bluuebunny/crossref_metadata_2025_split huggingface dataset:
Living with uncertainty: genetic imprints of climate shifts in East Pacific anchovy (Engraulis mordax) and sardine (Sardinops sagax)
Authors: LECOMTE F. , GRANT W. S. , DODSON J. J. , RODRÍGUEZ‐SÁNCHEZ R. , BOWEN B. W. 
Published: July 2004

AbstractIn the upwelling zone of the northeastern Pacific, cold nutrient‐rich conditions alternate with warm nutrient‐poor intervals on timescales ranging from months to millennia. In this setting, the abundances of Pacific sardine (Sardinops sagax) and northern anchovy (Engraulis mordax) fluctuate by several orders of magnitude, with sardine dominating during warm conditions and anchovy dominating during cool conditions. Two population models can explain the response of these fishes to adverse conditions. Under the basin model, species distributions contract to a central (optimal) range during population crashes. Expectations of this model may include a single range‐wide population with a decline in genetic diversity on both sides of a central refuge. In contrast, the self‐recruitment model invokes a series of local oceanographic domains that maintain semi‐isolated subpopulations. During adverse conditions, some subpopulations cannot complete the life cycle within the local environment and are extirpated. Expectations of this model include some degree of population genetic structure and no clear gradient in genetic diversity. We examined mitochondrial DNA cytochrome bsequences to assess these competing models for anchovy (N = 196; 539 bp) and sardine (N = 107; 425 bp). The mitochondrial DNA gene genealogies are shallow but diverse for both species. Haplotype frequencies are homogeneous among subpopulations, but genetic diversities peak for both species along Baja California and adjacent southern California. Mismatch distributions and Tajima'sD‐values reveal distinctive signatures of population bottlenecks and expansions. Sardine haplotypes coalesce at ~241 000 yearsbp, with an initial female effective population sizeNf0 = 0 followed by exponential growth toNf1 = 115 million. Anchovy haplotypes coalesce at ~282 000 yearsbp, with an initial population size ofNf0 = 14 000, followed by exponential growth toNf1 = 2.3 million. These results indicate a founder event for sardine and a severe population decline for anchovy in the California Current during the late Pleistocene. Overall, these data support the basin model on decadal timescales, although local recruitment may dominate on shorter timescales.
Identity and diversity of coral endosymbionts (zooxanthellae) from three Palauan reefs with contrasting bleaching, temperature and shading histories
Authors: FABRICIUS K. E. , MIEOG J. C. , COLIN P. L. , IDIP D. , H. VAN OPPEN M. J. 
Published: July 2004

AbstractThe potential of corals to associate with more temperature‐tolerant strains of algae (zooxanthellae, Symbiodinium) can have important implications for the future of coral reefs in an era of global climate change. In this study, the genetic identity and diversity of zooxanthellae was investigated at three reefs with contrasting histories of bleaching mortality, water temperature and shading, in the Republic of Palau (Micronesia). Single‐stranded conformation polymorphism and sequence analysis of the ribosomal DNA internal transcribed spacer (ITS)1 region was used for genotyping. A chronically warm but partly shaded coral reef in a marine lake that is hydrographically well connected to the surrounding waters harboured only two single‐stranded conformation polymorphism profiles (i.e. zooxanthella communities). It consisted only of Symbiodinium D in all 13 nonporitid species and two Porites species investigated, with the remaining five Porites harbouring C•. Despite the high temperature in this lake (> 0.5° above ambient), this reef did not suffer coral mortality during the (1998) bleaching event, however, no bleaching‐sensitive coral families and genera occur in the coral community. This setting contrasts strongly with two other reefs with generally lower temperatures, in which 10 and 12 zooxanthella communities with moderate to low proportions of clade D zooxanthellae were found. The data indicate that whole coral assemblages, when growing in elevated seawater temperatures and at reduced irradiance, can be composed of colonies associated with the more thermo‐tolerant clade D zooxanthellae. Future increases in seawater temperature might, therefore, result in an increasing prevalence of Symbiodinium phylotype D in scleractinian corals, possibly associated with a loss of diversity in both zooxanthellae and corals.
Colony structure and parentage in wild colonies of co‐operatively breeding Damaraland mole‐rats suggest incest avoidance alone may not maintain reproductive skew
Authors: BURLAND TAMSIN M. , BENNETT NIGEL C. , JARVIS JENNIFER U. M. , FAULKES CHRISTOPHER G. 
Published: July 2004

