The Experts below are selected from a list of 762 Experts worldwide ranked by ideXlab platform
Dina K N Dechmann - One of the best experts on this subject based on the ideXlab platform.
-
growth overshoot and seasonal size changes in the skulls of two weasel species
Royal Society Open Science, 2017Co-Authors: Scott D Lapoint, Lara Keicher, Martin Wikelski, Karol Zub, Dina K N DechmannAbstract:Ontogenetic changes in mammalian skulls are complex. For a very few species (i.e. some Sorex shrews), these also include seasonally driven, bidirectional size changes within individuals, presumably to reduce energy requirements during low resource availabilities. These patterns are poorly understood, but are likely most pronounced in high-metabolic species with limited means for energy conservation. We used generalized additive models to quantify the effect of location, Julian day, age and sex on the length and depth of 512 and 847 skulls of stoat ( Mustela erminea ) and weasel ( M. nivalis ) specimens collected throughout the northern hemisphere. Skull length of both species varies between sexes and geographically, with stoat skull length positively correlated with latitude. Both species demonstrate seasonal and ontogenetic patterns, including a rare, absolute growth overshoot in juvenile braincase depth. Standardized braincase depths of both species peak in their first summer, then decrease in their first winter, followed by a remarkable regrowth that peaks again during their second summer. This seasonal pattern varies in magnitude and timing between geographical regions and the sexes, matching predictions of Dehnel9s phenomenon. This suggests implications for the evolution of over-wintering strategies in mammals, justifying further research on their mechanisms and value, with implications for applied osteology research.
Robbie A. Mcdonald - One of the best experts on this subject based on the ideXlab platform.
-
stoats Mustela erminea provide evidence of natural overland colonization of ireland
Proceedings of The Royal Society B: Biological Sciences, 2007Co-Authors: Natalia Martinkova, Robbie A. Mcdonald, Jeremy B SearleAbstract:The current Irish biota has controversial origins. Ireland was largely covered by ice at the Last Glacial Maximum (LGM) and may not have had land connections to continental Europe and Britain thereafter. Given the potential difficulty for terrestrial species to colonize Ireland except by human introduction, we investigated the stoat (Mustela erminea) as a possible cold-tolerant model species for natural colonization of Ireland at the LGM itself. The stoat currently lives in Ireland and Britain and across much of the Holarctic region including the high Arctic. We studied mitochondrial DNA variation (1771 bp) over the whole geographical range of the stoat (186 individuals and 142 localities), but with particular emphasis on the British Isles and continental Europe. Irish stoats showed considerably greater nucleotide and haplotype diversity than those in Britain. Bayesian dating is consistent with an LGM colonization of Ireland and suggests that Britain was colonized later. This later colonization probably reflects a replacement event, which can explain why Irish and British stoats belong to different mitochondrial lineages as well as different morphologically defined subspecies. The molecular data strongly indicate that stoats colonized Ireland naturally and that their genetic variability reflects accumulation of mutations during a population expansion on the island.
-
the use of trapping records to monitor populations of stoats Mustela erminea and weasels m nivalis the importance of trapping effort
Journal of Applied Ecology, 1999Co-Authors: Robbie A. Mcdonald, Stephen HarrisAbstract:Summary 1. Trapping and hunting records are frequently used as an index of animal abundance. This study demonstrates that these records can be misleading if sampling effort is not controlled for. 2. Mean numbers of stoats Mustela erminea and weasels M. nivalis trapped by British gamekeepers have been decreasing since 1975 and 1961 respectively, giving rise to concern that populations of both species may be declining. However, trapping effort has not been quantified over this period. 3. A total of 203 gamekeepers in England were questioned about the trapping effort they expended and the number of stoats and weasels they trapped in 1997. The most significant factor affecting the number of stoats and weasels trapped was trapping effort. 4. Gamekeepers that relied on hand-rearing game birds for shooting regarded stoats and weasels as a less serious problem, and made substantially less trapping effort, than gamekeepers that relied on wild game birds. 5. The national decline in the numbers of stoats and weasels trapped may be the result of a decline in stoat and weasel populations. However, the decline is equally consistent with a reduction in trapping effort, corresponding to a national increase in reliance on hand-rearing game birds for shooting. 6. When the effect of trapping effort was controlled for, the number of weasels trapped by gamekeepers in 1997 was significantly lower in the south-west than in other regions of England and was unusually low in some local areas. 7. Trapping records can be used effectively to monitor populations of stoats and weasels, as long as gamekeepers record the number of traps set in each month and monthly totals of animals killed. Ideally, the sex of each animal and whether it was trapped or shot should also be recorded. Similar modifications should also be made to other wildlife monitoring schemes based on trapping and hunting records.
