| 1. |
- Alho, Jussi S., et al.
(författare)
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Increasing melanism along a latitudinal gradient in a widespread amphibian : local adaptation, ontogenic or environmental plasticity?
- 2010
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Ingår i: BMC Evolutionary Biology. - 1471-2148 .- 1471-2148. ; 10, s. 317-
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe thermal benefits of melanism in ectothermic animals are widely recognized, but relatively little is known about population differentiation in the degree of melanism along thermal gradients, and the relative contributions of genetic vs. environmental components into the level of melanism expressed. We investigated variation in the degree of melanism in the common frog (Rana temporaria; an active heliotherm thermoregulator) by comparing the degree of melanism (i) among twelve populations spanning over 1500 km long latitudinal gradient across the Scandinavian Peninsula and (ii) between two populations from latitudinal extremes subjected to larval temperature treatments in a common garden experiment.ResultsWe found that the degree of melanism increased steeply in the wild as a function of latitude. Comparison of the degree of population differentiation in melanism (PST) and neutral marker loci (FST) revealed that the PST > FST, indicating that the differences cannot be explained by random genetic drift alone. However, the latitudinal trend observed in the wild was not present in the common garden data, suggesting that the cline in nature is not attributable to direct genetic differences.ConclusionsAs straightforward local adaptation can be ruled out, the observed trend is likely to result from environment-driven phenotypic plasticity or ontogenetic plasticity coupled with population differences in age structure. In general, our results provide an example how phenotypic plasticity or even plain ontogeny can drive latitudinal clines and result in patterns perfectly matching the genetic differences expected under adaptive hypotheses.
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| 2. |
- Hedenas, Henrik, et al.
(författare)
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Changes Versus Homeostasis in Alpine and Sub-Alpine Vegetation Over Three Decades in the Sub-Arctic
- 2012
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Ingår i: Ambio. - : Springer Verlag (Germany). - 0044-7447 .- 1654-7209. ; 41, s. 187-196
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Tidskriftsartikel (refereegranskat)abstract
- Plant species distributions are expected to shift and diversity is expected to decline as a result of global climate change, particularly in the Arctic where climate warming is amplified. We have recorded the changes in richness and abundance of vascular plants at Abisko, sub-Arctic Sweden, by re-sampling five studies consisting of seven datasets; one in the mountain birch forest and six at open sites. The oldest study was initiated in 1977–1979 and the latest in 1992. Total species number increased at all sites except for the birch forest site where richness decreased. We found no general pattern in how composition of vascular plants has changed over time. Three species, Calamagrostis lapponica, Carex vaginata and Salix reticulata, showed an overall increase in cover/frequency, while two Equisetum taxa decreased. Instead, we showed that the magnitude and direction of changes in species richness and composition differ among sites.
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| 3. |
- Jönsson, K. Ingemar, 1959-, et al.
(författare)
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Sexual patterns of prebreeding energy reserves in the common frog Rana temporaria along a latitudinal gradient
- 2009
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Ingår i: Ecography. - : Wiley-Blackwell. - 0906-7590 .- 1600-0587. ; 32:5, s. 831-839
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Tidskriftsartikel (refereegranskat)abstract
- The ability to store energy is an important life history trait for organisms facing long periods without energy income, and in particular for capital breeders such as temperate zone amphibians, which rely on stored energy during reproduction. However, large scale comparative studies of energy stores in populations with different environmental constraints on energy allocation are scarce. We investigated energy storage patterns in spring (after hibernation and before reproduction) in eight common frog (Rana temporaria) populations exposed to different environmental conditions along a 1600 km latitudinal gradient across Scandinavia (range of annual activity period 3-7 months). Analyses of lean body weight (eviscerated body mass), weight of fat bodies, liver weight, and liver fat content, showed that (i) post-hibernation/pre-breeding energy stores increased with increasing latitude in both sexes, (ii) males generally had larger energy reserves than females and (iii) the difference in energy stores between sexes decreased towards the north. Larger energy reserves towards the north can serve as a buffer against less predictable and/or less benign weather conditions during the short activity period, and may also represent a risk-averse tactic connected with a more pronounced iteroparous life history. In females, the continuous and overlapping vitellogenic activity in the north may also demand more reserves in early spring. The general sexual difference could be a consequence of the fact that, at the time of our sampling, females had already invested their energy into reproduction in the given year (i.e. their eggs were already ovulated), while the males' main reproductive activities (e.g. calling, mate searching, sexual competition) occurred later in the season.
