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Peter J Hudson - One of the best experts on this subject based on the ideXlab platform.
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interactions between intrinsic and extrinsic mechanisms in a cyclic species testosterone increases parasite infection in red grouse
Proceedings of The Royal Society B: Biological Sciences, 2005Co-Authors: Linzi Seivwright, F Leckie, Stephen M Redpath, Francois Mougeot, Peter J HudsonAbstract:Field studies of mechanisms involved in population regulation have tended to focus on the roles of either intrinsic or extrinsic factors, but these are rarely mutually exclusive and their interactions can be crucial in determining dynamics. Experiments on red grouse Lagopus Lagopus scoticus have shown that population instability can be caused both by the effects of a parasitic nematode, Trichostrongylus tenuis, on host production or by changes in testosterone influencing aggressive behaviour and recruitment. We experimentally tested for an interaction between testosterone and T. tenuis in free-living male grouse. A total of 123 grouse were caught in autumn, treated with an anthelmintic to remove parasites, and then given either testosterone or empty, control, implants. After one month grouse were re-infected with a standard dose of parasites. We show that males with increased testosterone levels had greater parasite intensities than controls after one year. We discuss possible physiological and behavioural mechanisms linking testosterone and increased parasite intensity, and the implications for our understanding of complex, unstable population dynamics.
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experimentally increased aggressiveness reduces population kin structure and subsequent recruitment in red grouse Lagopus Lagopus scoticus
Journal of Animal Ecology, 2005Co-Authors: Francois Mougeot, F Leckie, Robert A. Moss, Stuart B. Piertney, Sharon A Evans, Steve Redpath, Peter J HudsonAbstract:Summary 1. According to the ‘territorial behaviour’ hypothesis, red grouse population cycles are caused by delayed density-dependent changes in male aggressiveness influencing recruitment. These lagged changes in aggressiveness might be caused by changes in the kin structuring of male populations and differential aggressive behaviour between kin and non-kin (‘kinship’ hypothesis). 2. A population-level manipulation of male aggressiveness in autumn affected the kin structure of male populations, their subsequent aggressiveness, and recruitment of both sexes. On two moors, we implanted the old territorial cocks in autumn with testosterone on an experimental area (T-areas) and with sham implants on a control area (C-areas). 3. Increased aggressiveness in autumn t reduced recruitment in autumns t and t + 1, and breeding density of both sexes in springs t + 1 and t + 2, confirming previous studies elsewhere. A new observation was that cocks on T-areas had bigger combs (an ornament whose size is testosterone-dependent) than those on C-areas for at least 1·5 years after treatment, evidence that they remained more aggressive. 4. Increased aggressiveness reduced not only subsequent density but also kin structuring among territorial cocks. This is consistent with the ‘kinship’ hypothesis that changes in the kin structure of male populations mediate year-to-year changes in male aggressiveness. 5. Increased aggressiveness did not increase intensity of infection by the dominant intestinal nematode Trichostrongylus tenuis , which might have affected recruitment through reduced breeding success. Moreover, breeding success after treatment was no lower on the T- than on the C-areas. 6. The results show for the first time that increased aggressiveness affects both kin structure and subsequent recruitment, supporting a key assumption of the kinship hypothesis for red grouse population cycles.
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Ticks need not bite their red grouse hosts to infect them with louping ill virus.
Proceedings of the Royal Society of London. Series B: Biological Sciences, 2004Co-Authors: Lucy Gilbert, Hugh W. Reid, Linda D. Jones, M. Karen Laurenson, E. A. Gould, Peter J HudsonAbstract:For pathogens transmitted by biting vectors, one of the fundamental assumptions is often that vector bites are the sole or main route of host infection. Here, we demonstrate experimentally a transmission route whereby hosts (red grouse, Lagopus Lagopus scoticus) became infected with a member of the tick-borne encephalitis virus complex, louping ill virus, after eating the infected tick vector. Furthermore, we estimated from field observations that this mode of infection could account for 73-98% of all virus infections in wild red grouse in their first season. This has potential implications for the understanding of other biting vector-borne pathogens where hosts may ingest vectors through foraging or grooming.
