When females choose a mate among a group of signaling males concentrated in a small area, a male's mating success is often determined not only by his absolute attractiveness but by the attractiveness ...of his neighbors as well. Multivariate analyses of sexual selection measurements based on absolute values of predictor variables are then misleading, because such analyses assume that the fitness of a given individual is not influenced by others. We addressed this problem of relative fitness in sexual selection by developing two adjustments of the predictor variables in the multivariate analyses by including group means in addition to absolute values and by using relative values, deviations from group means. In the lesser wax moth, Achroia grisella (Lepidoptera: Pyralidae), aggregated males produce ultrasonic signals attractive to females in the vicinity of honey bee colonies. Playback experiments showed that females prefer signals whose pulses are louder, longer, delivered at a faster rate, and include lengthy silent gaps within pulse pairs (long asynchrony intervals). To measure sexual selection on ultrasonic signals, attractiveness was assessed by observing the number of females orienting toward given males in four-choice trials. The various signal characters of the males were computed from ultrasound recordings. Multivariate regression and nonparametric analyses revealed that peak amplitude, asynchrony interval, and pulse rate were the direct targets of selection. Nonlinear stabilizing and correlational selection were also detected. Comparisons of results from multivariate analyses based on absolute values and on the two relative adjustments indicated that the quality of a four-male group did not affect the strength or direction of linear selection but changed the strength of nonlinear selection. Both relative adjustments improved the prediction of male attractiveness. Three-dimensional surface plots generated by the nonparametric regression analyses showed that attractiveness increased monotonically with any combination of the signal characters. This graphical technique also showed that female choice in A. grisella was based on a relative, as opposed to a threshold, decision rule. Overall, male attractiveness for the population remained consistent between testing days. However, attractiveness values for some individual males changed between successive testing days. In these cases, the change in attractiveness was related only to the change in peak amplitude.
Model Theory Hodges, Wilfrid
03/1993, Letnik:
v.Series Number 42
eBook
This is an up-to-date and integrated introduction to model theory, designed to be used for graduate courses (for students who are familiar with first-order logic), and as a reference for more ...experienced logicians and mathematicians. Model theory is concerned with the notions of definition, interpretation and structure in a very general setting, and is applied to a wide variety of other areas such as set theory, geometry, algebra (in particular group theory), and computer science (e.g. logic programming and specification). Professor Hodges emphasises definability and methods of construction, and introduces the reader to advanced topics such as stability. He also provides the reader with much historical information and a full bibliography, enhancing the book's use as a reference.
ABSTRACT IN GERMAN: Der Beitrag analysiert die Geburt von Kindern aus der Zeitperspektive des Lebenslaufs. Im Unterschied zur Lebenslaufanalyse hat dieser Ansatz zwei Vorzüge: In deskriptiver ...Hinsicht konzentriert sich der Ansatz auf eine Beschreibung des generativen Handelns, wobei Partnerwahlprozesse, Trennungen und erneute Partnerwahl- und Paarentwicklungsprozesse, die sich in der Lebenslaufanalyse mit generativen Entscheidungsprozessen überlagern, ausgeblendet werden. In analytischer Hinsicht stehen zudem die Merkmale beider Partner für die Untersuchung von generativen Entscheidungen zur Verfügung, und der Ansatz ist insofern zur Überprüfung theoretischer Zusammenhänge besser geeignet. Die Studie basiert auf einer Analyse des Familiensurvey 2000. Die Ergebnisse der paarbezogenen Darstellung des generativen Verhaltens zeigen in vielen Punkten ein anderes Bild, als es aus der Lebenslaufanalyse bekannt ist. Zu den wichtigsten Ergebnissen gehört zum einen, dass die Familiengründungsbereitschaft in den Partnerschaften aufeinanderfolgender Geburtsjahrgänge keineswegs abgenommen hat. Für die aus der Lebenslaufanalyse bekannten Kohortenunterschiede der dauerhaften Kinderlosigkeit erscheinen deshalb Veränderungen bezüglich der Existenz und der Dauerhaftigkeit von Partnerschaften ausschlaggebend. Bezüglich der Familienerweiterung ist zum anderen bedeutsam, dass die Stabilität einer Partnerschaft die Geburt eines zweiten Kindes fördert, wohingegen die Geburt eines dritten oder vierten Kindes erst verstärkt aus Anlass einer neuen Partnerschaft zustande kommt. // ABSTRACT IN ENGLISH: In this contribution, fertility is analysed within the course of male-female partnerships. In contrast to life course research, this approach has two advantages. On the one hand, for purposes of description, the effects of mate selection and of the instability of partnerships are disregarded. On the other, for purposes of analysis, the features of both partners in the decision to have a child can be analysed. The analysis is based on the Familiensurvey 2000, which is representative for Germany. The 'union course' approach provides quite a different picture of fertility development than does the life course approach. Among the main results: There is no increase in childlessness within unions, i.e. the considerable increase in childlessness in life course studies is to a considerable extent due to the lack of a partner. Also worth mentioning is the fact that the persistence of a union contributes to the decision to have a second child but limits couples from having further children. Reprinted by permission of Lucius & Lucius Verlagsgesellschaft
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