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| 4. |
- Söderquist, Pär, et al.
(författare)
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Wild Mallards have more ”goose-like” bills than their ancestors
- 2015
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Ingår i: 4th Pan-European Duck Symposium, Hangö, Finland, 7-11/4, 2015. ; , s. 38-
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Konferensbidrag (refereegranskat)abstract
- Wild populations of the world’s most common dabbling duck, the Mallard (Anas platyrhynchos), run the risk of genetic introgression by farmed conspecifics released for hunting purposes. We tested whether bill morphology of free-living birds has changed since large-scale releases of farmed Mallards started. Three groups of Mallards from Sweden, Norway and Finland were compared: historical wild (before large-scale releases started), present-day wild, and present-day farmed. Higher density of bill lamellae was observed in historical wild Mallards (only males). Farmed Mallards had wider bills than present-day and historical wild ones. Present-day wild and farmed Mallards also had higher and shorter bills than historical wild Mallards. Present-day Mallards thus tend to have more ‘‘goose-like’’ bills (wider, higher, and shorter) than their ancestors. Our study suggests that surviving released Mallards affect morphological traits in wild population by introgression. We discuss how such anthropogenic impact may lead to a maladapted and genetically compromised wild Mallard population. Our study system has bearing on other taxa where large-scale releases of conspecifics with ‘alien genes’ may cause a cryptic invasive process that nevertheless has fitness consequences for individual birds.
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| 5. |
- Schill, Ralph O., et al.
(författare)
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Food of tardigrades : a case study to understand food choice, intake and digestion
- 2011
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Ingår i: Journal of Zoological Systematics and Evolutionary Research. - 0947-5745 .- 1439-0469. ; 49:Suppl. 1, s. 66-70
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Tidskriftsartikel (refereegranskat)abstract
- Mosses are an excellent habitat for tardigrades because of their ability to ensure a high humidity and to provide a rich food supply for both carnivorous and herbivorous species. Food choice can be correlated with the morphology of the buccal apparatus, and consequentially, their distribution is sometimes linked to food availability (nematodes, rotifers, plant cells, algae, yeast and bacteria). In many species, material containing chlorophyll is often observed in the midgut. However, little information has been available until now on the actual food preference of tardigrades. Since trophic interactions within soil food webs are difficult to study, here we use a polymerase chain reaction–based approach as a highly sensitive detection method. The study was carried out to investigate the presence of chlorophyll matter in the gut of active specimens, based on sequence analyses of the chloroplast ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene from mosses and algae. The sequences found in the gut of Macrobiotus sapiens were derived from the moss families Pottiaceae and Erpodiaceae, in Macrobiotus persimilis and Echiniscus granulatus from the moss family Grimmiaceae, and in Richtersius coronifer from the green algae genus Trebouxia. Furthermore, we show the emission of green autofluorescence from the chloroplasts in the algae within the gut of tardigrades and followed the progress of digestion over a 48-h period. The autofluorescent emission level declined significantly, and after 2 days, the signal level was similar to the level of the starved control.
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| 6. |
- Strong, Emily A., et al.
(författare)
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Seeking greener pastures : crop selection by Greylag Geese (Anser anser) during the moulting season
- 2021
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Ingår i: Ornis Fennica. - : Finnish Omithological Soc. - 0030-5685. ; 98:1, s. 16-32
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Tidskriftsartikel (refereegranskat)abstract
- Over the last 40 years, many goose populations have recovered from historic lows and are now more numerous than ever. At the same time, geese have shifted from natural foraging habitats to securing most of their nutritional demands from agricultural fields, leading to crop damage and conflict with agriculture. We studied field use by Greylag Geese (Anser anser) in the agricultural landscape surrounding a main breeding and moulting lake in Sweden. From 2012 to 2016, weekly roadside surveys were conducted from May to July. Data were collected on goose numbers, crop type and sward height in agricultural fields. Using a compositional analysis, we demonstrate that Greylag Geese show a strong selection for ley and pasture fields compared to other crop types (rank order: ley/pasture > oat > barley > wheat > other crops). This selection was consistent across years and between pre- and post-moult. Aside from ley and pasture, no other croptypes were selected for, as they were used less than expected given their availability. Irrespective of crop type, geese foraged predominantly on short (0–10 cm) swards. The strong selection for ley and pasture may have been driven by higher nutritional quality of short, managed grass swards relative to other available foods. This suggests that during the summer grass fields may be more vulnerable to damage compared to other crop types. Our study provides a deeper understanding of the ecology of Greylag Geese, which may be used to inform management strategies focused on mitigating crop damage and alleviating conflict.