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faecal egg counts provide a reliable measure of trichostrongylus tenuis intensities in free living red grouse Lagopus Lagopus scoticus
Journal of Helminthology, 2004Co-Authors: Linzi Seivwright, Stephen M Redpath, Francois Mougeot, L Watt, Peter J HudsonAbstract:The reliability of different egg counting methods for estimating the intensity of Trichostrongylus tenuis infections in red grouse, Lagopus Lagopus scoticus, was investigated in the autumn, when grouse may harbour high parasite intensities. Possible limitations to the use of these methods were also examined. Faecal egg counts were found to accurately estimate T. tenuis worm intensities, at least up to an observed maximum of c. 8000 worms. Two egg counting methods (smear and McMaster) gave consistent results, although the exact relationship with worm intensity differed according to the method used. Faecal egg counts significantly decreased with increasing length of sample storage time, but egg counts were reliable for estimating worm intensity for three weeks. The concentration of eggs in the caecum was also found to reliably estimate worm intensity. However, egg counts from frozen gut samples cannot be used to estimate worm intensities. These results conclude that, despite some limitations, faecal and caecum egg counts provide useful and reliable ways of measuring T. tenuis intensities in red grouse.
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Rising burden of immature sheep ticks (Ixodes ricinus) on red grouse (Lagopus Lagopus scoticus) chicks in the Scottish uplands.
Medical and Veterinary Entomology, 2004Co-Authors: A. D. Kirby, A. A. Smith, Tim G. Benton, Peter J HudsonAbstract:The sheep tick Ixodes ricinus (L.) (Acari: Ixodidae) is an ectoparasite of major economic and pathogenic importance in Scotland. Its distribution in the Scottish uplands is assumed to be governed by the abundance and distribution of its definitive hosts (deer and sheep) and climatic variables such as temperature and rainfall. As the numbers of its major host in Scotland, red deer, have increased dramatically and climatic conditions have become more favourable, the level of parasitism could have been expected to rise. We use data gathered from tick counts on over 4000 red grouse chicks Lagopus Lagopus scoticus Latham (Galliformes: Tetraonidae) in various experiments over the past 19 years to ascertain whether the intensity and prevalence of parasitism has been increasing. From 1985 to 2003 the average tick burden of a parasitized red grouse chick has grown from 2.60 � 1.12 ticks per chick to 12.71 � 1.44. Over this period the percentage of chicks of a given brood parasitized has also increased from 4 � 2% to 92 � 3%. The possible implications of this increase in parasitism for red grouse production are discussed.
Francois Mougeot - One of the best experts on this subject based on the ideXlab platform.
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Insights into population ecology from long-term studies of red grouse Lagopus Lagopus scoticus.
Journal of Animal Ecology, 2013Co-Authors: Jesús Martínez-padilla, Stephen M Redpath, Mohammed Zeineddine, Francois MougeotAbstract:Summary Long-term studies have been the backbone of population ecology. The red grouse Lagopus Lagopus scoticus is one species that has contributed widely to this field since the 1950s. This paper reviews the trajectory and profound impact that these studies have had. Red grouse research has combined long-term studies of marked individuals with demographic studies over wide geographical areas and replicated individual- and population-level manipulations. A main focus has been on understanding the causes of population cycles in red grouse, and in particular the relative importance of intrinsic (behaviour) and extrinsic (climate, food limitation and parasite) mechanisms. Separate studies conducted in different regions initially proposed either the nematode parasite Trichostrongylus tenuis or changes in male aggressiveness in autumn as drivers of population cycles. More recent experiments suggest that parasites are not a necessary cause for cycles and have highlighted that behavioural and parasite-mediated mechanisms are interrelated. Long-term experiments show that parasites and aggressiveness interact. Two outstanding questions remain to be tested experimentally. First, what intrinsic mechanism causes temporal variation in patterns of male aggressiveness? The current favoured mechanism is related to patterns of kin structuring although there are alternative hypotheses. Second, how do the dual, interacting mechanisms, affect population dynamics? Red grouse studies have had an important impact on the field of population ecology, in particular through highlighting: (1) the impact of parasites on populations; (2) the role of intrinsic mechanisms in cyclic dynamics and (3) the need to consider multiple, interacting mechanisms.
