| 1. |
- Bach, Lars, et al.
(författare)
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Assessing re-introductions of the African Wild dog (Lycaon pictus) in the Limpopo Valley Conservancy, South Africa, using the stochastic simulation program VORTEX
- 2010
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Ingår i: Journal for Nature Conservation. - : Elsevier BV. - 1617-1381. ; 18:4, s. 237-246
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Tidskriftsartikel (refereegranskat)abstract
- The African wild dog (Lycaon pictus) is one of Africa's most endangered species and therefore classified as endangered by IUCN. Earlier distributions included most of Africa but currently the African wild dog only has populations larger than 300 individuals in three countries (Botswana, Tanzania and South Africa). In 1998, a plan was launched in South Africa to manage sub-populations of the African wild dog in several small, geographically isolated, conservation areas. This management program involved the reintroduction of wild dogs into suitable conservation areas and periodic translocations among them. We used the stochastic population simulation model VORTEX to evaluate the Limpopo Valley Conservancy in the north of South Africa, as a possible reintroduction site for African wild dogs. The simulations showed that the size of the initial population released only had a small effect on the population dynamics. However, when individuals were supplemented and harvested over a longer period the probability of persistence increased. Number of females breeding, male mortality, and carrying capacity were key factors in the population dynamics, but according to VORTEX the severity of natural catastrophes had the greatest influence on the extinction risk and inbreeding. We suggest that the reintroduction program may be successful, if areas are properly secured, the dogs are held in a boma before release, wild animals or at least a mix of wild and captive animals are used for the release and the animals are vaccinated against rabies. It is, however, essential to continue monitoring followed by modelling efforts to re-evaluate the success of the reintroduction program. (C) 2009 Elsevier GmbH. All rights reserved.
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| 2. |
- Bach, Lars, et al.
(författare)
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Diminishing return of investment in genetic diversity
- 2012
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Ingår i: Evolutionary Ecology Research. - 1522-0613. ; 14:7, s. 793-801
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Tidskriftsartikel (refereegranskat)abstract
- Motive: Priorities in conservation management are often difficult to determine because we lack comparable biodiversity metrics. So that actions can be cost-effective, conservation decision-making and management needs such metrics. Question: What suitable metrics can compare efforts and investments in biodiversity conservation? How can established measures of genetic diversity be combined with the economic return-of-investment paradigm? Method: Use the return-of-investment approach, which has previously been restricted to issues of species diversity. Extend it to include genetic diversity. Use Taylor's power law to relate mean abundance, rates of genetic deterioration, and principles of return-of-investment. Key assumptions: We can specify the relationship between cost of conservation and population size. Time-series data are available for each population. We can approximate the effective population size (N-e) of a fluctuating population as the harmonic mean population size. Conclusion: As the financial investment in conservation increases, the estimated marginal increase in genetic diversity diminishes. One can rank actions that increase mean population size according to their associated marginal increases in genetic diversity, thus evaluating which improvements offer the most value for money.
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| 3. |
- Demontis, Ditte, et al.
(författare)
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Efficiency of selection, as measured by single nucleotide polymorphism variation, is dependent on inbreeding rate in Drosophila melanogaster
- 2009
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 18:22, s. 4551-4563
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Tidskriftsartikel (refereegranskat)abstract
- It is often hypothesized that slow inbreeding causes less inbreeding depression than fast inbreeding at the same absolute level of inbreeding. Possible explanations for this phenomenon include the more efficient purging of deleterious alleles and more efficient selection for heterozygote individuals during slow, when compared with fast, inbreeding. We studied the impact of inbreeding rate on the loss of heterozygosity and on morphological traits in Drosophila melanogaster. We analysed five noninbred control lines, 10 fast inbred lines and 10 slow inbred lines; the inbred lines all had an expected inbreeding coefficient of approximately 0.25. Forty single nucleotide polymorphisms in DNA coding regions were genotyped, and we measured the size and shape of wings and counted the number of sternopleural bristles on the genotyped individuals. We found a significantly higher level of genetic variation in the slow inbred lines than in the fast inbred lines. This higher genetic variation was resulting from a large contribution from a few loci and a smaller effect from several loci. We attributed the increased heterozygosity in the slow inbred lines to the favouring of heterozygous individuals over homozygous individuals by natural selection, either by associative over-dominance or balancing selection, or a combination of both. Furthermore, we found a significant polynomial correlation between genetic variance and wing size and shape in the fast inbred lines. This was caused by a greater number of homozygous individuals among the fast inbred lines with small, narrow wings, which indicated inbreeding depression. Our results demonstrated that the same amount of inbreeding can have different effects on genetic variance depending on the inbreeding rate, with slow inbreeding leading to higher genetic variance than fast inbreeding. These results increase our understanding of the genetic basis of the common observation that slow inbred lines express less inbreeding depression than fast inbred lines. In addition, this has more general implications for the importance of selection in maintaining genetic variation.