AbstractColonies of co‐operatively breeding African mole‐rats have traditionally been thought to be composed of a single breeding female, one or two breeding males, and their offspring. In the naked mole‐rat (Heterocephalus glaber), the occurrence of facultative inbreeding means incest avoidance cannot prevent reproduction in subordinate group members, and physiological suppression of reproductive function by the breeding female occurs in both sexes. In contrast, previous studies of captive colonies of the Damaraland mole‐rat (Cryptomys damarensis) suggest that breeding within a colony is restricted to a single breeding pair, simply because all other colony members are highly related (first‐ or second‐order relatives) and this species is an obligate outbreeder. Using microsatellite markers, we investigated parentage and colony composition in 18 wild Damaraland mole‐rat colonies to determine whether inbreeding avoidance alone can explain the high levels of reproductive skew in this species. Multiple and unidentified paternity was widespread within colonies and immigrants of both sexes were regularly identified. Unrelated, opposite‐sex nonbreeders were found coexisting in two colonies. These results suggest that, in the wild, conditions exist where nonreproductive females can come into contact with unrelated males, even when they do not disperse from their natal colony. Inbreeding avoidance alone is therefore insufficient to maintain the high levels of reproductive skew identified in this species suggesting that the breeding female somehow suppresses the reproductive function in nonbreeding females.
Natural hybridization betweenSenecio jacobaeaandSenecio aquaticus: molecular and chemical evidence
Authors: KIRK HEATHER , MÁČEL MIRKA , KLINKHAMER PETER G. L. , VRIELING KLAAS 
Published: July 2004

AbstractHybridization is known to be involved in a number of evolutionary processes, including species formation, and the generation of novel defence characteristics in plants. The genusSenecioof the Asteraceae family is highly speciose and has historically demonstrated significant levels of interspecific hybridization. The evolution of novel chemical defence characteristics may have contributed to the success ofSeneciohybrids. Chemical defence against pathogens and herbivores has been studied extensively in the model speciesSenecio jacobaea, which is thought to hybridize in nature withSenecio aquaticus. Here, we use amplified fragment length polymorphisms (AFLPs) and pyrrolizidine alkaloid (PA) composition to confirm that natural hybridization occurs betweenS. jacobaeaand the closely related speciesS. aquaticus. AFLPs are also used to estimate the ancestry of hybrids. We also demonstrate that even highly back‐crossed hybrids can possess a unique mixture of defence chemicals specific to each of the parental species. This hybrid system may therefore prove to be useful in further studies of the role of hybridization in the evolution of plant defence and resistance.
No evidence of an MHC‐based female mating preference in great reed warblers
Authors: WESTERDAHL HELENA 
Published: July 2004

AbstractFemale mate‐choice based on genetic compatibility is an area of growing interest. The major histocompatibility complex (MHC) genes are likely candidates for such mate‐choice since these highly polymorphic genes may both increase offspring viability and also provide direct cues for mate‐choice. In great reed warblers, females actively choose a breeding partner out of a handful of males that they visit and evaluate; thus, female preference for compatible or heterozygous MHC genes could have evolved. Here, I investigate whether great reed warbler females preferentially mate with males with dissimilar MHC class I alleles or with males that are heterozygous at MHC class I. Despite favourable conditions, a thorough screening method and a large sample size, there was no evidence of an MHC‐based female mating preference based on either genetic compatibility or heterozygosity in this population. Power analyses of the data sets revealed that relatively small differences (15% and 8%, respectively) between true and random pairs should have been detected.
Rapid recovery of genetic diversity of dogwhelk (Nucella lapillus L.) populations after local extinction and recolonization contradicts predictions from life‐history characteristics
Authors: COLSON I. , HUGHES R. N. 
Published: July 2004

AbstractThe dogwhelk Nucella lapillus is a predatory marine gastropod populating North Atlantic rocky shores. As with many other gastropod species, N. lapillus was affected by tributyltin (TBT) pollution during the 1970s and 1980s, when local populations became extinct. After a partial ban on TBT in the United Kingdom in 1987, vacant sites have been recolonized. N. lapillus lacks a planktonic larval stage and is therefore expected to have limited dispersal ability. Relatively fast recolonization of some sites, however, contradicts this assumption. We compared levels of genetic diversity and genetic structuring between recolonized sites and sites that showed continuous population at three localities across the British Isles. No significant genetic effects of extinction/recolonization events were observed in SW Scotland and NE England. In SW England we observed a decrease in genetic diversity and an increase in genetic structure in recolonized populations. This last result could be an artefact, however, due to the superposition of other local factors influencing the genetic structuring of dogwhelk populations. We conclude that recolonization of vacant sites was accomplished by a relatively high number of individuals originating from several source populations (the ‘migrant‐pool’ model of recolonization), implying that movements are more widespread than expected on the basis of development mode alone. Comparison with published data on genetic structure of marine organisms with contrasted larval dispersal supports this hypothesis. Our results also stress the importance of local factors (geographical or ecological) in determining genetic structure of dogwhelk populations.
Microsatellite variation reveals high levels of genetic variability and population structure in the gorgonian coralPseudopterogorgia elisabethaeacross the Bahamas
Authors: GUTIÉRREZ‐RODRÍGUEZ CARLA , LASKER HOWARD R. 
Published: July 2004