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environmental heterogeneity influences the reliability of secondary sexual traits as condition indicators
Journal of Evolutionary Biology, 2012Co-Authors: Pablo Vergara, F Leckie, Francois Mougeot, Jesus Martinezpadilla, Stephen M RedpathAbstract:Numerous studies have shown positive associations between ornaments and condition, as predicted by indicator models of sexual selection. However, this idea is continuously challenged by opposite results, which reveal our lack of full understanding of how sexual selection works. Environmental heterogeneity may explain such inconsistencies, but valid field tests of this idea are currently lacking. We first analysed the relationship between condition and ornament expression from nine populations over 7 years in a wild bird, the red grouse Lagopus Lagopus scoticus. We then manipulated male aggressiveness at the population level by means of testosterone implants in a replicated field experiment. We found that the relationship between condition and ornamentation varied greatly between environments and became stronger when environmental conditions (ECs) were worse or when aggressiveness in the population was experimentally increased. Some ornaments may therefore reliably advertise a better condition only in adverse ECs. Considering environmental heterogeneity can help reconcile conflicting findings regarding the reliability of ornaments as indicators of condition and will help our understanding of sexual selection processes.
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testing the interactive effects of testosterone and parasites on carotenoid based ornamentation in a wild bird
Journal of Evolutionary Biology, 2010Co-Authors: Jesus Martinezpadilla, Francois Mougeot, Lucy M I Webster, Lorenzo Perezrodriguez, Stuart B. PiertneyAbstract:Testosterone underlies the expression of most secondary sexual traits, playing a key role in sexual selection. However, high levels might be associated with physiological costs, such as immunosuppression. Immunostimulant carotenoids underpin the expression of many red-yellow ornaments, but are regulated by testosterone and constrained by parasites. We manipulated testosterone and nematode burdens in red grouse (Lagopus Lagopus scoticus) in two populations to tease apart their effects on carotenoid levels, ornament size and colouration in three time-step periods. We found no evidence for interactive effects of testosterone and parasites on ornament size and colouration. We showed that ornament colouration was testosterone-driven. However, parasites decreased comb size with a time delay and testosterone increased carotenoid levels in one of the populations. This suggests that environmental context plays a key role in determining how individuals resolve the trade-off between allocating carotenoids for ornamental coloration or for self-maintenance needs. Our study advocates that adequately testing the mechanisms behind the production or maintenance of secondary sexual characters has to take into account the dynamics of sexual trait expression and their environmental context.
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Ornamental comb colour predicts T-cell-mediated immunity in male red grouse Lagopus Lagopus scoticus.
Naturwissenschaften, 2007Co-Authors: Francois MougeotAbstract:Sexual ornaments might reliably indicate the ability to cope with parasites and diseases, and a better ability to mount a primary inflammatory response to a novel challenge. Carotenoid-based ornaments are amongst the commonest sexual signals of birds and often influence mate choice. Because carotenoids are immuno-stimulants, signallers may trade-off allocating these to ornamental colouration or using them for immune responses, so carotenoid-based ornaments might be particularly useful as honest indicators of immuno-compentence. Tetraonid birds, such as the red grouse Lagopus Lagopus scoticus, exhibit supra-orbital yellow–red combs, a conspicuous ornament which functions in intra- and inter-sexual selection. The colour of combs is due to epidermal pigmentation by carotenoids, while their size is testosterone-dependent. In this study, I investigated whether comb characteristics, and in particular, comb colour, indicated immuno-competence in free-living male red grouse. I assessed T-cell-mediated immunity using a standardised challenge with phytohaemagglutinin. Red grouse combs reflect in the red and in the ultraviolet spectrum of light, which is not visible to humans but that grouse most likely see, so I measured comb colour across the whole bird visible spectrum (300–700 nm) using a reflectance spectrometer. I found that males with bigger and redder combs, but with less ultraviolet reflectance, had greater T-cell-mediated immune response. Comb colour predicted T-cell-mediated immune response better than comb size, indicating that the carotenoid-based colouration of this ornament might reliably signal this aspect of male quality.
