Dynamics of multiple sexual signals in relation to climatic conditions

Question: Can trait-specific phenotypic plasticity in response to annual environmental variation lead to changes in the strength of sexual selection through the relative expression of sexual ornaments at the population level? Data description: We recorded breeding dates and the sizes of white forehead and wing patches of male collared flycatchers (Ficedula albicollis) from 1998 to 2005 in a nestboxbreeding population in the Pilis Mountains, Hungary. As environmental predictors, we used the North Atlantic Oscillation (NAO) index and local weather data, classified as direct or indirect effects relative to the moult of the given ornament. Search method: First, we used general linear mixed models to assess environmental effects on the within-individual changes and absolute yearly sizes of forehead and wing patches. We then used similar models to determine whether the relative sizes of the two plumage traits at the population level varied among years. Finally, we used multiple regressions to establish if the relative yearly expression of an ornament affected standardized sexual selection gradients on this ornament in the given year. Conclusions: Within-individual changes in forehead and wing patch size were predicted by the climate of their moulting season (winter and summer, respectively). There was also an indirect effect of previous winter climate on changes in wing patch size. Environmental effects on the absolute expression of ornaments at the population level followed the within-individual patterns. The relative population-level expression of forehead and wing patches fluctuated significantly among years. Sexual selection on a given ornament increased with its relative expression in that year

Determinants of male territorial behavior in a Hungarian collared flycatcher population: plumage traits of residents and challengers

In intrasexual conflicts, contestants can rely on relative or absolute size of status badges to mediate aggressive behavior. Most studies focus on the response of focal animals to variation in status badges of their competitors; few have simultaneously considered the traits of both participants under experimental conditions. By simulating territorial intrusions, we tested the importance of two sexual traits [forehead patch size (FPS) and wing patch size (WPS)] in territorial behavior of males in a Hungarian population of the collared flycatcher, Ficedula albicollis. We presented a stimulus male to an unpaired resident male to examine whether the characteristics of the territory owner or those of the challenger were associated with the latency of the first attack of the owner, which is a good predictor of the territorial behavior in general. WPS of the stimulus male was a significant determinant of the latency of the first attack, as males with a larger WPS elicited quicker attacks from the residents than males with a small WPS. From the residents' perspective, age appeared to influence their territorial behavior, as yearlings had shorter attack latencies than older males. Additionally, latency could be considered an individual-specific attribute because it varied consistently among males, even when the WPS of the stimulus male was controlled, and it was associated with pairing success. Contrary to findings in a Swedish population, FPS seemed to be unimportant in male-male competition in our population, which suggests population differences in the role of the two plumage traits. Our results indicate that in a territorial conflict, the characteristics of both participants are important

Understanding FRET as a Research Tool for Cellular Studies

Communication of molecular species through dynamic association and/or dissociation at various cellular sites governs biological functions. Understanding these physiological processes require delineation of molecular events occurring at the level of individual complexes in a living cell. Among the few non-invasive approaches with nanometer resolution are methods based on Förster Resonance Energy Transfer (FRET). FRET is effective at a distance of 1–10 nm which is equivalent to the size of macromolecules, thus providing an unprecedented level of detail on molecular interactions. The emergence of fluorescent proteins and SNAP- and CLIP- tag proteins provided FRET with the capability to monitor changes in a molecular complex in real-time making it possible to establish the functional significance of the studied molecules in a native environment. Now, FRET is widely used in biological sciences, including the field of proteomics, signal transduction, diagnostics and drug development to address questions almost unimaginable with biochemical methods and conventional microscopies. However, the underlying physics of FRET often scares biologists. Therefore, in this review, our goal is to introduce FRET to non-physicists in a lucid manner. We will also discuss our contributions to various FRET methodologies based on microscopy and flow cytometry, while describing its application for determining the molecular heterogeneity of the plasma membrane in various cell types