bluuebunny/crossref_metadata_2025 huggingface dataset:
Diatoms from the surface sediments of the Skagerrak and the Kattegat and their relationship to the spatial changes of environmental variables
Authors: Jiang Hui
Published: December 2004

This paper deals with the distribution of diatoms in the surface sediments of the Skagerrak and the Kattegat and its correlation with the spatial changes of eight environmental variables. Eigenvalues and the values of the species‐environmental correlation show that the measured environment variables account for the major gradients of diatom composition. The results of forward selection of the environmental variables and Monte Carlo permutation tests of statistical significance, together with canonical coefficients and intra‐set correlations between environmental variables and the axes, show that summer and winter surface salinities are the most important environmental factors affecting diatom distribution in this area. Five diatom assemblages are distinguished in the Skagerrak and the Kattegat. The distribution of these assemblages is clearly correlated with the strong variations in salinity, and in particular with surface salinities during summer and winter.
Dutch consensus on diagnosis and treatment of hearing impairment in children and adults with intellectual disability
Authors: Evenhuis H. M. ,   Consensus Committee
Published: December 2004

This is an abridged transiation of a recent Dutch consensus on diagnosis and treatment of hearing impairment in children and adults with intellectual disability. Available diagnostic methods are discussed. Tbe use of Oto‐Acoustic Emissions as a rapid and low‐cost objective screening method is particularly encouraged. Risk groups, protocols for early identification and diagnostic screening in older children and adults, recommendations for treatment and support, and priorities for research have been formulated.
A comparison of the effects of four therapy procedures on concentration and responsiveness in people with profound learning disabilities
Authors: Lindsay W. R. , Pitcaithly D. , Geelen N. , Buntin L. , Broxholme S. , Ashby M.
Published: December 2004

This paper is an investigation into the efficacy of four therapeutic treatment procedures increasingly used with people with profound learning disabilities: snoezelen, hand massage/aromatherapy, relaxation, and active therapy (a bouncy castle). In particular, the effects of these procedures on concentration and responsiveness were examined. Eight subjects with profound learning disabilities took part in the study and each subject received each of the treatments. To assess the effects of the treatments, simple concentration tasks were administered and the subjects' responsiveness to each treatment was rated by independent observers. The results suggest that both snoezelen and relaxation had a positive effect on concentration and seemed to be the most enjoyable therapies for clients, whereas hand massage/aromatherapy and active therapy had no or even negative effects on concentration and appeared less enjoyable.
Acquired cutis laxa associated with cutaneous angiocentric T‐cell lymphoma
Authors: Chartier Suzanne , Faucher Lise , Tousignant Jacqueline , Rochette Linda
Published: December 2004

A 64‐year‐old man presenting with adenomegaly was diagnosed with stage IV A angiocentric cutaneous T‐cell lymphoma in 1988. Since he showed a poor response to psoralen plus UVA (PUVA) after 1 year of therapy, he was switched to systemic chemotherapy (COP), and was considered to be in remission after completion of 5 months of this regimen. In December 1989, the patient noted an asymptomatic lesion at the superior and internal aspect of his right thigh; on examination, there was a poorly circumscribed, noninflammatory, whitish, atrophic macula near the inguinal fold and a palpable adenopathy; its surface was irregular, showing small wrinkling, and could be depressed on palpation. There were no preceding inflammatory lesions and no cutaneous lymphoma lesions at this site. Slowly, the initial macule extended, and new similar lesions insidiously appeared symmetrically on the left thigh. In October 1990, the patient received electron beam therapy for a relapse that presented as troncular nodules and responded well to this therapy. In the months that followed, the skin of his whole body became progressively sagging and pendulous, without recoil. This was not preceded by an inflammatory phase or eruption. There was no family history of elastolytic disorder, and the patient was not taking any medication other than that described above. On questioning, there were no symptoms suggesting systemic involvement of this elastolytic disorder. On physical examination, the patient's whole body skin seemed redundant, nonresllient, and wrinkled, this being most obvious in the axillae, inguinal region, antecubital fossa, neck, and trunk, where loose and pendulous skin folds could be seen (Fig. 1). Also, the patient's face was excessively wrinkled and sagging and he had bilateral ectropion. At the superior and internal aspect of both thighs, large, poorly circumsoribed, but distinct, round patches of 1‐5 cm in diameter were observed; they were atrophic and whitish, with an uneven surface, and could be depressed on palpation. Apart from 1 cm, mobile, but firm, axillary and inguinal adenopathy and three subcutaneous nodules on the arm and trunk, the rest of the physical examination was unremarkable.

