bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for a putative antennal clock in Mamestra brassicae: Molecular cloning and characterization of two clock genes –period and cryptochrome– in antennae
Authors: Merlin C. , François M.‐C. , Queguiner I. , Maïbèche‐Coisné M. , Jacquin‐Joly E. 
Published: March 2006

AbstractCircadian rhythms are generated by endogenous circadian clocks, organized in central and peripheral clocks. An antennal peripheral clock has been demonstrated to be necessary and sufficient to generate Drosophila olfactory rhythms in response to food odours. As moth pheromonal communication has been demonstrated to follow daily rhythms, we thus investigated the occurence of a putative antennal clock in the noctuid Mamestra brassicae. From moth antennae, we isolated two full‐length cDNAs encoding clock genes, period and cryptochrome, which appeared to be expressed throughout the body. In the antennae, expression of both transcripts was restricted to cells that likely represent olfactory sensory neurones. Our results suggest the occurence of a putative antennal clock that could participate in the pheromonal communication rhythms observed in vivo.
Reversible introduction of transgenes in natural populations of insects
Authors: Le Rouzic A. , Capy P. 
Published: March 2006

AbstractThe most serious challenge concerning genetically modified insects remains their invasion ability. Indeed, transgenic insects often show lower fitness than wild individuals, and the transgene does not seem able to spread through a natural population without a driving system. The use of remobilizable vectors, based on the invading properties of transposable elements, has been frequently suggested. Simulations show that this strategy can be efficient. Moreover, if the transgene is designed to use transposition machinery already present in the genome, the transgene invasion appears to be potentially reversible after a few hundred generations, leading to new experimental perspectives.
The mitochondrial genome of the bristletail Petrobius brevistylis (Archaeognatha: Machilidae)
Authors: Podsiadlowski L. 
Published: March 2006

AbstractThe complete mitochondrial genome of the bristletail Petrobius brevistylis has been determined. The genome is 15 698 bp long and bears the standard set of genes common to all arthropods as well as a major non‐coding A + T‐rich region, the putative mitochondrial control region. A unique gene order was revealed as it differs from other hexapod and crustacean mitochondrial genomes in the position of tRNA‐Tyr. Genome features like nucleotide composition and codon usage are compared with that of other insect taxa. A + T content is similar in species of Archaeognatha and Zygentoma, but obviously lower than in Collembola and Pterygota. This A + T bias significantly affects also amino acid frequencies and may be a problem for phylogenetic analyses.
Genomic organization and functional characterization of the alcohol dehydrogenase locus of Ceratitis capitata (Medfly)
Authors: Brogna Saverio , Bourtzis Kostas , Gomulski Ludvik M. , Denaxa Myrto , Babaratsas Alekos , Gasperi Giuliano , Savakis Charalambos 
Published: March 2006

AbstractApproximately 30 kb of genomic DNA enclosing the Adh locus from the medfly, Ceratitis capitata have been cloned and about 15 kb has been structurally and functionally characterized. The locus consists of two genes, Adh‐1 and Adh‐2, separated by an intergenic region, which is polymorphic in size ranging from ≈ 6.4 kb to 8.1 kb. Both genes consist of three exons and two introns. The introns are below 200 bp in size, except the 1st intron of Adh‐1, which is unexpectedly long, variable in size and contains a deleted mariner‐like element (postdoc). The two genes are transcribed in different orientations. The Adh‐2 gene shows the typical pattern of transcription seen in the homologous genes of Drosophilidae presenting high levels of expression in the fat body, gut and ovaries. The Adh‐1 gene is only expressed in the body muscle tissues of embryos, larvae and adult flies, raising the question of what its biological function may be. A DNA fragment containing bases −102 to −1666 relative to the first base of the initiating ATG of Adh‐1 is sufficient to drive the expression of a reporter gene in body muscles of Drosophila melanogaster embryos, larvae and adult flies. The study provides further insights into the evolution of the Adh genes of higher diptera.
Rain forest promotes trophic interactions and diversity of trap‐nesting Hymenoptera in adjacent agroforestry
Authors: KLEIN ALEXANDRA‐MARIA , STEFFAN‐DEWENTER INGOLF , TSCHARNTKE TEJA 
Published: March 2006