-
Anticoagulant rodenticides in stoats (Mustela erminea) and weasels (Mustela nivalis) in England
Environmental Pollution, 1998Co-Authors: Robbie A. Mcdonald, Stephen Harris, G Turnbull, Peter M. Brown, M FletcherAbstract:Concentrations of six anticoagulant rodenticides were examined in the livers of stoats Mustela erminea L. and weasels Mustela nivalis L. trapped or shot by gamekeepers between August 1996 and March 1997. Residues of rodenticides were detected in nine out of 40 stoats (23%) and three out of ten weasels (30%) from five out of eight estates in central and eastern England. Bromadiolone (0.04–0.38 mg kg−1 wet wt) was detected in three stoats and one weasel, coumatetralyl (0.0085–0.06 mg kg−1) in six stoats and three weasels and brodifacoum (0.12 mg kg−1) in one stoat. One stoat and one weasel contained combinations of two rodenticides. Exposure to rodenticides was more prevalent in female stoats than in males. Rodenticides were widely used away from buildings on the sampled estates and so mustelids need not forage around buildings to be exposed. We conclude that stoats and weasels are secondarily exposed to rodenticides mainly by eating non-target species.
Moira Pryde - One of the best experts on this subject based on the ideXlab platform.
-
control of introduced mammalian predators improves kaka nestor meridionalis breeding success reversing the decline of a threatened new zealand parrot
Biological Conservation, 2003Co-Authors: Ron Moorhouse, Terry C Greene, Peter J Dilks, Ralph G Powlesland, Les R Moran, Genevieve Taylor, Alan Jones, Jaap Knegtmans, Dave Wills, Moira PrydeAbstract:Abstract The kaka (Nestor meridionalis) is a threatened, endemic New Zealand parrot that is declining primarily because of predation by introduced mammals. Numbers of female kaka surviving to sexual maturity more than compensated for adult female mortality at three sites with predator control but not at three unmanaged sites. Nesting success at the sites with predator control was significantly greater (⩾80%) than at unmanaged sites (⩽38%) while predation on adult females was significantly less (5% c.f. 65%). Predation was the most common cause of nesting failure at all sites. Stoats (Mustela erminea) appeared to be the main predator, although evidence of possum (Trichosurus vulpecula) predation on eggs, nestlings and nesting females was also found. These results suggest that control of stoats and possums can potentially reverse the decline of the kaka on the main islands of New Zealand.
-
large scale stoat control to protect mohua mohoua ochrocephala and kaka nestor meridionalis in the eglinton valley fiordland new zealand
2003Co-Authors: Peter Dilks, Murray Willans, Moira Pryde, Ian FraserAbstract:To enhance the breeding success and survival of kaka (Nestor meridionalis) and mohua (Mohoua ochrocephala), we initiated stoat (Mustela erminea) control in the Eglinton Valley (13 000 ha), Fiordland, New Zealand using a single 40 km line of traps spaced 200 m apart with traps set continuously. This low intensity stoat control regime permitted successful kaka breeding and fledgling survival was high. A large irruption of rats, probably due to two consecutive years of heavy seeding by beech and mild winters, complicated assessment of the benefits of the technique for protecting breeding mohua. However, no stoat predation on breeding was
Joseph A Cook - One of the best experts on this subject based on the ideXlab platform.