Routine blood tests were normal, as was a chest X‐ray. Sezary cells were absent on blood smear, and borrelia and syphilis serology were negative. Thyroid function tests, angiotensin converting enzyme, and immunoelectrophoresis were within normal limits, and antinuclear antigen was negative. Two cutaneous biopsies were performed: one in an atrophic herniating lesion of the right thigh and the one on the abdomen. Both showed, on hematoxylin‐phloxin‐safran staining, a mild dermal perivascular inflammatory infiltrate with a predominance of mononuclear cells. On Weigert staining, both were marked by a net reduction in elastic fibers throughout the dermis.
Tungiasis in New York
Authors: Mashek Helen , Licznerski Barbara , Pincus Stephanie
Published: December 2004

A 33‐year‐old African woman was evaluated for tender nodules on her feet. Accompanied by her four children, she had recently immigrated from Somalia. Before her immigration, she resided in a Kenyan refugee camp for approximately 1 year, where she walked barefoot in sand and dirt. The patient stated that she and her four children, as well as many people living in the same compound, had similar, tender lesions on their feet. Her children were “treated” by their grandmother, who removed the contents of their lesions with a safety pin.

On physical examination the patient had numerous tender, isolated, and clustered hyperkeratotic, crusted papules, measuring 4–6 mm, on the plantar and periungual surfaces. Several lesions were ulcerated (Figs 1 and 2). The hyperkeratotic masses were debrided with a surgical blade. An intact, white, coiled structure was curetted from each papule, leaving numerous empty crater‐like lesions (Fig. 3), which were identified on histologic sections as Tunga penetrans. Microscopic examination of unstained specimens showed branching, thin, translucent tubular structures with numerous eggs. Ring‐shaped cross‐sections of the organism's respiratory and digestive tracts were seen on hematoxylin and eosin stain (Fig. 4).

The patient received a 10‐day course of dicloxacillin and topical bacitracin ointment. All lesions were healed within 1 week of therapy.
Mauricio Goihman‐Yahr, MD, PhD, Editor
Authors: Prieto Manuel Angel Rodriguez , Lopez Pilar Manchado , Gonzalez Inmaculada Ruiz
Published: December 2004

The Correspondence Section serves as a forum for opinion exchange, about subjects of general interest such as dermatologic training, relations between dermatologists and pharmaceutical houses, governmental control of dermatology and medical practice in general, peculiarities of dermatoiogy related to geographic, climatic, or racial factors, the flow of information and publications, as weil as other concerns the readership might have. Contributions are welcome and should conform to the usual format for correspondence. Manuscripts will undergo standard editorial procedures. Submit ali correspondence to Mauricio Goihman‐Yahr, MD.PhD, Editor, Jet Internationai M‐154, PO Box 020010, Miami, FL 33102.
Mauricio Goihman‐Yahr, MD, PhD, Editor
Authors: Clark Adele R. , Feldman Steven R.
Published: December 2004

The Correspondence Section serves as a forum for opinion exchange about subjects of general interest such as dermatoiogic training, relations between dermatologists and pharmaceutical houses, governmental control of dermatology and medical practice in general, peculiarities of dermatology related to geographic, climatic, or racial factors, the flow of information and publications, as well as other concerns the readership might have. Contributions are welcome and should conform to the usual format for correspondence. Manuscripts will undergo standard editorial procedures. Submit all correspondence to Mauricio Goihman‐Yahr, md,phd, Editor, Jet International M‐154, PO Box 020010, Miami, FL 33102.
Mauricio Goihman‐Yahr, MD, PhD, Editor
Authors: Klinker Hartwig , Langmann Peter , Schwinn Andreas , Richter Ernst
Published: December 2004

The Correspondence Section serves as a forum for opinion exchange about subjects of general interest such as dermatologic training, relations between dermatologists and pharmaceutical houses, governmental control of dermatology and medical practice in general, peculiarities of dermatology related to geographic, climatic, or racial factors, the flow of information and publications, as well as other concerns the readership might have. Contributions are welcome and should conform to the usual format for correspondence. Manuscripts will undergo standard editorial procedures. Submit all correspondance to Mauricio Goihman‐Yahr, MD, phD, Editor, Jet International M‐154, PO Box 020010, Miami, FL 33102.
Perspectives on colorectal cancer screening: a focus group study
Authors: Goel Vivek , Gray Ross , Chart Pam , Fitch Marg , Saibil Fred , Zdanowicz Yola
Published: December 2004

Objective  To assess attitudes and acceptability of Ontario consumers and doctors towards colorectal screening with faecal occult blood testing (FOBT) and colonoscopy.

Design, setting and participants  Focus groups with gender‐specific samples of the population, high‐risk gastroenterology patients and family doctors.

Method  Semi‐structured interview guides used by facilitator to lead groups through knowledge of risk factors and prevention of colorectal cancer, the screening modalities, requirements for implementing screening programmes, barriers to screening and preferences towards screening.

Main findings  There were low levels of knowledge about colorectal cancer and its prevention in the general population. FOBT was an acceptable screening modality, but considerable education about its use and benefits would be necessary to implement a screening programme. Colonoscopy was not perceived to be a good choice for a primary screen in the general population. The high‐risk group supported use of FOBT in the general population and emphasized the need for education. The doctors were more reluctant about screening, requesting clear guidelines. They also identified the time and resources that would be required if a screening programme were initiated.