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the effects of autumn testosterone on survival and productivity in red grouse Lagopus Lagopus scoticus
Animal Behaviour, 2006Co-Authors: Stephen M Redpath, F Leckie, Francois Mougeot, Sharon A EvansAbstract:There are costs and benefits to individuals of having high levels of circulating testosterone, and the costs can be particularly apparent outside the breeding season. Unlike many birds, red grouse have high testosterone levels in autumn and in this study we explored the consequences of variation in autumn testosterone levels, in terms of survival and breeding success. We caught 123 male grouse in September, from six sites in Scotland and England, U.K. Grouse were given either testosterone or control implants, then fitted with radiotransmitters and released. Control males tended to survive better, but the difference was not statistically significant. During the first 3 months, cause of mortality varied with treatment, with birds of prey killing only testosterone-implanted birds. In spring, females paired with testosterone-implanted males had larger combs (sexual ornaments) than those with controls, suggesting that they might have been better-quality individuals. Testosterone-implanted birds were more likely to be paired and to be bigamous, and each bird alive in spring produced on average 2.5 more offspring than control birds. The benefits of investing in elevated levels of testosterone are clearly high for those males that survive the winter. However, these benefits are reduced by overwinter mortality and the reproductive success of all males alive at the start of the experiment did not vary statistically with treatment. We discuss the longer-term consequences of high testosterone levels, which are likely to be very different to short-term ones.
Stephen M Redpath - One of the best experts on this subject based on the ideXlab platform.
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the role of parasite driven selection in shaping landscape genomic structure in red grouse Lagopus Lagopus scotica
Molecular Ecology, 2016Co-Authors: Marius A. Wenzel, Stephen M Redpath, Marianne C. James, Alex Douglas, Stuart B. PiertneyAbstract:Landscape genomics promises to provide novel insights into how neutral and adaptive processes shape genome-wide variation within and among populations. However, there has been little emphasis on examining whether individual-based phenotype-genotype relationships derived from approaches such as genome-wide association (GWAS) manifest themselves as a population-level signature of selection in a landscape context. The two may prove irreconcilable as individual-level patterns become diluted by high levels of gene flow and complex phenotypic or environmental heterogeneity. We illustrate this issue with a case study that examines the role of the highly prevalent gastrointestinal nematode Trichostrongylus tenuis in shaping genomic signatures of selection in red grouse (Lagopus Lagopus scotica). Individual-level GWAS involving 384 SNPs has previously identified five SNPs that explain variation in T. tenuis burden. Here, we examine whether these same SNPs display population-level relationships between T. tenuis burden and genetic structure across a small-scale landscape of 21 sites with heterogeneous parasite pressure. Moreover, we identify adaptive SNPs showing signatures of directional selection using F(ST) outlier analysis and relate population- and individual-level patterns of multilocus neutral and adaptive genetic structure to T. tenuis burden. The five candidate SNPs for parasite-driven selection were neither associated with T. tenuis burden on a population level, nor under directional selection. Similarly, there was no evidence of parasite-driven selection in SNPs identified as candidates for directional selection. We discuss these results in the context of red grouse ecology and highlight the broader consequences for the utility of landscape genomics approaches for identifying signatures of selection.
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Insights into population ecology from long-term studies of red grouse Lagopus Lagopus scoticus.
Journal of Animal Ecology, 2013Co-Authors: Jesús Martínez-padilla, Stephen M Redpath, Mohammed Zeineddine, Francois MougeotAbstract:Summary Long-term studies have been the backbone of population ecology. The red grouse Lagopus Lagopus scoticus is one species that has contributed widely to this field since the 1950s. This paper reviews the trajectory and profound impact that these studies have had. Red grouse research has combined long-term studies of marked individuals with demographic studies over wide geographical areas and replicated individual- and population-level manipulations. A main focus has been on understanding the causes of population cycles in red grouse, and in particular the relative importance of intrinsic (behaviour) and extrinsic (climate, food limitation and parasite) mechanisms. Separate studies conducted in different regions initially proposed either the nematode parasite Trichostrongylus tenuis or changes in male aggressiveness in autumn as drivers of population cycles. More recent experiments suggest that parasites are not a necessary cause for cycles and have highlighted that behavioural and parasite-mediated mechanisms are interrelated. Long-term experiments show that parasites and aggressiveness interact. Two outstanding questions remain to be tested experimentally. First, what intrinsic mechanism causes temporal variation in patterns of male aggressiveness? The current favoured mechanism is related to patterns of kin structuring although there are alternative hypotheses. Second, how do the dual, interacting mechanisms, affect population dynamics? Red grouse studies have had an important impact on the field of population ecology, in particular through highlighting: (1) the impact of parasites on populations; (2) the role of intrinsic mechanisms in cyclic dynamics and (3) the need to consider multiple, interacting mechanisms.
