| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Forslund, Pär, et al.
(författare)
-
Age-related reproductive success in the barnacle goose
- 1992
-
Ingår i: Journal of Animal Ecology. - : British Ecological Society. - 0021-8790 .- 1365-2656. ; 61, s. 195-204
-
Tidskriftsartikel (refereegranskat)abstract
- 1. We studied age-related reproductive success in a recently established breeding colony of barnacle goose Branta leucopsis on the island of Gotland, Sweden.2. Associations of age and breeding experience with several reproductive parameters were investigated by comparing the success of individuals of 2, 3, 4 and >=5 years of age. Also, we measured the within-individual changes in reproductive parameters as the individuals grew older.3. Associations between survival and reproductive success were investigated by comparing the reproductive success of 2, 3 and 4-year-old birds that returned or did not return, respectively, in the subsequent breeding season.4. The reproductive success increased up to an age of 4-5 years. Thus, clutch size, number of hatched young and number of fledged young increased, and hatching date was advanced with increasing age. This was due to the fact that individuals increased in reproductive success as they grew older.5. A possibly higher probability of survival among individuals that perform well in reproduction could not explain the higher reproductive success in older age-classes as compared to young age-classes of geese, because there were no associations between survival and reproductive success, and very few individuals did actually disappear between any two breeding seasons.6. Path analysis suggested age effects only at earlier stages of reproduction, i. e. timing of breeding and clutch size. These characters, in turn, were associated with number of fledged young. These findings were further supported by measurements of hatching success and rearing success, which did not seem to increase with age.7. Increased breeding experience was associated with early hatching date and larger clutch size in males, and with larger clutch size in females. This was concluded from path analysis and from comparisons of individuals of the same age but with different breeding experience.8. The increase in reproductive success with age in the barnacle goose is probably a result of age-related skills in individuals and the direct effects of these skills on reproductive success, but possibly also because of increased reproductive effort with age owing to these age-related skills.
|
|
| 5. |
- Forslund, Pär, et al.
(författare)
-
Breeding range expansion of the barnacle goose Branta leucopsis in the Baltic area
- 1991
-
Ingår i: Ardea. - : Netherlands Ornithologists’ Union. - 0373-2266 .- 2213-1175. ; 79:2, s. 343-346
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the development of Barnacle Goose Branta leucopsis breeding colonies in the Baltic area. The largest colony is situated on the eastern coast of Gotland. Sweden, and consisted in 1988 of 970 breeding pairs. Breeding birds have also been observed in nine other Baltic localities within the 1980s. Differences in reproductive success at different localities suggest that density-dependent effects are important. Young nonbreeding geese frequently move between colonies during the summer. Intraspecific competition may increase the propensity for natal dispersal by geese from the main colony on Gotland
|
|
| 6. |
|
|
| 7. |
- Forslund, Pär, et al.
(författare)
-
Intraspecific nest parasitism in the barnacle gooseFjärrlån IN : behavioural tactics of parasites and hosts
- 1995
-
Ingår i: Animal Behaviour. - : Elsevier. - 0003-3472 .- 1095-8282. ; 50:2, s. 509-517
-
Tidskriftsartikel (refereegranskat)abstract
- Intraspecific nest parasitism in the barnacle goose,Branta leucopsis, was recorded by direct observations of females trying to lay eggs in the nests of other females. This was observed on 36 occasions. Parasitic egg-laying attempts were observed both in mornings and evenings, and lasted on average at least 20 min. Parasitic females approached host nests very fast and immediately sat down on or close to the nest. Host females attacked parasitic females intensively, but host males were much less aggressive. Males paired to the parasitic females were sometimes seen, but they never took any active part in the parasitic egg-laying attempts. Parasitic females probably successfully laid an egg most of the times, as the clutch size in host nests was on average 0·9 eggs larger than in nests where parasitic egg-laying attempts were not observed. Host females were observed to retrieve eggs laid outside the nest cup. Of 27 known cases, parasitic females made their egg-laying attempts before or at the host's start of incubation on 12 occasions, and after the start of incubation 15 times. It is suggested that parasitic females exploited features in the behaviour of potential hosts, such as egg retrieval and low aggressiveness in host males, to succeed in their egg-laying attempts. Nest parasitism seems to be a facultative, ‘best-of-a-bad-job’ tactic in barnacle geese, as parasitic females were observed to have nests of their own before or after the year they behaved parasitically, but never in that particular year.
|
|
| 8. |
- Forslund, Pär, et al.
