bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biases associated with population estimation using molecular tagging
Authors: Waits Juliann L. , Leberg Paul L. 
Published: February 2006

AbstractAlthough capture–recapture techniques are often used to estimate population size, these approaches are difficult to implement for a wide variety of species. Highly polymorphic microsatellite markers are useful in individual identification, and these ‘molecular tags’ can be collected without having to capture or trap the individual. However, several sources of error associated with molecular identification techniques, including failure to identify individuals with the same genotype for these markers as being different, and incorrect assignment of individual genotypes, could bias population estimates. Simulations of populations sampled for the purpose of estimating population size were used to assess the extent of these potential biases. Population estimates tended to be biased downward as the likelihood of individuals sharing the same genotype increased (as measured by the probability of identity (PI) of the multi‐locus genotype); this bias increased with population size. Populations of 1000 individuals were underestimated by ≥5% when the PI was as small as 1.4 × 10−7. A similar‐sized bias did not occur for populations of 50 individuals until the PI had increased to approximately 2.5 × 10−5. Errors in genotype assignment resulted in overestimates of population size; this problem increased with the number of samples and loci that were genotyped. Population estimates were often >200% the size of the simulated populations when the probability of making a genotyping error was 0.05/locus and 7–10 loci were used to identify individuals. This bias was substantially reduced by decreasing genotyping error rate to 0.005. If possible, only highly polymorphic loci that are critical for the identification of the individual should be used in molecular tagging, and considerable efforts should be made to minimize errors in genotype determination.
Metapopulation viability of the marsupial Micoureus demerarae in small Atlantic forest fragments in south‐eastern Brazil
Authors: Brito Daniel , Fernandez Fernando A. S. 
Published: February 2006

AbstractA population viability analysis (PVA) was carried out for populations of the arboreal didelphid Micoureus demerarae in eight small (1.5–15.0 ha) forest fragments in south‐eastern Brazil. Analysis was based on field data obtained through demographic studies carried out since 1995. Populations are small, but connected by dispersing individuals, thus forming a metapopulation. Frequency of catastrophic fires was estimated from the Reserve's historical records. We used the computer package VORTEX for all analyses. All populations and the metapopulation were found to be endangered within 100 years (extinction probability > 0.98). A sensitivity analysis was run varying six parameters: three demographic (sex ratio, migration and mortality rates), two environmental (K, fire frequency) and one genetic (level of inbreeding depression). Genetics, K, mortality rates and sex ratio seemed to play major roles to population persistence, whereas catastrophes and migration rates had a secondary role. Among demographic factors, extinction rate was least sensitive to migration rate. Micoureus demerarae can be used as a model species, thus improving our knowledge of how extinction‐prone populations of neotropical arboreal marsupials in forest fragments might be, and which management actions could decrease such risks.
Improving translocation success: an experimental study of anti‐stress treatment and release method for wild rabbits
Authors: Letty Jérôme , Marchandeau Stéphane , Clobert Jean , Aubineau Jack 
Published: February 2006

AbstractTranslocation is an important tool in conservation biology. However, translocation success is generally low for numerous animal species, therefore experiments are required for improvement. We carried out an experimental translocation of European wild rabbits (Oryctolagus cuniculus). The results may be of great interest for conservation biology, although we used a common species. As rabbits are known to experience a high mortality during the first days following release, it was necessary to assess the influence of handling trauma and environment novelty, respectively, and ways of suppressing them. Both tranquillization treatment during handling and a ‘soft’ release protocol (acclimatization pens in the new territory) were tested. Tranquillization did not increase survival, while the effect of acclimatization depended on sex. Females survived better when acclimatized, while males showed the opposite tendency. This difference is discussed in terms of sex‐specific social behaviour, which is possibly an important correlate of translocation success. Finally, environmental stress seemed to override handling stress in determining the level of early survival for translocated wild rabbits.
Microsatellite analysis reveals that domestic cat (Felis catus) and southern African wild cat (F. lybica) are genetically distinct
Authors: Wiseman R. , O'Ryan C. , Harley E. H. 
Published: February 2006

