bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breeding success of male brook trout (Salvelinus fontinalis) in the wild
Authors: Blanchfield Paul J. , Ridgway Mark S. , Wilson Chris C. 
Published: December 2003

AbstractCompetition for females generally results in some males adopting alternative reproductive tactics to acquire matings. For fish, the ecological and evolutionary consequences of these tactics are not well understood because of an inability to link directly the interactions of individuals on the breeding grounds with genetic data. This study combines behavioural observations with genetic estimates of male reproductive success within an intensively studied wild population of lacustrine brook trout (Salvelinus fontinalis). Male brook trout exhibit a conditional reproductive strategy with small males adopting a peripheral position to that of larger dominant males in their proximity to spawning females. Parentage analysis of eggs collected from wild redds confirmed the reproductive success of individual males. Males relegated to peripheral positions during spawning participated frequently in spawning events, but in most cases the first male to spawn was the sole contributor, and no more than two males contributed successfully to a single brood. While behavioural observations of salmonines suggests that reproduction is partitioned among males in a manner dependent upon body size and proximity to spawning females, the genetic evidence from this study suggests a more limited distribution of reproductive success in the field. The genetic contributions of male brook trout are highly skewed towards larger males for this population. A review of the salmonine literature suggests little difference in individual reproductive success for males exhibiting size‐related tactics within a conditional mating strategy vs. precocial maturation. Collectively, these genetic studies provide new insights on the evolution of alternative life histories among salmonines.
Molecular interactions between an insect predator and its herbivore prey on transgenic potato expressing a cysteine proteinase inhibitor from rice
Authors: Bouchard Edith , Michaud Dominique , Cloutier Conrad 
Published: December 2003

AbstractTransgenic plants expressing resistance to herbivorous insects may represent a safe and sustainable pest control alternative if they do not interfere with the natural enemies of target pests. Here we examined interactions between oryzacystatin I (OCI), a proteinase inhibitor from rice genetically engineered into potato (Solanum tuberosum cv. Kennebec, line K52) to increase resistance to insect herbivory, and the insect predator Perillus bioculatus. This stinkbug is a relatively specialized predator of caterpillars and leaf‐beetle larvae, and may also include plant sap in its predominantly carnivorous diet. One of its preferred prey is Colorado potato beetle (Leptinotarsa decemlineata), a major target of insect resistance development for potato field crops. Gelatin/sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) confirmed that a major fraction of proteinase (gelatinase) activity in P. bioculatus extracts is OCI‐sensitive. Among five gelatinolytic bands detected, the slowest‐moving one (proteinase I) was inhibited strongly by purified OCI expressed in Escherichia coli or by OCI‐transgenic potato extracts, while three other proteinases were partly sensitive to these treatments. There was also evidence of slight inhibition of proteinase I by untransformed potato foliage, suggesting the presence of a natural inhibitor related to OCI at low level in potato foliage. Interestingly, only about 50% of the maximum potential activity of proteinase I was recovered in extracts of P. bioculatus feeding on L. decemlineata larval prey on a diet of OCI‐potato foliage, indicating that the predator was sensitive to OCI in the midgut of its prey. However, P. bioculatus on OCI‐prey survived, grew and developed normally, indicating ability to compensate prey‐mediated exposure to the OCI inhibitor. Confinement of P. bioculatus to potato foliage provided no evidence that potato plant‐derived nutrition is a viable alternative to predation, restriction to potato foliage in fact being inferior to free water for short‐term survival of nonfeeding first‐instar larvae. These results support the view that OCI, an effective inhibitor of a substantial fraction of digestive enzymatic potential in P. bioculatus, should not interfere with its predation potential when expressed in potato plants fed to its prey at a maximum level of ∼0.8% of total soluble proteins in mature foliage.
Oryzacystatin I expressed in transgenic potato induces digestive compensation in an insect natural predator via its herbivorous prey feeding on the plant
Authors: Bouchard Édith , Cloutier Conrad , Michaud Dominique 
Published: December 2003