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| 7. |
- Åkesson, Susanne, et al.
(författare)
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Autumn migratory orientation and route choice in early and late dunlins Calidris alpina captured at a stopover site in Alaska
- 2021
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Ingår i: Biology open. - : The Company of Biologists Ltd. - 2046-6390. ; 10:4, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the migratory orientation of early and late captured dunlins, Calidris alpina, by recording their migratory activity in circular orientation cages during autumn at a staging site in southwest Alaska and performed route simulations to the wintering areas. Two races of dunlins breeding in Alaska have different wintering grounds in North America (Pacific Northwest), and East Asia. Dunlins caught early in autumn (presumably Calidris alpina pacifica) oriented towards their wintering areas (east-southeast; ESE) supporting the idea that they migrate nonstop over the Gulf of Alaska to the Pacific Northwest. We found no difference in orientation between adult and juveniles, nor between fat and lean birds or under clear and overcast skies demonstrating that age, energetic status and cloud cover did not affect the dunlins' migratory orientation. Later in autumn, we recorded orientation responses towards south-southwest suggesting arrival of the northern subspecies Calidris alpina arcticola at our site. Route simulations revealed multiple compass mechanisms were compatible with the initial direction of early dunlins wintering in the Pacific Northwest, and for late dunlins migrating to East Asia. Future high-resolution tracking would reveal routes, stopover use including local movements and possible course shifts during migration from Alaska to wintering sites on both sides of the north Pacific Ocean.
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| 8. |
- Jönsson, K. Ingemar, 1959-, et al.
(författare)
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On the disparate terminological use of the concept cryptobiosis
- 2004
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Ingår i: Journal of Fish Diseases. - : Wiley-Blackwell. - 0140-7775 .- 1365-2761. ; 27:3, s. 175-176
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Tidskriftsartikel (refereegranskat)abstract
- Conceptual and terminological consistency is an important component of science, promoting clarity and preventing confusion. Scientists should therefore always try to avoid giving different meanings to the same term. Apart from this general aspect, multiple definitions of a single term also give rise to practical problems, particularly in connection with literature search. In this note, I will bring attention to a term, cryptobiosis, that has relatively recently appeared in the field of fish disease research, but which has a much longer history and use in a completely different area.The concept of cryptobiosis was introduced by Keilin (1959) and defined as ‘the state of an organism when it shows no visible signs of life and when its metabolic activity becomes hardly measurable, or comes reversibly to a standstill’ (Keilin 1959, p. 166). Cryptobiosis replaced the earlier term anabiosis, and is today generally accepted as the common term for different ametabolic life forms (e.g. Clegg 2001; Wright 2001). Cryptobiosis means ‘hidden life’, an appropriate name for a state in which all traditional attributes of life (metabolism, reproduction, DNA replication) are absent. Cryptobiotic life forms have been documented in a variety of organisms, including both plants and animals, but in the latter category mainly among invertebrates (Wright, Westh & Ramløv 1992). Cryptobiosis is commonly induced by desiccation (so-called anhydrobiosis; e.g. Keilin 1959; Jönsson 2001), and aquatic invertebrates such as rotifers, nematodes and tardigrades living in microhabitats exposed to rapid desiccation frequently enter a cryptobiotic state. The research field dealing with cryptobiotic, sensu ametabolic, life forms has expanded considerably during the last 30 years, to a large extent fuelled by the detection of the ability of the disaccharide trehalose to protect dry and frozen biological cells (Crowe 2002).More recently, a completely different use of the term cryptobiosis has appeared in the literature on fish disease. In this literature, the term refers to infections of fish by biflagellated protozoa of the genus Cryptobia. Because of the economic importance of salmonid fish, much of the Cryptobia research has focused on Cryptobia salmositica (Katz) that infects salmonids (Woo 2001). The origin of the term cryptobiosis within fish pathology and studies of Cryptobia is unclear, but the earliest record of the term that I have found is Obradovic & Fijan (1979) who used it in a paper on chemotherapeutic treatment against Cryptobia in carp. From 1987 onwards, Woo et al. have used the term