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environmental heterogeneity influences the reliability of secondary sexual traits as condition indicators
Journal of Evolutionary Biology, 2012Co-Authors: Pablo Vergara, F Leckie, Francois Mougeot, Jesus Martinezpadilla, Stephen M RedpathAbstract:Numerous studies have shown positive associations between ornaments and condition, as predicted by indicator models of sexual selection. However, this idea is continuously challenged by opposite results, which reveal our lack of full understanding of how sexual selection works. Environmental heterogeneity may explain such inconsistencies, but valid field tests of this idea are currently lacking. We first analysed the relationship between condition and ornament expression from nine populations over 7 years in a wild bird, the red grouse Lagopus Lagopus scoticus. We then manipulated male aggressiveness at the population level by means of testosterone implants in a replicated field experiment. We found that the relationship between condition and ornamentation varied greatly between environments and became stronger when environmental conditions (ECs) were worse or when aggressiveness in the population was experimentally increased. Some ornaments may therefore reliably advertise a better condition only in adverse ECs. Considering environmental heterogeneity can help reconcile conflicting findings regarding the reliability of ornaments as indicators of condition and will help our understanding of sexual selection processes.
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the direct and indirect effects of predation by hen harriers circus cyaneus on trends in breeding birds on a scottish grouse moor
Ibis, 2008Co-Authors: David Baines, Stephen M Redpath, Michael Richardson, Simon J ThirgoodAbstract:Two phases of an experimental reduction in management at Langholm Moor in southwest Scotland provided an insight into factors that determined trends in the abundance of moorland birds. In 1992 the historical control of breeding Hen Harriers Circus cyaneus stopped and in 2000 grouse moor management was discontinued. Golden Plover Pluvialis apricaria, Lapwing Vanellus vanellus, Curlew Numenius arquata and Red Grouse Lagopus Lagopus scoticus declined, whilst Carrion Crow Corvus corone and Snipe Gallinago gallinago increased. Hen Harriers increased from two to 20 breeding females, then declined back to two. Lapwing abundance was positively associated with that of Hen Harriers, and moorland passerines (Skylark Alauda arvensis, Meadow Pipit Anthus pratensis and Stonechat Saxicola torquata) were negatively associated. Golden Plover, Lapwing, Curlew, Red Grouse, Skylark and Hen Harrier were more abundant when the moor was managed for grouse, whilst Carrion Crow, a common predator of clutches of ground-nesting birds, increased during the second half when management ceased. Increased Crow numbers, together with an increase in Red Foxes Vulpes vulpes, probably contributed to the observed bird declines.
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the effects of autumn testosterone on survival and productivity in red grouse Lagopus Lagopus scoticus
Animal Behaviour, 2006Co-Authors: Stephen M Redpath, F Leckie, Francois Mougeot, Sharon A EvansAbstract:There are costs and benefits to individuals of having high levels of circulating testosterone, and the costs can be particularly apparent outside the breeding season. Unlike many birds, red grouse have high testosterone levels in autumn and in this study we explored the consequences of variation in autumn testosterone levels, in terms of survival and breeding success. We caught 123 male grouse in September, from six sites in Scotland and England, U.K. Grouse were given either testosterone or control implants, then fitted with radiotransmitters and released. Control males tended to survive better, but the difference was not statistically significant. During the first 3 months, cause of mortality varied with treatment, with birds of prey killing only testosterone-implanted birds. In spring, females paired with testosterone-implanted males had larger combs (sexual ornaments) than those with controls, suggesting that they might have been better-quality individuals. Testosterone-implanted birds were more likely to be paired and to be bigamous, and each bird alive in spring produced on average 2.5 more offspring than control birds. The benefits of investing in elevated levels of testosterone are clearly high for those males that survive the winter. However, these benefits are reduced by overwinter mortality and the reproductive success of all males alive at the start of the experiment did not vary statistically with treatment. We discuss the longer-term consequences of high testosterone levels, which are likely to be very different to short-term ones.