AbstractThe primary mechanism of gene flow in marine sessile invertebrates is larval dispersal. InPseudopterogorgia elisabethae, a commercially important Caribbean gorgonian coral, a proportion of the larvae drop to the substratum within close proximity to the maternal colony, and most matings occur between individuals in close proximity to each other. Such limited dispersal of reproductive propagules suggests that gene flow is limited in this gorgonian. In this study, we characterized the population genetic structure ofP. elisabethaeacross the Bahamas using six microsatellite loci.P. elisabethaewas collected from 18 sites across the Bahamas. Significant deviations from Hardy–Weinberg equilibrium due to deficits of heterozygotes within populations were detected for all 18 populations in at least one of the six screened loci. Levels of genetic structure among populations ofP. elisabethaewere high and significant. A distance analysis placed populations within three groups, one formed by populations located within Exuma Sound, a semi‐isolated basin, another consisting of populations located outside the basin and a third group comprising two populations from San Salvador Island. The patterns of genetic variation found in this study are concordant with the life‐history traits of the species and in part with the geography of the Bahamas. Conservation and management plans developed forP. elisabethaeshould considered the high degree of genetic structure observed among populations of the species, as well as the high genetic diversity found in the San Salvador and the Exuma Sound populations.
DNA analysis on fox faeces and competition induced niche shifts
Authors: DALÉN LOVE , ELMHAGEN BODIL , ANGERBJÖRN ANDERS 
Published: July 2004

AbstractInterference competition can force inferior competitors to change their distribution patterns. It is, however, possible that the dominant competitor poses a higher threat during certain times of the year, for example during reproduction. In such cases, the inferior competitor is expected to change its distribution accordingly. We used a molecular species identification method on faeces to investigate how the spatial overlap between arctic and red foxes changes between seasons. The results show that arctic and red foxes are sympatric during winter, but allopatric in summer as arctic foxes retreat to higher altitudes further from the tree‐line during the breeding season.
Individual variability in herbivore‐specific elicitors from the plant's perspective
Authors: RODA AMY , HALITSCHKE RAYKO , STEPPUHN ANKE , BALDWIN IAN T. 
Published: July 2004

AbstractLepidopteran larvae oral secretions and regurgitant (R), which contain a plethora of potential elicitors, are known to dramatically change a plant's wound response. We demonstrate, with a detailed microarray and secondary metabolite analysis, that the two most abundant fatty acid‐amino acid conjugates (FACs) in the R of the specialist herbivore Manduca sexta (Lepidoptera, Sphingidae) can account for all measured direct (trypsin proteinase inhibitor: TPI) and indirect (cis‐α‐bergamotene) defences, the endogenous jasmonic acid burst that elicits them, and 86% of the induced transcriptional changes (89% up and 83% down) in its native host Nicotiana attenuata and hence are necessary and sufficient for the Manduca‐specific modulation of the wound response. FACs were not found in eggs, but detected in larvae of all instars after their first meal. FACs were found in all regions of the alimentary canal and in the frass, but did not occur in salivary or mandibular glands, extracts of which were not active in any assay. Individual larvae differed substantially in their FAC composition and two FAC chemotypes were discernible: N‐linolenoyl‐L‐glutamine biased R and N‐linolenoyl‐L‐glutamate biased R. We created synthetic blends of FACs to mimic these chemical phenotypes and determined whether plants respond differently to the different R chemotypes. Micorarray and TPI analysis revealed that plants do not differentiate. N. attenuata plants use FACs from feeding caterpillars to tailor their wound responses but do not use the variability in FAC ratios to recognize attack from an individual caterpillar.
Extreme queen‐mating frequency and colony fission in African army ants
Authors: KRONAUER DANIEL J. C. , SCHÖNING CASPAR , PEDERSEN JES S. , BOOMSMA JACOBUS J. , GADAU JÜRGEN 
Published: July 2004

AbstractArmy ants have long been suspected to represent an independent origin of multiple queen‐mating in the social Hymenoptera. Using microsatellite markers, we show that queens of the African army ant Dorylus (Anomma) molestus have the highest absolute (17.3) and effective (17.5) queen‐mating frequencies reported so far for ants. This confirms that obligate multiple queen‐mating in social insects is associated with large colony size and advanced social organization, but also raises several novel questions. First, these high estimates place army ants in the range of mating frequencies of honeybees, which have so far been regarded as odd exceptions within the social Hymenoptera. Army ants and honeybees are fundamentally different in morphology and life history, but are the only social insects known that combine obligate multiple mating with reproduction by colony fission and extremely male‐biased sex ratios. This implies that the very high numbers of matings in both groups may be due partly to the relatively low costs of additional matings. Second, we were able to trace recent events of colony fission in four of the investigated colonies, where the genotypes of the two queens were only compatible with a mother–daughter relationship. A direct comparison of male production between colonies with offspring from one and two queens, respectively, suggested strongly that new queens do not produce a sexual brood until all workers of the old queen have died, which is consistent with kin selection theory.
World‐wide survey of anAccordinsertion and its association with DDT resistance inDrosophila melanogaster
Authors: CATANIA F. , KAUER M. O. , DABORN P. J. , YEN J. L. , FFRENCH‐CONSTANT R. H. , SCHLÖTTERER C. 
Published: July 2004

