bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contrasting seasonal dynamics in fleas of the Siberian flying squirrel (Pteromys volans) in Finland
Authors: HAUKISALMI VOITTO , HANSKI ILPO K. 
Published: July 2007

Abstract 1. The seasonal and spatial variation of the adult flea fauna (Siphonaptera) was examined in connection with live‐trapping studies of the Siberian flying squirrel (Pteromys volans) in three study areas in southern Finland between 1997 and 2005.2. The numerically dominant flea species of the Siberian flying squirrel were Tarsopsylla octodecimdentata octodecimdentata and Ceratophyllus (Monopsyllus) indages indages (Ceratophyllidae); the latter being a host specialist of the Siberian flying squirrel. Tarsopsylla octodecimdentata, which also commonly occurs on the red squirrel (Sciurus vulgaris), infected a large proportion of the host population throughout the winter, whereas C. indages occurred predominantly during the summer and autumn, being practically the only flea species in nests during the flying squirrels’ breeding season and on juveniles still inhabiting their natal nest.3. The use of nest boxes by flying squirrels did not have any positive effects on flea populations, but it may have had a negative impact on T. octodecimdentata.4. The potentially vulnerable C. i. indages is a predictable, widespread component in the flea fauna of the Siberian flying squirrel at various spatial scales, and it is likely to occur in most of the permanent flying squirrel populations in Finland.
Modelling and analysing evolution of dispersal in populations at expanding range boundaries
Authors: HUGHES CLARE L. , DYTHAM CALVIN , HILL JANE K. 
Published: July 2007

Abstract 1. Species would be expected to shift northwards in response to current climate warming, but many are failing to do so because of fragmentation of breeding habitats. Dispersal is important for colonisation and an individual‐based spatially explicit model was developed to investigate impacts of habitat availability on the evolution of dispersal in expanding populations. Model output was compared with field data from the speckled wood butterfly Pararge aegeria, which currently is expanding its range in Britain.2. During range expansion, models simulated positive linear relationships between dispersal and distance from the seed location. This pattern was observed regardless of quantity (100% to 10% habitat availability) or distribution (random vs. gradient distribution) of habitat, although higher dispersal evolved at expanding range margins in landscapes with greater quantity of habitat and in gradient landscapes. Increased dispersal was no longer evident in any landscape once populations had reached equilibrium; dispersal values returned to those of seed populations. However, in landscapes with the least quantity of habitat, reduced dispersal (below that of seed populations) was observed at equilibrium.3. Evolutionary changes in adult flight morphology were examined in six populations of P. aegeria along a transect from the distribution core to an expanding range margin in England (spanning a latitudinal distance of >200 km). Empirical data were in agreement with model output and showed increased dispersal ability (larger and broader thoraxes, smaller abdomens, higher wing aspect ratios) with increasing distance from the distribution core. Increased dispersal ability was evident in populations from areas colonised >30 years previously, although dispersal changes were generally evident only in females.4. Evolutionary increases in dispersal ability in expanding populations may help species track future climate changes and counteract impacts of habitat fragmentation by promoting colonisation. However, at the highest levels of habitat loss, increased dispersal was less evident during expansion and reduced dispersal was observed at equilibrium indicating that, for many species, continued habitat fragmentation is likely to outweigh any benefits from dispersal.
Genetic diversity, host‐specificity and unusual phylogeography of a cryptic, host‐associated species complex of gall‐inducing scale insects
Authors: COOK LYN G. , ROWELL DAVID M. 
Published: July 2007