AbstractWe observed recently that the rice cysteine proteinase inhibitor, oryzacystatin I (OCI) expressed in transgenic potato does not affect growth and development of the two‐spotted stinkbug predator (Perillus bioculatus) via its herbivorous prey feeding on the plant. Here we monitored the inhibitory activity of recombinant OCI along this potato → herbivore → predator continuum, to determine if the absence of effect was associated with a digestive compensatory response of the predator following inhibition of its proteinases by the recombinant cystatin. After confirming that OCI is present in the plant, and ingested in an active form by potato beetle larvae, quantitative and electrophoretic assays allowed us to determine that the recombinant cystatin (representing about 0.8% of total soluble proteins in leaves) was entirely bound to a ∼30‐kDa target proteinase in the prey's midgut, forming a sodium dodecyl sulphate (SDS)‐stable complex detected on immunoblots with an anti‐OCI polyclonal antibody. Despite the apparent absence of free, residual OCI in the beetle's midgut, digestive protease activity in the predator, known to include OCI‐sensitive activity, was altered negatively when the prey was fed the modified plant. This inhibitory process at the third trophic level was accompanied by a compensatory response in the predator, by which serine‐type proteinases were synthesized de novo. Overall, our data suggest that the affinity between OCI and the predator's OCI‐sensitive proteinases is: (i) as strong as (or stronger than) the affinity between OCI and the potato beetle 30‐kDa‐sensitive proteinase; and (ii) stronger than the affinity between these enzymes and the plant endogenous homologue of OCI, potato multicystatin, induced in the plant by potato beetle feeding. Our results also show that predatory organisms can adapt their digestive metabolism to the presence of plant antidigestive proteins ingested by their herbivorous preys. In a broader context, this study stresses the need to monitor the inhibitory effects of PI‐expressing plants not only on the herbivorous insects targeted, but also on the organisms likely to consume these pests in the environment.
Genome mapping of the orange blotch colour pattern in cichlid fishes
Authors: Streelman J. Todd , Albertson R. Craig , Kocher Thomas D. 
Published: December 2003

AbstractThe dramatic variation of cichlid fish colour pattern is thought to function in mate choice, evolve by sexual selection, and contribute to explosive speciation. Here, we combine linkage mapping and population genetic analyses to identify a single region of the cichlid genome responsible for the orange blotch (OB) colour phenotype. In each analysis, OB is tightly linked to the c‐ski1 gene. Additionally, we use comparative mapping information from the Takifugu rubripes and human genomes to suggest positional candidate loci for OB. Our work should engender a more comprehensive understanding of the molecular ecology of OB and its role in cichlid speciation. Moreover, we have assembled the components of a method to focus upon the genetic basis of evolutionarily and ecologically significant phenotypes.
Oceanic interchange and nonequilibrium population structure in the estuarine dependent Indo‐Pacific tasselfish, Polynemus sheridani
Authors: Chenoweth Stephen F. , Hughes Jane M. 
Published: December 2003

AbstractWe assayed mtDNA haplotype [300 base pairs (bp) control region] geography and genealogy in the Indo‐Pacific tasselfish, Polynemus sheridani from its contiguous estuarine distribution across northern Australia (n = 169). Eight estuaries were sampled from three oceanographic regions (Timor Sea, Gulf of Carpentaria and the Coral Sea) to assess the impact of Pleistocene sea level changes on the historical connectivity among P. sheridani populations. Specifically, we investigated the genetic consequences of disruption to Indian‐Pacific Ocean connectivity brought about by the closure of the Torres Strait. Overall there was significant population subdivision among estuaries (FST = 0.161, ΦST = 0.187). Despite a linear distribution, P. sheridani did not show isolation by distance over the entire sampled range because of genetic similarity of estuaries greater than 3000 km apart. However, significant isolation by distance was detected between estuaries separated by less than 3000 km of coastline. Unlike many genetic studies of Indo–Pacific marine species, there was no evidence for an historical division between eastern and western populations. Instead, phylogeographical patterns were dominated by a starlike intraspecific phylogeny coupled with evidence for population expansion in both the Gulf of Carpentaria and the Coral Sea but not the Timor Sea. This was interpreted as evidence for recent west to east recolonization across of northern Australia following the last postglacial marine advance. We argue that although sufficient time has elapsed postcolonization for populations to approach gene flow‐drift equilibrium over smaller spatial scales (< 3000 km), the signal of historical colonization persists to obscure the expected equilibrium pattern of isolation by distance over large spatial scales (> 3000 km).
Population genetic analysis of white shrimp,Litopenaeus setiferus,using microsatellite genetic markers
Authors: Ball Amy O. , Chapman Robert W. 
Published: December 2003