(författare)
-
The effect of mate change an new partner's age on reproductive success in the barnacle goose, Branta leucopsis
- 1991
-
Ingår i: Behavioral Ecology. - : Oxford University Press. - 1045-2249 .- 1465-7279. ; 2:2, s. 116-122
-
Tidskriftsartikel (refereegranskat)abstract
- Mate retention frequencies and correlations between mate change and reproductive performance were estimated in a population of barnacle geese, Branta leucopsis, breeding on the island of Gotland in the Baltic. About 90% of the pairs remained together from one breeding season to the next. Only 2.4% of the pairs divorced, most mate changes being consequences of the death of one partner. Divorces were not forecast by low reproductive success, and seemed to be accidental. In the season before mate change, there was no difference in reproductive performance, measured as clutch size, hatching date, and number of fledged young, between faithful pairs and pairs where one partner was subsequently changed. However, in the first season with a new partner, clutch size and number of fledged young decreased on average. Hence, because mate change led to a reduction in reproductive success, it was concluded that mate retention is advantageous. Our results suggest that this reduction is more likely due to the lower average age or breeding experience of new partners than to the benefits of breeding experience with one particular partner.
|
|
| 9. |
- Jeppsson, Tobias, et al.
(författare)
-
Can Life History Predict the Effect of Demographic Stochasticity on Extinction Risk?
- 2012
-
Ingår i: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 179, s. 706-720
-
Tidskriftsartikel (refereegranskat)abstract
- Demographic stochasticity is important in determining extinction risks of small populations, but it is largely unknown how its effect depends on the life histories of species. We modeled effects of demographic stochasticity on extinction risk in a broad range of generalized life histories, using matrix models and branching processes. Extinction risks of life histories varied greatly in their sensitivity to demographic stochasticity. Comparing life histories, extinction risk generally increased with increasing fecundity and decreased with higher ages of maturation. Effects of adult survival depended on age of maturation. At lower ages of maturation, extinction risk peaked at intermediate levels of adult survival, but it increased along with adult survival at higher ages of maturation. These differences were largely explained by differences in sensitivities of population growth to perturbations of life history traits. Juvenile survival rate contributed most to total demographic variance in the majority of life histories. Our general results confirmed earlier findings, suggesting that empirical patterns can be explained by a relatively simple model. Thus, basic life history information can be used to assign life history-specific sensitivity to demographic stochasticity. This is of great value when assessing the vulnerability of small populations.
|
|
| 10. |
|
|
| 11. |
- Jeppsson, Tobias, et al.
(författare)
-
Oh, how we pick and choose: on theoretical constructs in subfields of ecology
- 2016
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Ecology consists of a large number of theoretical constructs, empirical patterns and methods; a pool from which applied ecology can draw ideas when exploring practical problems. Subfields of applied ecology - including pest control, conservation, and wildlife management - deal with the management of biological populations, and should therefore rest on the same ecological foundations. But is this really the case? We study this issue by analyzing recent citation rates (2010-2014) to more than 130 highly cited, classic publications, covering a wide range of topics. Using ordination methods, we find a clear clustering of journals, where conservation occupies another part of the ordination space than pest control. Classifying papers into broad topics reveals that the ordination patterns are driven by striking differences in how often ecological concepts are used in different subfields. While some patterns are easy to understand, e.g. the use of biodiversity concepts in conservation, others are left unexplained. For instance, the lack of spatial concepts and competition in pest control, predation in conservation journals, and foodweb ideas in wildlife journals are harder to understand. Microbial ecology also appears devoid of large parts of ecological theory. These patterns imply distinct divides within ecology, where subfields selectively use certain parts of ecological theory. Therefore, we argue that work in applied ecology would benefit from broader theoretical perspectives. Collaboration and inspiration across sub-disciplines could be one way to achieve this, perhaps inspiring novel research directions.
|
|
| 12. |
- Jeppsson, Tobias, et al.
