MULTIVARIATE PHENOTYPIC DIFFERENTIATION AMONG BOTTLENECK LINES OF THE HOUSEFLY

Multivariate phenotypic differentiation in eight morphometric traits was examined in bottleneck lines of the housefly initiated with one, four, or 16 pairs of flies from a natural outbred population. Differentiation was assessed using a Mahalanobis' distance metric in units of additive genetic variance and covariance estimated from the ancestral population (i.e., generalized genetic distance). This distance metric was partitioned into contributions of size and shape to total distance. Bottleneck lines of all sizes diverged significantly from the ancestral line, but the direction of these shifts differed among the lines of different initial founding size. Those populations founded with single pairs diverged from the ancestral line mostly in shape; the 16-pair lines differentiated almost entirely in size, and the four-pair lines were intermediate in the relative contribution of shape to differentiation from the control. Bottlenecks serve to alter the genetic relationships among traits within the derived populations and in doing so could promote speciation by permitting differentiation of the populations along evolutionary trajectories less accessible to the base population.     

Steuerung und potentielle Evolutionsgeschwindigkeit des obligaten Teilzieherverhaltens: Ergebnisse eines Zweiweg-Selektionsexperiments mit der M?nchsgrasmücke (Sylvia atricapilla)

Zusammenfassung 1. In Südfrankreich lebt eine obligat teilziehende Population der Mönchsgrasmücke (Sylvia atricapilla) mit rund drei Vierteln Zugvögeln und einem Viertel Standvögeln. Das Teilzugverhalten dieser Population wird in beträchtlichem Umfang von genetischen Faktoren gesteuert (Berthold &Querner 1982). Der starke Selektionserfolg eines Zweiweg-Selektionsexperiments bis zur F₁-Generation ließ eine hohe potentielle Evolutionsgeschwindigkeit des obligaten Teilzieherverhaltens vermuten (2). Wir haben das Evolutionspotential in einem Langzeit-Selektionsversuch experimentell untersucht.2. Wir zogen insgesamt 267 Individuen der freilebenden Mönchsgrasmückenpopulation in fünf Gruppen von Hand auf, und alle fünf Stichproben zeigten entsprechende Verhältnisse von Ziehern und Nichtziehern. Wir konnten das Langzeit-Zweiweg-Selektionsexperiment bis zu einer F₆-Generation durchführen und konnten dabei insgesamt 455 Mönchsgrasmücken in Volieren züchten.3. Das Zweiweg-Selektionsexperiment zeigt, daß die untersuchte teilziehende Mönchsgrasmückenpopulation bereits nach drei Generationen eine ausschließlich ziehende und nach vier bis sechs Generationen eine fast nicht mehr ziehende Population werden kann.4. Das Zweiweg-Selektionsexperiment zeigt starken Selektionserfolg und hohe Heritabilitätswerte (ca. 0,6–1), die deutlich höher liegen als bisher für das Verhalten von (meist domestizierten) Wirbeltieren angegeben. Demnach sind genetische Faktoren für die Steuerung dieses obligaten Teilzugs sehr bedeutsam und wahrscheinlich dominant über Umwelteinflüsse.5. Die Versuchsergebnisse lassen im Falle von schnellen Umweltveränderungen und der Wirkung von starken Selektionsfaktoren ein enorm großes Evolutionspotential des obligaten Teilzieherverhaltens annehmen und damit allgemein eine schnelle Mikroevolution der Ortsbewegung von Vögeln. Sollten die von Meteorologen prophezeiten Klimaänderungen in Bälde eintreten (Erwärmung aufgrund von Verunreinigungen der Atmosphäre durch den Menschen, Treibhauseffekt), dann könnten viele obligate Teilzieher auf genetischer Basis rasch zu Standvögeln werden und wenig ausgeprägte Zieher rasch zu Teilziehern. Unter diesem allgemeinen Anwachsen von Standvögeln könnten ausgeprägte Zugvögel mehr und mehr zu leiden haben.6. Eine genetische Kontrolle obligaten Teilzugs scheint weit verbreitet zu sein, und sie stellt wohl auch für alle Individuen den zuverlässigsten Steuerungsmechanismus dar. Beim fakultativen Teilzug hingegen dürften Umweltfaktoren mehr unmittelbar steuernd wirken.

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Control and evolutionary potential of obligate partial migration: results of a two-way selective breeding experiment with the Blackcap (Sylvia atricapilla)

Summary 1. In southern France breeds an obligate partially migratory population of the Blackcap with about three quarters of migrants and one quarter of residents. Partial migration of this population is considerably controlled by genetic factors (Berthold &Querner 1982). The large selection response of a two-way selective breeding experiment up to F₁-generations suggested a high evolutionary potential of obligate partial migration (2). We have this evolutionary potential experimentally investigated in a long-term selective breeding study.2. We raised by hand a total of 267 individuals of the free-living Blackcap population in five groups, and all five samples showed corresponding ratios of migrants and nonmigrants. We were able to conduct the long-term selective breeding experiment up to a F₆-generation, and thereby a total of 455 Blackcaps could be bred in aviaries.3. The two-way selective breeding experiment shows, that the investigated partially migratory Blackcap population can become completely migratory in just three generations and almost exclusively sedentary in just four to six generations.4. The two-way selective breeding experiment yielded large selection responses and high heritability values (about 0.6–1) which are distinctly higher than those previously reported for behavioural traits of (mostly domesticated) vertebrates. Hence, genetic factors are very important for the control of this obligate partial migration and are presumedly dominant over environmental influences.5. In case of rapid environmental changes and the effect of strong selection factors the experimental results suggest a strikingly high evolutionary potential of obligate partial migration and thus in general a rapid microevolution of bird movements. If climatic changes would occur in the near future as they are predicted by meteorologists (rise in temperature due to man-made pollution of the atmosphere, greenhouse-effect) then many obligate partial migrants could rapidly become sedentary on a genetic basis and many less typical migrants could then considerably suffer from the general increase of residents.6. A genetic control of obligate partial migration appears to be widespread and it also appears to be the most reliable control mechanism for all individuals of such a partially migratory population. Facultative partial migration, however, appears to be controlled more directly by environmental factors.