AbstractThe white shrimp (Litopenaeus setiferus) is a commercially and recreationally valuable species, yet little is known of its population structure or genetic diversity. White shrimp are distributed along the Atlantic coast of the United States and from the west coast of Florida to the Bay of Campeche, Mexico. In this study, shrimp were collected from North Carolina, South Carolina (four separate collections were taken from 1995 to 1999), Georgia, the Atlantic and Gulf coasts of Florida, Louisiana, Texas and Mexico. DNA was isolated from these individuals, and genetic variation was assessed at six microsatellite loci. These loci were, for the most part, highly polymorphic with an average expected heterozygosity of 0.68. Deviations from Hardy–Weinberg proportions were observed over all samples, but experimental results suggested the presence of null alleles, which confounded a biological interpretation of this result. Pairwise tests of the similarity of allele frequency distributions and distance measure analyses showed broad‐scale genetic homogeneity superimposed over occasional indications of random geographical and temporal differentiation.FSTandRSTestimates over all loci and samples were 0.002 or less and indicated little population structure. Weak but significant genetic differentiation was evident only between pooled western Atlantic and pooled Gulf of Mexico samples. Within the Gulf of Mexico or within the western Atlantic, the large‐scale genetic homogeneity observed may be a consequence of genetic mixing resulting from pelagic larvae and adult migrations, while the random local genetic differentiation may be a result of genetic sampling or experimental sampling error. The weak differentiation between shrimp from the Gulf of Mexico and the western Atlantic can be explained by a relatively recent separation of these two populations and/or small amounts of ongoing gene flow.
Estimating seed vs. pollen dispersal from spatial genetic structure in the common ash
Authors: Heuertz M. , Vekemans X. , Hausman J.‐F. , Palada M. , Hardy O. J. 
Published: December 2003

AbstractSpatial genetic structure was analysed with five highly polymorphic microsatellite loci in a Romanian population of common ash (Fraxinus excelsior L.), a wind‐pollinated and wind‐dispersed tree species occurring in mixed deciduous forests over almost all of Europe. Contributions of seed and pollen dispersal to total gene flow were investigated by analysing the pattern of decrease in kinship coefficients among pairs of individuals with geographical distance and comparing it with simulation results. Plots of kinship against the logarithm of distance were decomposed into a slope and a shape component. Simulations showed that the slope is informative about the global level of gene flow, in agreement with theoretical expectations, whereas the shape component was correlated with the relative importance of seed vs. pollen dispersal. Hence, our results indicate that insights into the relative contributions of seed and pollen dispersal to overall gene flow can be gained from details of the pattern of spatial genetic structure at biparentally inherited loci. In common ash, the slope provided an estimate of total gene dispersal in terms of Wright's neighbourhood size of Nb = 519 individuals. No precise estimate of seed vs. pollen flow could be obtained from the shape because of the stochasticity inherent to the data, but the parameter combinations that best fitted the data indicated restricted seed flow, σs £ 14 m, and moderate pollen flow, 70 m £ σp £ 140 m.
Male dominance, paternity, and relatedness in the Jamaican fruit‐eating bat (Artibeus jamaicensis)
Authors: Ortega Jorge , Maldonado Jesús E. , Wilkinson Gerald S. , Arita Héctor T. , Fleischer Robert C. 
Published: December 2003