AbstractThe amount of genetic differentiation between the African wild cat (Felis lybica) and the domestic cat (F. catus) in southern Africa is not known, but there is concern that interbreeding between the two may have been sufficiently extensive to threaten the status of the wild cat as a genetically distinct population. Eight hypervariable microsatellite loci were therefore used to determine the genetic relationships within and among wild and domestic cat populations. Measures of genetic differentiation, including FST and RST, confirmed significant differentiation between the wild and domestic cat populations and no significant differentiation between two widely separate domestic cat populations. Our data indicate that the level of genetic introgression is lower than previously thought. This enhances the conservation status of the African wild cat and demonstrates the need for the implementation of feral cat control in and around game reserves and rural areas.
Effects of forest fragmentation on the distribution of the lizard Psammodromus algirus
Authors: Díaz José A. , Carbonell Roberto , Virgós Emilio , Santos Tomás , Tellería José L. 
Published: February 2006

AbstractThis study reports the population responses of the lizard Psammodromus algirus to forest fragmentation by comparing its distribution in two contrasting situations of habitat conservation: a well connected mosaic landscape (forest patches larger than 2000 ha and/or connected by corridors that prevent their isolation), and an archipelago of forest remnants embedded within a matrix of cereal fields. The frequency of occurrence of P. algirus was larger in the unfragmented habitats (14 out of 19 censused plots) than in the fragments (two out of of 21 wood‐lots). Vegetation structure was a good predictor of lizard occurrence under conditions of no fragmentation, but not in the fragments, where high plant cover seemed a necessary, but insufficient, condition for the survival of lizard populations, and where remnant size was the only variable that differed significantly between wood‐lots with and without lizards. Historical fragmentation of the habitat is also crucial for understanding the current distribution of lizards, as shown by their absence from a large forest that was highly fragmented in the past but which has been regenerating for decades. It is hypothesized that the combined effects of fragmentation and predation in small remnants have led to the extinction of P. algirus in fragments smaller than c. 90 ha, recolonization being prevented by the very limited dispersal abilities of these forest lizards.
Microsatellite analysis of population structure and genetic variability in peregrine falcons (Falco peregrinus)
Authors: Nesje M. , Røed K. H. , Bell D. A. , Lindberg P. , Lifjeld J. T. 
Published: February 2006

AbstractGenetic variability and population structure in the endangered peregrine falcon (Falco peregrinus) were studied using DNA microsatellite markers. Special emphasis was placed on the subspeciesF. p. peregrinusliving in Scandinavia and Scotland. For comparative purposes, three North American peregrine subspecies (F. p. tundrius,F. p. pealeiandF. p. anatum) and one Tasmanian subspecies (F. p. macropus) were included in this analysis. Twelve DNA microsatellite loci were analysed across a total of 146 individuals. The amount of genetic variation did not differ in peregrine populations for which adequate sample sizes were obtained. WithinF. p. peregrinus, significant genetic differentiation was found between populations in northern and southern Scandinavia and between the Scandinavian and Scottish populations, while the populations in south‐eastern Norway and south‐western Sweden did not differ significantly. Analysis of cliff‐nesting peregrines in northern Sweden and bog‐nesting peregrines in northern Finland/Sweden suggests that the difference in nesting habitat is not associated with genetic differentiation. Population structuring inF. p. peregrinusis further supported by an assignment test, wherein simulated genotypes are correctly assigned to the northern and southern Scandinavian and Scottish populations with relatively high probabilities, and by analysis of allele‐sharing among individuals. Cluster analysis of genetic distances grouped populations of peregrines in accordance with their subspecific designation, and peregrines on either side of the Atlantic Ocean were clearly separated.
Multipack dynamics and the Allee effect in the African wild dog, Lycaon pictus
Authors: Courchamp Franck , Clutton‐Brock Tim , Grenfell Bryan 
Published: February 2006

