Selektive Partnerwahl der Aaskr?he (Corvus corone) in der Hybridisierungszone von Rabenkr?he (C. c. corone) und Nebelkr?he (C. c. cornix)

Zusammenfassung Die als Unterarten klassifizierten europäischen Formen der Aaskrähe, Rabenkrähe und Nebelkrähe, besiedeln verschiedene, aneinandergrenzende Verbreitungsgebiete und hybridisieren in der Kontaktzone. Die Nachkommen von Mischpaaren sind fruchtbar und können sowohl mit anderen Hybriden als auch mit Raben- und Nebelkrähen erfolgreich brüten. Trotzdem kommt es zu keiner völligen Vermischung der Formen und/oder Verlagerung der Verbreitungsgebiete. Vor diesem Hintergrund untersuchten wir die Partnerwahl von Aaskrähen in der Hybridisierungszone auf der nordfriesischen Insel Amrum und stellten fest, daß Partner gleichen Phänotyps häufiger miteinander verpaart waren, als stochastisch zu erwarten gewesen wäre. Unsere Daten bestätigen vergleichbare Studien aus Hybridisierungszonen in Italien und Sibirien. Wir schließen daraus, daß phänotypisch selektive Partnerwahl bei der Aaskrähe ein allgemeines Phänomen sein könnte und diskutieren, warum dieses Verhalten anfitness-relevante Parameter gekoppelt sein sollte. Um welche es sich dabei handeln könnte, wurde bisher nicht hinreichend untersucht und muß deshalb offen bleiben.

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Non-random mating of Crows (Corvus corone) in a hybrid zone of Carrion Crow (C. c. corone) and Hooded Crow (C. c. cornix)

Summary Carrion Crow and Hooded Crow are regarded as subspecies of the Crow. They show frequent hybridisation along the adjacent borders of their distribution. Mixed pairs produce fertile offspring which are able to breed successfully with both hybrids and mates of either phenotype. However, hybridisation does not lead to phenotypic changes of Carrion and Hooded Crows in general nor in their distinct distribution. We studied the mating behaviour of Crows in the hybrid zone on the Island of Amrum (Schleswig-Holstein, Germany) and found evidence that Crows may prefer mates of the same phenotype. Our data confirm previous studies which reported assortative mating with respect to plumage coloration from hybrid zones in Italy and Siberia. We discuss why this behaviour should be related tofitness traits which in our opinion have not yet been studied adequately nor identified.

     

The effect of pressure and cooling rate on spermatoza, kidney tissue, and the whole kidney

Application of high hydrostatic pressure as a cryoprotective was evaluated for the bovine sperm cell, kidney tissue, and the whole kidney. Spermatozoa samples were pressurized between 172 and 1724 bar for various lengths of time. The effect of pressure and cooling at 5 °C/min, 35 °C/min, and 55 °C/min to ?60 °C was investigated. Application of pressure to sperm cells resulted in extensive damage, as shown by a decrease in motility, an increase in morphological a bnormalities, and the release of enzymes. Freezing of sperm cells, kidney tissue, and the whole kidney under high pressure was significantly more damaging than freezing at the same rates at atmospheric pressure. Pressure did not act as a cryoprotective agent but instead led to gross cellular damage, either when applied at 4 °C or during freeze-thaw procedures.     

The dynamics of seed harvesting in early successional communities by a tropical ant,Solenopsis geminata

Summary The neotropical ant, Solenopsis geminata, in the moist lowlands of southeastern Mexico was most abundant in agricultural fields and early second growth habitats. It was not found within forest habitats.In addition to its foraging for insects and general scavenging, this ant also harvests seeds. Under field experimental conditions, a wide variety of small seeds, especially grasses, were taken. Nest mound size and number were greatest on plots experimentally seeded to high grass density and low on plots consisting of grass-dicot mixtures, pure dicot stands, or a vegetative grass strain incapable of seed production. Paspalum conjugatum, an important grass weed, was the most common seed encountered in seed storage chambers in the mounds. Under experimental field conditions, Solenopsis geminata reduced seed densities of P. conjugatum and the malvaceous weed, Malachra sp. by 97 percent or more. Seed densities of the composite, Bidens pilosa were unaffected.     

Cardiovascular, catecholamine and psychological responses to TRH in four types of affective disorder patients

When 500 micrograms of TRH is given intravenously, an increase in TSH, blood pressure, plasma catecholamines and positive emotions follows. Four groups of patients with major, minor or bipolar depression or schizoaffective disorder increased their TSH levels by similar amounts after TRH. The neurohormone also significantly increased diastolic blood pressure by 5.5 +/- 1.6 mm Hg, and decreased heart rate by 7.6 +/- 1.3 beats/min. There was a weak trend for bipolar depressives to have less cardiovascular response to TRH than the other groups. Plasma norepinephrine (NE) was higher after TRH than after placebo. The NE response differed between patient groups (P = .0023) because of a smaller response by major depressives. TRH decreased anger, tension and depression, and increased friendliness. Positive emotional responses were significantly greater in the bipolar depressives than in other groups. Forty-one other studies have found a subnormal TSH response does not distinguish between subtypes of the affective disorders, but cardiovascular, catecholamine and mood responses may do so.     

A DATA MANAGER for the health information system Berlin.

The needs for permanently changing the logical and physical structure of a medical datebase during the development of a health information system have initiated the project of implementing a DATA MANAGER. The concept of the DATA MANAGER covers facilities for the development of the logical data structure model including documentation of the model and programming support for application programs accessing the health information system (HIS) database. The outstanding facilities of the INTERLISP system have been found to be appropriate for writing the DATA MANAGER. A first data structure model, on which the DATA MANAGER will operate, is roughly outlined.