SummaryHuman alteration of natural ecosystems to agroecosystems continues to accelerate in tropical countries. The resulting world‐wide decline of rain forest causes a mosaic landscape, comprising simple and complex agroecosystems and patchily distributed rain forest fragments of different quality. Landscape context and agricultural management can be expected to affect both species diversity and ecosystem services by trophic interactions.In Central Sulawesi, Indonesia, 24 agroforestry systems, differing in the distance to the nearest natural forest (0–1415 m), light intensity (37·5–899·6 W/m−2) and number of vascular plant species (7–40 species) were studied. Ten standardized trap nests for bees and wasps, made from reed and knotweed internodes, were exposed in each study site. Occupied nests were collected every month, over a period totalling 15 months.A total of 13 617 brood cells were reared to produce adults of 14 trap‐nesting species and 25 natural enemy species, which were mostly parasitoids. The total number of species was affected negatively by increasing distance from forest and increased with light intensity of agroforestry systems. The parasitoids in particular appeared to benefit from nearby forests. Over a 500‐m distance, the number of parasitoid species decreased from eight to five, and parasitism rates from 12% to 4%.The results show that diversity and parasitism, as a higher trophic interaction and ecosystem service, are enhanced by (i) improved connectivity of agroecosystems with natural habitats such as agroforestry adjacent to rain forest and (ii) management practices to increase light availability in agroforestry, which also enhances richness of flowering plants in the understorey.
Breeding birds on small islands: island biogeography or optimal foraging?
Authors: RUSSELL GARETH J. , DIAMOND JARED M. , REED TIMOTHY M. , PIMM STUART L. 
Published: March 2006

Summary

We test MacArthur and Wilson's theory about the biogeography of communities on isolated habitat patches using bird breeding records from 16 small islands off the coasts of Britain and Ireland.
A traditional examination of patterns of species richness on these islands suggests that area and habitat diversity are important predictors, but that isolation and latitude have a negligible impact in this system.
Unlike traditional studies, we directly examine the fundamental processes of colonization and local extinction (cessation of breeding), rather than higher‐order phenomena such as species richness.
We find that many of MacArthur and Wilson's predictions hold: colonization probability is lower on more isolated islands, and extinction probability is lower on larger islands and those with a greater diversity of habitats.
We also find an unexpected pattern: extinction probability is much lower on more isolated islands. This is the strongest relationship in these data, and isolation is the best single predictor of colonization and extinction.
Our results show that examination of species richness alone is misleading. Isolation has a strong effect on both of the dynamic processes that underlie richness, and in this system, the reductions in both colonization and extinction probability seen on more distant islands have opposing influences on species richness, and largely cancel each other out.
We suggest that an appropriate model for this system might be optimal foraging theory, which predicts that organisms will stay longer in a resource patch if the distance to a neighbouring patch is large. If nest sites and food are the resources in this system, then optimal foraging theory predicts the pattern we observe.
We advance the hypothesis that there is a class of spatial systems, defined by their scale and by the taxon under consideration, at which decision‐making processes are a key driver of the spatiotemporal dynamics. The appropriate theory for such systems will be a hybrid of concepts from biogeography/metapopulation theory and behavioural ecology.
Recruitment pulses induce cannibalistic giants in Arctic char
Authors: BYSTRÖM PÄR 
Published: March 2006

Summary

Recent theoretical studies on the population dynamic consequences of cannibalism have focused on mechanisms behind the emergence of large cannibals (giants) in size‐structured populations. Theoretically, giants emerge when a strong recruiting cohort imposes competition induced mortality on stunted adults, but also provides a profitable resource for a few adults that accelerate in growth and reach giant sizes.
Here the effects of a recruitment pulse on the individual and population level in an allopatric Arctic char population have been studied over a 5‐year period and these results were contrasted with theoretical model predictions for the conditions necessary for the emergence of cannibalistic giants.
The recruitment pulse had negative effects on invertebrate resource abundance, and the decrease in body condition and increase in mortality of adult char suggested that strong intercohort competition took place.
The frequency of cannibalism increased and a few char accelerated in growth and reached ‘giant’ sizes.
The main discrepancy between model predictions and field data was the apparently small effect the recruited cohort had on resources and adult char performance during their first summer. Instead, the effects became pronounced when the cohort was 1 year old. This mismatch between model predictions and field observations was suggested to be due to the low per capita fecundity in char and the restricted nearshore habitat use in young‐of‐the‐year (YOY) char.
This study provides empirical evidence that the emergence of giants is associated with the breakthrough of a strong recruiting cohort and also suggests that the claimed stable char populations with large cannibals may instead be populations with dynamic size structure that results in intermittent breakthroughs of recruitment pulses, providing the conditions necessary for char to enter the cannibalistic niche.
The data suggest that increased recruit survival through restricted habitat use may destabilize dynamics and cause the emergence of giants. However, they also suggest that this does not necessarily develop into populations with bi‐modal size structure in populations with low per capita fecundity and size‐ and density‐dependent habitat use of recruiting cohorts.
Spatio‐temporal dynamics of alternative male phenotypes in coho salmon populations in response to ocean environment
Authors: KOSEKI YUSUKE , FLEMING IAN A. 
Published: March 2006