Andrew P Dobson - One of the best experts on this subject based on the ideXlab platform.
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Harvesting unstable populations: red grouse Lagopus Lagopus scoticus (Lath.) in the United Kingdom
Wildlife Biology, 2001Co-Authors: Peter J Hudson, Andrew P DobsonAbstract:The optimal harvesting strategies for unstable populations are explored using first discrete time models and second a continuous time model specifically applied to the destabilising effects of the caecal nematode Trichostrongylus tenuis on the dynamics of red grouse Lagopus Lagopus scoticus. In discrete time models, with overcompensation generating either cyclic or chaotic fluctuations in abundance harvesting can act as both a stabilising and a destabilising process. Maximum yields occur at the harvesting rate that coincides with the point where the harvesting stabilises the overcompensation. Optimal harvesting rates increase with the degree of overcompensation although these are more vulnerable to overharvesting. Harvesting in the continuous time model provides similar results, although observed hunting records do not appear to be stabilised by harvesting. Empirical data on the mortality caused by other natural enemies of red grouse, the hen harrier Circus cyaenus and the louping ill virus, show that the...
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transmission dynamics and host parasite interactions of trichostrongylus tenuis in red grouse Lagopus Lagopus scoticus
Journal of Parasitology, 1997Co-Authors: Peter J Hudson, Andrew P DobsonAbstract:Two components of the transmission dynamics of Trichostrongylus tenuis in red grouse are examined and quantified, namely parasite transmission rate and density-dependent reductions in egg production. Age-intensity data for birds of known age suggest that the rate of parasite uptake increases during the first 6 mo of a bird's life and this increase reflects an increase in feeding rate with age and exhibits no signs of self-cure. Analysis of these age-intensity curves permits us to estimate the transmission rate of the free-living infective stages. Reinfection rates of adults treated to reduce parasite intensities were not significantly different from infection rates of naive immature grouse. Secondary infections continued to rise over a period of 18 mo and this suggests that there is no strong host-mediated response against the parasite. Any density-dependent reduction in parasite fecundity is probably very weak and would act through interspecific competition between parasites. Initial analysis of worm egg production in relation to the intensity of worm infection found weak evidence of density-dependent suppression of egg production at high worm intensities. However, a more rigorous analysis found that such a relationship suffered from Type I errors and was a consequence of the aggregated distribution of the parasites. Any density-dependent suppression of parasite egg production is too weak to be detected and would only occur at high worm intensities. The potential density-dependent reductions in fecundity on the population dynamics of T. tenuis and red grouse are examined using a mathematical model. The model suggests that the presence of density-dependent reductions in worm fecundity could produce significant reductions in the propensity of the grouse-nematode system to exhibit population cycles. The sustained cycles observed in the long-term dynamics of the grouse populations in the study area suggest that density-dependent reductions in worm fecundity and establishment are either absent or only operating at levels that are not detectable in field studies.
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regulation and stability of a free living host parasite system trichostrongylus tenuis in red grouse i monitoring and parasite reduction experiments
Journal of Animal Ecology, 1992Co-Authors: Peter J Hudson, David Newborn, Andrew P DobsonAbstract:Intensive population studies were conducted for 10 years on red grouse (Lagopus Lagopus scoticus) and the parasitic nematode, Trichostrongylus tenuis, in northern England. Winter loss was the key factor determining changes in grouse numbers, although breeding losses were also important. T. tenuis had an aggregated distribution within the adult grouse population, even though the degree of aggregation was relatively low compared with other parasite systems
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regulation and stability of a free living host parasite system trichostrongylus tenuis in red grouse ii population models
Journal of Animal Ecology, 1992Co-Authors: Andrew P Dobson, Peter J HudsonAbstract:The population dynamics of red grouse, Lagopus Lagopus scoticus and the parasitic nematode, Trichostrongylus tenuis were explored to determine whether interactions between the parasite and host were sufficient to generate cycles in grouse abundance. Two alternative models were used that explicitly consider the dynamics of either the free-living, or arrested larval stages of the parasite. Providing that the life expectancy of the free-living larvae is more than 2-4 weeks, the parasite can readily establish in gousse populations
Jacob Höglund - One of the best experts on this subject based on the ideXlab platform.