AbstractThe current decline of the highly endangered African wild dog (Lycaon pictus) may be partly due to the population dynamics induced by their social system. African wild dogs are obligate co‐operators, and their need for helpers could generate inverse density dependence at the pack level. We show, through a mathematical model, that this can create an Allee effect, leading to a lower population size and a higher risk of population extinction, compared to populations with direct density dependence. This is due to three different processes. All three processes can increase population extinction individually and probably occur simultaneously in African wild dogs. First, inverse density dependence causes significantly higher rates of pack extinction. Second, it also increases the probability of failure to colonize territories by founders. Third, the Allee effect at the pack level (with a critical number of individuals), generates an Allee effect at the population level (with a critical number of packs). These three processes are likely to apply to other obligate co‐operative breeders. Furthermore, our results suggest that habitat fragmentation and destruction, as well as increased human pressure, increase the effects of inverse density dependence. Direct and indirect anthropogenic effects may thus be more detrimental to obligate co‐operative breeders than to other species.
Cryptic local populations in a temperate rainforest bat Chalinolobus tuberculatus in New Zealand
Authors: O'Donnell Colin F. J. 
Published: February 2006

AbstractPopulation structure of the threatened long‐tailed bat (Chalinolobus tuberculatus) was studied over five summers between 1993 and 1998, in temperate Nothofagus rainforest in Fiordland, New Zealand. Composition of 95 communal groups was sampled and spatial distribution of individually marked bats investigated. Individual C. tuberculatus moved to new roost sites virtually every day. Long term non‐random associations among individuals were found by a cluster analysis that revealed three distinct social groups. Groups contained on average 72.0 (± 26.0) (mean ± SD), 99.3 (± 19.0) and 131.7 (± 16.5) marked individuals/year. Collective foraging ranges of the three groups overlapped but roosting occurred in three geographically distinct adjacent areas. Only 1.6% of individuals switched between groups. Non‐reproductive females and males switched between groups more often than reproductive females but individuals switched only once or twice during the study and then just for one night. Juveniles of both sexes were associated with their natal group as 1 year‐olds and then later when breeding. Social groups were cryptic because foraging ranges of groups overlapped, bats belonging to each group spread over many roosts each day, and these roost sites changed from day to day. Bats moved infrequently between groups, potentially linking the local population assemblages. Future research should explore whether the population is structured in demes. Population structure did not conform to traditional metapopulation models because groups occurred in homogeneous habitat extending over a large geographical area. Conserving bat populations should entail preserving a representative number of subgroups but development of models for predicting minimum number of effective local populations is still required.
A preliminary assessment of the contribution of nature reserves to biodiversity conservation in Great Britain
Authors: Hopkinson Paul , Travis Justin M. J. , Prendergast John R. , Evans Julianne , Gregory Richard D. , Telfer Mark G. , Williams Paul H. 
Published: February 2006

AbstractAs a signatory of the Convention on Biological Diversity, the United Kingdom (UK) Government is obliged to conserve and enhance biodiversity. One step towards addressing this goal is to determine the level of biodiversity conservation already achieved within the current array of protected areas. We used national distribution data for ten taxonomic groups, and location information for three reserve networks, to assess the contribution of nature reserves to biodiversity conservation in Great Britain at the 10 km square (=100 km2) resolution. For several taxonomic groups, 10 km squares containing nature reserves had a significantly greater overlap than random networks with both hotspots (areas of high species richness) and complementary areas (sets of sites within which all species are represented). In addition, more than 94% of species from each taxonomic group have been recorded within the 10 km squares of the three reserve networks. These results provide some encouragement in terms of the UK meeting its commitment to conserve biodiversity.
Conservation benefits of marine reserves for fish populations
Authors: Mosquera Iago , Côté Isabelle M. , Jennings Simon , Reynolds John D. 
Published: February 2006

