Alle Publikationen
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2017
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(2017): Antioxidant allocation modulates sperm quality across changing social environments. In: PLoS one 12 (5). DOI: 10.1371/journal.pone.0176385
DOI: http://www.ncbi.nlm.nih.gov/pubmed/28472052 Abstract: In promiscuous species, male reproductive success depends on their ability to mate with fertile females and on the fertilizing ability of their sperm. In such species, theory predicts that, owing to a trade-off between pre- and post-copulatory reproductive traits, males with lesser access to females should increase resource investment into those sperm traits that enhance fertilization success-usually referred to as ejaculate quality. This prediction has been validated in several taxa, yet studies on the physiological mechanisms modulating ejaculate quality are lacking. Sperm cells are highly vulnerable to oxidative stress, which impairs male fertility. Therefore, males that better protect their sperm from oxidative stress are expected to achieve higher ejaculate quality. Based on theoretical expectations, and since social dominance is a major determinant of mating opportunity, we predicted that subordinate males should invest more into the antioxidant protection of their sperm in order to achieve higher ejaculate quality. We maintained 60 male and 60 female wild-caught house sparrows Passer domesticus in outdoor aviaries, where we experimentally manipulated male social status to test our predictions. We measured cellular oxidative stress and enzymatic antioxidant activity in blood and sperm both before and after manipulating social ranks. Before manipulating the social status, we found that ejaculate viability correlated with oxidative stress level in sperm, with dominant males producing more oxidized and less viable ejaculates. Further, males at the lower end of the hierarchy produced ejaculates of similar quality to those of dominant males, suggesting that restricted access to resources might limit male reproductive strategies. After experimentally manipulating the social status, males matched their ejaculate quality to their new rank, while increases in antioxidant investment into ejaculates paralleled increases in ejaculate viability. Oxidative stress has been proposed as a general constraint to the evolution of life histories. Our results highlight oxidative stress and strategic antioxidant allocation as important proximate physiological mechanisms underlying male reproductive strategies.
2016
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(2016): Agent-based modelling in applied ethology. An exploratory case study of behavioural dynamics in tail biting in pigs. In: Applied Animal Behaviour Science 183, S. 10-18. DOI: 10.1016/j.applanim.2016.07.011
Abstract: Understanding behavioural dynamics in pigs is important to assess pig welfare in current intensive pig production systems. Agent-based modelling (ABM) is an approach to gain insight into behavioural dynamics in pigs, but its use in applied ethology and animal welfare science has been limited so far. We used ABM in a case study on tail biting behaviour in pigs to explore the use of ABM in gaining more insight into emergent injurious pig behaviour and related welfare issues in intensive production systems. We developed an agent-based model in Netlogo 5.1.0 to simulate tail biting behaviour of pigs housed in conventional pens in groups of 10. Pigs in the model started as neutral pigs (not involved in biting incidents), but could change into a biter, victim, or both biter and victim. Tail biting behaviour could emerge when pigs were unable to fulfil their internal motivation to explore. The effects of a redirected exploratory motivation, behavioural changes in victims and preference to bite a lying pig on tail biting patterns were tested in our model. The simulations with the agent-based model showed that coincidence in development of a redirected exploratory motivation can lead to tail biting behaviour in pigs and can explain the strong variations in incidence of tail biting behaviour observed in conventionally housed pigs. Behavioural changes in victims and preference to bite a lying pig seem to be of minor importance in the causation of tail biting patterns. The behavioural time budget of a pig might be an important factor in predisposing pigs to or preventing them from becoming a tail biter or a victim. ABM showed to be useful in analysing behavioural dynamics and welfare issues. An advantage for ABM in applied ethology is the availability of data from empirical studies.
2014
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(2014): Social behaviours in dog-owner interactions can serve as a model for designing social robots. In: Interaction Studies 15 (2), S. 143-172. DOI: 10.1075/is.15.2.01far
Abstract: It is essential for social robots to fit in the human society. In order to facilitate this process we propose to use the family dog's social behaviour shown towards humans as an inspiration. In this study we explored dogs' low level social monitoring in dog-human interactions and extracted individually consistent and context dependent behaviours in simple everyday social scenarios. We found that proximity seeking and tail wagging were most individually distinctive in dogs, while activity, orientation towards the owner, and exploration were dependent on the context and/or the activity of the owner. The functional analogues of these dog behaviours can be implemented in social robots of different embodiments in order to make them acceptable and more believable for humans. The paper presents an ethological perspective on designing robot behaviors for successful social interactions with humans. In particular, the types of behaviors that occur in interactions between dogs and their owners are analyzed to provide insights into how robot behaviors should be created. It is essential for social robots to fit in the human society. In order to facilitate this process we propose to use the family dog's social behaviour shown towards humans as an inspiration. In this study we explored dogs' low level social monitoring in dog-human interactions and extracted individually consistent and context dependent behaviours in simple everyday social scenarios. We found that proximity seeking and tail wagging were most individually distinctive in dogs, while activity, orientation towards the owner, and exploration were dependent on the context and/or the activity of the owner. The functional analogues of these dog behaviours can be implemented in social robots of different embodiments in order to make them acceptable and more believable for humans.
2005
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(2005): The decorum of a defecating dog. In: PRINT QUARTERLY 22 (2), S. 119-132
Abstract: In his otherwise grandiose, monumental woodcut, the "Submersion of Pharaoh's Army in the Red Sea", Titian included a realistic depiction of a defecating dog (figs. 39-40). The dog is one small figure in a huge work, but is prominently placed in the foreground, so that it and Moses' commanding arm are the only elements projecting into a block otherwise filled with water. The few scholars who have commented on this detail have tended to dismiss it as an insignificant vulgarity or tasteless lapse in decorum.
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