Selection on multiple sexual signals in two Central and Eastern European populations of the barn swallow

Variation in intensity and targets of sexual selection on multiple traits has been suggested to play a major role in promoting phenotypic differentiation between populations, although the divergence in selection may depend on year, local conditions or age. In this study, we quantified sexual selection for two putative sexual signals across two Central and East European barn swallow (Hirundo rustica rustica) populations from Czech Republic and Romania over multiple years. We then related these differences in selection to variation in sexual characters among barn swallow populations. Our results show that tail length and ventral coloration vary between populations, sexes, and age classes (first‐time breeders vs. experienced birds). We found that selection on tail length was stronger in first‐time breeders than in experienced birds and in males than in females in the Romanian population, while these differences between age groups and sexes were weak in Czech birds. We suggest that the populational difference in selection on tail length might be related to the differences in breeding conditions. Our results show that ventral coloration is darker (i.e., has lower brightness) in the Romanian than in the Czech population, and in experienced birds and males compared with first‐time breeders and females, respectively. The sexual difference in ventral coloration may suggest sexual selection on this trait, which is supported by the significant directional selection of ventral coloration in first‐time breeding males on laying date. However, after controlling for the confounding effect of wing length and tarsus length, the partial directional selection gradient on this trait turned nonsignificant, suggesting that the advantage of dark ventral coloration in early breeding birds is determined by the correlated traits of body size. These findings show that ventral coloration may be advantageous over the breeding season, but the underlying mechanism of this relationship is not clarified

Aplikace elektrofyzikalni metody pri urcovani kvality prirodni slozky prostredi - drevin.

Each type of plant demonstrates its own phyto-electric (P-E) currents. The value of the P-E currents increases with the tree's age. Plants annually maintain a periodical course with maximum values during summer and minimum values in winter. The highest P-E activity is always concentrated in the trunk cambia layers. The comparison of the health state and the values of P-E currents have brought new dimensions in the classification of tree vitality. Healthy trees reach the highest P-E currents. The worst is the state of a tree the quicker is the rate of deterioration. The entire changing process of a tree's health state can be precisely monitored. Assessing a tree's health state with visual methods is not precise. Changes of the mesh electric conduction are related to changes in water capacity and electrolytes concentration. Electric conduction of the mesh seldom changes at short intervals. Measuring electric impedance or electric conduction of a tree mesh in cambial zones can be used to determine cambial activity, which correlates to tree vitality. During the dormant phase vitality decreases and electric resistence in the mesh increases. The given electric characteristics are influenced by certain physiological processes such as the metabolism and growth intensity. However, these factors are co-related to the tree's vitality. Measuring electronic resistance of the mesh in the cambial zone has proved that its changes are co-related to season changes. The lower resistance values correlates to higher relative vitality of the tree. One can name it electric impedance or electric conduction of tree tree mesh. Both mentioned terms have their own physical unitis which can be compared to tree vitality and then mathematically calculated.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Temporal Stability and the Effect of Transgenerational Transfer on Fecal Microbiota Structure in a Long Distance Migratory Bird

Animal bodies are inhabited by a taxonomically and functionally diverse community of symbiotic and commensal microorganisms. From an ecological and evolutionary perspective, inter-individual variation in host-associated microbiota contributes to physiological and immune system variation. As such, host-associated microbiota may be considered an integral part of the hosts phenotype, serving as a substrate for natural selection. This assumes that host-associated microbiota exhibits high temporal stability, however, and that its composition is shaped by trans-generational transfer or heritable host-associated microbiota modulators encoded by the host genome. Although this concept is widely accepted, its crucial assumptions have rarely been tested in wild vertebrate populations. We performed 16S rRNA metabarcoding on an extensive set of fecal microbiota (FM) samples from an insectivorous, long-distance migratory bird, the barn swallow (Hirundo rustica). Our data revealed clear differences in FM among juveniles and adults as regards taxonomic and functional composition, diversity and co-occurrence network complexity. Multiple FM samples from the same juvenile or adult collected within single breeding seasons exhibited higher similarity than expected by chance, as did adult FM samples over two consecutive years. Despite low effect sizes for FM stability over time at the community level, we identified an adult FM subset with relative abundances exhibiting significant temporal consistency, possibly inducing long-term effects on the host phenotype. Our data also indicate a slight maternal (but not paternal) effect on FM composition in social offspring, though this is unlikely to persist into adulthood. We discuss our findings in the context of both evolution and ecology of microbiota vs. host interactions and barn swallow biology