Phylogeography of willow grouse (Lagopus lagopus) in the Arctic: taxonomic discordance as inferred from molecular data

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.     

Genetic variation among endangered Irish red grouse (<Emphasis Type="Italic">Lagopus lagopus hibernicus</Emphasis>) populations: implications for conservation and management

Extant populations of Irish red grouse (Lagopus lagopus hibernicus) are both small and fragmented, and as such may have an increased risk of extinction through the effects of inbreeding depression and compromised adaptive potential. Here we used 19 microsatellite markers to assay genetic diversity across 89 georeferenced samples from putatively semi-isolated areas throughout the Republic of Ireland and we also genotyped 27 red grouse from Scotland using the same markers. The genetic variation within Ireland was low in comparison to previously published data from Britain and the sample of Scottish red grouse, and comparable to threatened European grouse populations of related species. Irish and Scottish grouse were significantly genetically differentiated (F_ST = 0.07, 95% CI = 0.04–0.10). There was evidence for weak population structure within Ireland with indications of four distinct genetic clusters. These correspond approximately to grouse populations inhabiting suitable habitat patches in the North West, Wicklow Mountains, Munster and Cork, respectively, although some admixture was detected. Pair-wise F_ST values among these populations ranged from 0.02 to 0.04 and the overall mean allelic richness was 5.5. Effective population size in the Munster area was estimated to be 62 individuals (95% CI = 33.6–248.8). Wicklow was the most variable population with an AR value of 5.4 alleles/locus. Local (Munster) neighbourhood size was estimated to 31 individuals corresponding to an average dispersal distance of 31 km. In order to manage and preserve Irish grouse we recommend that further fragmentation and destruction of habitats need to be prevented in conjunction with population management, including protection of the integrity of the existing population by refraining from augmenting it with individuals from mainland Britain to maximise population size.     

Genetic diversity and differentiation among Lagopus lagopus populations in Scandinavia and Scotland: evolutionary significant units confirmed by SNP markers

Single Nucleotide Polymorphism in four Scandinavian populations of willow grouse (Lagopus lagopus) and two Scottish populations of red grouse (Lagopus lagopus scoticus) were assessed at 13 protein‐coding loci. We found high levels of diversity, with one substitution every 55 bp as an average and a total of 76 unlinked parsimony informative SNPs. Different estimators of genetic diversity such as: number of synonymous and non‐synonymous sites, average number of alleles, number and percentage of polymorphic loci, mean nucleotide diversity (π_s, π_a) and gene diversity at synonymous and non‐synonymous sites showed higher diversity in the northern populations compared to southern ones. Strong levels of purifying selection found in all the populations together with neutrality tests conforming to neutral expectations agree with large effective population sizes. Assignment tests reported a clear distinction between Scandinavian and Scottish grouse suggesting the existence of two different evolutionary significant units. The divergence time between willow and red grouse ranging between 12 500 and 125 000 years, in conjunction with the presence of ‘specific’ markers for each subspecies prompt a reassessment of the taxonomical status of the Scottish red grouse.     

Morphological diversity of the red squirrel, <Emphasis Type="Italic">Sciurus vulgaris</Emphasis>, in Ireland

The red squirrel in Britain and Ireland has been described as a separate subspecies, Sciurus vulgaris leucourus, based on bleaching of the tail and ear tufts. However, recent investigations in northern England found this light colour confined to one area, probably due to the rapid spread of introduced continental European red squirrels. This study reports the first detailed survey of tail colour and cranial measurements in the Irish red squirrel population to (1) investigate the distribution of the light colour morph in Ireland and (2) determine whether the Irish red squirrel population is morphologically divergent from populations elsewhere in the species range. The light tail colour was found in 57% of individuals and in all regions, although it was most common in the northwest. The mixture of different colour morphs indicates the Irish population is a mixture of different subspecies, including S. vulgaris leucourus, while the cranial measurements suggest the Irish squirrel may be morphologically divergent from populations elsewhere. Combined, these results support previous suggestions that conservation measures seek to maintain the diversity within the Irish red squirrel population.     

