distance in wild ducks surviving long enough to start fall migration has decreased over the last 50 years. Indeed, wild mallards lived longer than hand-reared (19 versus 9 months in Swedish birds and 13 versus 4 months in Finnish birds). Compared to wild mallards, a smaller proportion of hand-reared birds survived long enough to have the chance to enter the wild breeding population; less than 25 % of the Swedish birds and less than 10 % of the Finnish birds lived a year or longer. Wild birds migrated farther than hand-reared (mean distance in Swedish birds, 676 versus 523 km; in Finnish birds, 1,213 versus 157 km), a pattern caused by both shorter life span and lower migration speed in hand-reared birds. Mean migration distance in wild Swedish mallards was 787 km in 1947–1972 but 591 km in 1977–1993. This difference was not statistically significant, though, possibly due to the limited sample size and lack of data from the last two decades. In general, our study provides a conservative test of the predictions addressed, calling for more research about the consequences of restocking duck populations.
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