Weak Polygyny in California Sea Lions and the Potential for Alternative Mating Tactics

Female aggregation and male territoriality are considered to be hallmarks of polygynous mating systems. The development of genetic parentage assignment has called into question the accuracy of behavioral traits in predicting true mating systems. In this study we use 14 microsatellite markers to explore the mating system of one of the most behaviorally polygynous species, the California sea lion (Zalophus californianus). We sampled a total of 158 female-pup pairs and 99 territorial males across two breeding rookeries (San Jorge and Los Islotes) in the Gulf of California, Mexico. Fathers could be identified for 30% of pups sampled at San Jorge across three breeding seasons and 15% of sampled pups at Los Islotes across two breeding seasons. Analysis of paternal relatedness between the pups for which no fathers were identified (sampled over four breeding seasons at San Jorge and two at Los Islotes) revealed that few pups were likely to share a father. Thirty-one percent of the sampled males on San Jorge and 15% of the sampled males on Los Islotes were assigned at least one paternity. With one exception, no male was identified as the father of more than two pups. Furthermore, at Los Islotes rookery there were significantly fewer pups assigned paternity than expected given the pool of sampled males (p<0.0001). Overall, we found considerably lower variation in male reproductive success than expected in a species that exhibits behavior associated with strongly polygynous mating. Low variation in male reproductive success may result from heightened mobility among receptive females in the Gulf of California, which reduces the ability of males to monopolize groups of females. Our results raise important questions regarding the adaptive role of territoriality and the potential for alternative mating tactics in this species

Equal autophonic level curves under different room acoustics conditions

The indirect auditory feedback from one's own voice arises from sound reflections at the room boundaries or from sound reinforcement systems. The relative variations of indirect auditory feedback are quantified through room acoustic parameters such as the room gain and the voice support, rather than the reverberation time. Fourteen subjects matched the loudness level of their own voice (the autophonic level) to that of a constant and external reference sound, under different synthesized room acoustics conditions. The matching voice levels are used to build a set of equal autophonic level curves. These curves give an indication of the amount of variation in voice level induced by the acoustic environment as a consequence of the sidetone compensation or Lombard effect. In the range of typical rooms for speech, the variations in overall voice level that result in a constant autophonic level are on the order of 2 dB, and more than 3 dB in the 4 kHz octave band. By comparison of these curves with previous studies, it is shown that talkers use acoustic cues other than loudness to adjust their voices when speaking in different rooms. (C) 2011 Acoustical Society of America. [DOI: 10.1121/1.3598429]status: publishe

Hearing ones own voice during phoneme vocalization-Transmission by air and bone conduction

The relationship between the bone conduction (BC) part and the air conduction (AC) part of ones own voice has previously not been well determined. This relation is important for hearing impaired subjects as a hearing aid affects these two parts differently and thereby changes the perception of ones own voice. A large ear-muff that minimized the occlusion effect while still attenuating AC sound was designed. During vocalization and wearing the ear muff the ear-canal sound pressure could be related to the BC component of a persons own voice while the AC component was derived from the sound pressure at the entrance of an open ear-canal. The BC relative to AC sensitivity of ones own voice was defined as the ratio between these two components related to the ear-canal sound pressure at hearing thresholds for BC and AC stimulation. The results of ten phonemes showed that the BC part of ones own voice dominated at frequencies between 1 and 2 kHz for most of the phonemes. The different phonemes gave slightly different results caused by differences during vocalization. However, similarities were seen for phonemes with comparable vocalization.Original Publication:Sabine Reinfeldt, Per Ostli, Bo Hakansson and Stefan Stenfelt, Hearing one’s own voice during phoneme vocalization-Transmission by air and bone conduction, 2010, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, (128), 2, 751-762.http://dx.doi.org/10.1121/1.3458855Copyright: Acoustical Society of Americahttp://asa.aip.org