Summary

The coexistence of alternative reproductive phenotypes will probably be shaped by spatial and temporal variability in the environment. However, the effects of such variability on coexistence and the scale at which it operates are seldom understood.
To quantify such effects, we examined spatial and temporal dynamics in the abundance and frequency of alternative phenotypes of male coho salmon, Oncorhynchus kisutch Walbaum, which mature as either large fighters (age‐3 ‘hooknoses’) or small sneakers (age‐2 ‘jacks’). Using over 20 years of data on coded‐wire tagged fish released from nine Oregon hatcheries, we tested for the effects of ocean environment independent of those due to freshwater rearing.
Annual fluctuations of the abundance of jack and hooknose males within populations were correlated strongly by brood year (cohort) but not by return year (breeding group). This occurred independently of significant effects of release practice (i.e. the number of fish released, body size at release and date of release), indicating that a synchronized fluctuation in mortality during the first year at sea was the predominant cause. As a result, the annual frequency of the alternative phenotypes at breeding varied considerably within populations.
Spatial patterns in the annual fluctuations of the two phenotypes were similar (i.e. synchronous among populations), except that jacks showed local spatial structure (decreased synchrony with distance) not evident among hooknoses. This suggests that oceanic processes affecting the two phenotypes operate at different spatial scales. Despite effects on salmon abundance, the ocean environment had little influence through its effects on salmon growth on the relative frequencies of the alternative phenotypes within and among populations.
The results provide insight into the evolutionary dynamics of alternative phenotypes, including an intragenerational time lag that increases annual variability in phenotype frequencies at breeding (return years) and the significance of local freshwater processes, rather than oceanic processes, on phenotype expression. Freshwater processes, such as juvenile growth, timing of migration and breeding competition, operating at evolutionary and intragenerational time‐scales, are probably the predominant forces affecting phenotype frequency.
Quantitative analysis of bottlenose dolphin movement patterns and their relationship with foraging
Authors: BAILEY HELEN , THOMPSON PAUL 
Published: March 2006

Summary

Broad‐scale telemetry studies have greatly improved our understanding of the ranging patterns and habitat‐use of many large vertebrates. However, there often remains considerable uncertainty over the function of different areas or the factors influencing habitat selection. Further insights into these processes can be obtained through analyses of finer scale movement patterns. For example, search behaviour may be modified in response to prey distribution and abundance.
In this study, quantitative analysis techniques are applied to the movements of bottlenose dolphins, recorded from land using a theodolite, to increase our understanding of their foraging strategies. Movements were modelled as a correlated random walk (CRW) and a biased random walk (BRW) to identify movement types and using a first‐passage time (FPT) approach, which quantifies the time allocated to different areas and identifies the location and spatial scale of intensive search effort.
Only a quarter of the tracks were classed as CRW movement. Turning angle and directionality appeared to be key factors in determining the type of movement adopted. A high degree of overlap in search effort between separate movement paths indicated that there were small key sites (0·3 km radius) within the study area (4 km2). Foraging behaviour occurred mainly within these intensive search areas, indicating that they were feeding sites.
This approach provides a quantitative method of identifying important foraging areas and their spatial scale. Such techniques could be applied to movement paths for a variety of species derived from telemetry studies and increase our understanding of their foraging strategies.
Delayed population explosion of an introduced butterfly
Authors: BOGGS CAROL L. , HOLDREN CHERYL E. , KULAHCI IPEK G. , BONEBRAKE TIMOTHY C. , INOUYE BRIAN D. , FAY JOHN P. , MCMILLAN ANN , WILLIAMS ERNEST H. , EHRLICH PAUL R. 
Published: March 2006

SummaryThe causes of lagged population and geographical range expansions after species introductions are poorly understood, and there are relatively few detailed case studies.We document the 29‐year history of population dynamics and structure for a population ofEuphydryas gillettiiBarnes that was introduced to the Colorado Rocky Mountains, USA in 1977.The population size remained low (< 200 individuals) and confined to a single habitat patch (∼2·25 ha) to 1998. These values are similar to those of many other populations within the natural geographical range of the species.However, by 2002 the population increased dramatically to > 3000 individuals and covered ∼70 ha, nearly all to the south of the original site. The direction of population expansion was the same as that of predominant winds.By 2004, the butterfly's local distribution had retracted mainly to three habitat patches. It thus exhibited a ‘surge/contraction’ form of population growth. Searches within 15 km of the original site yielded no other new populations.In 2005, butterfly numbers crashed, but all three habitat patches remained occupied. The populations within each patch did not decrease in the same proportions, suggesting independent dynamics that are characteristic of metapopulations.We postulate that this behaviour results, in this species, in establishment of satellite populations and, given appropriate habitat structure, may result in lagged or punctuated expansions of introduced populations.
Habitat type and density influence vocal signal design in satin bowerbirds
Authors: NICHOLLS JAMES A. , GOLDIZEN ANNE W. 
Published: March 2006

