Fig 1.
Schematic overview of four types of potential fitness benefits of mate choice.
This study aims at separating direct from indirect benefits of mate choice for compatibility (red arrow), while experimentally controlling for effects of overall quality (red parentheses).
Table 1.
Treatment effect on breeding parameters and sexual behaviors.
The structure of each model (fixed and random effects) is given, as well as the mean estimates (±SE) of each treatment group. Underlying data for each test can be found in S1 Data.
Fig 2.
Relative fitness estimates (mean ± SE) of males (n = 84) and females (n = 84) from chosen and non-chosen pairs.
Parameter estimates and SE were given by the general linear mixed-effect models T1-1 and T1-2. Underlying data for both tests can be found in S1 Data.
Table 2.
Effect of pair bond duration when included as a fixed effect in the models presented in Table 1.
Underlying data for each test can be found in S1 Data.
Fig 3.
Embryo (A) and offspring (B) mortality rates (parameter estimates [mean ± SE]) in chosen and non-chosen pairs.
Parameter estimates and SE were given by the generalized linear mixed-effect models T1-5 and T1-6 based on n = 707 fertilized eggs and n = 594 hatched eggs, respectively. Underlying data for both tests can be found in S1 Data.
Fig 4.
Experimental design and timeline.
Chosen pairs (C, n = 46, filled red hearts) resulted from free choice. Non-chosen pairs (NC, n = 38, broken yellow hearts) resulted from force-pairing (by being put together in a cage; experimental stage 2) between individuals that expressed a choice (during experimental stage 1), but who were separated from their initial chosen partner (event symbolized by yellow lightning). Fitness of all pairs was measured during experimental stage 3. The follow-up study (S6 Text) took place in spring 2014. All experimental birds had hatched in the summer of 2011.