frequently (e.g. Woo, Leatherland & Lee 1987; Woo 1987, 1998, 2001), but apparently without any comments on the original proposal of the term. Curiously, few other researchers on Cryptobia seem to have adopted the cryptobiosis terminology, at least as judged from an examination of published titles. Other authors have instead used the expression ‘infections by Cryptobia’. Although using cryptobiosis as a term for infections by Cryptobia is consistent with the rule of creating names for infectious diseases by putting -osis as a post-fix to the name of the infecting organism, in the current case it creates terminological confusion.The problems of using the term cryptobiosis in several unrelated fields are obvious. A title such as ‘The biology of cryptobiosis’ would attract the attention of many students interested in ametabolic life forms. They would be disappointed, however, if the paper turned out to be about Cryptobia infection biology. Similarly, fish biologists would find the publication irrelevant to their research if it were properly confined to ametabolic life forms.Because ‘cryptobiosis’ as a term for ametabolic life forms is well established and has been used for more than 40 years, it should have priority over the more recent and limited use within fish pathology. I therefore hope that fish pathologists will avoid using the term cryptobiosis and instead use ‘infections by Cryptobia’, ‘cryptobiasis’ or some other term that does not interfere with already established terminology.
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| 9. |
- Jönsson, K. Ingemar, 1959-, et al.
(författare)
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Radiation tolerance in the eutardigrade Richtersius coronifer
- 2005
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Ingår i: International Journal of Radiation Biology. - : Taylor & Francis. - 0955-3002 .- 1362-3095. ; 81:9, s. 649-656
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Tardigrades have a reputation of being extremely tolerant to extreme environmental conditions including tolerance to ionizing radiation while in a desiccated, anhydrobiotic state. However, the evidence for radio-tolerance in tardigrades is based on only one previous report, and there is an obvious need for complementary studies. In this paper we report an investigation on radio-tolerance in desiccated and hydrated specimens of the eutardigrade Richtersius coronifer.MATERIALS AND METHODS: Groups of 30 - 50 tardigrades were exposed to gamma-radiation at doses between 1.0 - 9.0 (anhydrobiotic animals) or 0.5 - 5.0 (hydrated animals) kGy and the animals were followed until all were dead. Radiation tolerance of both desiccated and hydrated tardigrades was studied.RESULTS: Both desiccated and hydrated animals irradiated with 0.5 and 1 kGy did not deviate in survival from the control groups. Animals from all exposed groups underwent their moulting and egg production cycle, but at decreasing frequency for doses above 1 kGy. No eggs laid by irradiated animals hatched, while eggs laid by controls did so.CONCLUSION: Our study suggests that radiation tolerance in tardigrades is not due to biochemical protectants connected with the desiccated state. Rather, cryptobiotic tardigrades may rely on efficient mechanisms of DNA repair, the nature of which is currently unknown.
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| 10. |
- Arvidsson, Fredrik, et al.
(författare)
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Geographic location, not forest type, affects the diversity of spider communities sampled with malaise traps in Sweden
- 2016
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Ingår i: Annales Zoologici Fennici. - : Finnish Zoological and Botanical Publishing Board. - 0003-455X .- 1797-2450 .- 0003-3847. ; 53:3-4, s. 215-227
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Tidskriftsartikel (refereegranskat)abstract
- The latitudinal diversity gradient predicts higher species richness at lower latitudes. Here, we utilize the data from a long-term monitoring with malaise traps to analyse if spider communities in Sweden are affected by geographic gradients and if these effects hold independent of forest type. The species richness and the effective number of species in spider communities were not significantly related to the latitudinal gradient. The effective number of species and the taxonomic distinctness of spider communities were related to longitude, with a higher number, but fewer related species in western parts of Sweden. The species and family composition were significantly related to latitude independent of forest type, with a dominance of Linyphiidae individuals and species in the north. Our study demonstrates the suitability of malaise trap sampling to contribute to a better understanding of local spider communities, as several rare and locally new species were recorded in this study.
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