Sexual Isolation Between Sympatric and Allopatric Populations of <Emphasis Type="Italic">Drosophila pseudoobscura</Emphasis> and <Emphasis Type="Italic">D. persimilis*</Emphasis>

According to reinforcement theory, sexual isolation between species in sympatry is strengthened by natural selection against maladaptive hybrids. Drosophila pseudoobscura and D. persimilis from four locations where these species are sympatric, and from three locations where only D. pseudoobscura has been found, were utilized in studies of sexual isolation. Multiple-choice observation chambers were used to record matings between sympatric and allopatric strains of the two species. There was a wide variation in sexual isolation between the two species in the four localities we studied. The average isolation index for sympatric strains of the species was not significantly different from the average index for allopatric strains. There were no meaningful differences between the isolation indices in sympatric and allopatric strains of the species. The failure to find a relationship is likely the result of gene flow among populations within the two species.This paper is dedicated to Prof. Lee Ehrman – excellent scientist, friend, and mentor.     

Experimental Manipulation of Sexual Selection and the Evolution of Courtship Song in <Emphasis Type="Italic">Drosophila pseudoobscura</Emphasis>

Courtship song serves as a sexual signal and may contribute to reproductive isolation between closely related species. Using lines of Drosophila pseudoobscura experimentally selected under different sexual selection regimes, we tested whether increased promiscuity and enforced monogamy led to evolutionary changes in courtship song elements. In D. pseudoobscura, males produce both a low and high rate repetition song. We found that both song types diverged after selection and that the direction of changes was consistent with ordered hypotheses of predicted directions of change under the different mating system structures. In particular, latency to the initiation of song and duration of the interpulse interval (IPI) decreased in highly promiscuous lines and increased in monogamous lines. These results suggest that courtship song may rapidly evolve under different mating system structures, representing either functional evolution of more stimulatory song under conditions of strong sexual selection, or might result from increased courtship vigor, or represent correlated evolution. Some speciation theory predicts that increased sexual selection should result in increased variance of traits between allopatric populations, facilitating reproductive isolation. We also found that courtship song elements were not equally variable between replicate lines.     

Sexual isolation between North American and Bogota strains of Drosophila pseudoobscura

Sexual isolation, the reduced ability of organisms of different species to successfully mate, is one of the reproductive barriers that prevent gene flow between different taxa. Various species-specific signals during courtship are attributed to the sexual isolation between them. Drosophila pseudoobscura has been widely used to study the behavioral and genetic mechanisms underlying selection for sexual isolation, as a model system for speciation. D. pseudoobscura and its sibling species, D. persmilis, live together in many locations but are reproductively isolated from one another. North American geographic strains of D. pseudoobscura from the American West mate at random. Several decades ago, D. pseudoobscura was collected in the vicinity of Bogota, Colombia, and later named the subspecies D. pseudoobscura bogotana. Nearly 5,000 matings were observed in this study. We analyzed mating behavior and cuticular hydrocarbon profiles as well as courtship within and between North American and Bogota strains of D. pseudoobscura. Here we report for the first time that Bogota strains of D. pseudoobscura do show statistically significant sexual isolation from North American strains. In addition, there are quantitative variations in cuticular hydrocarbons as well as in courtship behavior between Bogota and North American strains, and females of both North American and Bogota strains show strong preference for North American strain males having high mating propensities, suggesting that the Bogota strains are at an early stage that could lead to a separate species.     

A survey of intra -and interspecific variation for pupation height inDrosophila

Pupation heights of various natural and laboratory populations ofDrosophila melanogaster, D. simulans, andD. pseudoobscura were observed in the laboratory under conditions of continuous darkness or continuous light. Generally higher mean pupation heights were observed under conditions of darkness.D. melanogaster tended to pupate higher than theD. pseudoobscura populations, andD. pseudoobscura tended to pupate higher thanD. simulans. The order of these species differences was similar whether pupation was measured in light or in darkness. Results of selection for pupation height inD. melanogaster suggest the presence of genetic variation for this character. The possibility that a relationship exists between adult and larval behaviors was explored by measuring the pupation heights of larvae from strains selected for geotactic behavior as adults, and also by measuring geotaxis of adults from strains selected for pupation height.This work was supported by NIH Grant GM 19583.     