No Evidence for Resistance to Fenbendazole in Trichostrongylus tenuis,a Nematode Parasite of the Red Grouse

ABSTRACT The parasitic nematode Trichostrongylus tenuis has a detrimental effect on red grouse (Lagopus lagopus scoticus) at the individual and population levels. Treatment using grit coated with the anthelmintic fenbendazole hydrochloride reduces parasite infection and increases grouse density. However, a frequent and low dose of anthelmintic increases selection pressure for parasite resistance, a serious practical and economic problem. We used an egg hatch assay to test resistance of T. tenuis from 12 moors in northern England, which differed in grit treatment intensity. The anthelmintic concentration that prevented 50% and 95% of T. tenuis eggs from hatching (ED₅₀ and ED₉₅, respectively) did not differ among moors and were not related to treatment. We suggest annual monitoring and responsible anthelmintic use to prevent resistance so that medicated grit continues to enhance red grouse management.     

Adaptive and neutral genetic differentiation among Scottish and endangered Irish red grouse (<Emphasis Type="Italic">Lagopus lagopus scotica</Emphasis>)

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 (F_ST = 0.084) and the MHC-BLB genes (F_ST: 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.     

A review of the status and decline in abundance of the Irish Hare (Lepus timidus hibernicus) in Northern Ireland

The Northern Ireland Hare Survey documented the distribution of the Irish Hare (Lepus timidus hibernicus). Historical game bag records and other, more contemporary, records of hare distribution were examined. These data indicate how numbers of L. t. hibernicus may have changed over the last 140 years. The results of the Northern Ireland Hare Survey suggested that L. t. hibernicus was widespread throughout Northern Ireland. Current average densities are no more than 0.65 hares/km². Game bag records indicate that hare densities may have been much higher in the past, with a maximum of 138 hares/km² recorded on Crom Estate, Co. Fermanagh, in 1864. Evidence from hare distribution recorded during the Northern Ireland Rabbit Survey indicates that hare numbers declined between 1984 and 1994. Evidence from all sources suggests that L. t. hibernicus has declined in abundance substantially, with present total population estimates for Northern Ireland ranging from 8250 to 21 000 individuals. Flushing data indicate that rushes and hedgerows are important diurnal resting areas for hares. While the principal reason for the decline in numbers of L. t. hibernicus in Northern Ireland is not clear, more species‐rich pasture and provision of areas of cover, such as rushes, may arrest further declines, or indeed promote numbers of hares, particularly in lowland areas.     

European hare (Lepus europaeus) invasion ecology: implication for the conservation of the endemic Irish hare (Lepus timidus hibernicus)

European hare Lepus europaeus populations have undergone recent declines but the species has successfully naturalised in many countries outside its native range. It was introduced to Ireland during the mid-late nineteenth century for field sport and is now well established in Northern Ireland. The native Irish hare Lepus timidus hibernicus is an endemic subspecies of mountain hare L. timidus and has attracted major conservation concern following a long-term population decline during the twentieth century and is one of the highest priority species for conservation action in Ireland. Little is known about the European hare in Ireland or whether it poses a significant threat to the native mountain hare subspecies by compromising its ecological security or genetic integrity. We review the invasion ecology of the European hare and examine evidence for interspecific competition with the mountain hare for habitat space and food resources, interspecific hybridisation, disease and parasite transmission and possible impacts of climate change. We also examine the impact that introduced hares can have on native non-lagomorph species. We conclude that the European hare is an emerging and significant threat to the conservation status of the native Irish hare. Invasive mammal species have been successfully eradicated from Ireland before and immediate action is often the only opportunity for cost-effective eradication. An urgent call is issued for further research whilst the need for a European hare invasive Species Action Plan (iSAP) and Eradication strategy are discussed.     

A model to test how ticks and louping ill virus can be controlled by treating red grouse with acaricide

Ticks are the most important vectors of disease‐causing pathogens in Europe. In the U.K., Ixodes ricinus L. (Ixodida: Ixodidae) transmits louping ill virus (LIV; Flaviviridae), which kills livestock and red grouse, Lagopus lagopus scoticus Lath. (Galliformes: Phasianidae), a valuable game bird. Tick burdens on grouse have been increasing. One novel method to reduce ticks and LIV in grouse may be acaricide treatment. Here, we use a mathematical model parameterized with empirical data to investigate how the acaricide treatment of grouse might theoretically control ticks and LIV in grouse. Assuming a situation in which ticks and LIV impact on the grouse population, the model predicts that grouse density will depend on deer density because deer maintain the tick population. In low deer densities, no acaricide treatment is predicted to be necessary because abundances of grouse will be high. However, at higher deer densities, the model predicts that grouse densities will increase only if high numbers of grouse are treated, and the efficacy of acaricide is high and lasts 20 weeks. The qualitative model predictions may help to guide decisions on whether to treat grouse or cull deer depending on deer densities and how many grouse can be treated. The model is discussed in terms of practical management implications.     