(författare)
-
Species' traits explain differences in Red list status and long-term population trends in longhorn beetles
- 2014
-
Ingår i: Animal Conservation. - : Wiley. - 1367-9430 .- 1469-1795. ; 17, s. 332-341
-
Tidskriftsartikel (refereegranskat)abstract
- Some species are more likely to go extinct than others and this is partially due to species' traits. Therefore, it is important to establish links between traits and extinction risks. Different aspects of a species' biology also relates to different sources of threat, such as fragmented populations or low population growth rate. In a comparative study of Swedish longhorn beetles (Coleoptera: Cerambycidae), we related species' traits to two aspects of extinction risk - population decline and small/fragmented populations - measured by long-term population trends and IUCN Red list classifications. Trait relationships were analysed with generalized linear models and multi-model inference. We found that extinction risk generally increased with longer generation times, corresponding to slower life histories. Adult activity period was also related to both metrics of extinction risk, but in different ways. We also found that extinction risk increased with larval host plant specialization, but only for Red list classification. Large body size was related to increased Red list classification in species overwintering as adults, and overwintering stage also structured the effects of several other traits. Our results show that both intrinsic demographic traits and ecological traits affect extinction risks, and also suggest that risks are shaped by multiple mechanisms. Therefore, researchers should carefully choose their metric of extinction risk for comparative studies, as the Red list classification may best capture current risk, whereas population trends can be used more proactively but may reflect historical relationships between traits and extinction risk.
|
|
| 13. |
- Jeppsson, Tobias, et al.
(författare)
-
The use of historical collections to estimate population trends: A case study using Swedish longhorn beetles (Coleoptera: Cerambycidae)
- 2010
-
Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 143, s. 1940-1950
-
Tidskriftsartikel (refereegranskat)abstract
- Long term data to estimate population trends among species are generally lacking. However, Natural History Collections (NHCs) can provide such information, but may suffer from biases due to varying sampling effort. To analyze population trends and range-abundance dynamics of Swedish longhorn beetles (Coleoptera: Cerambycidae), we used collections of 108 species stretching over 100 years. We controlled for varying sampling effort by using the total number of database records as a reference for non-red-listed species. Because the general frequency of red-listed species increased over time, a separate estimate of sampling effort was used for that group. We observed large interspecific variation in population changes, from declines of 60% to several hundred percent increases. Most species showed stable or increasing ranges, whereas few seemed to decline in range. Among increasing species, rare species seemed to expand their range more than common species did, but this pattern was not observed in declining species. Historically, rare species did not seem to be at larger risk of local extinction, and population declines were mostly due to lower population density and not loss of sub-populations. We also evaluated the species' declines under IUCN red-list criterion A, and four currently not red-listed species meet the suggested threshold for Near Threatened (NT). The results also suggested that species' declines may be overlooked if estimated only from changes in species range. (C) 2010 Elsevier Ltd. All rights reserved.
|
|
| 14. |
- Konke, Linn Andersson, et al.
(författare)
-
How Does Temperament in Toddlers at Elevated Likelihood for Autism Relate to Symptoms of Autism and ADHD at Three Years of Age?
- 2022
-
Ingår i: Journal of autism and developmental disorders. - : Springer Science and Business Media LLC. - 0162-3257 .- 1573-3432. ; 52, s. 995-1006
-
Tidskriftsartikel (refereegranskat)abstract
- The current study investigated longitudinal associations between parent-rated temperament, observed exuberance and accelerometer activity level at 18-months and symptoms of ASD and ADHD at 36-months in a sample of 54 children at elevated likelihood for ASD. For the specific parent-rated temperament scales, most observed significant associations appeared to be specific for either ASD or ADHD symptoms. Indeed, by controlling for overlapping symptoms a different pattern of associations emerged. These results illustrate how temperamental measures may signal risk for later ASD versus ADHD symptomatology in infants at elevated likelihood for ASD. In addition, they indicate the potential of adopting a broader view on neurodevelopmental disorders by investigating not only ASD traits, but also co-occurring disorders such as ADHD in samples of elevated likelihood for ASD.
|
|
| 15. |
- Larsson, Kjell, et al.