Photobehavioral differentiation in natural populations ofDrosophila pseudoobscura andDrosophila persimilis

The photoresponses of natural populations ofD. pseudoobscura andD. persimilis, occurring sympatrically, are measured in two environmental conditions (at rest and disturbed). Comparisons of the responses, intraspecifically and interspecifically, lead to the following conclusions. These must be considered within the confines of the operational nature of the measurement of laboratory photoresponses. (1) Within each species population, significant nonenvironmental differentiation has been allowed or produced by selection in the at rest photoresponse. No significant nonenvironmental differentiation is found in the photoresponse measured in a disturbed condition. (2) Within each species population, a higher mean disturbed photoresponse has been favored. The intensities or patterns of selection acting on these two photoresponses have differed such that more intrapopulation differentiation has been allowed or produced in the at rest photoresponse. (3) A higher mean photoresponse has been favored inD. persimilis for both conditions. The intensities or patterns of selection acting between these two species populations on the at rest photoresponse have differed such that more intrapopulation differentiation has been allowed or produced inD. persimilis. (4) Comparisons of this study with one on intraspecific and interspecific differentiaiton in wing length lead to the conclusion that the selective differences inferred above have acted at a level more specifically attuned to photobehavior.     

Genetic variability of sexual behavior in a natural population ofDrosophila melanogaster

Although many experiments on laboratory stocks ofDrosophila have suggested that mate choice is a major feature of sexual selection in this organism, few attempts have been made to measure its extent in wild populations. In this study, a crossing design was used to obtain a set of 13 genetically identical independent lines representative of genotypes from an African population ofDrosophila melanogaster. They were tested for variation in sexual behavior using dyadic tests. Significant variation in orientation and vibration latencies was found for males, and in mating speed and copulation duration for both sexes. No evidence of assortative mating, either positive or negative, was found. The absence of a correlation in mating speed between males and females sharing the same genotype leads us to doubt the applicability of the notion of male eagerness and female reluctancy inDrosophila and the importance of vigor as a factor in mating speed. The absence of mate choice in natural populations ofDrosophila seems to us the most likely hypothesis on the basis of both theory and empirical evidence.     

Courtship song and mating speed in hybrids betweenDrosophila melanogaster andDrosophila simulans

Courtship song and mating speed of hybrids betweenDrosophila melanogaster andD. simulans were investigated. The courtship song of hybrid males is identical to that ofD. simulans, suggesting that X chromosome determination, known from the cross betweenD. pseudoobscura andD. persimilis, is also possible here. Wingbeat frequency of hybrids is intermediate between that of the two parents, demonstrating that courtship song and wingbeat frequency are inherited independently of each other. In mating tests, hybrid males court and are accepted byD. simulans females more than hybrid females (presumably because their song is more acceptable to the former).D. melanogaster females reject hybrid males. Hybrid females acceptD. melanogaster males readily, hybrids less readily, andD. simulans least.F. v. S was supported by a scholarship from the German Academic Exchange Service.     

Even a stopped clock tells the right time twice a day: circadian timekeeping in Drosophila

“Even a stopped clock tells the right time twice a day, and for once I’m inclined to believe Withnail is right. We are indeed drifting into the arena of the unwell... What we need is harmony. Fresh air. Stuff like that” “Bruce Robinson (1986, ref. 1)”. Although a stopped Drosophila clock probably does not tell the right time even once a day, recent findings have demonstrated that accurate circadian time-keeping is dependent on harmony between groups of clock neurons within the brain. Furthermore, when harmony between the environment and the endogenous clock is lost, as during jet lag, we definitely feel unwell. In this review, we provide an overview of the current understanding of circadian rhythms in Drosophila, focussing on recent discoveries that demonstrate how approximately 100 neurons within the Drosophila brain control the behaviour of the whole fly, and how these rhythms respond to the environment.     

<Emphasis Type="Italic">Lamellodiscus theroni</Emphasis> sp. nov. (Monogenea,Diplectanidae), a gill parasite from <Emphasis Type="Italic">Diplodus puntazzo</Emphasis> (Teleostei,Sparidae) from the Mediterranean Sea

We propose to name as Lamellodiscus theroni sp. nov., the gill parasite of Diplodus puntazzo (Cetti) that was reported by Euzet (1984) as L. ergensi Euzet and Oliver, 1966 in Kerkennah Island (Tunisia). L. theroni sp. nov. was also found specific to D. puntazzo in Algiers Bay (Algeria) and in Gulf of Lion (France). The host specificity of various Lamellodiscus species on D. puntazzo is briefly discussed. Within Lamellodiscus, L. theroni belongs to the “ignoratus” group characterized by a “lyre” shaped male copulatory organ and to the “ergensi” subgroup, characterized by a complex morphology of the haptoral dorsal bars. L. theroni differs from the five other species of this subgroup (L. ergensi, L. kechemirae, L. tomentosus, L. sanfilippoi, L. baeri) by the morphology and the size of the haptoral dorsal bar. L. theroni, as well as, L. hilii, L. bidens, L. impervius, was only reported on the sparid Diplodus puntazzo. These parasite species are all considered as oioxenic.     

