Female and male serins ( Serinus serinus ) respond differently to derived song traits

Abstract We tested if male or female behavior towards manipulated song indicates intra- or inter-sexual selection of two characteristics of serin song that are extreme and evolutionarily derived in this species: high frequency and fast syllable rate. In a first experiment, we monitored vocal responses and attendance to song playbacks. Female behavior indicated a preference for high-frequency song and suggested an aggressive function for fast syllable rates, as fast songs inhibited vocal response. Males did not show discrimination of frequency or syllable rate with this experimental design. The second experiment used a simple approach/no approach design, and in this experiment, males showed stronger discrimination between stimuli than did females. Therefore, sex differences in discrimination appear not to result from differences in perceptual abilities but from differences in the context of stimulus presentation. The second experiment also supported a role of song frequency in female choice, as the effect of frequency was limited to females: males did not respond differently to song frequency and approached high-frequency songs less than females did. Results of this experiment also supported an aggressive function for fast syllable rates, as the effect of fast songs did extend to male behavior. Taken together, our results indicate that the high frequency and fast syllable rate of serin song cannot result from a single selection process: while high frequency may have evolved by inter-sexual selection, syllable rate provokes a pattern of response that is more consistent with intra-sexual selection

Stable (H, O, C) and noble-gas (He and Ar) isotopic compositions from calcite and fluorite in the Speewah Dome, Kimberley Region, Western Australia: implications for the conditions of crystallization and evidence for the influence of crustal-mantle fluid mixing

In this study, the C-O-isotopic data from calcite at Yungul and Wilmott (Speewah. Western-Australia) are integrated with microthermometry, H2O-, CO2-content and H-He-Ar-isotopic data from fluid inclusions in genetically related calcite and fluorite to map the origin and crystallization paths of the fluids. In addition to the hydrogen isotopic compositions of fluid inclusions in fluorite, oxygen isotopic compositions were also determined by cavity ring-down spectroscopy. The geochemical data suggest mixing of a CO2-dominated mantle fluid and a H2O-domintated crustal brine. The fluid produced by this mixing is characterized by radiogenic (crustal-like) He-3/He-4 ratios, crustal-like dD values, relatively high salinity (19-24wt.% NaCl eq.), moderate homogenization temperatures (150-450 degrees C) and mantle-like CO2/He-3 ratios. Moreover, the large isotopic and elemental variations found in calcite indicate that its formation was accompanied by an extensive degassing (open system) leading to a decrease in dD and an increase in the CO2/He-3 values relative to the starting fluid composition. This degassing is consistent with the fluidal- and breccia-like texture of calcite observed in the field. In contrast, the fluorite which has coarse-grained banded to vughy textures formed in a passive aqueous system. Apparently the fluid that formed the fluorite has the same origin as the calcite, but the higher water content and the more radiogenic He-3/He-4 ratios reflect a greater involvement of crustal fluids. The historical description of the calcite-fluorite system in the Speewah area as "carbonatite" is now considered inappropriate because there is no evidence that crystallization is dominated by magmatic processes