Abstract 1. Australia has a unique and speciose gall‐inducing scale insect fauna that is primarily associated with Myrtaceae. Much of the diversity is currently undescribed or uncharacterised.2. This study concerns Apiomorpha munita (Hemiptera), a scale insect that induces characteristic four‐horned galls on eucalypts of subgenus Symphyomyrtus and exhibits extraordinary karyotypic diversity (2n = 6 – 2n > 100). The three described subspecies of A. munita are each confined to hosts in different sections of Eucalyptus. Previous chromosomal data, however, cast doubt on the validity of the groupings, as two of the subspecies share multiple, different karyotypes (2n = 6, 20, 22, and 24).3. Allozyme data were used to examine species delimitation, chromosome evolution, host associations and population structure in A. munita.4. A cryptic‐species radiation was revealed, with at least five taxa each restricted to a discrete set of host eucalypt species. This is consistent with host‐associated speciation.5. Karyotypic variation within A. munita partially fits the five distinct genetic groups, but there are additional chromosomal changes that are not accompanied by detected genetic differentiation.6. The population structure of taxa within the A. munita species complex suggests that there are high levels of inbreeding, as would be expected for scale insects in which adult females are sessile. Some genotypes, however, are found over great distances (up to 1100 km). This is an unusual population structure because it combines low mobility and local differentiation with occasional long‐distance dispersal, probably mediated by wind‐dispersal of first‐instar nymphs.
Unequal distribution of local mating opportunities in an egg parasitoid
Authors: MARTEL VÉRONIQUE , BOIVIN GUY 
Published: July 2007

Abstract 1. The Local Mate Competition (LMC) model predicts that, in gregarious and quasi‐gregarious species, a lone female exploiting a host patch will lay only the minimal number of sons necessary to inseminate all daughters, but as the number of foundresses increases, the proportion of sons deposited by these females also increases.2. For off‐patch mating to occur, non‐sperm‐depleted males must leave the patch and find virgin females.3. To investigate the distribution of matings among males, the sperm stock at dispersal and the time of dispersal were quantified for male Trichogramma turkestanica (Hymenoptera: Trichogrammatidae).4. Matings were not distributed equally among males: some successful males acquired more matings than others. Because of this, a high variability in the sperm stock at dispersal was observed. While few males dispersed almost empty or almost full, the majority of males dispersed with enough sperm to be able to mate with females outside the emergence patch.5. The mating capacity was thus higher than necessary for local mating and could be explained by an unequal distribution of mating opportunities and the occurrence of off‐patch mating.
The use of honeydew in foraging for aphids by larvae of the ladybird beetle, Coccinella septempunctata L. (Coleoptera: Coccinellidae)
Authors: IDE TORU , SUZUKI NOBUHIKO , KATAYAMA NOBORU 
Published: July 2007

Abstract 1. To clarify the use of honeydew in foraging for aphids by larvae of the ladybird beetle, Coccinella septempunctata L., searching behaviour of ladybird larvae for Aphis craccivora Koch and Acyrthosiphon pisum Harris and the abundance of honeydew under aphid colonies were examined in laboratory experiments.2. More larvae responded by climbing the plants with aphids than responded to plants without aphids. When the plants were replaced with sticks, in order to exclude visual and olfactory cues from plants and aphids, more larvae of C. septempunctata climbed sticks above the area that contained honeydew than climbed sticks above the area that did not contain honeydew. Then, ladybird larvae use honeydew as a contact kairomone when foraging for aphids.3. Aphis craccivora deposited a larger number of honeydew droplets beneath the plants than did similar numbers of A. pisum. Thus, C. septempunctata larvae licked more frequently the honeydew of A. craccivora than that of A. pisum and spent longer searching on the area containing honeydew of A. craccivora than that of A. pisum. Consequently, a larger number of larvae climbed a stick above honeydew of A. craccivora than that of A. pisum.4. It may be also considered that C. septempunctata larvae can distinguish honeydew of the two aphid species and respond more strongly to A. craccivora than A. pisum.
Estimating the contribution of carnivorous waterbirds to nutrient loading in freshwater habitats
Authors: HAHN STEFFEN , BAUER SILKE , KLAASSEN MARCEL 
Published: July 2007

