bluuebunny/crossref_metadata_2025_split huggingface dataset:
A long-term study on interactions between the Adh and αGpdh allozyme polymorphisms and the chromosomal inversion In(2L)t in a seminatural population of D. melanogaster
Authors: Kamping  , Delden W. Van 
Published: March 2003

Abstract
The Adh and αGpdh allozyme loci (both located on the second chromosome) showed considerable fluctuations in allele frequencies in a seminatural population of Drosophila melanogaster during 1972–97. Both long-term and short-term fluctuations were observed. The short-term fluctuations occurred within almost all years and comparison of allele frequencies between winters and summers showed significantly higher AdhS (P &lt; 0.001) and αGpdhF (P &lt; 0.01) allele frequencies in summers. Frequencies of these alleles were significantly positively correlated with environmental temperature, suggesting the adaptive significance of these allozyme polymorphisms. Frequency changes of the Odh locus (located on the third chromosome) showed no seasonal pattern and were not correlated with environmental temperature. Almost all short-term and long-term increases in AdhS frequency were accompanied by a corresponding decrease in αGpdhS frequency (r = –0.82, P &lt; 0.001) and vice versa. Further analysis showed that gametic disequilibria between the Adh and αGpdh loci, which frequently occurred, were due to the presence of inversion In(2L)t located on the same chromosome arm and In(2L)t frequencies were positively correlated with environmental temperature. Gametic disequilibria between Adh and Odh and between Odh and αGpdh were hardly observed. Because In(2L)t is exclusively associated with the AdhS/αGpdhF allele combination, the observed correlated response in Adh/αGpdh allele frequencies is (at least partly) explained by hitchhiking effects with In(2L)t. This means that the adaptive value of the allozyme polymorphisms has been overestimated by ignoring In(2L)t polymorphism. Fluctuations in Adh allele frequencies are fully explained by selection on In(2L)t polymorphism, whereas we have shown that αGpdh frequency fluctuations are only partly explained by chromosomal hitchhiking, indicating the presence of selective differences among αGpdh genotypes in relation with temperature and independent of In(2L)t. Frequency fluctuations of αGpdh and In(2L)t are consistent with their latitudinal distributions, assuming that temperature is the main environmental factor varying with latitude that causes directly or indirectly these frequency distributions. However, the results of the tropical greenhouse population show no correlation of Adh (independent of In(2L)t) and Odh allele frequencies with environmental temperature, which may indicate that the latitudinal distribution in allele frequencies for these loci is not the result of selection on the F/S polymorphism in a direct way.
Mate recognition systems in a species flock of Mexican pupfish
Authors: Strecker U. , Kodric-Brown A. 
Published: March 2003

Abstract
The pupfishes of Lake Chichancanab (Mexico) provide a unique opportunity to study the evolution of premating reproductive barriers. This group of endemic species is of recent origin and the lineages differ in morphological traits indicating trophic specialization, but show very little genetic change. We studied the function of visual and chemical cues in the mate recognition system of three morphospecies, Cyprinodon beltrani, C. labiosus and C. maya. Only in C. maya, which is genetically the most distinct member of the group, do females show the ability to identify males of their own type, both visually and chemically. C. labiosus females discriminated between their own and C.  beltrani males based on chemical but not visual cues. C. beltrani, which is morphologically the least differentiated member of the group, showed no interspecific mate recognition. Females responded more strongly to the visual and chemical cues of their own males than to their own females, but they did not discriminate between their own males and those of the other two morphospecies based upon either type of cue. These results suggest that different levels of behavioural isolation have been established: most isolated is C. maya, and the least is C. beltrani. C. labiosus has an intermediate position. The results also suggest that species recognition cues based on different sensory modalities do not necessarily evolve together, and may evolve at different rates.
What does the male function hypothesis claim?
Authors: Burd  , Callahan  
Published: March 2003

Abstract
Paternal, rather than maternal, fitness consequences of reproductive traits are the lynchpin in many hypotheses about reproductive evolution in hermaphroditic angiosperms. These hypotheses often differ in their predictions, so that supporting or contradictory evidence for one hypothesis may not reflect similarly on another, even though both may be referred to as ‘the male function hypothesis’. We provide graphical representations of four male function hypotheses from the recent literature in order to highlight their differences. We offer and explain two recommendations to reduce ambiguity in terminology: (1) male function hypotheses should address the evolution of excess flowers per se, rather than total flower number, which is usually highly plastic in modular organisms with open growth form; and (2) attention must be given to whole plant fitness, rather than fitness per flower or per inflorescence. In empirical studies, we recommend the use of path analysis to dissect the multiple pathways (through both male and female function) by which selection may act on excess flower number.
Local adaptation of a holoparasitic plant, Cuscuta europaea: variation among populations
Authors: Koskela  , Salonen  , Mutikainen  
Published: March 2003