-
geographic and host range of the nematode soboliphyme baturini across beringia
Journal of Parasitology, 2007Co-Authors: Anson V Koehler, Eric P Hoberg, Nikolai E Dokuchaev, Joseph A CookAbstract:The nematode Soboliphyme baturini Petrov, 1930, was found to represent a single species with a relatively broad geographic range across Beringia and northwestern North America on the basis of the assessment of molecular sequence data for adult and juvenile parasites. Refuted are hypotheses suggesting that several cryptic species could be partitioned either among an array of mustelid definitive hosts or across the vast region that links North America and Eurasia. Host specificity for this species is examined on the basis of a comprehensive list for definitive hosts, derived from new field surveys and existing literature for S. baturini. Only 5 mustelids (Gulo gulo, Martes americana, M. caurina, M. zibellina, and Neovison vison) appear to have significant roles in the life history, persistence, and transmission of this nematode. Soboliphyme baturini readily switches among M. americana, M. caurina, Mustela erminea ,o rN. vison at any particular locality throughout its geographic range in North America, although Martes spp. could represent the source for nematodes in a broader array of mustelids. Molecular analyses (243 base pairs of mitochondrial gene nicotinamide dehydrogenase (ND4)) suggest that hypotheses for host specificity across an array of mustelid definitive hosts are not supported. The life cycle of S. baturini is explored through a review of diet literature for 2 marten species, M. americana and M. caurina, and other mustelids across the Holarctic. Shrews (Soricomorpha: Soricidae) comprise 8% of prey for these species of Martes, suggesting their putative role as paratenic hosts. Juvenile nematodes found in the diaphragms of soricids are genetically identical to adult S. baturini found in the stomachs of mustelids at the same locations in both Asia and North America, corroborating a role in transmission for species of Sorex. Establishing the roles for each participant in a parasite's life cycle is essential to interpreting ecology, epidemiology, distri- bution, and phylogeographic history. Hosts that are components of the life cycle can be defined as definitive (parasite achieves sexual maturity), intermediate (parasite develops, but does not reach sexual maturity), and paratenic (parasite undergoes no development stages, but might be transported from one trophic level to another) (Roberts and Janovy, 2005). Hosts can also be defined as incidental, when the parasite fails to reach sexual maturity. In this case, the host is unnecessary to the parasite
-
phylogeography of endemic ermine Mustela erminea in southeast alaska
Molecular Ecology, 2002Co-Authors: Melissa A Fleming, Joseph A CookAbstract:The North Pacific Coast (NPC) of North America is a region of high mammalian endemism, possibly due to its highly fragmented landscape and complex glacial history. For example, four island and one mainland subspecies of ermine, Mustela erminea, have been described as endemic to southeast Alaska alone. To better understand the role of past climatic change in generating diversity in the region, we examined DNA sequence variation in the mitochondrial cytochrome b gene of 210 ermine from across North America, with an emphasis on Alaska and British Columbia. We found three distinct (1.5-3.6% uncorrected 'p') lineages of ermine, all of which occur in southeast Alaska. One lineage includes a southeast Alaska endemic and specimens from Alaska (outside of southeast) and Eurasia. A second lineage includes two southeast Alaskan endemics and ermine from western Canada and the coterminous United States. The close relationships of these purported endemics to ermine outside of southeast Alaska suggest that they colonized the region from Beringian and southern glacial refugia, respectively, following deglaciation of the NPC. The third lineage appears restricted to the Prince of Wales Island complex in southeast Alaska (two subspecies) and Graham Island (Haida Gwaii), British Columbia. This restricted distribution suggests that these populations may be derived from relicts that persisted in a coastal refugium during the Wisconsin glaciation. Studies of nuclear genes and adaptive morphological evolution are necessary to further explore discrepancies between the geographical pattern of differentiation based on mtDNA and the existing subspecific taxonomy based on morphology.
Pia Lassen - One of the best experts on this subject based on the ideXlab platform.
-
Concentrations of anticoagulant rodenticides in stoats Mustela erminea and weasels Mustela nivalis from Denmark
Science of The Total Environment, 2011Co-Authors: Morten Elmeros, Thomas Kjær Christensen, Pia LassenAbstract:Anticoagulant rodenticides are widely used to control rodent populations but they also pose a risk of secondary poisoning in non-target predators. Studies on anticoagulant rodenticide exposure of non-target species have mainly reported on frequency of occurrence. They have rarely analyzed variations in residue concentrations. We examine the occurrence and concentrations of five anticoagulant rodenticides in liver tissue from 61 stoats (Mustela erminea) and 69 weasels (Mustela nivalis) from Denmark. Anticoagulant rodenticides were detected in 97% of stoats and 95% of weasels. 79% of the animals had detectable levels of more than one substance. Difenacoum had the highest prevalence (82% in stoats and 88% in weasels) but bromadiolone was detected in the highest concentrations in both stoat (1.290 μg/g ww) and weasel (1.610 μg/g ww). Anticoagulant rodenticide concentrations were highest during autumn and winter and varied with sampling method. Anticoagulant rodenticide concentrations were higher in stoats and weasels with unknown cause of death than in specimens killed by physical trauma. There was a negative correlation between anticoagulant rodenticide concentrations and body condition. Our results suggest that chemical rodent control in Denmark results in an extensive exposure of non-target species and may adversely affect the fitness of some stoats and weasels.