Conclusion  While colorectal screening is acceptable in this sample, information and decision aids are required to enable consumers and providers to make effective decisions. Implementation of colorectal screening programmes requires substantial educational efforts for both consumers and doctors.
Estimating relative parental investment in sons versus daughters
Authors: Bull J. J. , Pease C. M.
Published: December 2004

Fisher proposed that natural selection would adjust the population sex ratio so that parental expenditure on sons equals expenditure on daughters. Thus if two daughters can be produced for every son, the Fisherian equilibrium is ⅓ sons and ⅔ daughters. The relative cost of a son versus a daughter is necessarily manifested in the trade‐off between family size and sex ratio, and we offer a method to estimate this trade‐off from data on family compositions. Simulation studies indicate that the method works well in some cases but not others. Application of the method to data on a polychaete suggests that sons are much costlier than daughters; the observed sex ratio in fact significantly favored daughters, but not to the extreme predicted by our measure of differential cost.
An evolutionary interpretation of the “motivation to oviposit”
Authors: Mangel Marc
Published: December 2004

The ovipositional behavior of parasitoids and other insects is often described by phrases such as “motivation to oviposit” or “ovipositional drive”. This paper shows how an evolutionary (i.e. functional) interpretation can be given to such phrases. A detailed model for the parasitisation of Sycamore aphids by M. pseudoplatani is developed, using experiments by Collins and Dixon (1986). Two models are developed: i) one in which egg complement is the only state variable and ii) one in which egg complement and information concerning host densities are state variables. Comparisons of the behaviour of simulated parasitoids, using the decisions associated with the models, and the experiments suggest that both egg complement and information are important for the parasitoid's decision making. Accepting previously parasitized hosts may be optimal, and not simply an error in parasitoid perception. A number of other detailed predictions are made, such as the relative fitness of first and second eggs in superparasitized hosts and the nature of the memory of the parasitoid.
Does runaway sexual selection work in finite populations?
Authors: Nichols Richard A. , Butlin Roger K.
Published: December 2004

Fisher's runaway process is an explanation for the origin of conspicuous features which make one sex more attractive to the other. It has been suggested that it could lead to the evolution of sexual characters that significantly impair viability. Runaway selection requires a genetic correlation between alleles affecting the sexual character and alleles affecting the preference. Correlations may be expected because of assortative mating when there is variation in both the sexual character and sexual preferences. We contend that such genetic correlations are unlikely to persist in finite populations. We present simulations which confirm our expectations. They suggest that assortative mating is inefficient at generating correlations, especially if sexual selection maintains characters away from their viability optimum. In finite populations, such weak correlations will be overwhelmed by drift.
Esterase‐6 and the pheromonal effects of cis‐vaccenyl acetate in Drosophila melanogaster
Authors: Costa Rodolfo
Published: December 2004

In Drosophila melanogaster the polymorphic enzyme Est‐6 and a male specific lipid, cis‐vaccenyl acetate (cVA), are components of the seminal fluid. It has been suggested that cVA could be a physiological substrate for Est‐6, constituting, together with the hypothetical hydrolytic product, cis‐vaccenyl alcohol (cVOH), a pheromonal system active in the regulation of the sexual attractiveness of mated females. However, some doubt exists concerning the physiological conversion of cVA to cVOH in females. Est‐6 is also known to affect sperm motility, sperm use and female fecundity.

The results of a study on qualitative and quantitative effects of topical treatment of females with cis‐vaccenyl acetate and cis‐vaccenyl alcohol on courtship behaviour are presented. The inhibition of courtship produced by cVOH was more persistent; this was possibly related to its lower volatility. The hypothesis was tested that different Est‐6 allozymes could produce different amounts of cis‐vaccenyl alcohol in vivo by differential hydrolysis of cis‐vaccenyl acetate, and thus affect the timing of remating. For this purpose highly homogeneous Est‐6S and Est‐6F homozygous lines, with almost certainly identical levels of Est‐6 and cVA, were used. They were obtained after 100 generations of inbreeding and selection of the heterozygotes at each generation. The Est‐6S and Est‐6F products of the Est‐6 structural gene did not differentially affect the timing of remating. This could imply that the two allozymes have similar catalytic properties. However, such results could be obtained even if cVA is not converted to cVOH in vivo by Est‐6.

The effects of Est‐6 allozymes on sperm use after remating were also investigated. The general effect of second males was a very high elimination of first male fertilizations. No evidence for a different contribution of the two allozymes to the fitness through sperm predominance was obtained. Remating and sperm predominance experiments were performed at three temperatures: 18, 25 and 30° C. A more general—not species specific—role of cis‐vaccenyl esters is suggested by preliminary results on their presence in the ejaculate of other Drosophila species.
Karyotype evolution: Evidence from the common shrew (Sorex araneus L.)
Authors: Bengtsson Bengt O. , Frykman Ingrid
Published: December 2004

The common shrew is an exceptionally variable animal with respect to its chromosomes. We here review the evidence from the species concerning general questions of karyotype evolution.