AbstractWe analysed variation at 14 nuclear microsatellite loci to assess the genetic structure, relatedness, and paternity of polygynous Jamaican fruit‐eating bats. A total of 84 adults captured in two caves exhibited little genetic differentiation between caves (FST = 0.008). Average relatedness among adult females in 10 harem groups was very low (R = 0.014 ± 0.011), providing no evidence of harem structure. Dominant and subordinate males shared paternity in large groups, while dominant and satellite males shared paternity in smaller groups. However, our results suggest that male rank influences paternity. Dominant males fathered 69% of 40 offspring, followed by satellite (22%) and subordinate males (9%). Overall adult male bats are not closely related, however, in large harem groups we found that subordinate and dominant males exhibited relatedness values consistent with a father‐offspring relationship. Because dominant and subordinate males also sired all the pups in large groups, we propose that their association provides inclusive fitness to them.
Aggressiveness is associated with genetic diversity in landlocked salmon (Salmo salar)
Authors: Tiira Katriina , Laurila Anssi , Peuhkuri Nina , Piironen Jorma , Ranta Esa , Primmer Craig R. 
Published: December 2003

AbstractThe amount of intraindividual genetic variation has often been found to have profound effects on life history traits. However, studies concerning the relationship between behaviour and genetic diversity are scarce. Aggressiveness is an important component of competitive ability in juvenile salmonids affecting their later performance and survival. In this study, we used an experimental approach to test the prediction that juveniles with low estimated genetic diversity should be less aggressive than juveniles with high estimated genetic diversity in fry from a highly endangered population of land‐locked salmon (Salmo salar). This was achieved by using a method enabling the accurate estimation of offspring genetic diversity based on parental microsatellite genotype data. This allowed us to create two groups of offspring expected to have high or low genetic diversity in which aggressive behaviour could be compared. Salmon fry with low estimated genetic diversity were significantly less aggressive than fry with high estimated genetic diversity. Closer analysis of the data suggested that this difference was due to differences in more costly acts of aggression. Our result may reflect a direct effect of genetic variation on a fitness‐related trait; however, we cannot rule out an alternative explanation of allele‐specific phenotype matching, where lowered aggression is expressed towards genetically more similar individuals.
Comparative genetic study confirms exceptionally low genetic variation in the ancient and endangered relictual conifer, Wollemia nobilis (Araucariaceae)
Authors: Peakall Rod , Ebert Daniel , Scott Leon J. , Meagher Patricia F. , Offord Cathy A. 
Published: December 2003

AbstractThe Wollemi pine, Wollemia nobilis (Araucariaceae), was discovered in 1994 as the only extant member of the genus, previously known only from the fossil record. With fewer than 100 trees known from an inaccessible canyon in southeastern Australia, it is one of the most endangered tree species in the world. We conducted a comparative population genetic survey at allozyme, amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) loci in W. nobilis, Araucaria cunninghamii and Agathis robusta — representatives of the two sister genera. No polymorphism was detected at 13 allozyme loci, more than 800 AFLP loci or the 20 SSR loci screened in W. nobilis. In Ag. robusta only one of 12 allozyme loci, five of 800 AFLP loci and none of the 15 SSR loci were variable. For A. cunninghamii, 10 of > 800 AFLP loci and five of 20 SSR loci were variable. Thus low genetic diversity characterizes all three species. While not ruling out the existence of genetic variation, we conclude that genetic diversity is exceptionally low in the Wollemi pine. To our knowledge this is the most extreme case known in plants. We conclude that the combination of small population effects, clonality and below‐average genetic variation in the family are probable contributing factors to the low diversity. The exceptionally low genetic diversity of the Wollemi pine, combined with its known susceptibility to exotic fungal pathogens, reinforces current management policies of strict control of access to the pines and secrecy of the pine locations.
Direct selection on allozymes is not required to explain heterogeneity among marker loci across a Mytilus hybrid zone
Authors: Bierne N. , Daguin C. , Bonhomme F. , David P. , Borsa P. 
Published: December 2003