Retracing the history and planning the future of the red squirrel (<Emphasis Type="Italic">Sciurus vulgaris</Emphasis>) in Ireland using non-invasive genetics

The Eurasian red squirrel’s (Sciurus vulgaris) history in Ireland is largely unknown, but the original population is thought to have been driven to extinction by humans in the seventeenth century, and multiple records exist for its subsequent reintroduction in the nineteenth century. However, it is currently unknown how these reintroductions affect the red squirrel population today, or may do so in the future. In this study, we report on the development of a DNA toolkit for the non-invasive genetic study of the red squirrel. Non-invasively collected red squirrel samples were combined with other samples collected throughout Ireland and previously published mitochondrial DNA (mtDNA) data from Ireland, Great Britain and Continental Europe to give an insight into population genetics and historical introductions of the red squirrel in Ireland. Our findings demonstrate that the Irish red squirrel population is on a national scale quite genetically diverse, but at a local level contains relatively low levels of genetic diversity, and there is also evidence of genetic structure. This is likely an artefact of the introduction of a small number of genetically similar animals to specific sites. A lack of continuous woodland cover in Ireland has prevented further mixing with animals of different origins that may have been introduced even to neighbouring sites. Consequently, some of these genetically isolated populations are or may in the future be at risk of extinction. The Irish red squirrel population contains mtDNA haplotypes of both a British and Continental European origin, the former of which are now extinct or simply not recorded in contemporary Great Britain. The Irish population is therefore important in terms of red squirrel conservation not only in Ireland, but also for Great Britain, and should be appropriately managed.     

The effect of landscape heterogeneity and host movement on a tick-borne pathogen

Landscape heterogeneity can be instrumental in determining local disease risk, pathogen persistence and spread. This is because different landscape features such as habitat type determine the abundance and spatial distributions of hosts and pathogen vectors. Therefore, disease prevalence and distribution are intrinsically linked to the hosts and vectors that utilise the different habitats. Here, we develop a simplified reaction diffusion model of the louping-ill virus and red grouse (Lagopus lagopus scoticus) system to investigate the occurrence of a tick-borne pathogen and the effect of host movement and landscape structure. Ticks (Ixodes ricinus), the virus-vector, are dispersed by a virally incompetent tick host, red deer (Cervus elephus), between different habitats, whilst the virus infects only red grouse. We investigated how deer movement between different habitats (forest and moorland) affected tick distribution and hence prevalence of infected ticks and grouse and hence, the effect of habitat size ratio and fragmentation on infection. When habitat type has a role in the survival of the pathogen vector, we demonstrated that habitat fragmentation can have a considerable effect on infection. These results highlight the importance of landscape heterogeneity and the proximity and size of adjacent habitats when predicting disease risk in a particular location. In addition, this model could be useful for other pathogen systems with generalist vectors and may inform policy on possible disease management strategies that incorporate host movements.     

Origin of, and conservation units in, the Irish red squirrel (Sciurus vulgaris) population

Knowledge of genetic relationships among wildlife populations is fundamental to their conservation, particularly where translocations are concerned. This study involved a survey of mitochondrial DNA variation in the Irish red squirrel population. Our main aims were: (1) to determine whether the Irish red squirrel population is distinct from that found in Britain, given known translocations that took place from Britain in the 1800’s; and (2) whether inclusion of Irish data into a reanalysis of European red squirrel data could reveal patterns of postglacial spread in Ireland. We found evidence that the current Irish red squirrel population may be a mixture of native and translocated stock, and relationships between Irish and European haplotypes supported a number of colonisation events of the island. Although only one haplotype was common to both Ireland and Britain, it is probable that the most common haplotypes in Ireland are British introductions that have since become extinct in Britain. There was a significant regional genetic structure in Ireland (P < 0.001), as well as between all Irish and British regions. Although it is likely that the red squirrel will not be fundamental in tracing the colonisation of Ireland by mammals, the data demonstrated that individual regions within Ireland, as well as the Irish population as a whole, are distinct both from the British population and from each other and, therefore, these populations should be treated as separate Management Units (MU) in conservation strategies.     