AbstractWe synthesize the results of empirical studies of marine reserves to assess the potential benefits of protection for fish populations. Our meta‐analyses demonstrate that the overall abundance of fishes inside reserves is, on average, 3.7 times higher than outside reserve boundaries. This enhancement is mainly a result of a significant increase in abundance of species that are the target of fisheries. Non‐target species are equally abundant inside and outside reserves. Large‐bodied species also respond more to protection, irrespective of their fishery status. Species within genera show great heterogeneity in their response to protection despite similarities in their life histories. Our study confirms that marine reserves benefit fish populations and highlights the need for monitoring prior to reserve establishment to provide more accurate, habitat‐controlled studies of the effects of marine reserves on fish populations.
Modelling the effects of life‐history traits and changing ecological conditions on the population dynamics and persistence of the endangered Malagasy giant jumping rat (Hypogeomys antimena)
Authors: Sommer S. , Hommen U. 
Published: February 2006

AbstractWe designed an individual‐based model to explore the effects of unusual life‐history parameters and changing ecological conditions on the population dynamics and persistence of the monogamous Hypogeomys antimena, a Malagasy rodent with a recently dramatic decline in its geographical range. Model parameters were derived from extensive field studies carried out since 1992. The simulations predict that Hypogeomys is quite sensitive to small fluctuations in reproductive rate, offspring and adult mortality. Minimum habitat requirements of a viable population that is able to cope for the next 100 years with fluctuating ecological conditions were reached in forest areas of about 3000 ha. However, this habitat size will not represent a stable population. Under current conditions, the population size will continuously decline almost independently of the modelled forest block size. A stable population demography can only be reached by slightly improving the life‐history conditions. The survival prospect of the largest at least partly protected forest fragment currently inhabited by H. antimena are discussed.
Can fluctuating asymmetry be used to detect inbreeding and loss of genetic diversity in endangered populations?
Authors: Gilligan Dean M. , Woodworth Lynn M. , Montgomery Margaret E. , Nurthen Roderick K. , Briscoe David A. , Frankham Richard 
Published: February 2006

AbstractFluctuating asymmetry (FA), a measure of developmental stability, has been proposed as a simple technique for identifying populations suffering from inbreeding and a loss of genetic diversity. However, there is controversy regarding the relationship between FA and both allozyme heterozygosity and pedigree inbreeding coefficients (F). FA of sternopleural bristle number in Drosophila melanogaster was measured in populations maintained at effective sizes of 25 (8 replicates), 50 (6), 100 (4), 250 (3) and 500 (2) for 50 generations (inbreeding coefficients of 0.05—0.71). FA was calculated from the same data set using three different indices (FA1, FA5 and FA6). There was no significant relationship of FA with pedigree inbreeding coefficients for any of the three indices. The relationship between FA and allozyme heterozygosity was non‐significant for indices FA5 and FA6 (the more powerful indices) and only significant for FA1. A second comparison of highly inbred (F ∼ 1) populations with their outbred base population showed significantly greater FA in the inbred populations only when analysed with FA6. Analysis of the same data using FA1 and FA5 showed non‐significant relationships in the opposite direction. If a relationship between FA and genetic diversity does exist, it is weak and inconsistent. Consequently, our results do not support the use of FA as a monitoring tool to detect inbreeding or loss of genetic diversity.
The conservation value for birds of cacao plantations with diverse planted shade in Tabasco, Mexico
Authors: Greenberg Russell , Bichier Peter , Angón Andrea Cruz 
Published: February 2006