(författare)
-
Body size declines despite positive directional selection on heritable size traits in a barnacle goose population
- 1998
-
Ingår i: Evolution. - : Society for the Study of Evolution. - 0014-3820 .- 1558-5646. ; 52:4, s. 1169-1184
-
Tidskriftsartikel (refereegranskat)abstract
- Analyses of more than 2000 marked barnacle geese (Branta leucopsis) in the largest Baltic colony, Sweden, showed that structurally large females generally produced larger clutches and larger eggs, hatched their broods earlier in the season, and produced more and heavier young than smaller females. In males, the corresponding relationships between reproductive parameters and structural body size were weaker or nonsignificant. Because structural body size traits have previously been found to be significantly heritable and positively genetically correlated, an increase in mean structural body size of individuals as a response to selection might have been expected. By contrast, we found that the mean adult head length and mean adult tarsus length decreased significantly in the largest colony by approximately 0.7 and 0.5 standard deviations, respectively, in both males and females during the 13-year study period. Environmental factors, such as the amount of rain in different years, were found to affect the availability of high-quality food for growing geese. As a consequence of this temporal variability in the availability of high-quality food, the mean adult structural body size of different cohorts differed by up to 1.3 standard deviations. Comparisons of mean body size of cohorts born in different colonies suggest that the most likely explanation for the body-size decline in the main study colony is that a density-dependent process, which mainly was in effect during the very early phase of colony growth, negatively affected juvenile growth and final size. We conclude that large environmental effects on growth and final structural body size easily can mask microevolutionary responses to selection. Analyses of environmental causes underlying temporal and spatial body size variation should always be considered in the reconstruction and prediction of evolutionary changes in natural populations.
|
|
| 16. |
- Larsson, Kjell, et al.
(författare)
-
Environmentally induced morphological variation in the Barnacle Goose, Branta leucopsis
- 1991
-
Ingår i: Journal of Evolutionary Biology. - : John Wiley & Sons. - 1010-061X .- 1420-9101. ; 4:4, s. 619-636
-
Tidskriftsartikel (refereegranskat)abstract
- The environmental conditions to which juvenile barnacle geese (Branta leucopsis) were exposed during growth were found to affect their body size at fledging as well as their final adult body size. Small juveniles showed compensatory growth from the time of fledging up to one year of age, but this did not fully compensate the differences in body size that were established before fledging. The variation in protein content in plants eaten during growth could probably explain the observed body size differences, sometimes of more than 10%, between different categories of adult geese. Our results imply that one cannot infer selection on morphological characters from differences between samples of adult birds from different localities or from different cohorts within a population, without first showing that environmental conditions during growth do not affect the development of the characters under study.
|
|
| 17. |
- Larsson, Kjell, et al.
(författare)
-
From the High Arctic to the Baltic : The successful establishment of a Barnacle Goose Branta leucopsis population on Gotland, Sweden
- 1988
-
Ingår i: Ornis Scandinavica. - : John Wiley & Sons. - 0908-8857 .- 0030-5693. ; 19:3, s. 182-189
-
Tidskriftsartikel (refereegranskat)abstract
- Fecundity, survival, immigration and emigration in a recently established population of Barnacle Goose on Gotland, Sweden, are analysed using data from 1971 to 1985. During this period numbers increased from one to 450 breeding pairs. A simulation of population growth using a deterministic population growth model showed that immigration must have occurred during this period, probably mainly during the late 1970s and early 1980s. This net influx together with a high and stable reproductive success and a high annual survival rate resulted in exponential increase in numbers. Several fecundity parameters were higher in the Gotland population than in the Arctic populations of Barnacle Goose. This successful establishment in a temperate area more than 1,300 km south of and 2,000 km away form the species' usual breeding range, questions many explanations of Arctic distributions in geese, for example the hypothesis that a too low protein content in the food plants prevents breeding at lower latitudes.
|
|
| 18. |
- Larsson, Kjell
(författare)
-
Genetic and social inheritance of body and egg size in the barnacle goose (Branta leucopsis)
- 1992
-
Ingår i: Evolution. - : Society for the Study of Evolution. - 0014-3820 .- 1558-5646. ; 46:1, s. 235-244
-
Tidskriftsartikel (refereegranskat)abstract
- We present heritability estimates for final size of body traits and egg size as well as phenotypic and genetic correlations between body and egg traits in a recently established population of the barnacle goose (Branta leucopsis) in the Baltic area. Body traits as well as egg size were heritable and, hence, could respond evolutionarily to phenotypic selection. Genetic correlations between body size traits were significantly positive and of similar magnitude or higher than the corresponding phenotypic correlations. Heritability estimates for tarsus length obtained from fullsib analyses were higher than those obtained from midoffspring-midparent regressions, and this indicates common environment effects on siblings. Heritabilities for tarsus length obtained from midoffspring-mother regressions were significantly higher than estimates from midoffspring-father regressions. The results suggest that this discrepancy is not caused by maternal effects through egg size, nor by extra-pair fertilizations, but by a socially inherited foraging site fidelity in females.
|
|
| 19. |
- Larsson, Kjell, et al.