It appears as if chromosomal heterozygotes always are at a fitness disadvantage and that there is no exceptional amount of inbreeding that may alleviate this heterozygous effect. No other factor has been found that convincingly explain the spread of new chromosomal types and the great karyotypic variability in the species.

The species is split into a number of races with incompatible karyotypes. Studies of the hybrid zones between such karyotypic races show that gene flow goes through the chromosomal barrier despite the fact that the chromosomal hybrid zones are very sharp.

It has also been shown that secondary evolutionary processes in the hybrid zones tend to decrease the genetic isolation between the races involved. There is, thus, no evidence from the common shrew which indicates that simple chromosome mutations play a special role in speciation.
Morphological asymmetry and interspecific hybridization: A case study using hylid frogs
Authors: Lamb Trip , Novak James M. , Mahoney Diane L.
Published: December 2004

The limited studies addressing developmental stability of interspecific hybrids suggest a positive association between the level of fluctuating asymmetry and 1) the degree of divergence between parental species, and 2) the recency of the contact zone. To evaluate these associations, we examined asymmetry in a recently‐established hybrid population of treefrogs (Hyla cinerea and H. gratiosa) that show marked structural gene divergence. Fluctuating asymmetry (FA), directional asymmetry, and antisymmetry were assessed for eight paired osteometric traits in allozymically‐defined parental and hybrid categories. FA levels varied considerably among traits. Nonetheless, for any given trait, the hybrid categories did not demonstrate elevated levels of FA compared to the parental categories, or compared to frogs from a non‐hybridizing parental population. The only trait that differed statistically among categories (pterygoid length) involved a significantly lower FA value for the F1 hybrids. Thus, observed FA values do not support expectations that the hybrid categories should experience decreased developmental stability.
Coming of age in fringillid birds: heterochrony in the ontogeny of secondary sexual characters
Authors: Björklund Mats
Published: December 2004

The great variation in the timing of development of adult plumages in North American male passerine birds has in recent years provoked much theoretical interest. It has commonly been assumed that the heterochronic process involved is invariably a retardation of the development of adult plumages. On the basis of a phylogenetic analysis of the nine‐primaried oscines (Fringillidae), I suggest that the heterochronic process that has operated most frequently in North American taxa is not a retardation, but an acceleration. I also suggest that sexual dimorphism in plumage, and late plumage maturation in males, may arise as a secondary result of selection for neoteny in females with a correlated response in males, and not necessarily, as traditionally thought, as a result of selection for bright plumages in males.
The evolution of queen‐rearing nepotism in social Hymenoptera: Effects of discrimination costs in swarming species
Authors: Ratnieks Francis L. W. , Reeve Hudson Kern
Published: December 2004

Polyandry by social hymenopteran queens leads to a potential worker reproductive strategy of rearing full‐sister queens in preference to half‐sister queens. If there is no cost to discrimination, discriminatory queen rearing will be the ESS. However, if discrimination has a cost this conclusion is weakened. This study examines the effect of a “worker efficiency cost” (i.e. discriminatory, nepotistic workers are less effective than non‐nepotistic workers in working to increase total colony reproductive output) on the invasion of rare “nepotist” and “non‐nepotist” alleles in a population in which the other allele is near fixation. Efficiency costs are considered of special relevance to species with swarm founded colonies (e.g., army ants, honey bees).

Two analyses are presented: 1) A general model exploring the effects of efficiency costs, the queen‐rearing‐biasing ability of nepotists, and queen mating frequency on invasion of nepotists and non‐nepotists; 2) a discriminatory removal model, in which the actual amount of biasing is dependent on recognition abilities and the discriminatory intensity of nepotists, queen mating frequency, and whether or not removed immature queens are replaced.

The results of the removal model indicate that when queen mating frequency is close to one (i.e., because of double mating with unequal sperm use or mixed double and single mating) non‐nepotist is likely to be the ESS. At a higher mating frequency nepotist will become the ESS. At even higher mating frequencies, non‐nepotist may reinvade. This latter conclusion is robust across all models. In particular, non‐nepotists may reinvade at the high mating frequencies found in the honey bee (10–20) if their work efficiency is only a few percent higher than nepotists (the exact amount depends on recognition errors and the intensity of discrimination), resulting in a genetic polymorphism of both nepotists and non‐nepotists. Results of a recent study of patriline discrimination in honey bees (Page et al., 1989) are consistent with such a polymorphism.
Homology and hierarchies: Problems solved and unresolved
Authors: Roth V. Louise
Published: December 2004

Homology as a topic in phylogenetic analysis has to do with what is conserved in evolution. The problem of homology in systematics — to find homologues, and in so doing, to identify taxa — is distinct from the problem of identifying what kinds of features tend to be conserved, how and why. The two sets of issues are fundamentally interdependent at the point that one selects the appropriate taxonomic units, identifies the characters one wishes to study, or decides what constitutes a single character.

