| 1. |
- Bach, Lars, et al.
(author)
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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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In: Journal for Nature Conservation. - : Elsevier BV. - 1617-1381. ; 18:4, s. 237-246
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Journal article (peer-reviewed)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.
(author)
-
Diminishing return of investment in genetic diversity
- 2012
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In: Evolutionary Ecology Research. - 1522-0613. ; 14:7, s. 793-801
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Journal article (peer-reviewed)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. |
- Givskov Sørensen, Jesper, et al.
(author)
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Effects of predator exposure on Hsp70 expression and survival in tadpoles of the Common Frog (Rana temporaria)
- 2011
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In: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 89:12, s. 1249-1255
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Journal article (peer-reviewed)abstract
- Predator-induced changes in prey behavior and morphology are widespread, but little is known about physiological and cellular-level responses in prey in response to predation risk. We investigated whether predator (larvae of the dragonfly Aeshna Fabricius, 1775) presence elevated the expression level of heat-shock protein 70 (Hsp70)-a commonly found response to stress-in tadpoles of the Common Frog (Rana temporaria L., 1758). In another experiment, we tested the survival of tadpoles in the presence of a free-ranging predator. Prior to this encounter, the tadpoles were exposed to either an Hsp-inducing environmental stress in the form of heat (31 degrees C) or to predator cues from a caged predator. We found no evidence for increased Hsp70 expression in tadpoles either in the presence of fed or starved predators. We did not find any effects of prior exposure to neither heat nor predator presence on survival at the end of experiment. Our results do not point to either Hsp70-mediated effect of predator-induced responses or to beneficial effects of the stress response on survival under predation risk.
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| 4. |
- Mucci, Nadia, et al.
(author)
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Genetic diversity and landscape genetic structure of otter (Lutra lutra) populations in Europe
- 2010
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In: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 11:2, s. 583-599
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Journal article (peer-reviewed)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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