(författare)
-
Intraspecific nest parasitism and adoption of young in the barnacle goose : effects on survival and reproductive performance
- 1995
-
Ingår i: Animal Behaviour. - : Elsevier. - 0003-3472 .- 1095-8282. ; 50:5, s. 1349-1360
-
Tidskriftsartikel (refereegranskat)abstract
- DNA fingerprinting was used to determine the proportion of extra-pair young in a population of barnacle geese, Branta leticopsis, breeding in the Baltic area, Sweden. Of 137 analysed fledged young 17% were found to be extra-pair young. One or more extra-pair young were found in 27% of the 63 analysed families. The proportion of extra-pair young differed between years. No case of extra-pair fertilization was detected. All extra-pair young at fledgling originated either from intraspecific nest parasitism or from adoptions of foreign hatched young. Broods with extra-pair young at fledgling were significantly larger than broods without extra-pair young. However, the number of within-pair young did not differ significantly in broods with and without extra-pair young. Body mass, survival or subsequent reproductive performance did not differ between parents with and without extra-pair fledged young. Post-fledgling survival and age at first breeding were not significantly different between the three analysed classes of fledged young, i.e., within-pair young in families without extra-pair young, within-pair young in families with at least one extra-pair young, and extra-pair young. It is concluded that possible costs or benefits associated with caring for extra-pair fledged young are small or absent in this population.
|
|
| 20. |
- Larsson, Kjell, et al.
(författare)
-
Population dynamics of the barnacle goose Branta leucopsis in the Baltic area : density-dependent effects on reproduction
- 1994
-
Ingår i: Journal of Animal Ecology. - : British Ecological Society. - 0021-8790 .- 1365-2656. ; 63:4, s. 954-962
-
Tidskriftsartikel (refereegranskat)abstract
- 1. The three largest breeding colonies of barnacle geese Branta leucopsis in the Baltic area were studied from their natural establishments in 1971, 1982 and 1987, respectively, to 1993. The number of breeding pairs increased from one pair in 1971 to 1550, 225 and 150 pairs in the largest, second largest, and third largest colonies, respectively, in 1993. 2. Data on clutch size and number of hatched and fledged young were collected from the beginning or the middle of the 1980s. In the largest colony most data on reproductive success were obtained from observations of individually marked geese. 3. Mean clutch size differed among years and colonies. However, there was no trend for decreasing mean clutch size with increasing density in any of the colonies. Hatching success did not decrease with increasing density in the largest colony. 4. The production of fledged young per breeding pair declined drastically in the largest colony as numbers of breeding pairs rose. This decline was mainly caused by an increasing proportion of the breeding pairs failing to produce any fledged young at all. 5. The relative contribution of the smaller colonies to the total production of fledged young in the Baltic area increased considerably over the study years. In 1993, colony 2 hosted only about 13% of the number of breeding pairs in colonies 1 and 2 combined, but it produced about 38% of the fledged young. 6. Our results point out the need to study populations of colonially nesting geese on a colony by colony basis in order to detect density-dependent effects on reproduction.
|
|
| 21. |
|
|
| 22. |
- Nord, Maria, et al.
(författare)
-
Environmental Gradients Explain Species Richness and Community Composition of Coastal Breeding Birds in the Baltic Sea
- 2015
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Scientifically-based systematic conservation planning for reserve design requires knowledge of species richness patterns and how these are related to environmental gradients. In this study, we explore a large inventory of coastal breeding birds, in total 48 species, sampled in 4646 1 km(2) squares which covered a large archipelago in the Baltic Sea on the east coast of Sweden. We analysed how species richness (alpha diversity) and community composition (beta diversity) of two groups of coastal breeding birds (specialists, i.e. obligate coastal breeders; generalists, i.e. facultative coastal breeders) were affected by distance to open sea, land area, shoreline length and archipelago width. The total number of species per square increased with increasing shoreline length, but increasing land area counteracted this effect in specialists. The number of specialist bird species per square increased with decreasing distance to open sea, while the opposite was true for the generalists. Differences in community composition between squares were associated with differences in land area and distance to open sea, both when considering all species pooled and each group separately. Fourteen species were nationally red-listed, and showed similar relationships to the environmental gradients as did all species, specialists and generalists. We suggest that availability of suitable breeding habitats, and probably also proximity to feeding areas, explain much of the observed spatial distributions of coastal birds in this study. Our findings have important implications for systematic conservation planning of coastal breeding birds. In particular, we provide information on where coastal breeding birds occur and which environments they seem to prefer. Small land areas with long shorelines are highly valuable both in general and for red-listed species. Thus, such areas should be prioritized for protection against human disturbance and used by management in reserve selection.
|
|
| 23. |
- Nord, Maria, et al.