Homology as a phenomenon is a manifestation of replication and of continuity of biological information. Replication occurs at many levels in the biological hierarchy: from the DNA replication that accompanies cell replication, to the replication of gross phenotypic characteristics within individual organisms that results in iterative homologues, to the replication of individuals to form a population that persists (in replication through successive generations) in evolutionary time. In replication, biological information may persist unchanged, or it may be disrupted or transformed. Different patterns of change may be expressed at different levels of the biological hierarchy. Here a concept developed in arguments on levels of selection becomes useful: change at one level of the hierarchy — e.g., genes or gross phenotype — may be screened off from changes at other levels. Understanding the manner in which phenotypic features develop or are replicated, the mechanisms of screening off, and the evolutionary origin and transformation of these mechanisms is a major challenge for understanding the biological basis of homology.

The recognition or coding of characters for a phylogenetic analysis calls for decisions on what level of description and how complex a unit character is to be recognized. Here an additional point of comparison within the biological hierarchy — the relationship between organisms and taxa — becomes important. We use characters of organisms to trace phylogenies of taxa; yet because traits can arise and subsequently become fixed in different segments of a population linage, phylogenies of organismal characters can conflict with the phylogeny of the taxa that compairse them.

For these reasons, a full understanding of evolutionary changes undergone in lineages will require us to combine phylogenetic analyses with analyses of development, studies of developmental and population genetics, and comparisons of gross phenotype.
Survivorship and fecundity of the radiate and non‐radiate morphs of Groundsel, Senecio vulgaris L., raised in pure stand and mixture
Authors: Abbott Richard J. , Horrill J. Christopher
Published: December 2004

British populations of Senecio vulgaris frequently contain two common capitulum morphs (radiate and non‐radiate) and one rare intermediate morph. The radiate morph shows a higher maternal rate of intermorph outcrossing than the non‐radiate morph and due to the ‘cost of outcrossing’ should decline in frequency, ultimately to be lost from a population. To determine whether the radiate morph exhibits some inherent advantage in fitness to offset the ‘cost of outcrossing’, a comparison was made of the survivorship and fecundity of the radiate and non‐radiate morphs raised in pure stands and 1 : 1 mixture at three planting dates (autumn 1983, and spring and autumn 1984). Plants in stands established in spring 1984 were harvested in late August 1984, while plants in stands established in autumn overwintered before being harvested the following summer. In spring planted stands, the two morphs exhibited equivalent survivorships, while the fecundity of the non‐radiate morph tended to be greater than the radiate morph. In autumn planted stands, survivorship and Net Reproductive Output (survivorship × fecundity) of the non‐radiate morph was greater than that of the radiate morph in mixture, and also in pure stands established in 1983. In no instance was the Net Reproductive Output of either morph significantly greater in mixture than in pure stand. Density had a contrasting effect on morph survivorship and fecundity in the spring and autumn 1984 planted stands. Whereas, in spring stands, fecundity was subject to compensating density dependent regulation while survivorship was density independent, the opposite trend was observed in autumn planted stands. It is concluded that under the conditions of the experiments, the radiate morph exhibited no fitness advantage which might offset the inherent disadvantage it suffers in natural polymorphic populations due to the ‘cost of outcrossing’.
A comparison of methods to partition selection acting via components of fitness: Do larger male bullfrogs have greater hatching success?
Authors: Koenig Walter D. , Albano Stephen S. , Dickinson Janis L.
Published: December 2004

We contrast three methods for measuring selection at sequential fitness components (here called the additive, changing variance, and independent methods). The independent method (Koenig and Albano, 1987; Conner, 1988) describes the relationship between a phenotypic character and one fitness component independent of other components. This method is appropriate when the question is whether or not a character has fitness consequences independent of selection at other stages. The additive (Arnold and Wade, 1984a) and changing variance (Kalisz, 1986; Koenig and Albano, 1987) methods measure selection via one component of fitness, taking into consideration constraints imposed by selection via earlier components in the sequence. These methods therefore more accurately track selection over a sequence of fitness components. Of these latter two methods, the changing variance method yields erratic results in simulation studies and is not recommended in its unmodified form. The additive method (equivalent to the changing variance method weighted as described in Wade and Kalisz [1989]) explicitly partitions selection into additive components and is useful for measuring selection taking into account the constraints imposed by selection acting via prior fitness components.

The methods often yield very different estimates of the relative degree to which the mean of a character is changed by selection acting via a particular component of fitness (the “strength” of selection). However, neither the additive nor independent method is inherently superior to the other; rather, these measures are complementary.
Genetic differentiation and habitat partition of Robertsonian house mouse populations (Mus musculus domesticus) of Tunisia
Authors: Said Khaled , Britton‐Davidian Janice
Published: December 2004

The karyological analysis of Tunisian populations of house mice revealed the existence of a Robertsonian (Rb) chromosomal race carrying nine pairs of metacentric chromosomes in central Tunisia.