Summary

This study provided a thorough test of the acoustic adaptation hypothesis using a within‐species comparison of call structure involving a wide range of habitat types, an objective measure of habitat density and direct measures of habitat‐related attenuation.
The structure of the bower advertisement call of the satin bowerbird was measured in 16 populations from throughout the species’ range and related to the habitat type and density at each site. Transmission of white noise, pure tones and different bowerbird dialects was measured in five of six habitat types inhabited by satin bowerbirds.
Bowerbird advertisement call structure converged in similar habitats but diverged among different habitats; this pattern was apparent at both continent‐wide and local geographical scales. Bowerbirds’ call structures differed with changes in habitat density, consistent with the acoustic adaptation hypothesis. Lower frequencies and less frequency modulation were utilized in denser habitats such as rainforest and higher frequencies and more frequency modulation were used in the more open eucalypt‐dominated habitats.
The white noise and pure tone transmission measurements indicated that different habitats varied in their sound transmission properties in a manner consistent with the observed variation in satin bowerbird vocalizations.
There was no effect of geographical proximity of recording locations, nor was there the predicted inverse relationship between frequency and body size.
These findings indicate that the transmission qualities of different habitats have had a major influence on variation in vocal phenotypes in this species. In addition, previously published molecular data for this species suggest that there is no effect of genetic relatedness on call similarity among satin bowerbird populations.
Hybridization increases measures of innate and cell‐mediated immunity in an endangered bird species
Authors: TOMPKINS DANIEL M. , MITCHELL ROBIN A. , BRYANT DAVID M. 
Published: March 2006

Summary

Given the increasing threat of ‘emerging infectious diseases’ (EIDs), and the vulnerability of small inbred populations to such novel challenges (at least partly through compromised immunity), a degree of interspecific hybridization may improve the viability of endangered species by enriching depauperate gene pools.
To investigate this hypothesis, we quantified indicators of the strength of both innate and cell‐mediated immunity in wild populations of hybridizing parakeets on the Chatham Islands, New Zealand.
We show that both measures of immune function are markedly higher in the cosmopolitan red‐crowned parakeet Cyanoramphus novaezelandiae than in the island endemic Forbes’ parakeet C. forbesi, as is to be expected when comparing relatively outbred vs. relatively inbred species.
In addition, we show that both measures of immune function are higher in Forbes’× red‐crowned parakeet hybrids than in the Forbes’ parakeet. Even those individuals with few red‐crowned characteristics, suggesting they are the products of matings between hybrids and Forbes’ parakeets, have significantly higher measures of immune function.
As at least one of the immune indicators measured correlates directly with both survivorship and the viability of small bird populations, this study reveals a potential management option for hybridizing species of conservation concern, where an increase in resilience to novel disease challenges could outweigh some loss of genetic integrity.
A silver spoon for a golden future: long‐term effects of natal origin on fitness prospects of oystercatchers (Haematopus ostralegus)
Authors: VAN DE POL MARTIJN , BRUINZEEL LEO W. , HEG DIK , VAN DER JEUGD HENK P. , VERHULST SIMON 
Published: March 2006

SummaryLong‐term effects of conditions during early development on fitness are important for life history evolution and population ecology. Using multistrata mark–recapture models on 20 years of data, we quantified the relation between rearing conditions and lifetime fitness in a long‐lived shorebird, the oystercatcher (Haematopus ostralegus). We addressed specifically the relative contribution of short‐ and long‐term effects of rearing conditions to overall fitness consequences.Rearing conditions were defined by differences in natal habitat quality, in which there is a clear dichotomy in our study population. In the first year of life, fledglings from high‐quality natal origin had a 1·3 times higher juvenile survival. Later in life (age 3–11), individuals of high‐quality natal origin had a 1·6 times higher adult prebreeder survival. The most striking effect of natal habitat quality was that birds that were reared on high‐quality territories had a higher probability of settling in high‐quality habitat (44% vs. 6%). Lifetime reproductive success of individuals born in high‐quality habitat was 2·2 times higher than that of individuals born in low‐quality habitat. This difference increased further when fitness was calculated over several generations, due to a correlation between the quality of rearing conditions of parents and their offspring.Long‐term effects of early conditions contributed more to overall fitness differences as short‐term consequences, contrary to common conceptions on this issue.This study illustrates that investigating only short‐term effects of early conditions can lead to the large underestimation of fitness consequences. We discuss how long‐term consequences of early conditions may affect settlement decisions and source–sink population interactions.