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| 4. |
- Holm Andersen, Line, 1988-, et al.
(författare)
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Can reintroduction of beavers improve insect biodiversity?
- 2023
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 337
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Tidskriftsartikel (refereegranskat)abstract
- Ecosystem engineering species, such as beavers, may help the restoration of biodiversity. Through the building of dams and lodges and altering the natural hydrology, beavers change the habitat structure and create multiple habitats that facilitate a wide variety of other organisms including terrestrial invertebrate communities. Here we study the effect of beaver reintroduction in Klosterheden in Denmark on biomass of flying invertebrates and diversity of moths. Further, aerial photos were used to assess riparian structure and productivity using the normalized difference vegetation index (NDVI). Our findings show that the presence of beavers affected flying invertebrate biomass, but that this was dependent on time of the year. Further, a strong effect of presence of beavers was found on diversity of moths. The results also show an increase in vegetation productivity and structural heterogeneity at sites with presence of beavers. Overall, our results demonstrate the importance of beavers as important ecosystem engineers that affect invertebrate species composition and abundance, as well as riparian structure and productivity.
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| 5. |
- McDevitt, Allan D., et al.
(författare)
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Next-generation phylogeography resolves post-glacial colonization patterns in a widespread carnivore, the red fox (Vulpes vulpes), in Europe
- 2022
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 31:3, s. 993-1006
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Tidskriftsartikel (refereegranskat)abstract
- Carnivores tend to exhibit a lack of (or less pronounced) genetic structure at continental scales in both a geographic and temporal sense and this can confound the identification of post-glacial colonization patterns in this group. In this study we used genome-wide data (using genotyping by sequencing [GBS]) to reconstruct the phylogeographic history of a widespread carnivore, the red fox (Vulpes vulpes), by investigating broad-scale patterns of genomic variation, differentiation and admixture amongst contemporary populations in Europe. Using 15,003 single nucleotide polymorphisms (SNPs) from 524 individuals allowed us to identify the importance of refugial regions for the red fox in terms of endemism (e.g., Iberia). In addition, we tested multiple post-glacial recolonization scenarios of previously glaciated regions during the Last Glacial Maximum using an Approximate Bayesian Computation (ABC) approach that were unresolved from previous studies. This allowed us to identify the role of admixture from multiple source population post-Younger Dryas in the case of Scandinavia and ancient land-bridges in the colonization of the British Isles. A natural colonization of Ireland was deemed more likely than an ancient human-mediated introduction as has previously been proposed and potentially points to a larger mammalian community on the island in the early post-glacial period. Using genome-wide data has allowed us to tease apart broad-scale patterns of structure and diversity in a widespread carnivore in Europe that was not evident from using more limited marker sets and provides a foundation for next-generation phylogeographic studies in other non-model species.
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| 6. |
- Moghadam, Neda N., et al.
(författare)
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Effects of photoperiod on life-history and thermal stress resistance traits across populations of Drosophila subobscura
- 2019
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Ingår i: Ecology and Evolution. - : WILEY. - 2045-7758. ; 9:5, s. 2743-2754
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Organisms use environmental cues to match their phenotype with the future availability of resources and environmental conditions. Changes in the magnitude and frequency of environmental cues such as photoperiod and temperature along latitudes can be used by organisms to predict seasonal changes. While the role of temperature variation on the induction of plastic and seasonal responses is well established, the importance of photoperiod for predicting seasonal changes is less explored. Materials and methods Here we studied changes in life-history and thermal stress resistance traits in Drosophila subobscura in response to variation in photoperiod (6:18, 12:12 and 18:6 light:dark cycles) mimicking seasonal variations in day length. The populations of D. subobscura were collected from five locations along a latitudinal gradient (from North Africa and Europe). These populations were exposed to different photoperiods for two generations, whereafter egg-to-adult viability, productivity, dry body weight, thermal tolerance, and starvation resistance were assessed. Results We found strong effects of photoperiod, origin of populations, and their interactions on life-history and stress resistance traits. Thermal resistance varied between the populations and the effect of photoperiod depended on the trait and the method applied for the assessment of thermal resistance. Perspectives Our results show a strong effect of the origin of population and photoperiod on a range of fitness-related traits and provide evidence for local adaptation to environmental cues (photoperiod by population interaction). The findings emphasize an important and often neglected role of photoperiod in studies on thermal resistance and suggest that cues induced by photoperiod may provide some buffer enabling populations to cope with a more variable and unpredictable future climate.