Summary1. We estimated nitrogen (N) and phosphorus (P) loading into wetlands by carnivorous waterbirds with alternative physiological models using a food‐intake and an excreta‐production approach. The models were applied for non‐breeding and breeding Dutch inland carnivorous waterbird populations to quantify their contribution to nutrient loading on a landscape scale.2. Model predictions based on food intake exceeded those based on excretion by 59–62% for N and by 2–36% for P, depending on dietary assumptions. Uncertainty analysis indicated that the intake model was most affected by errors in energy requirement, while the excretion model was dependent on faecal nutrient composition.3. Per capita loading rate of non‐breeders increased with body mass from 0.3–0.8 g N day−1 and 0.15 g P day−1 in little gulls Larus minutus to 4.5–11.5 g N day−1 and 2.1–3.2 g P day−1 in great cormorants Phalacrocorax carbo. For breeding birds, the estimated nutrient loading by a family unit over the entire breeding period ranged between 17.6–443.0 g N and 8.6 g P for little tern Sterna albifrons to 619.6–1755.6 g N and 316.2–498.1 g P for great cormorants.4. We distinguished between external (i.e. importing) and internal (i.e. recycling) nutrient loading by carnivorous waterbirds. For the Netherlands, average external‐loading estimates ranged between 38.1–91.5 tonnes N and 16.7–18.2 tonnes P per year, whilst internal‐loading estimates ranged between 53.1–140.5 tonnes N and 25.2–39.2 tonnes P and per year. The average contribution of breeding birds was estimated to be 17% and 32% for external and internal loading respectively. Most important species were black‐headed gull Larus ridibundus and mew gull Larus canus for external loading, and great cormorant and grey heron Ardea cinerea for internal loading.5. On a landscape scale, loading by carnivorous waterbirds was of minor importance for freshwater habitats in the Netherlands with 0.26–0.65 kg N ha−1 a−1 and 0.12–0.16 kg P ha−1 a−1. However, on a local scale, breeding colonies may be responsible for significant P loading.
Predator regime influences innate anti‐predator behaviour in the freshwater gastropod Lymnaea stagnalis
Authors: DALESMAN SARAH , RUNDLE SIMON D. , COTTON PETER A. 
Published: July 2007

Summary1. Predation incurs high fitness costs in aquatic organisms either through direct consumption or through avoidance responses that reduce time for activities such as feeding and reproduction. Hence, avoidance responses of aquatic organisms should vary to match closely the predation threat in their environment.2. The freshwater gastropod Lymnaea stagnalis occurs in a variety of environments which vary in the presence or absence of predatory fish. We used naïve snails reared from six populations of this species experiencing different predator regimes (three co‐occurring with molluscivorous fish and three without) to assess whether populations differed in the type and degree of their avoidance behaviours. Innate behavioural responses to four treatments (control, conspecific alarm cues, fish kairomones and fish kairomones paired with alarm cue) were compared in laboratory trials.3. The primary anti‐predator behaviour of L. stagnalis in response to fish kairomones was to crawl out of the water rather than seek refuge under water. This response was strongest when fish kairomones were paired with alarm cues, and varied depending on population origin; snails reared from populations co‐occurring with predatory fish showed a stronger response than those raised from populations not experiencing such predators. In addition, populations co‐occurring with predatory fish responded to the fish kairomones presented alone.4. Our findings suggest that the degree of innate anti‐predator behaviour shown by L. stagnalis, in terms of both the level of risk to which it responds and the degree of response, varies depending on the predator regime experienced by field populations. Together with previous work on cue association, this demonstrates that this gastropod is able to match its avoidance behaviour very closely to short and long term predation threats within its habitat.
Does freshwater macroinvertebrate diversity along a pH‐gradient reflect adaptation to low pH?
Authors: PETRIN ZLATKO , LAUDON HJALMAR , MALMQVIST BJÖRN 
Published: July 2007

Summary1. The impacts of anthropogenic surface water acidification are much better known than those of natural acidity. Recent studies have indicated biodiversity is not degraded and species composition unaltered in naturally acidic compared to circumneutral watercourses.2. Here, we use a geographically extensive dataset comprising sites in more than 200 Swedish streams to test whether the lack of effects on macroinvertebrate species diversity is due to exaptation and adaptation to natural acidity.3. To this end, we modelled pH associated with spring flood episodes, which inflict the most challenging hydrochemical conditions to the biota. We compared taxonomic richness and species composition along the modelled pH gradient in northern Sweden, where acidity is largely natural, with southern Sweden, a region influenced by significant anthropogenic acidification.4. We found Plecoptera richness did not respond to varying pH either in northern or southern Sweden. Ephemeroptera richness was sensitive to pH in both regions, while that of Trichoptera increased with increasing pH in southern Sweden, but decreased in the north. The taxonomic composition of Plecoptera changed along the pH gradient in both regions, whereas that of Ephemeroptera and Trichoptera changed more strongly with pH in southern Sweden.5. Our results support the hypothesis that stream invertebrates are able to tolerate low pH through exaptation or adaptation, but that this capability varies among taxonomic groups.
The role of adaptive plasticity in a major evolutionary transition: early aquatic experience affects locomotor performance of terrestrial snakes
Authors: AUBRET F. , BONNET X. , SHINE R. 
Published: July 2007