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Adaptive and neutral genetic differentiation among Scottish and endangered Irish red grouse (Lagopus Lagopus scotica)
Conservation Genetics, 2016Co-Authors: Yvonne Meyer-lucht, Marianne C. James, Stuart B. Piertney, Kevin P. Mulder, Barry J. Mcmahon, Kieran Buckley, Jacob HöglundAbstract:Studying patterns of intra-specific genetic variation among populations allows for a better understanding of population structure and local adaptation. However, those patterns may differ according to the genetic markers applied, as neutral genetic markers reflect demographic processes and random genetic drift, whereas adaptive markers also carry the footprint of selection. In combination, neutral and adaptive genetic markers permit to assess the relative roles of drift and selection in shaping population structure. Among the best understood adaptive genetic loci are the genes of the major histocompatibility complex (MHC). We here study variation and differentiation at neutral SNP markers and MHC class II genes in red grouse (Lagopus Lagopus scotica) from Ireland and Scotland. Irish red grouse populations are fragmented and drastically declining, but red grouse are abundant in Scotland. We find evidence for positive selection acting on the MHC genes and variation in MHC gene copy numbers among Irish individuals. Furthermore, there was significant population differentiation among red grouse from Ireland and Scotland at the neutral SNP markers (FST = 0.084) and the MHC-BLB genes (FST: BLB1 = 0.116, BLB2 = 0.090, BLB3 = 0.104). Differentiation at the MHC-BLB1 was significantly higher than at the neutral SNP markers, suggesting that selection plays an important role in shaping MHC variation, in addition to genetic drift. We speculate that the observed differentiation pattern might be due to local adaptation to different parasite regimes. These findings have strong conservation implications and we advise against the introduction of Scottish red grouse to supplement Irish populations.
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Phylogeography of willow grouse (Lagopus Lagopus) in the Arctic: taxonomic discordance as inferred from molecular data
Biological Journal of the Linnean Society, 2013Co-Authors: Jacob Höglund, Biao Wang, Thomas Axelsson, María QuintelaAbstract:Using independently segregating nuclear single nucleotide polymorphisms (SNPs) and mitochondrial control region sequences, we found an east-west division among sampled willow grouse Lagopus Lagopus subspecies. This division cut across the range of the subspecies with the largest distribution (Lagopus) and thus contradicted existing taxonomic classifications. Russian Lagopus Lagopus Lagopus tended to cluster with North American willow grouse partly classified as other subspecies. Scandinavian willow grouse (L. l. Lagopus) clustered with red grouse from Britain and Ireland (Lagopus Lagopus scoticus and Lagopus Lagopus hibernicus) but substructuring confirmed the monophyly of the latter. In North America, we could not detect any major genetic divisions apart from two birds described as alexandrae from the Heceta Island (Alaska) when using mitochondrial sequences. Other samples from North America were intermingled regardless of whether they were described as muriei, alexandrae or Lagopus .A specimen described as alexandrae was to some extent distinct when analysing the SNP data. The genetic analyses indicated some concordance between genetics and taxonomy but not complete congruence. This is particularly evident for mitochondrial DNA network analyses. We suggest that the taxonomy of this species would benefit by a careful re-examination of the available evidence for subspecies. It appears as if subspecies status is a poor proxy for assigning evolutionary significant units and management units in this species. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110, 77-90. ADDITIONAL KEYWORDS: alexandrae - evolutionary significant unit - hibernicus - kamschatkensis - Lagopus Lagopus - muriei - phylogeography - scoticus - willow grouse subspecies.
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Sequence polymorphism in candidate genes for differences in winter plumage between Scottish and Scandinavian Willow Grouse (Lagopus Lagopus).