Abstract
Locally adapted parasites have higher infectivity and/or fitness on sympatric than on allopatric hosts. We tested local adaptation of a holoparasitic plant, Cuscuta europaea, to its host plant, Urtica dioica. We infected hosts from five sites with holoparasites from the same five sites and measured local adaptation in terms of infectivity and parasite performance (biomass) in a reciprocal cross-infection experiment. The virulence of the parasite did not differ between sympatric and allopatric hosts. Overall, parasites had higher infectivity on sympatric hosts but infectivity and parasite performance varied among populations. Parasites from one of the populations showed local adaptation in terms of performance, whereas parasites from one of the populations had higher infectivity on allopatric hosts compared with sympatric hosts. This among-population variation may be explained by random variation in parasite adaptation to host populations or by time-lagged co-evolutionary oscillations that lead to fluctuations in the level of local adaptation.
Temperature and clinal variation in larval growth efficiency in Drosophila melanogaster
Authors: Robinson S. J. W. , Partridge L. 
Published: March 2003

Abstract
Geographic clines in ectotherm species including Drosophila melanogaster have been found throughout the world, with genetically larger body size and shorter development time occurring at high latitudes. Temperature is thought to play a major role in the evolution of this clinal variation. Laboratory thermal selection has effects similar to those seen in geographical clines. Evolution at low temperatures results in more rapid development to larger adult flies. This study investigated the effects of geographical origin and experimental temperature on larval growth efficiency in D. melanogaster. Larvae from populations that had evolved at high latitudes were found to use limited food more efficiently, so that the overall adult body size achieved was larger. Larvae reared at a lower experimental temperature (18 °C) used food more efficiently than those reared at a higher temperature (25 °C). The increases in growth efficiency found in populations from high latitudes could explain their increased body size and more rapid development.
The interplay between colonization history and gene flow in passively dispersing zooplankton: microsatellite analysis of rotifer resting egg banks
Authors: Gómez A. , Adcock G. J. , Lunt D. H. , Carvalho G. R. 
Published: March 2003

Abstract
Zooplanktonic organisms that disperse passively as diapausing eggs often exhibit surprisingly strong population subdivision given their high colonization ability. Here we attempt to disentangle the impacts of colonization history and gene flow on these organisms by studying the population genetic structure of the rotifer Brachionus plicatilis. The resting egg banks of B. plicatilis in fourteen salt lake populations in the Iberian Peninsula were examined using seven microsatellite loci. A remarkably high degree of geographical structuring was found (Fst=0.43), with a significant pattern of isolation by distance. Microsatellite loci were in genetic equilibrium, ruling out inbreeding as an important force in population structuring. Comparisons are drawn with previously published phylogeographical data. Surprisingly, introgression of nuclear genes was detected in neighbouring populations with divergent mtDNA haplotypes. These results stress the long lasting impact of colonization history and the modulating effect of gene flow at local scales in these organisms.
A cost of maternal care in the dung beetle Onthophagus taurus?
Authors: Hunt J. , Simmons L. W. , Kotiaho J. S. 
Published: March 2003

Abstract
Parental care theory assumes that investment in current offspring will trade against future investment. A number of field studies on birds have used clutch size manipulations to demonstrate a survival cost to chick rearing. However, such studies do not account for costs accrued during earlier stages of reproduction because not all aspects of reproductive effort are manipulated by varying the number of nestlings. In this study, we investigate the effect of reproductive effort on female survival in the dung beetle, Onthophagus taurus. By experimentally manipulating mating status and dung availability, we demonstrate that virgin females survive longer than mated females and that the survival of mated females was negatively associated with the number of brood masses produced. Using a novel manipulation of the mating system, we separated the effects of egg production and maternal care on female survival. Previously, we have shown that females provisioning with the assistance of a major male provide relatively less care than unassisted females. However, paternal assistance did not alter the number of brood masses produced and hence the amount of reproductive effort that was allocated to egg production. Therefore, our finding that female survival was increased when receiving paternal assistance provides, to our knowledge, the first definitive evidence that maternal care reduces female lifespan. These results are of major importance to theoretical models on the evolution of parental care.
Seasonal butterfly design: morphological plasticity among three developmental pathways relative to sex, flight and thermoregulation
Authors: Van Dyck H. , Wiklund C. 
Published: March 2003