Modelling the impact of hen harrier management measures on a red grouse population in the UK

Human‐wildlife conflict is one of the greatest barriers to effective conservation. The recovery of the hen harrier Circus cyaneus in the United Kingdom has been limited due to illegal persecution, a consequence of the raptors’ predation on the economically valuable game‐bird, the red grouse Lagopus lagopus scoticus. To improve management of the system it is necessary to understand the interactions between the two species in their broader community context. We therefore developed a multi‐species model in which the life history and interactions of each of the two bird species are described through linked process models. This model was fit to population data using a Bayesian state–space framework and used to investigate the effectiveness of a conflict–mitigation technique known as diversionary feeding, in which harrier nests are provided with food in an attempt to reduce consumption of grouse chicks. To explore the utility of diversionary feeding we specified four scenarios in which 1) harriers were absent from the system, 2) there was no diversionary feeding of harriers, 3) only a portion of the harrier nests were provided with diversionary food and 4) all nests were provided with diversionary food. The results from fitting the model under the different scenarios were used to determine the strength of harriers’ impact on grouse density, as well as the effectiveness of diversionary feeding. Given the lack of information on other grouse predators and only two years of data on supplementary feeding, our results need to be implanted with caution. However, we found theoretical support for the hen harriers’ suppression of grouse cycle amplitude and average density. Furthermore, our results suggest that on grouse estates where diversionary feeding is the only active management, diversionary feeding is only marginally successful and not sufficient to mitigate the consequences of hen harrier predation on red grouse chicks.     

Physiological stress links parasites to carotenoid‐based colour signals

Vertebrates commonly use carotenoid‐based traits as social signals. These can reliably advertise current nutritional status and health because carotenoids must be acquired through the diet and their allocation to ornaments is traded‐off against other self‐maintenance needs. We propose that the coloration more generally reveals an individual’s ability to cope with stressful conditions. We tested this idea by manipulating the nematode parasite infection in free‐living red grouse (Lagopus lagopus scoticus) and examining the effects on body mass, carotenoid‐based coloration of a main social signal and the amount of corticosterone deposited in feathers grown during the experiment. We show that parasites increase stress and reduce carotenoid‐based coloration, and that the impact of parasites on coloration was associated with changes in corticosterone, more than changes in body mass. Carotenoid‐based coloration appears linked to physiological stress and could therefore reveal an individual’s ability to cope with stressors.     

Bird numbers in relation to grazing on a grouse moor from 1957–61 to 1988–98

Birds were counted before and after heavy grazing on a Scottish grouse moor. Oystercatchers Haematopus ostralegus, Lapwings Vanellus vanellus and Curlews Numenius arquata increased where high sheep stocks and grass seeding converted much ling Calluna vulgaris to smooth grass, but not where heath remained. A heathy part that held many gamebirds in 1957–61 but later became short grass had no Red Grouse Lagopus lagopus scoticus, Black Grouse Tetrao tetrix or Grey Partridge Perdix perdix in 1989–98. The study area held many Golden Plover Pluvialis apricaria in 1957–61 but none in 1988–98.     

Interactions between population processes in a cyclic species: parasites reduce autumn territorial behaviour of male red grouse