Summary

Many phylogenetic lineages of animals have undergone major habitat transitions, stimulating dramatic phenotypic changes as adaptations to the novel environment. Although most such traits clearly reflect genetic modification, phenotypic plasticity may have been significant in the initial transition between habitat types.
Elapid snakes show multiple phylogenetic shifts from terrestrial to aquatic life. We raised young tigersnakes (a terrestrial taxon closely related to sea‐snakes) in either a terrestrial or aquatic environment for a 5‐month period.
The snakes raised in water were able to swim 26% faster, but crawled 36% more slowly, than did their terrestrially‐raised siblings. A full stomach impaired locomotor performance, but snakes were less impaired when tested in the environment in which they had been raised.
Thus, adaptively plastic responses to local environments may have facilitated aquatic performance (and impaired terrestrial performance) in ancestral snakes as they shifted from terrestrial to aquatic existence.
Such plasticity may have influenced the rate or route of this evolutionary transition between habitats, and should be considered when comparing habitat‐specific locomotor abilities of present‐day aquatic and terrestrial species.
Immune activity suppresses reproduction in food‐limited female tree lizards Urosaurus ornatus
Authors: FRENCH S. S. , JOHNSTON G. I. H. , MOORE M. C. 
Published: July 2007

Summary

When resources are scarce, organisms are faced with critical challenges trying to optimize competing functions. Reproduction and immune function are both resource intensive and important to most species. Most studies have reported a down‐regulation of immune function during reproduction. Conversely, it is unclear whether mounting an immune response can affect the reproductive process and few studies have examined competition for resources between these two processes.
Here we report evidence for direct competition for resources between the reproductive and immune systems in a vertebrate model system, the tree lizard (Urosaurus ornatus). We manipulated food intake in reproductive female tree lizards, where half of the females were undergoing cutaneous wound healing and the other half were not. We then measured reproductive investment in all animals and wound healing rate in all wounded animals.
We found that animals with unlimited access to food sustained both reproduction and immune function whereas animals maintained on a restricted diet were not. Specifically, when food was unlimited, females were able to invest in reproduction and heal their wounds. However, when food was limited, females forced to heal a cutaneous wound had significantly smaller follicles than their non‐wounded counterparts. Under extreme food limitation (i.e. no food) both reproductive investment and wound healing were suppressed.
These results clearly demonstrate resource competition between the reproductive and immune systems, whereby physiological trade‐offs between the two systems only arise when resources are limiting. Furthermore, this type of facultative regulation is adjustable and allows animals to respond to changing environmental conditions.
Carotenoid pigmentation does not reflect total non‐enzymatic antioxidant activity in plasma of adult and nestling great tits, Parus major
Authors: ISAKSSON CAROLINE , McLAUGHLIN PATRICIA , MONAGHAN PAT , ANDERSSON STAFFAN 
Published: July 2007