Abstract
The temperate-zone butterfly Pararge aegeria can use three developmental pathways corresponding to different seasonal cohorts: (1) development with a pupal winter diapause resulting in early spring adults; (2) development with a larval winter diapause resulting in late-spring adults and (3) direct development resulting in summer or second generation adults. In order to test adaptive predictions, we compared variation in flight- and thermoregulation-related morphology among adult males and females from the three pathways using both field data (i.e. wild-caught butterflies) and experimental breeding data (i.e. reared under different photoperiod regimes). Morphological patterns among the pathways were largely similar in the field and rearing data. Seasonal patterns differed between the sexes for most traits, including (relative) size measures and wing colour. Our results suggest sex-related, adaptive seasonal plasticity for morphological traits related to flight behaviour in a multivoltine insect.
Effects of spatial autocorrelation, natal philopatry and phenotypic plasticity on the heritability of laying date
Authors: Van Der Jeugd H. P. , McCleery R. 
Published: March 2003

Abstract
We investigated the effect of spatial autocorrelation on heritability (h2) estimates of laying date and clutch size in a population of great tits Parus major. We found that h2 of laying date, but not clutch size, declined significantly with increasing distance between the nestbox of mothers and daughters. This decline was caused by a decreasing effect of spatial autocorrelation in laying date, rather than by the existence of genotype–environment interactions (GEI). After correcting for the effect of spatial autocorrelation, h2 of laying date was low (0.16 ± 0.07), but significant, and surprisingly consistent with increasing distance between parental and offspring environments. The h2 of clutch size was not much affected by spatial autocorrelation.
Most previously published estimates of the heritability of laying date include various degrees of common environment effects, which can bias estimates both upwards and downwards. We suggest that using techniques that take spatial autocorrelation into account might be a fruitful approach to estimate h2 of traits that show a high degree of plasticity.
An empirical test of the `predictability' hypothesis for the evolution of viviparity in reptiles
Authors: Shine R. 
Published: March 2003

Abstract
Viviparity (live-bearing) has evolved from oviparity (egg-laying) &gt;100 times in reptile phylogeny, but the selective forces responsible remain unclear. Tinkle & Gibbons (1977) proposed that prolonged uterine retention of eggs (leading ultimately to viviparity) is favoured by natural selection when it allows the reproducing female to better predict the incubation conditions that will occur in alternative potential nest-sites, and hence select the optimal site in which to deposit her eggs. This ingenious hypothesis has never been tested empirically. Over a 7-year period, I monitored temperatures inside 124 natural nests of egg-laying scincid lizards at three different elevations in the Brindabella Range of south-eastern Australia. As a measure of thermal predictability, I used correlation coefficients from comparisons of temperatures early vs. later in incubation among nests within each site. Both the mean and standard deviation of nest temperatures were examined in this way for each week through incubation. I performed these calculations under two models: one where the female assesses nest temperatures at the time of oviposition only, and one where she monitors temperatures constantly from the usual oviposition date until the actual time of laying. These analyses falsified two major assumptions of the ‘predictability’ hypothesis. First, nest temperatures at higher elevations were no less predictable than were those at lower elevations; instead, predictability was high in all situations. Secondly, a longer delay before oviposition decreased rather than increased the predictability of thermal conditions during subsequent incubation. I conclude that critical assumptions of the ‘predictability’ hypothesis are not supported in this study system.
Population consequences of maternal effects: sex-bias in egg-laying order facilitates divergence in sexual dimorphism between bird populations
Authors: Badyaev A. V. , Hill G. E. , Whittingham L. A. 
Published: March 2003

Abstract
When costs and benefits of raising sons and daughters differ between environments, parents may be selected to modify their investment into male and female offspring. In two recently colonized environments, breeding female house finches (Carpodacus mexicanus) modified the sex and growth of their offspring in relation to the order in which eggs were laid in a clutch. Here we show that, in both populations, these maternal effects strongly biased frequency distribution of tarsus size of fully grown males and females and ultimately produced population divergence in this trait. Although in each population, male and female offspring show a wide range of growth patterns, maternal modifications of sex-ratio in relation to egg-laying order resulted in under-representation of the morphologies that were selected against and over-representation of morphologies that were favoured by the local selection on juveniles. The result of these maternal adjustments was fast phenotypic change in sexual size dimorphism within and between populations. Maternal manipulations of offspring morphologies may be especially important at the initial stages of population establishment in the novel environments and may have facilitated recent colonization of much of North America by the house finch.
Functional trade-offs in the limb muscles of dogs selected for running vs. fighting
Authors: Pasi B. M. , Carrier D. R. 
Published: March 2003