Divergence estimates showed that they are genetically differentiated from local all‐acrocentric populations and have a reduced level of genic variability. The Rb populations are restricted to urban habitats, whereas all‐acrocentric populations occur in rural areas. Contact zones between these two types of habitat yield chromosomally polymorphic populations. Analysis of gene flow indicates that it is reduced and limited to populations bordering the contact areas.

The reduced genic variability and patchy distribution exhibited by the Tunisian Rb mice do not agree with results from previous studies of the European Rb populations. Two hypotheses are presented to account for this discrepancy based on local differentiation versus introduction of the Tunisian Rb race.
Populational interactions among underdominant chromosome rearrangements help them to persist in small demes
Authors: Spirito Franco , Rossi Carla , Rizzoni Marco
Published: December 2004

Populational interactions among unlinked chromosomal rearrangements with partial heterozygote sterility and multiplicative fitness were studied to verify whether they help such rearrangements to persist in small populations, in spite of a considerable migration rate with a large population. A deterministic island‐continent model was studied by exact recurrence relations connecting gametic frequencies in successive generations.

The increase in the number of chromosomal rearrangements with the same sterility rate (s) causes an increase in the critical value of the migration rate (mc) over which the chromosomal rearrangements are eliminated from the small population, mainly for medium s values (0.2 ≤ s ≤ 0.5) (“reciprocal stabilization” of the chromosomal rearrangements).

A comparison was made between the velocities of the fixation of a few rearrangements with high heterozygote sterility (low n/high s) and that of many rearrangements with low heterozygote sterility (high n/low s), to reach a given level of populational stability of the rearranged karyotype measured by mc. The former process was shown to be more rapid in small demes, the latter in large ones. However, the increase in the number of unlinked chromosomal rearrangements is more efficient in reducing the neutral gene flow than in increasing the populational stability of the rearranged karyotype.
Within‐island microgeographic variation in the colour pattern of the skink, Chalcides sexlineatus: Pattern and cause
Authors: Brown Richard P. , Thorpe Roger S.
Published: December 2004

The colour pattern of the Gran Canarian skink is described with eight independent colour pattern characters. Significant geographic variation occurs in each character. There are generally high levels of congruence between the patterns of geographic variation in each character although some differences exist. In canonical variate analyses, the first canonical variate expresses most of the among‐locality variation in colour pattern, indicating a largely unidimensional pattern. Patterns of geographic variation in the colour pattern are portrayed by contouring. This reveals north‐east/south‐west clines for seven of the individual characters and the generalized pattern (CV1). Four causal hypotheses were erected which predicted four different unidimensional patterns of geographic variation. Mantel tests and partial correlation analyses were used to compare the observed patterns of microgeographic variation with the four hypothesized patterns. This method suggests differential selection occurring between ecotones as the cause of the microgeographic variation. Microgeographic variation in some aspects of the colour pattern can be explained by selection for different anti‐predator strategies in the hot, arid southern areas vs the cooler, lusher northern areas.
A biomechanical perspective on the use of forelimb length as a measure of sexual selection in frogs
Authors: Emerson Sharon B.
Published: December 2004

Differences in forelimb length between male and female frogs and between amplexing and non‐amplexing males have been interpreted to be the results of sexual selection on forelimb length. The causal feature of the forelimb that has been posited to cause such selection is the observation that non‐amplexing males attempt to disrupt breeding by prying amplexing males from females. A biomechanical model of forelimb function suggests that total length per se may not be the most appropriate measure to use. There are more functionally significant aspects of forelimb morphology, such as lever arm lengths, that should influence amplexing ability and may make measures of overall forelimb length misleading. This example highlights the relevance of functional analysis to current questions in evolutionary biology that rely on postulated roles for morphological structures under selection.
The selective advantage of reaction norms for environmental tolerance
Authors: Gabriel Wilfried , Lynch Michael
Published: December 2004

A tolerance curve defines the dependence of a genotype's fitness on the state of an environmental gradient. It can be characterized by a mode (the genotype's optimal environment) and a width (the breadth of adaptation). It seems possible that one or both of these characters can be modified in an adaptive manner, at least partially, during development. Thus, we extend the theory of environmental tolerance to include reaction norms for the mode and the width of the tolerance curve. We demonstrate that the selective value of such reaction norms increases with increasing spatial heterogeneity and between‐generation temporal variation in the environment and with decreasing within‐generation temporal variation. Assuming that the maintenance of a high breadth of adaptation is costly, reaction, norms are shown to induce correlated selection for a reduction in this character. Nevertheless, regardless of the magnitude of the reaction norm, there is a nearly one to one relationship between the optimal breadth of adaptation and the within‐generation temporal variation perceived by the organism. This suggests that empirical estimates of the breadth of adaptation may provide a useful index of this type of environmental variation from the organism's point of view.
Mitochondrial gene frequencies in Africanized honeybees (Apis mellifera L.): Theoretical model and empirical evidence
Authors: Moritz Robin F. A. , Meusel Michael S.
Published: December 2004