The causes of population cycles fascinate and perplex ecologist. Most work have focused on single processes, whether extrinsic or intrinsic, more rarely on how different processes might interact to cause or mould the unstable population dynamics. In red grouse (Lagopus lagopus scoticus), two causal mechanisms have been supported: territorial behaviour (changes in autumn aggressiveness) and parasites (parasite induced reduction in fecundity). Here, we report on how these two regulatory processes might interact, by testing whether the parasite suspected to cause the grouse cycles, the nematode Trichostrongylus tenuis, reduces male autumn territorial behaviour. We either treated males with an anthelmintic, to remove parasites (dosed or D-males), or challenged them with infective T. tenuis larvae, to increase parasite intensity (challenged or C-males). We first show that dosing was effective in removing T. tenuis parasites, while parasite intensities increased in challenged birds during the autumn. Because old males initially had more parasites than young males, the treatments generated greater differences in parasite intensity in old than in young males. We also show that various aspects of territorial behaviour (increase in testosterone-dependent comb size in autumn, territorial call rate, likelihood of winning territorial interactions and over-winter survival) were significantly higher in dosed than in challenged males, but in old birds only. Our data thus supported the hypothesis that parasites reduce male aggressiveness during the autumn territorial contests, and could thereby influence recruitment. Our results also highlight that the territorial behaviour of young males, which have fewer parasites, is not as limited by parasites as that of old, previously territorial males. We discuss the implications of these findings for our understanding of the processes regulating red grouse populations and causing their complex, unstable population dynamics.     

Testing the interactive effects of testosterone and parasites on carotenoid‐based ornamentation in a wild bird

Abstract 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.     

Testosterone, immunocompetence, and honest sexual signaling in male red grouse

The expression of sexual ornaments has been suggested to reliablyindicate individual quality, such as the ability to cope withparasites and diseases. The Immunocompetence Handicap Hypothesis(IHH) states that testosterone-dependent ornaments honestlysignal such quality because of physiological costs associatedwith testosterone, such as impaired immune function. We testedpredictions of the IHH both correlatively and experimentallyin red grouse Lagopus lagopus scoticus. Male grouse exhibitsupra-orbital red combs whose size is testosterone-dependent.We found that comb size was not correlated to infection intensityby two parasites (coccidia and the nematode Trichostrongylustenuis), but it was significantly positively correlated withcondition and T-cell-mediated immunity (the ability to mounta primary inflammatory response). We manipulated testosteroneby means of implants and re-caught males after a month to investigatethe effects on comb size, condition, immunity, and parasiteload. Males implanted with testosterone had increased comb size,lost more condition, and had lower T-cell-mediated immunitythan control males. Increased testosterone also resulted ina significant increase in coccidia infection intensity but hadno effect on T. tenuis burden. The results are consistent withpredictions of the IHH and suggest that comb size honestly indicatesimmunocompetence and males' ability to cope with certain parasites.Females could thus benefit from choosing mates based on theexpression of this sexual trait.     

Characterising functionally important and ecologically meaningful genetic diversity using a candidate gene approach

Over the past two decades the fields of molecular ecology and population genetics have been dominated by the use of putatively neutral DNA markers, primarily to resolve spatio-temporal patterns of genetic variation to inform our understanding of population structure, gene flow and pedigree. Recent emphasis in comparative functional genomics, however, has fuelled a resurgence of interest in functionally important genetic variation that underpins phenotypic traits of adaptive or ecological significance. It may prove a major challenge to transfer genomics information from classical model species to examine functional diversity in non-model species in natural populations, but already multiple gene-targeted candidate loci with major effect on phenotype and fitness have been identified. Here we briefly describe some of the research strategies used for isolating and characterising functional genetic diversity at candidate gene-targeted loci, and illustrate the efficacy of some of these approaches using our own studies on red grouse (Lagopus lagopus scoticus). We then review how candidate gene markers have been used to: (1) quantify genetic diversity among populations to identify those depauperate in genetic diversity and requiring specific management action; (2) identify the strength and mode of selection operating on individuals within natural populations; and (3) understand direct mechanistic links between allelic variation at single genes and variance in individual fitness.     

Social class,socially-induced loss,recruitment and breeding of red grouse

Summary Individually marked red grouse (Lagopus lagopus scoticus) could be distinguished as territorial or non-territorial from November till the next spring. Territorial birds survived well and many reared young, but numerous nonterritorial birds died or disappeared, and none paired up or reared young. Differences in spring sex ratio between years had already been set in the previous autumn's territorial stock. Many old birds which had been territorial in earlier seasons lost territories after an annual re-distribution of territory each October–November. Thereafter very few of them were seen alive on the area over the winter, and many were found dead, whereas nearly all old birds that kept their territories were still there in spring. The number of birds in spring and the fate of individuals over winter were predicted reasonably accurately from observations of behaviour in the previous November–December. Thus, differences of social class in autumn were critical to a bird's survival to breed in the next summer and to its chances of contesting for territory and breeding in subsequent years.