Abstract
The physical demands of rapid and economical running differ from those of physical fighting such that functional trade-offs may prevent simultaneous evolution of optimal performance in both behaviours. Here we test three hypotheses of functional trade-off by measuring determinants of limb musculoskeletal function in two breeds of domestic dogs that have undergone intense artificial selection for running (Greyhound) or fighting performance (Pit Bull). We found that Greyhounds differ from Pit Bulls in having relatively less muscle mass distally in their limbs, weaker muscles in their forelimbs than their hindlimbs, and a much greater capacity for elastic storage in the in-series tendons of the extensor muscles of their ankle joints. These observations are consistent with the hypothesis that specialization for rapid or economical running can limit fighting performance and vice versa. We suggest that functional trade-offs that prevent simultaneous evolution of optimal performance in both locomotor and fighting abilities are widespread taxonomically.
Geographic range size, life history and rates of diversification in Australian mammals
Authors: Cardillo M. , Huxtable J. S. , Bromham L. 
Published: March 2003

Abstract
What causes species richness to vary among different groups of organisms? Two hypotheses are that large geographical ranges and fast life history either reduce extinction rates or raise speciation rates, elevating a clade's rate of diversification. Here we present a comparative analysis of these hypotheses using data on the phylogenetic relationships, geographical ranges and life history of the terrestrial mammal fauna of Australia. By comparing species richness patterns to null models, we show that species are distributed nonrandomly among genera. Using sister-clade comparisons to control for clade age, we then find that faster diversification is significantly associated with larger geographical ranges and larger litters, but there is no evidence for an effect of body size or age at first breeding on diversification rates. We believe the most likely explanation for these patterns is that larger litters and geographical ranges increase diversification rates because they buffer species from extinction. We also discuss the possibility that positive effects of litter size and range size on diversification rates result from elevated speciation rates.
Genotyping fetal DNA by non‐invasive means: extraction from maternal plasma
Authors: Nelson M. , Eagle C. , Langshaw M. , Popp H. , Kronenberg H. 
Published: March 2003

Background and ObjectivesIdentification of fetal DNA in maternal plasma may allow genetic analysis without the use of invasive techniques. The aim of this study was to extract DNA from maternal plasma, identify fetal material through the presence of SRY or RHD gene sequences and assess the reliability of these results.Materials and MethodsA polymerase chain reaction (PCR) method of a commercial kit was used with primers for SRY or exon 10 of the RHD gene sequence.ResultsMultiple plasma samples were collected from 60 women who were evaluable for either SRY or RHD, or both, fetally derived DNA sequences. Fetal DNA was present in the plasma throughout the pregnancies and for some hours or days after delivery.ConclusionFetal DNA can be reliably detected in maternal plasma from early in pregnancy and normally is cleared within days of delivery.
Paediatric transfusion
Authors: Simpson J. , Kinsey S. 
Published: March 2003

Paediatric transfusion encompasses a wide range of clinical circumstances including the consideration of maternal antibodies, the changing nature of the transfusion recipient with respect to growth and development, and the management of inherited conditions which if optimally treated in early life may have problems which are delayed or less severe in adult life.Whilst the transfusion of adults and children has much in common, a child cannot be considered as a scaled down adult; there are many important differences. Developmental changes are most marked in the neonate and, together with the fact that their antibodies are maternally derived, this population provide some of the most striking challenges. The increased use of intra uterine transfusion adds an extra dimension here.A particular paediatric concern is the long‐term consequences of transfusion. It is to be hoped that paediatric transfusion recipients will live long enough that any potential problems will manifest themselves, thus the aim must be to minimize transfusion risks.
A rapid and reliable flow cytometric routine method for counting leucocytes in leucocyte‐depleted platelet concentrates
Authors: Backteman K. , Ledent E. , Berlin G. , Ernerudh J. 
Published: March 2003

Background and Objectives To ensure a proper quality control it is important to use a reliable method to count low numbers of leucocytes in leucocyte‐reduced platelet concentrates (PCs).Materials and Methods A modified flow cytometric method for counting low numbers of leucocytes, based on a reference population contained in tubes with an exact number of fluorescent beads and staining with propidium iodide was used. To increase the number of events, the original sample volume was increased.Results There was a good correlation in the number of leucocytes (r = 0·99) between the modified flow cytometric method and microscopy of samples from unfiltered and expected numbers from serially diluted PCs. Samples from leucocyte‐reduced PCs obtained by apheresis or filtered buffy coats showed no correlation between results from the modified flow cytometric method and microscopy (Nageotte).Conclusion Counting by microscopy gave a lower number of leucocytes than the modified flow cytometric method when counting a low number of cells. However, analysis of the serially diluted PCs proved that the modified flow cytometric method was reliable and rapid, making it suitable for clinical routine use.