A population genetical model is used to investigate the effects of queen and drone fitness and swarming ability on nuclear and mitochondrial (mt) DNA variation in honeybees. The analysis of both types of DNA is particularly useful for a genetic study of the Africanized bee problem in the Americas. Both an analytical model and a Monte Carlo simulation show that even if mtDNA proves to be selectively neutral, Africanized mitotypes are expected at high frequencies because of the more frequent swarming of Africanized honeybees. Since the fitness of Africanized drones is higher than that of European drones, European and African mitotypes are expected to be polymorphic and consequently unreliable as diagnostic tools to discriminate between the two types. Samples of Africanized honeybees in Brazil reveal high mtDNA polymorphisms as predicted by the theoretical models.
Gene flow rates in Yugoslavian populations of the smooth newt Triturus vulgaris
Authors: González‐Candelas Fernando , Crnobrnja Jelka , Kalezic Milos L. , Moya Andrés
Published: December 2004

Allozymic variation in 22 loci in several Yugoslavian populations of four subspecies of the smooth newt Triturus vulgaris, has been analyzed. The frequency of private alleles and the coefficient of genetic differentiation, FST, give very different indirect estimates of the effective number of migrants per generation, Nm. However, such Nm estimates, in most cases higher than 1, imply that gene flow between populations is large enough as to prevent differentiation by random drift. In the case of T.v. vulgaris, of which sixteen populations amply distributed through Yugoslavia were sampled, there is evidence that frequent extinction and recolonization processes might be responsible for the observed genetic structure. This conclusion has been reached after testing the correlation between genetic, environmental and geographical matrices.
Sexual selection in the monogamous barn swallow (Hirundo rustica). II. Mechanisms of sexual selection
Authors: Møller Anders Pape
Published: December 2004

Mechanisms of sexual selection in the monogamous, sexually dimorphic barn swallow (Hirundo rustica) were studied during a seven‐year period. First, the sex ratio of reproducing adults was male‐biased, and mated males had significantly longer tail ornaments than unmated males. Secondly, some of the unmated individuals later committed infanticide and became mated with the mother of the killed brood. Fathers of killed broods had significantly shorter tails than other males, and there was a tendency for infanticidal males to have longer tail ornaments than other unmated males. Thirdly, long‐tailed male barn swallows were more successful in acquiring extra‐pair copulations than other males, and females involved in extra‐pair copulations, as compared to females not involved in such copulations, had mates with shorter tail ornaments. Fourthly, male barn swallows having long tails as compared to short‐tailed males acquired mates in better body condition. Females mated to long‐tailed males reproduced earlier, laid more eggs and were more likely to have two clutches than were females mated to short‐tailed males. Finally, females mated to long‐tailed males put more effort into reproduction than did other females, as evidenced by their relatively larger contribution to feeding of offspring. Thus, at least five different components of sexual selection affected male reproductive success. Selection arising from differential success during extra‐pair copulations, differential reproductive success and differential male reproductive effort thus accounted for most of the selection on tail ornaments in male barn swallows.
A narrow hybrid zone between two crayfish species from a Mexican cave
Authors: Cesaroni Donatella , Allegrucci Giuliana , Sbordoni Valerio
Published: December 2004

In Northern Chiapas (Mexico), two newly discovered species of Procambarus crayfish inhabit a subterranean stream. These species can be morphologically distinguished only by comparing extreme phenotypes (dark, thick‐eyed, surface dwelling‐like individuals vs light, elongated, microphtalmic, cave dwelling‐like individuals). Individuals with intermediate phenotypes co‐occur with those exhibiting extreme phenotypes.

Crayfish were assayed electrophoretically and individual patterns at 23 gene loci were obtained. Unusually high levels of heterozygosity in both species and a clear discrimination between the two gene pools were revealed. The relationships between individuals were investigated by means of multivariate analysis on individual multilocus genotype profiles. Results showed the occurrence of individuals genetically intermediate between the two major clusters, which shared allozymic variants with both species. Due to the occurrence of alternative alleles in the two gene pools, we could quantify patterns of introgression, which revealed asymmetric gene flow between the two species. Moreover, differential levels of introgression in subsamples within the surface‐like species were found: most introgressed individuals came from the inner section of the cave, where the two species were greatly mixed. These results are also discussed in reference to the morphometric results from a companion paper.

