Search

Distinguished ways are used to measure hierarchical rank between partners in surveys. Aim of this thesis was to study preference for partner of particular hierarchical rank towards respondent 1) according to rating of photographs, 2) according to respondent's ideas about his/her future partnership organization, 3) according to respondent's natural tendency to lead or to yield, and to compare these ways of preference assessment. Questionnaires from 95 female university students aged to 25 years inc. were processed. Respondents, who claimed they will submit their partner or they will take turns in subordination with their partner half and half, were more submissive in ordinary life than respondents, who claimed they will be equal to their partner. Expected connection between idea about future partnership organization or submissiveness in ordinary life and choice of photograph depicting figurant with particular signs of nonverbal dominance was not found. Nevertheless, differences in choices of photographs were found between females using hormonal contraceptives and females not using any hormonal contraceptives. Key words: mate-choice, dominance, submissiveness, attractiveness.

Sexual dimorphism is important in mate choice in many species and can be appraised via multiple traits in any one individual. Thus, one question that arises is whether sexual dimorphism in different traits influences preferences consistently. Here, we examined human preferences for masculinity/femininity in different types of stimuli. For face and body stimuli, images were manipulated to be more or less masculine using computer graphic techniques. Voice stimuli were made more or less masculine by manipulating pitch. For smell, we used variation among male aftershaves as a proxy for manipulating masculinity of real male smell and used relatively masculine/feminine odors. For women, we found that preferences for more masculine stimuli were greater for short-term than for long-term relationships across all stimuli types. Further analyses revealed consistency in preferences for masculinity across stimuli types, at least for short-term judgments, whereby women with preferences for masculinity in one domain also had preferences for masculinity in the other domains. For men, we found that preferences for more feminine stimuli were greater for short-term than for long-term judgments across face and voice stimuli, whereas the reverse was true for body stimuli. Further analyses revealed consistency in preferences for masculinity across stimuli types for long-term judgments, whereby men with preferences for femininity in one domain also had preferences for femininity in the other domains. These data suggest that masculinity/femininity as a trait may be assessed via different modalities and that masculinity/femininity in the different modalities might be representing a single underlying quality in individuals. Key words: attractiveness, cross-modal, mate-choice, relationship context, sexual dimorphism. [Behav Ecol]

The vast majority of bird species build a nest in which to breed. Some species build more than one nest, but the function of most multiple nest-building remains unclear. Here we describe the unusual nest-building behaviour of the Australian Reed Warbler Acrocephalus australis, and test experimentally the hypotheses that multiple nest-building is related to individual condition or territory quality, and plays a role in mate assessment. Australian Reed Warblers built two types of nest structures: 'type I' nests, which were used for eggs and nestlings, and 'type II' nests, which were structurally distinct from type I nests, did not support eggs, nestlings or adults and were not essential for successful breeding. The number of type II nests built in each territory varied. Type II nests were only built before breeding had commenced in a territory and females were not observed participating in their construction, supporting a role in female mate choice. Birds provided with supplementary food built significantly more type II nests than control birds. However, supplementary-fed birds did not have greater pairing success, and the addition of further type II nests to territories did not increase the pairing rate or type II nest construction in those territories. There was no relationship between the presence of type II nests and either reproductive success or likelihood of nest predation. We discuss the implications of these results in light of previous suggestions regarding the function of multiple nest-building in birds.

Female zebra finches may be influenced by the choices of other females when selecting mates, challenging the view that mate-choice copying should not occur in species with biparental care.

In this thesis, different genetic tools are used to investigate pre- and postzygotic barriers to gene exchange and their role in speciation in the pied flycatcher (Ficedula hypoleuca) and the collared flycatcher (F. albicollis). This species complex consists of four genetically distinct clades that apparently diverged in allopatry (I). Sequencing of introns from autosomal and Z-linked genes from the two species reveals signs of selection on the Z-chromosome. Sexual selection acting on Z-linked genes might explain this pattern (II). By using large-scale genotyping of single nucleotide polymorphisms (SNPs), introgression is observed at autosomal- but not Z-linked loci, mostly from the pied- to the collared flycatcher. Male plumage characters and genes involved in hybrid fitness are largely mapped to the Z-chromosome (III). By studying mate choice of female hybrids I show that there is a link between female preferences and the Z chromosome (IV). The rate of introgression in island versus clinal hybrid zones is consistent with regional differences in hybrid fertility. Asymmetric gene flow from allopatry on the islands may oppose reinforcement, leading to introgression and a partial breakdown of postzygotic isolation. Adaptive introgression may explain the high rate of introgression observed at one of the genetic markers (V). For late breeding female collared flycatchers it appears to be adaptive to use pied flycatchers as social fathers but conspecific males as genetic fathers. Additionally, females in mixed species pairs may reduce hybridization costs by producing an excess of male hybrid offspring that are more fertile than females (VI). In conclusion, the Z-chromosome appears to play a major role in flycatcher speciation. Sexual selection and reinforcement are important mechanisms in the divergence of these birds. However, gene flow from allopatry, introgression of adaptive genes and adaptive hetrospecific pairing by late breeding collared flycatcher females may work in the opposite direction.