(författare)
-
The effectiveness of area protection to capture coastal bird richness and occurrence in the Swedish archipelago
- 2019
-
Ingår i: Global Ecology and Conservation. - : Elsevier BV. - 2351-9894. ; 17
-
Tidskriftsartikel (refereegranskat)abstract
- Protected areas are a key component in biodiversity conservation strategies, but evaluations of how effective they are in capturing species diversity is lacking for many ecosystems. We compared different protection types (animal sanctuaries, nature reserves and unprotected areas) using data on species richness and occurrence of coastal breeding bird species in a large archipelago in the Baltic Sea. Data were from extensive inventories based on a grid with 1 x 1 km resolution covering 4646 km(2) on the East coast of Sweden. We focused on specialist species breeding exclusively in coastal habitats since these species are of specific conservation concern, but considered generalists, which also breeds in inland wetlands, as well. Animal sanctuaries had significantly higher species richness of specialist species than unprotected areas and nature reserves. Nature reserves had even lower richness of specialist species than unprotected areas. Further, a rarity-weighted diversity index showed that animal sanctuaries were better in capturing hotspots of bird diversity compared to nature reserves and unprotected areas. Hotspots, both protected and unprotected, were scattered throughout the entire archipelago. The rarity-weighted richness is therefore useful to identify gaps in the protected area network. Overall, we conclude that the establishment of animal sanctuaries has been a successful conservation measure for protecting specialist species in several aspects. Ongoing human exploitation of the Baltic archipelagos prompt further consideration of protecting still unprotected but species rich shorelines for the benefit of many coastal breeding birds.
|
|
| 24. |
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
|
|
| 28. |
- Olofsson, Anna, et al.
(författare)
-
Monitoring changes in lichen resources for range management purposes in reindeer husbandry
- 2011
-
Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X .- 1872-7034. ; 11, s. 1149-1159
-
Tidskriftsartikel (refereegranskat)abstract
- Mat-forming lichens are important as food source for reindeer during the winter, and thus a vital resource to manage in reindeer husbandry. In this paper we suggest a method for monitoring of changes in lichen height with the purpose to early detect changes in lichen abundance in reindeer grazing areas. The method is intended for measuring geographically uniform lichen areas, evenly used for reindeer grazing. We analysed spatial variations in lichen height at the meter and 100 m scales, and calculated sample size requirements, and estimated effects of forest density and age, lichen moisture and lichen density on lichen height, and assessed the correspondence between lichen height and biomass. The variation in lichen height differed considerably between sites and, hence, the required sample size to detect a 5 mm change in lichen height with a power of 0.95 ranged from 200 to 2000, depending on the standard deviation of measured heights. Based on the autocorrelation in lichen height found between adjacent measurement points, a minimum distance of 4 m between measurement points is also recommended. Lichen height was significantly affected by lichen moisture, and the results suggest that this effect of moisture might vary with lichen density. Lichen height varied spatially within the study sites, and the spatial variations were partly caused by forest age and density. Thus, gradual changes in the forest characteristics are likely to alter the spatial variation in lichen height and it is therefore important to regularly re-evaluate the locations of measurement points within the monitored area. This study provides suggestions for a variable that could be used as an indicator of changes in the lichen resource, and aspects that should be considered when designing a monitoring program. The accuracy of detecting changes depends on the monitoring efforts, i.e. the number and distribution of measurement points and how often an area is monitored. In conclusion, our results indicate that measurements of lichen height have considerable potential for monitoring of changes in lichen resources within reindeer husbandry
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
- Paquet, Matthieu, et al.