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| 7. |
- Mucci, Nadia, et al.
(författare)
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Genetic diversity and landscape genetic structure of otter (Lutra lutra) populations in Europe
- 2010
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 11:2, s. 583-599
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Tidskriftsartikel (refereegranskat)abstract
- Eurasian otter populations strongly declined and partially disappeared due to global and local causes (habitat destruction, water pollution, human persecution) in parts of their continental range. Conservation strategies, based on reintroduction projects or restoration of dispersal corridors, should rely on sound knowledge of the historical or recent consequences of population genetic structuring. Here we present the results of a survey performed on 616 samples, collected from 19 European countries, genotyped at the mtDNA control-region and 11 autosomal microsatellites. The mtDNA variability was low (nucleotide diversity = 0.0014; average number of pairwise differences = 2.25), suggesting that extant otter mtDNA lineages originated recently. A star-shaped mtDNA network did not allow outlining any phylogeographic inference. Microsatellites were only moderately variable (H (o) = 0.50; H (e) = 0.58, on average across populations), the average allele number was low (observed A (o) = 4.9, range 2.5-6.8; effective A (e) = 2.8; range 1.6-3.7), suggesting small historical effective population size. Extant otters likely originated from the expansion of a single refugial population. Bayesian clustering and landscape genetic analyses however indicate that local populations are genetically differentiated, perhaps as consequence of post-glacial demographic fluctuations and recent isolation. These results delineate a framework that should be used for implementing conservation programs in Europe, particularly if they are based on the reintroduction of wild or captive-reproduced otters.
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| 8. |
- Pertoldi, Cino, et al.
(författare)
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On the brink between extinction and persistence
- 2008
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Ingår i: Biology Direct. - : Springer Science and Business Media LLC. - 1745-6150. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The nature of size fluctuations is crucial in forecasting future population persistence, independently of whether the variability stems from external forces or from the dynamics of the population renewal process. The risk of intercepting zero is highly dependent on the way the variance of the population size relates to its mean. The minimum population size required for a population not to go extinct can be determined by a scaling equation relating the variance to the arithmetic mean. By the use of a derived expression for the harmonic mean defined by the parameters of the scaling equation we show how it is possible to separate the domains of persistence from those of extinction and to facilitate the identification of populations on the brink of extinction.
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| 9. |
- Pertoldi, Cino, et al.
(författare)
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Scaling of the mean and variance of population dynamics under fluctuating regimes
- 2014
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Ingår i: Theory in Biosciences. - : Springer Science and Business Media LLC. - 1431-7613 .- 1611-7530. ; 133:3-4, s. 165-173
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical ecologists have long sought to understand how the persistence of populations depends on the interactions between exogenous (biotic and abiotic) and endogenous (e.g., demographic and genetic) drivers of population dynamics. Recent work focuses on the autocorrelation structure of environmental perturbations and its effects on the persistence of populations. Accurate estimation of extinction times and especially determination of the mechanisms affecting extinction times is important for biodiversity conservation. Here we examine the interaction between environmental fluctuations and the scaling effect of the mean population size with its variance. We investigate how interactions between environmental and demographic stochasticity can affect the mean time to extinction, change optimal patch size dynamics, and how it can alter the often-assumed linear relationship between the census size and the effective population size. The importance of the correlation between environmental and demographic variation depends on the relative importance of the two types of variation. We found the correlation to be important when the two types of variation were approximately equal; however, the importance of the correlation diminishes as one source of variation dominates. The implications of these findings are discussed from a conservation and eco-evolutionary point of view.
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| 10. |
- Pertoldi, Cino, et al.
(författare)
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The Novel Concept of "Behavioural Instability" and Its Potential Applications
- 2016
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Ingår i: Symmetry. - : MDPI AG. - 2073-8994. ; 8:11
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Tidskriftsartikel (refereegranskat)abstract
- The concept of developmental instability (DI) is a well-known indicator of environmental and genetic stress and is often investigated using various indices such as fluctuating asymmetry, directional asymmetry, antisymmetry and phenotypic variance. Investigations dealing with DI are using morphometric traits. The aim of this investigation is to present the novel concept of behavioural instability in which the trait measured is a behavioural trait. We apply the conventional indices used for the estimation of developmental instability on directional movement-clockwise (CW) and counter-clockwise (CCW) movement of 19 highly inbred lines of Drosophila melanogaster tested in a circular arena. We show that it is possible to quantify behavioural instability using the indices traditionally used to investigate DI. Results revealed several significant differences among lines, depending on the index utilized. The perspectives of utilizing the concept in biological research such as toxicology, evolutionary and stress biology are discussed.
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