Summary

Based on carotenoids’ antioxidant and pro‐vitamin functions, carotenoid pigmentation, particularly in birds, has been hypothesized to honestly advertize condition and health. As antioxidants, carotenoids protect the body from oxidative damage caused by internal or external stressors (e.g. growth, infection and anthropogenic pollution). However, the relative importance of carotenoids in the avian antioxidant defence has been questioned, and the positive relationship between colouration and health may be a ‘red herring’.
In the present study, we investigate carotenoid‐based plumage colouration and circulating carotenoids in relation to plasma non‐enzymatic total antioxidant activity (TAA) in adult and nestling great tits (Parus major). The study was conducted in urban vs. rural populations, with documented differences in oxidative stress level and plumage pigmentation.
First, we found that there was no relationship between TAA and plumage pigmentation (carotenoid chroma) or plasma carotenoids. Second, urban environment significantly influenced TAA; old (2+ years) urban birds had higher activity than old rural birds, and also compared to younger (1 year) urban adults. This is likely to be due to the increased demand for plasma antioxidants as a consequence of urban environmental stress. Third, nestlings’ TAA showed no difference between urban and rural environments. However, it was highly influenced by brood, but not related to parental levels, therefore most likely due to differences in the nestling environment.
We suggest that carotenoids are not significant contributors to extra‐cellular antioxidant defence in great tits, and that carotenoid pigmentation may be an overrated health indicator in this respect. Honest carotenoid signalling, when present, is thus likely to be mediated by some other constraint, such as nutrition or uptake, or other health‐modulating mechanisms.
The disappearance of relict permafrost in boreal north America: Effects on peatland carbon storage and fluxes
Authors: TURETSKY M. R. , WIEDER R. K. , VITT D. H. , EVANS R. J. , SCOTT K. D. 
Published: July 2007

AbstractBoreal peatlands in Canada have harbored relict permafrost since the Little Ice Age due to the strong insulating properties of peat. Ongoing climate change has triggered widespread degradation of localized permafrost in peatlands across continental Canada. Here, we explore the influence of differing permafrost regimes (bogs with no surface permafrost, localized permafrost features with surface permafrost, and internal lawns representing areas of permafrost degradation) on rates of peat accumulation at the southernmost limit of permafrost in continental Canada. Net organic matter accumulation generally was greater in unfrozen bogs and internal lawns than in the permafrost landforms, suggesting that surface permafrost inhibits peat accumulation and that degradation of surface permafrost stimulates net carbon storage in peatlands. To determine whether differences in substrate quality across permafrost regimes control trace gas emissions to the atmosphere, we used a reciprocal transplant study to experimentally evaluate environmental versus substrate controls on carbon emissions from bog, internal lawn, and permafrost peat. Emissions of CO2 were highest from peat incubated in the localized permafrost feature, suggesting that slow organic matter accumulation rates are due, at least in part, to rapid decomposition in surface permafrost peat. Emissions of CH4 were greatest from peat incubated in the internal lawn, regardless of peat type. Localized permafrost features in peatlands represent relict surface permafrost in disequilibrium with the current climate of boreal North America, and therefore are extremely sensitive to ongoing and future climate change. Our results suggest that the loss of surface permafrost in peatlands increases net carbon storage as peat, though in terms of radiative forcing, increased CH4 emissions to the atmosphere will partially or even completely offset this enhanced peatland carbon sink for at least 70 years following permafrost degradation.
Cytochrome P450s in Papilio multicaudatus and the transition from oligophagy to polyphagy in the Papilionidae
Authors: Mao W. , Schuler M. A. , Berenbaum M. R. 
Published: July 2007

AbstractAlthough substrate‐specific CYP6B1 and CYP6B3 enzymes in Papilio polyxenes contribute to specialization on furanocoumarin‐containing host plants, CYP6B4 and CYP6B17 enzymes in the polyphagous Papilio glaucus and Papilio canadensis have a broader range of substrates. Papilio multicaudatus, an oligophage with one furanocoumarin‐containing host, is putatively ancestral to polyphagous Papilio species. Furanocoumarin‐inducible CYP6B33–CYP6B37 and CYP6AB6 were characterized from this species. Heterologous expression of CYP6B33 revealed furanocoumarin metabolism resembling that of CYP6B4–CYP6B17 enzymes from P. glaucus and P. canadensis. Molecular models of CYP6B33 and CYP6B4 indicate that seven conserved aromatic side chains stabilize their hydrophobic catalytic sites and that a Lys484–Ser484 substitution enlarges the CYP6B4 active site pocket to increase the predicted distance between the substrate and reactive oxygen relative to CYP6B1. Loss of specialization in this lineage may have resulted from relatively few mutational changes, allowing acquisition of broader catalytic activities without loss of ancestral furanocoumarin‐metabolizing activities.