(författare)
-
Integrated population models poorly estimate the demographic contribution of immigration
- 2021
-
Ingår i: Methods in Ecology and Evolution. - 2041-210X. ; 12, s. 1899-1910
-
Tidskriftsartikel (refereegranskat)abstract
- Estimating the contribution of demographic parameters to changes in population growth is essential for understanding why populations fluctuate. Integrated population models (IPMs) offer a possibility to estimate the contributions of additional demographic parameters, for which no data have been explicitly collected-typically immigration. Such parameters are often subsequently highlighted as important drivers of population growth. Yet, accuracy in estimating their temporal variation, and consequently their contribution to changes in population growth rate, has not been investigated. To quantify the magnitude and cause of potential biases when estimating the contribution of immigration using IPMs, we simulated data (using northern wheatear Oenanthe oenanthe population estimates) from controlled scenarios to examine potential biases and how they depend on IPM parameterization, formulation of priors, the level of temporal variation in immigration and sample size. We also used empirical data on populations with known rates of immigration: Soay sheep Ovis aries and Mauritius kestrel Falco punctatus with zero immigration and grey wolf Canis lupus in Scandinavia with near-zero immigration. IPMs strongly overestimated the contribution of immigration to changes in population growth in scenarios when immigration was simulated with zero temporal variation (proportion of variance attributed to immigration = 63% for the more constrained formulation and real sample size) and in the wild populations, where the true number of immigrants was zero or near-zero (kestrel 19.1%-98.2%, sheep 4.2%-36.1% and wolf 84.0%-99.2%). Although the estimation of the contribution of immigration in the simulation study became more accurate with increasing temporal variation and sample size, it was often not possible to distinguish between an accurate estimation from data with high temporal variation versus an overestimation from data with low temporal variation. Unrealistically, large sample sizes may be required to estimate the contribution of immigration well. To minimize the risk of overestimating the contribution of immigration (or any additional parameter) in IPMs, we recommend to: (a) look for evidence of variation in immigration before investigating its contribution to population growth, (b) simulate and model data for comparison to the real data and (c) use explicit data on immigration when possible.
|
|
| 32. |
- Paquet, Matthieu, et al.
(författare)
-
Quantifying the links between land use and population growth rate in a declining farmland bird
- 2019
-
Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9, s. 868-879
-
Tidskriftsartikel (refereegranskat)abstract
- Land use is likely to be a key driver of population dynamics of species inhabiting anthropogenic landscapes, such as farmlands. Understanding the relationships between land use and variation in population growth rates is therefore critical for the management of many farmland species. Using 24 years of data of a declining farmland bird in an integrated population model, we examined how spatiotemporal variation in land use (defined as habitats with Short and Tall ground vegetation during the breeding season) and habitat-specific demographic parameters relates to variation in population growth taking into account individual movements between habitats. We also evaluated contributions to population growth using transient life table response experiments which gives information on contribution of past variation of parameters and real-time elasticities which suggests future scenarios to change growth rates. LTRE analyses revealed a clear contribution of Short habitats to the annual variation in population growth rate that was mostly due to fledgling recruitment, whereas there was no evidence for a contribution of Tall habitats. Only 18% of the variation in population growth was explained by the modeled local demography, the remaining variation being explained by apparent immigration (i.e., the residual variation). We discuss potential biological and methodological reasons for high contributions of apparent immigration in open populations. In line with LTRE analysis, real-time elasticity analysis revealed that demographic parameters linked to Short habitats had a stronger potential to influence population growth rate than those of Tall habitats. Most particularly, an increase of the proportion of Short sites occupied by Old breeders could have a distinct positive impact on population growth. High-quality Short habitats such as grazed pastures have been declining in southern Sweden. Converting low-quality to high-quality habitats could therefore change the present negative population trend of this, and other species with similar habitat requirements.
|
|
| 33. |
- Paquet, Matthieu, et al.