Assortative Mating in <Emphasis Type="Italic">Drosophila</Emphasis> Adapted to a Microsite Ecological Gradient

Elucidating the causes of population divergence, and ultimately speciation, is a central objective of evolutionary biology. A number of previous studies of Drosophila populations from the Nahal Oren canyon (Mt Carmel, Israel) revealed significant interslope differences for a complex of fitness and behavioral traits. Peculiarities in courtship song patterns and nonrandom mating were observed, despite a small interslope distance. Single and multiple mate choice tests with D. melanogaster from the opposite slopes displayed highly significant assortative mating, with preference for sexual partners from the same slope. Here we report the results on mate choice in the sibling species D. melanogaster and D. simulans inhabiting Nahal Oren canyon. Significant assortative mating was found in both species. Genetic heterogeneity in mate choice was found among the isofemale lines of D. melanogaster. Samples of isofemale lines established from females collected in spring and fall seasons show the same mating patterns.     

Molecular pathology of well-differentiated thyroid carcinomas

The newly discovered molecular features of well-differentiated thyroid carcinomas derived from follicular cells are reviewed, within the frame of the 2004 WHO classification of thyroid tumours, under the following headings: “Follicular carcinoma”, “Papillary carcinoma”, “Follicular variant of papillary carcinoma” and “Hürthle cell tumours”. A particular emphasis is put on the meaning of PAX8–PPARγ rearrangements, RAS and BRAF mutations, and deletions and mutations of mitochondrial genes and of nuclear genes encoding for mitochondrial enzymes, for thyroid tumorigenesis.     

Lamellodiscus crampus sp. nov. (Monogenea, Diplectanidae), a parasite of Dentex maroccanus (Teleostei, Sparidae) from off Tunisia

Lamellodiscus crampus sp. nov. (Monogenea, Diplectanidae) is described from the gills of Dentex maroccanus (Valenciennes) collected from the Gulf of Gabès (Tunisia) in the oriental part of Mediterranean Sea. The new species belongs to the “ignoratus” group (sensu Oliver 1987) characterized by a lamellodisc with complete lamellae and a “lyre” shaped male copulatory organ, and the “ignoratus” sensu stricto subgroup, characterized by a haptor with simple lateral dorsal bars, as proposed by Amine and Euzet (2005). Lamellodiscus crampus can be easily distinguished from all the congeneric species of the subgroup “ignoratus” by the presence, in the “lyre” male copulatory organ, of five spines in the distal portion on the axial side of the paired piece.     

Unique origin of Andaman Islanders: insight from autosomal loci

Our mtDNA and Y chromosome studies lead to the conclusion that the Andamanese “Negrito” mtDNA lineages have survived in the Andaman Islands in complete genetic isolation from other South and Southeast Asian populations since the initial settlement of the region by the out-of-Africa migration. In order to obtain a robust reconstruction of the evolutionary history of the Andamanese, we carried out a study on the three aboriginal populations, namely, the Great Andamanese, Onge and Nicobarese, using autosomal microsatellite markers. The range of alleles (7–31.2) observed in the studied population and heterozygosity values (0.392–0.857) indicate that the selected STR markers are highly polymorphic in all the three populations, and genetic variability within the populations is significantly high, with a mean gene diversity of 77%. The Andaman “Negrito” populations do not show particular affinities either with the African populations or with the Indian populations, confirming their unique origin. In contrast, Nicobarese show close affinities with the Southeast Asian populations, suggesting their recent entry in the Islands.     

Enzyme levels in the lymph of febrile animals of different age groups

Fever in young rabbits was accompanied by more pronounced and longer-lasting changes in the lymph levels of various enzymes than in adult rabbits, suggesting a greater lability of metabolic processes, of cell membrane permeability, and of “enzymic homeostasis” in general in younger animals. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 8, pp. 139–141, August, 1995 Pressented by A. D. Ado. Member of the Russian Academy of Medical Sciences     

Homeostatic drive counteracting selection for positive and negative phototaxis and geotaxis inDrosophila pseudoobscura

Tested in Hirsch-Hadler mazes,Drosophila pseudoobscura is on the average geoneutral and photoneutral. Strongly geo- and photopositive and geo- and photonegative populations can be obtained by artificial selection, but upon relaxation of the selection they tend to relapse toward neutrality. This genetic homeostasis is due to natural selection favoring neutrality. Experiments are described in which artificial selection for positivity and for negativity was deliberately made so weak that it only counterbalanced the natural selection or homeostatic drive and the effects of cross-migration. Under these conditions, the behavior of the population artificially selected for positivity diverges only slightly from that of the population selected for negativity, but, at least in females, both populations move closer to neutrality.Research supported by National Science Foundation Grant No. NSF-GP-31505X (to H. L.).     