AbstractWe surveyed birds in cacao (Theobroma cacao) plantations in the state of Tabasco, Mexico. The shade canopy was planted by farmers and consisted of approximately 60 species of trees with no single dominant species. Canopy height averaged 15 m and the structure was multi‐storied. We conducted 220 ten minute, 25 m radius point counts for birds and detected 1550 individuals from 81 species. The average number of birds/point and the expected diversity in a fixed number of individuals within the cacao surveyed were well within the range of other lowland habitats, including agricultural sites, that we have surveyed previously in neighbouring Chiapas. In the Tabascan cacao, the migrant group was composed, in part, of forest species, and dimorphic species were represented primarily by males, which in other areas are known to dominate forest or forest‐like habitats. In contrast to the composition of migrant species, we found few resident forest specialists in Tabascan cacao. Instead, the tropical resident group was composed of large‐bodied generalist species that use small patches of trees in open habitats. These results (moderate diversity, low numbers of forest specialists) differ from the few studies completed in ‘rustic’ cacao systems located near large tracts of forest. The planted shade cacao agroecosystem – at least in the absence of nearby forest – may have a limited value for conserving lost tropical forest bird diversity, but it provides habitat for woodland‐associated migratory species. Our results also indicate that the planted shade cacao plantations supported few small omnivorous or frugivorous species, probably because cacao itself, as well as the dominant shade trees, produce primarily mammal or wind dispersed fruit and seeds.
Biogeographical change in the tiger, Panthera tigris
Authors: Kitchener Andrew C. , Dugmore Andrew J. 
Published: February 2006

AbstractThe number of tiger subspecies is a major conservation issue that is difficult to resolve owing to small fragmented extant populations and limited historical samples in museums, which compromise the rigour of both molecular and morphological taxonomic studies. Rather than considering a static taxonomic approach to geographical variation in the tiger, we consider the changing biogeographical range of the tiger through the last glacial‐interglacial cycle, based on habitat associations of modern tiger specimen records, and environmental reconstructions from the Last Glacial Maximum (LGM; approximately 20000 years before present (B.P.)). We regard this cycle as representative of the numerous glacial cycles that span the evolutionary history of the tiger since its appearance in the fossil record about two million years ago, thereby giving a deep‐time perspective. The key issue is to determine the extent to which ancestral populations of the tiger were geographically isolated. If no geographical isolation is likely, and gene flow between tiger populations could be maintained until modern times, then diagnosably distinct populations could not have evolved. Our reconstructions show that only two tiger populations were likely to have experienced significant geographical isolation from the main species distribution; these were to the west of Tibet (during the LGM) and on Japan (throughout the glacial cycle). In addition, the LGM is likely to have seen the partial separation of peninsular Malayan and Sunda Islands tigers from mainland populations. From a biogeographical perspective it seems probable that only three contemporary populations were sufficiently separated for the evolution of distinct populations, which can be regarded as subspecies or evolutionary significant units. Therefore, most variation in modern tiger populations is probably clinal, which has important implications for future conservation strategies both in the wild and in captivity.
Reintroducing the beaver (Castor fiber) to Scotland: a protocol for identifying and assessing suitable release sites
Authors: Macdonald David W. , Tattersall Françoise H. , Rushton Stephen , South Andy B. , Rao Shaila , Maitland Peter , Strachan Rob 
Published: February 2006

AbstractThe general problem of evaluating the potential success of mammalian reintroduction plans has been tackled by a case study illustrating a four‐phase approach to finding and assessing potential sites for the reintroduction of European beavers, Castor fiber, to Scotland, combining the use of Geographic Information Systems (GIS), fieldwork and population modelling. Phase 1 used GIS to investigate the wider availability of habitat for beavers in Scotland, and predicted that there is the capacity to support in the order of 180 to 390 beaver families. Phase 2 involved the preliminary assessment of nine sites using brief field surveys. Phase 3 focused further on the three most suitable sites, where a thorough habitat survey was used as a basis for calculating carrying capacities of between three and five families. Finally, phase 4 used population modelling to assess the viability and likely spread of beavers following release at these three best sites. High, medium and low parameters were derived from the literature, and populations were predicted to persist and spread as long as at least the medium parameters were used. This exercise illustrates the power of combining field surveys and GIS‐based population modelling as a tool for planning reintroductions in general, and as a foundation for planning the reintroduction of beavers in particular.