(författare)
-
Why we should care about movements: Using spatially explicit integrated population models to assess habitat source-sink dynamics
- 2020
-
Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 89, s. 2922-2933
-
Tidskriftsartikel (refereegranskat)abstract
- Assessing the source-sink status of populations and habitats is of major importance for understanding population dynamics and for the management of natural populations. Sources produce a net surplus of individuals (per capita contribution to the metapopulation > 1) and will be the main contributors for self-sustaining populations, whereas sinks produce a deficit (contribution < 1). However, making these types of assessments is generally hindered by the problem of separating mortality from permanent emigration, especially when survival probabilities as well as moved distances are habitat-specific. To address this long-standing issue, we propose a spatial multi-event integrated population model (IPM) that incorporates habitat-specific dispersal distances of individuals. Using information about local movements, this IPM adjusts survival estimates for emigration outside the study area. Analysing 24 years of data on a farmland passerine (the northern wheatearOenanthe oenanthe), we assessed habitat-specific contributions, and hence the source-sink status and temporal variation of two key breeding habitats, while accounting for habitat- and sex-specific local dispersal distances of juveniles and adults. We then examined the sensitivity of the source-sink analysis by comparing results with and without accounting for these local movements. Estimates of first-year survival, and consequently habitat-specific contributions, were higher when local movement data were included. The consequences from including movement data were sex specific, with contribution shifting from sink to likely source in one habitat for males, and previously noted habitat differences for females disappearing. Assessing the source-sink status of habitats is extremely challenging. We show that our spatial IPM accounting for local movements can reduce biases in estimates of the contribution by different habitats, and thus reduce the overestimation of the occurrence of sink habitats. This approach allows combining all available data on demographic rates and movements, which will allow better assessment of source-sink dynamics and better informed conservation interventions.
|
|
| 34. |
- Pärt, Tomas, et al.
(författare)
-
Unclear relationships between mean survival rate and its environmental variance in vertebrates
- 2024
-
Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 14:3
-
Tidskriftsartikel (refereegranskat)abstract
- Current environmental changes may increase temporal variability of life history traits of species thus affecting their long-term population growth rate and extinction risk. If there is a general relationship between environmental variances (EVs) and mean annual survival rates of species, that relationship could be used as a guideline for analyses of population growth and extinction risk for populations, where data on EVs are missing. For this purpose, we present a comprehensive compilation of 252 EV estimates from 89 species belonging to five vertebrate taxa (birds, mammals, reptiles, amphibians and fish) covering mean annual survival rates from 0.01 to 0.98. Since variances of survival rates are constrained by their means, particularly for low and high mean survival rates, we assessed whether any observed relationship persisted after applying two types of commonly used variance stabilizing transformations: relativized EVs (observed/mathematical maximum) and logit-scaled EVs. With raw EVs at the arithmetic scale, mean–variance relationships of annual survival rates were hump-shaped with small EVs at low and high mean survival rates and higher (and widely variable) EVs at intermediate mean survival rates. When mean annual survival rates were related to relativized EVs the hump-shaped pattern was less distinct than for raw EVs. When transforming EVs to logit scale the relationship between mean annual survival rates and EVs largely disappeared. The within-species juvenile-adult slopes were mainly positive at low (<0.5) and negative at high (>0.5) mean survival rates for raw and relativized variances while these patterns disappeared when EVs were logit transformed. Uncertainties in how to interpret the results of relativized and logit-scaled EVs, and the observed high variation in EV's for similar mean annual survival rates illustrates that extrapolations of observed EVs and tests of life history drivers of survival–EV relationships need to also acknowledge the large variation in these parameters.
|
|
| 35. |
|
|
| 36. |
- Snäll, Tord, et al.
(författare)
-
Evaluating temporal variation in Citizen Science Data against temporal variation in the environment
- 2014
-
Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 37, s. 293-300
-
Tidskriftsartikel (refereegranskat)abstract
- Citizen Science Data (CSD) is increasingly contributing to the assessment of biodiversity and ecosystems. However, there is a need to evaluate the usefulness of CSD for different purposes. Ideally, CSD from populations should be evaluated against independent population data collected using a proper sampling design, but such data are lacking for almost all species. We propose an approach for evaluating CSD against environmental data. First, an evaluation model is formulated based on knowledge of how environmental variables affect population dynamics. Second, the hypotheses of the evaluation model are tested statistically. Support for the evaluation model is interpreted as support for the CSD. We applied the approach to six longhorn beetle species using Swedish data from 1930-2000. The evaluation model assumed that early summer temperature affects larval development time. We found support for the evaluation model in two species, and some evidence in its favour in one species. This suggests that the CSD from these species reflect true inter-annual variation. We also found statistical evidence for population trends in three to four species. In two of these, the evaluation model was supported thus providing particular support for the trend estimates. Lack of support for the evaluation model may be due to biological inaccuracy, the general characteristics of CSD, or low resolution of the environmental evaluation data. We also discuss alternative environmental data for evaluating CSD.
|
|