AbstractPrevious work showed that insecticide resistance inDrosophila melanogasteris correlated with the insertion of anAccord‐like element into the 5′ region of the cytochrome P450 gene,Cyp6g1. Here, we study the distribution of theAccord‐like element in 673 recently collectedD. melanogasterlines from 34 world‐wide populations. We also examine the extent of microsatellite variability along a 180‐kilobase (kb) genomic region of chromosome II encompassing the resistance gene. We confirm a 100% correlation of theAccordinsertion with insecticide resistance and a significant reduction in variability extending at least 20 kb downstream of theCyp6g1gene. The frequency of theAccordinsertion differs significantly between East African (32–55%) and nonAfrican (85–100%) populations. This pattern is consistent with a selective sweep driving theAccordinsertion close to fixation in nonAfrican populations as a result of the insecticide resistance phenotype it confers. This study confirms that hitchhiking mapping can be used to identify beneficial mutations in natural populations.
The burden of atopy and asthma in children
Authors: O'Connell E. J. 
Published: July 2004

Background:  There has been a world‐wide increase in the prevalence of atopic diseases. These atopic diseases, including asthma, allergic rhinoconjunctivitis and atopic eczema/dermatitis, are common in childhood and create a challenge of management for physicians and parents.Methods:  MEDLINE was searched for articles related to atopy, allergy asthma, allergic rhinoconjunctivitis and atopic eczema/dermatitis.Results and conclusions:  The conditions of asthma, allergic rhinoconjunctivitis and atopic eczema/dermatitis cause very significant burdens regarding the discomfort to the affected individual, management problems for the parent and physician and the economic cost to the family and the nation.
Characterization of bovine serum albumin epitopes and their role in allergic reactions
Authors: Restani P. , Ballabio C. , Cattaneo A. , Isoardi P. , Terracciano L. , Fiocchi A. 
Published: July 2004

Objective:  This review provides updated information on conformational and sequential epitopes identified in bovine serum albumin (BSA) and summarizes available data about the role of structural modifications on BSA antigenicity/allergenicity.Data sources:  Data on beef allergy and BSA antigenicity are reported, with reference both to the basic literature and to clinical results obtained by our group.Results and discussion:  BSA is an important allergen involved in milk and beef allergy. The presence of conformational epitopes has been suggested by indirect evidence, while at least one sequential epitope has been experimentally identified. The role of structural modifications on BSA antigenicity is discussed as well as the increased tolerance observed in allergic subjects consuming beef as strained (homogenized) and freeze‐dried derivatives.Conclusion:  Study of the molecular characteristics of a known major allergen allows the identification of technological processes that may be capable of improving the tolerance of allergic subjects to a specific food. Even though any hoped for reduced allergenicity must be verified under medical supervision, the use of new products could obviate the need to avoid important foods such as meat in childhood.
Dietary treatment of childhood atopic eczema/dermatitis syndrome (AEDS)
Authors: Fiocchi A. , Bouygue G. R. , Martelli A. , Terracciano L. , Sarratud T. 
Published: July 2004

Objective:  This review summarizes the research and clinical evidence in favour of dietary intervention aimed at eliminating allergenic foods in the management of atopic eczema/dermatitis syndrome (AEDS).Data sources:  The data source was PubMed, using a search algorithm selecting for clinical studies of AEDS, diet therapy and food allergy in all children to October 2003. Also included is a commentary based on the authors' clinical experience in the allergy unit of a university hospital in Italy.Results:  Fourteen prospective studies matched the entry criteria. Diverse trial designs, diagnostic criteria, types of dietary intervention and length of observation periods precluded meta‐analytic methods. Allergenic food exclusion claimed efficacy in 13 of the 14 studies and was most useful in infants, in patients with elevated immunoglobulin E levels and/or multiple food sensitization and in patients with a diagnosis of food allergy.Conclusion:  Dietary intervention in the form of an elimination diet is efficacious in children with AEDS when a specific diagnosis of food allergy has been made. Diagnostic evaluation of food allergy should be performed in all children with eczema, particularly in younger children and those with severe forms of the disease.