     

Occurrence of Nitrate Reductase and Molybdopterin in Xanthomonas maltophilia

Fifteen of 23 ATCC strains and 2 of 9 clinical isolates of Xanthomonas maltophilia, all of which grew aerobically on ammonia, but not nitrate, as a sole nitrogen source, reduced nitrate to nitrite. X. maltophilia failed to grow anaerobically on complex medium with or without nitrate, so it is considered an obligate aerobe. Nitrate-reducing strains contained reduced methyl viologen nitrate reductase (MVH-NR) with specific activities ranging from 49.2 to 192 U mg of protein⁻¹. Strain ATCC 17666 doubled its cell mass after 3 h of growth on nitrate broth under low aeration, possessed maximal MVH-NR activity, and converted the added nitrate to nitrite, which accumulated. Dissolved oxygen above 15% saturation greatly suppressed nitrite formation. All strains, except ATCC 14535, possessed between 0.25 and 5.05 pmol of molybdopterin mg of protein⁻¹ as measured by the Neurospora crassa nit-1 assay. The molybdopterin activity in the soluble fraction sedimented as a single symmetrical peak with an s_20,w of 5.1. Studies identified MVH-NR in selected strains as a membrane-bound protein. The deoxycholate-solubilized MVH-NR sedimented as a single peak in sucrose density gradients with an s_20,w of 8.8. The MVH-NR of X. maltophilia has the physical characteristics of a respiratory nitrate reductase and may enable cells to use nitrate as an electron sink under semiaerobic conditions.     

Current Productivity and Prehistoric Use of Piñon (Pinus edulis,Pinaceae) in the Dolores Archaeological Project Area,Southwestern Colorado

The possible contribution of pinon (Pinus edulis) seed to the diet of an Anasazi population is investigated using present data on seed productivity and archaeological data on resource use. Annual estimates of total productivity for a 135.7 sq km study area in Montezuma County, Colorado, vary by a factor of 141 in a sample spanning 5 yr. Trees greater than about 25 cm (basal diameter) are usually monoecious and produce significantly more cones per tree but fewer good seeds per cone than smaller, usually dioecious specimens. Archaeological data suggest that piñon seed was a relatively unimportant food item after the initial period of Anasazi colonization of the Dolores River valley about a.D. 600. Use of piñon seed as food was inversely related to degree of agricultural intensification and use of piñon for fuel.     

Three-dimensional growth and morphogenesis of mouse submandibular epithelial cells in serum-free primary culture

Mouse submandibular epithelial cells can be grown in primary culture using the collagen gel matrix and a chemically defined medium consisting of insulin, transferrin, cholera toxin, and BSA (or FGF). Sustained cell growth leading to a 5–10-fold increase in cell number was observed in less than 2 weeks. In the presence of these additives, clumps of cells proliferate by extending ‘star-like’ projections into the matrix, resulting in three-dimensional outgrowths. The morphology of these outgrowths can be modulated to form a ‘cyst-like’ appearance by deleting BSA and adding cortisol to the basal medium containing insulin, transferrin, cholera toxin and FGF. In brief, a serum-free medium for sustained growth has been devised and a simple manipulation of supplements can modulate the three-dimensional colony morphology in the collagen gel matrix. Finally, the resulting outgrowths can produce epidermal growth factor (EGF) in response to dihydrotestosterone.     

Chi-Stimulated Recombination between Phage λ and the Plasmid λdv

Chi promotes Rec-mediated recombination between phage lambda DNA and the homologous plasmid lambda dv. In the absence of Chi, some of the interactions splice lambda dv into lambda, whereas others patch information from lambda dv into lambda. When Chi is in the phage DNA, splices and patches are increased in frequency by the same factor. This result strengthens the analogy between Chi and recombination-promoting elements in fungi. It also rules out one model for the previously reported orientation dependence of Chi phenotype.     

Biofeedback treatment of dysmenorrhea

Nine dysmenorrheic women were run in EMG and thermal biofeedback procedures with concurrent autogenic relaxation practice. Significant reductions in subjective estimates of symptomology associated with dysmenorrhea were noted in all subjects. EMG levels correlated positively with the reductions in symptoms. Thermal levels did not correlate with EMG. In fact no consistent patterns in thermal measures were noted. However, thermal biofeedback cannot be ruled out as an effective treatment for dysmenorrhea since reductions in symptoms occurred during thermal biofeedback training. Another significant aspect of the present study is the effectiveness of long treatment procedures. A six month period was employed and significant reductions in symptoms were noted following two months of biofeedback treatment. Finally, the importance of beginning biofeedback treatment prior to onset of menstrual symptoms is indicated.