| the role of parasite fecundity and longevity in the success of trichostrongylus tenuis in low density red grouse populations. | the prevalence of the caecal threadworm trichostrongylus tenuis in red grouse in the north of scotland was high despite low grouse densities. prevalence, intensity and aggregation of threadworms was higher in old than in young grouse. infections were long-lasting: populations of adult worms could survive for over 2 years in grouse, with little mortality. parasite egg output decreased with the age of a worm population, largely as a result of a decrease in the fecundity of ageing female worms. sea ... | 1989 | 2594416 |
| arrested development of trichostrongylus tenuis as third stage larvae in red grouse. | worms were counted in red grouse (lagopus lagopus scoticus) in north east scotland in march, april, august, september, november and december 1986. immature worms occurred as third (l3) and fourth (l4) stage larvae throughout. two kinds of evidence suggest that l3 larvae spent much of the winter in a state of arrested development. first, recently acquired l3 larvae could be distinguished by the fact that they retained outer l2 cuticles for a few days; these were present only in the august and sep ... | 1988 | 3194598 |
| caecal threadworms trichostrongylus tenuis in red grouse lagopus lagopus scoticus: effects of weather and host density upon estimated worm burdens. | trichostrongylus tenuis eggs were counted in faeces from individually marked wild red grouse for 8 years. egg counts varied seasonally and annually. in some years, a sudden increase in mid-april was consistent with delayed maturation of larvae which had overwintered in the birds in a hypobiotic state. a more gradual increase in summer was probably due to uninterrupted maturation of larvae ingested then. despite 30-fold year-to-year variation in mean egg counts, relative differences in egg counts ... | 1993 | 8414674 |
| cestodiasis in the red grouse in scotland. | little is known about the cestode parasites of red grouse lagopus lagopus scoticus. the carcasses of 71 free-living and grouse collected from northeastern scotland (uk) between june 1991 and september 1992 were examined for the cestode paroniella urogalli. over 70% of young and old birds were infected in summer and winter. cestode abundance ranged from 0 to 29 (mean +/- se = 5.54 +/- 0.81) worms per host and did not differ significantly between young and old grouse, or between seasons. cestode i ... | 1999 | 10231751 |
| 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 ... | 2005 | 15891828 |
| interactions between intrinsic and extrinsic mechanisms in a cyclic species: testosterone increases parasite infection in red grouse. | 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 ... | 2005 | 16191643 |
| digging for gold nuggets: uncovering novel candidate genes for variation in gastrointestinal nematode burden in a wild bird species. | the extent to which genotypic variation at a priori identified candidate genes can explain variation in complex phenotypes is a major debate in evolutionary biology. whereas some high-profile genes such as the mhc or mc1r clearly do account for variation in ecologically relevant characters, many complex phenotypes such as response to parasite infection may well be underpinned by a large number of genes, each of small and effectively undetectable effect. here, we characterize a suite of novel can ... | 2015 | 25752450 |
| seasonal forcing in a host-macroparasite system. | seasonal forcing represents a pervasive source of environmental variability in natural systems. whilst it is reasonably well understood in interacting populations and host-microparasite systems, it has not been studied in detail for host-macroparasite systems. in this paper we analyse the effect of seasonal forcing in a general host-macroparasite system with explicit inclusion of the parasite larval stage and seasonal forcing applied to the birth rate of the host. we emphasise the importance of ... | 2015 | 25445186 |
| fine-scale population epigenetic structure in relation to gastrointestinal parasite load in red grouse (lagopus lagopus scotica). | epigenetic modification of cytosine methylation states can be elicited by environmental stresses and may be a key process affecting phenotypic plasticity and adaptation. parasites are potent stressors with profound physiological and ecological effects on their host, but there is little understanding in how parasites may influence host methylation states. here, we estimate epigenetic diversity and differentiation among 21 populations of red grouse (lagopus lagopus scotica) in north-east scotland ... | 2014 | 24943398 |