FTO polymorphisms in oceanic populations

It has been suggested that Neel’s “thrifty genotype” model may account for high body weights in some Oceanic populations, which presumably arose in modern times. In European populations, common variants (rs1421085-C, rs17817449-G, and rs9939609-A) in the fat mass and obesity (FTO associated) were recently found to be associated with body mass index (BMI) or obesity. In this study, we investigated the population frequencies of these variants in six Oceanic populations (Melanesians, Micronesians, and Polynesians) and tested for an association with BMI. Unlike European populations, the Oceanic populations displayed no significant association between the FTO polymorphisms and BMI. These variants were in strong linkage disequilibrium. The population frequencies ranged between 4.2 and 30.3% in the six Oceanic populations, and were similar to those in southeast and east Asian populations. Our study of the FTO polymorphisms has generated no evidence to support the thrifty genotype hypothesis for Oceanic populations.     

Isolation from nervous effects: A mechanism of adaptation of biological systems to disease

A concept of functional isolation of the heart from nervous effects as a mechanism of heart adaptation to extreme states has been formulated. In moderate hypoxia, isolation of the cardiovasomotor center from nonhypoxic afferention provides the compliance of myocardial hyperfunction to the intensity of hypoxia and limits heart participation in different forms of activity of the organism. In thermal hypoxia, myocardial isolation from sympathetic and parasympathetic effects ensures its minimal function and economy of energy due to transfer to the autorhythmical mode of function and rules out heart participation in circulatory reactions. Functional isolation of the heart in hypoxia is caused by energy deficiency and depends on the training of an organism and coordination of the sympathetic and parasympathetic effects. High prevalence of isolation of cells, organs, and systems from regulating effects in health and disease is demonstrated and its mechanisms, levels, and impact are disclosed. Both the “extension” of nervous bonds and hyperfunction and the “narrowing” of nervous bonds and hypofunction of biological systems are aimed at adaptation of an organism. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 6, pp. 604–611, June, 1998     

Violence as a risk factor for postpartum depression in mothers: a meta-analysis

The objective of this paper is to examine the association between violence and postpartum depression (PPD). The data sources of this study are: Web of Science, PubMed, Elsevier, Springer Link were examined from their start date through July1, 2011. “Violence”, “domestic violence”, “physical violence”, “sexual violence”, “domestic violence”, “postpartum depression”, “postnatal depression”, and “puerperal depression” were some of the terms included in the purview of MeSH terms. Relevant studies from reference lists were also scanned. Studies examining the association between violence and postpartum depression have been included. A total of 679 studies were included in this screening. Essential information of these included studies was independently extracted by two raters. Newcastle–Ottawa scale was used to assess the clinical data of these research studies. Random-effects model was chosen in this meta-analysis for maintaining significant heterogeneity. Publication bias was evaluated with the help of a funnel plot. Six studies involving 3,950 participants were included in this clinical study. Violence was one of the factors responsible for PPD [OR = 3.47; 95% confidence interval (CI; 2.13–5.64)]. Significant heterogenity was found in this meta-analysis (P < 0.00001; I ² = 79%)and publication bias was detected through a funnel plot. A sensitivity analysis of 3.00, 95%CI (2.44–3.68), p < 0.00001 indicated that our findings were robust and reliable. Our meta-analysis indicated a positive correlation between violence and PPD. In women of reproductive age, PPD induced through violence can be prevented through early identification. In addition, due to heterogeneity and wide CIs in this meta-analysis, further research is evidently required.     

Developmental isolation and subsequent adult behavior ofDrosophila pseudoobscura

When isolated from all contact with other flies until the opportunity to exercise mating choices,Drosophila pseudoobscura displays genetically-mediated compensatory behavior: heterokaryotypic females are more vulnerable than homokaryotes to wholly restricted contact with conspecifics. They are less able to demonstrate normal frequency-dependent sexual selection after isolation than their own homokaryotypes. However, the later the isolation in this holometa-bolous insect-eggs, first instars, second instars, third instars, pupae, imagoes-the fewer the behavioral effects of this isolation.This work was generously supported by the Whitehall Foundation.     

Individual differences in responses to acute stress associated with type of behavior (Prediction of stress resistance)

On the basis of the initial parameters of behavior in the “open field,” “forced swimming,” and “emotional resonance” tests, the main behavioral parameters — the number of squares crossed, the number of standing postures, and the time of passive swimming — are shown to be predictable for stress in rats with different types of behavior. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 1, pp. 89–92, January, 1994 Presented by P. V. Simonov, Member of the Russian Academy of Medical Sciences