AbstractUnequal differentiation between two types of loci (allozyme and DNA markers) across a Mytilus hybrid zone has recently been claimed as evidence for direct selection on some allozyme loci. We provide here a counter‐example: a noncoding DNA locus that exhibits as much differentiation as the incriminated allozymes do. The levels of genetic differentiation varied widely among both allozymes and noncoding DNA markers and no clear difference emerged between the two types of markers. This suggests that the strong interlocus variance in genetic differentiation has been confounded with a discrepancy between marker types as a result of an insufficient and unbalanced locus sampling. Heterogeneity in differentiation among neutral loci can be created by stochastic variance during the allopatric divergence preceding a secondary contact. In hybrid zones, a further source of variance is differential introgression among chromosomal regions after the secondary contact owing to the local influence of selected genes on more or less distant markers. However, the degree of differentiation alone gives no way to distinguish indirect pseudo‐selection (a regular and ubiquitous feature of hybrid zones) from direct selection. More generally, we suggest that comparative neutrality tests based on discrepancies among marker types have to be applied with caution when the presence of semi–permeable genetic barriers to gene exchange is suspected.
Subduction‐flip during Iapetus Ocean closure and Baltica–Laurentia collision, Scandinavian Caledonides
Authors: Andréasson P. G. , Gee D. G. , Whitehouse M. J. , Schöberg H. 
Published: December 2003

AbstractEvidence is presented here from the northern Scandinavian Caledonides for development of an extensional basin of Ashgill to Mid Llandovery age along the Baltoscandian margin immediately prior to Baltica–Laurentia collision. U/Pb multigrain and ion microprobe zircon dating of plagiogranites in the Halti Igneous Complex complement previous baddeleyite and zircon dating of a dolerite dyke, and zircon dating of anatectic granite; they demonstrate that this dunite, troctolite, gabbro, sheeted‐dyke complex ranges in age from c. 445 to 435 Ma. The dolerite dykes intruded and melted arkoses of inferred Neoproterozoic age. This evidence, taken together with previous documentation of ophiolites (Solund–Stavfjord), ophiolite‐like associations (Sulitjelma Igneous Complex) and several other mafic suites (e.g. Råna, Artfjället) of Ashgill to Llandovery age further south in the northern Scandinavian Caledonides, implies that Scandian collisional orogeny along this nearly 2000‐km‐long mountain belt was immediately preceeded by development of short‐lived marginal basins. The latter developed during the final closure of the Iapetus Ocean and are inferred to be of back‐arc origin, some (perhaps all) related to E‐dipping subduction. Collision of the continents at c. 435 Ma is inferred to have induced a flip in subduction polarity, leading to underthrusting of Laurentia by Baltica.
Heat flow and geodynamics in the Tyrrhenian Sea
Authors: Zito G. , Mongelli F. , De Lorenzo S. , Doglioni C. 
Published: December 2003

AbstractThe present heat flow in the southern Tyrrhenian Sea appears as a transient thermal wave that has migrated eastward in time. The higher heat flow in the south‐eastern side of the basin confirms the suggestion of an eastward‐migrating rift. Punctuation of the Tyrrhenian backarc extension in lithospheric boudins is accompanied by a concentrated increase in heat flow generated by asthenospheric intrusions and related magmatism progressively moving eastward. The migration of the asthenosphere in the same direction could explain these phenomena.
Calculating the long‐term displacement rates of a normal fault from the high‐resolution stratigraphic record (early Tethyan rifting, French Alps)
Authors: Chevalier F. , Guiraud M. , Garcia J.‐P. , Dommergues J.‐L. , Quesne D. , Allemand P. , Dumont T. 
Published: December 2003

AbstractDisplacement rates of normal faults deduced from stratigraphic data are often unreliable. Here we calculate the velocity of motion on a normal fault from the variations in accommodation potential on both sides of the fault within a high‐resolution time‐frame established by biostratigraphy and physical stratigraphy. Our example is the Ornon normal fault bounding the Early Jurassic Bourg‐d'Oisans Basin formed during Tethyan rifting. We show that motion on the fault was discontinuous when examined at high resolution and over a long time interval. During a first interval (Hettangian to Sinemurian Arietites bucklandi zone) a low rate of displacement (=202–423 m Myr−1) coeval with diffused extensional deformation throughout the sedimentary basin is observed. A second interval of localized deformation (Early Sinemurian Caenisites turneri zone) is characterized by higher rates of displacement on the fault (1846 m Myr−1). Our results concur with recent numerical models identifying the main stages of extensional deformation.