PloS one, 2010Co-Authors: Pontus Skoglund, Jacob HöglundAbstract:BACKGROUND Population variation in the degree of seasonal polymorphism is rare in birds, and the genetic basis of this phenomenon remains largely undescribed. Both sexes of Scandinavian and Scottish Willow grouse (Lagopus Lagopus) display marked differences in their winter phenotypes, with Scottish grouse retaining a pigmented plumage year-round and Scandinavian Willow grouse molting to a white morph during winter. A widely studied pathway implicated in vertebrate pigmentation is the melanin system, for which functional variation has been characterised in many taxa. METHODOLOGY/PRINCIPAL FINDINGS We sequenced coding regions from four genes involved in melanin pigmentation (DCT, MC1R, TYR and TYRP1), and an additional control involved in the melanocortin pathway (AGRP), to investigate the genetic basis of winter plumage in Lagopus. Despite the well documented role of the melanin system in animal coloration, we found no plumage-associated polymorphism or evidence for selection in a total of approximately 2.6 kb analysed sequence. CONCLUSIONS/SIGNIFICANCE Our results indicate that the genetic basis of alternating between pigmented and unpigmented seasonal phenotypes is more likely explained by regulatory changes controlling the expression of these or other loci in the physiological pathway leading to pigmentation.
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a multilocus assay reveals high nucleotide diversity and limited differentiation among scandinavian willow grouse Lagopus Lagopus
BMC Genetics, 2008Co-Authors: Sofia Berlin, María Quintela, Jacob HöglundAbstract:Background There is so far very little data on autosomal nucleotide diversity in birds, except for data from the domesticated chicken and some passerines species. Estimates of nucleotide diversity reported so far in birds have been high (~10-3) and a likely explanation for this is the generally higher effective population sizes compared to mammals. In this study, the level of nucleotide diversity has been examined in the willow grouse, a non-domesticated bird species from the order Galliformes, which also holds the chicken. The willow grouse (Lagopus Lagopus) has an almost circumpolar distribution but is absent from Greenland and the north Atlantic islands. It primarily inhabits tundra, forest edge habitats and sub-alpine vegetation. Willow grouse are hunted throughout its range, and regionally it is a game bird of great cultural and economical importance.
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historical biogeography and a mitochondrial dna phylogeny of grouse and ptarmigan
Molecular Phylogenetics and Evolution, 2001Co-Authors: Vittorio Lucchini, Jacob Höglund, Siegfried Klaus, Jon E Swenson, Ettore RandiAbstract:Abstract We sequenced 2690 nucleotides of mitochondrial DNA (mtDNA) including the entire control region (CR), partial 12S and 16S ribosomal RNAs, NADH dehydrogenase subunit 2, and cytochrome b genes from representatives of all the 17 living species of grouse and ptarmigan (Aves; Galliformes; subfamily Tetraoninae). Substitution rates and phylogenetic signals were variable among genes, with the CR being more informative than protein-coding and rRNA genes. Phylogenetic trees, computed with the CR or the concatenated sequences, indicate that: (1) genus Bonasa is monophyletic and basal within the subfamily, (2) all the other currently recognized genera of Tetraoninae are monophyletic, except Dendragapus; (3) D. obscurus is related to Centrocercus urophasianus and divergent from former D. canadensis and D. falcipennis, which, accordingly, may be ascribed to the distinct genus Falcipennis; (4) Tympanuchus, Dendragapus, and Centrocercus form a clade comprising taxa distributed exclusively in North America; and (5) the North American species of Bonasa ( B. umbellus ) and Lagopus ( L. leucurus ) are basal to their Eurasian and Holarctic congeneric species. These findings, and a dispersal–vicariance analysis, support a North American origin of the subfamily and of all the genera of Tetraoninae, with the possible exception of Tetrao. Present species distributions might have been attained by at least three dispersal events from North America to Eurasia, involving the ancestors to Palearctic Bonasa, the ancestors to circumpolar Lagopus mutus/L. Lagopus, and the clade leading to Tetrao/Falcipennis. According to a “standard calibration” of the mtDNA molecular clock (2% sequence divergence per million years), Bonasa split about 5–6 million years ago, the other genera diverged during the upper Pliocene, and most of the congeneric species with North American and Eurasian distributions ( Bonasa, Lagopus, and Falcipennis ) originated during the lower Pleistocene, well before the last interruption of the Beringian land bridge.