A possible evolutionary pathway, leading to the situation in this cave, and possibly in neighbouring cave systems, is outlined. The hypothesis of a past history of allopatric divergence from a common ancestor and a subsequent secondary contact between these two Procambarus species is supported by geological studies. Crayfish sympatry and competitive exclusion are also discussed.
Homology and logical fallacy
Authors: Rieppel Olivier
Published: December 2004

The meaning of homology, is analyzed in a phylogenetic context. The notion of homology is unequivocal only if tied to recency of common ancestry, i.e. to the concept of monophyly. Processual analysis of the biological causes of similarity cannot provide guidance in the search for relations of homology. Instead, it is the reconstruction of the taxic hierarchy based on homology and congruence which provides guidance in the search for underlying causes of similarity. Pattern reconstruction is shown to have logical precedence over process explanations.
Application of the biogenetic law to behavioral ontogeny: a test using nest architecture in paper wasps
Authors: Wenzel John W.
Published: December 2004

General principles derived from studies of morphological ontogeny are useful in ethology. Behavioral ontogeny may be interpreted from an holistic view in which a series of behaviors is treated as an ontogeny toward a larger, complex, behavioral product. If the component behaviors are defined broadly, many taxa may be compared to find general principles that are not evident when behaviors are dissected to their smallest recognizable units. Flow charts can illustrate such general ontogenetic sequences in a manner that shows what sorts of modifications have evolved from the general pattern. Certain changes may illustrate forms of ontogenetic evolution that are well known for morphological development, such as addition or embellishment of terminal ontogenetic steps, or compression of ontogeny by acceleration or deletion of early steps. The major modifications in nest construction behavior of 28 genera of paper wasps are presented to test the predictions of the biogenetic rule with respect to character polarity. Cladistic analyses of separate morphological and behavioral data sets show that polarity is accurately inferred with respect to the five major patterns of nest construction in paper wasps.
Coexistence of ecologically similar colonising species. II. Population differentiation in Drosophila aldrichi and D. Buzzatii for competitive effects and responses at different temperatures and allozyme variation in D. aldrichi
Authors: Krebs Robert A. , Barker J. S. F.
Published: December 2004

Drosophila aldrichi
and
D. buzzatii
are cactophilic species that colonised Australia about 55–60 years ago. They are sympatric only in Australia. Thus they may be in the process of adapting to new environments and to each other, and diversifying among local, possibly isolated, populations. Larval competitive effects for three populations of each species (Roma, Planet Downs, and Binjour) were measured on semi‐natural cactus rots at three temperatures, with preadult viability, developmental time and adult body weight scored for each sex and species. Populations of both species varied in their responses to the other species as competitor, and one
D. buzzatii
population (Roma) reduced larval performance of
D. aldrichi
significantly more than did other
D. buzzatii
populations. Geographic divergence for the three traits was similar in both species, with a relative performance index derived from these traits highest for Roma, second for Binjour, and least for the Planet Downs population of each species. The Roma
D. aldrichi
population was the most different from the other populations for the performance index and in terms of genetic distances derived from allozyme frequencies. Additionally, comparisons of climatic variables among the population localities showed that the Roma environment was most different from the others. Differential natural selection in different areas of the cactus distribution may be a major cause of population divergence in both species.
Drosophila aldrichi
is superior for some fitness components at the highest temperature. Thus temperature variation throughout the cactus distribution may contribute to the different ranges of these two species, with competitive exclusion of
D. aldrichi in the southern, cooler region of the cactus distribution, but coexistence in the northern, warmer region.
Inheritance of size and shape in a natural population of collared flycatchers, Ficedula albicollis
Authors: Merilä Juha , Gustafsson Lars
Published: December 2004

Four external skeletal and three feather dimensions were measured on adult collared flycatchers (Ficedula albicollis) and their adult offspring. By using mid‐offspring‐midparent regressions, all traits were found to be heritable with an arithmetic mean heritability of 0.46. Heritability estimates from full‐sib analyses were about 1.5 times higher (mean 0.67), indicating that variation in traits was affected by shared nest environment among full‐sibs. The overall body size as measured by principal component one (PC1) was found to be heritable (h2 = 0.40). However, this multivariate measure of heritability was not significant in offspring‐father comparison, while highly so in offspring‐mother comparison (h2 = 0.60). Low offspring‐father resemblance was evident also in univariate estimates of heritability. Possible causes of this (extra‐pair copulations, maternal effects, sex‐linked variance) are discussed.

Genetic correlations among seven traits were estimated to be low (mean 0.22), and of similar magnitude or higher than phenotypic correlations (mean 0.18). All genetic correlations were positive. Genetic and phenotypic correlations as well as covariances were fairly similar to each other (r = 0.85 and r = 0.87, respectively). Environmental correlations did not follow the pattern of genetic correlations (r = 0.11), but were more similar to phenotypic correlations (r = 0.60). Given the low genetic correlations and moderate heritabilities, the overall conclusion is that the external morphology of collared flycatchers is largely under additive genetic control and that there is a strong potential for evolutionary change in morphology even under complex multivariate selection.