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Overli, O., Sorensen, C., Pulman, K. G. T., Pottinger, T. G., Korzan, W., Summers, C. H., et al. (2007). Evolutionary background for stress-coping styles: relationships between physiological, behavioral, and cognitive traits in non-mammalian vertebrates. Neurosci Biobehav Rev, 31(3), 396–412.
Abstract: Reactions to stress vary between individuals, and physiological and behavioral responses tend to be associated in distinct suites of correlated traits, often termed stress-coping styles. In mammals, individuals exhibiting divergent stress-coping styles also appear to exhibit intrinsic differences in cognitive processing. A connection between physiology, behavior, and cognition was also recently demonstrated in strains of rainbow trout (Oncorhynchus mykiss) selected for consistently high or low cortisol responses to stress. The low-responsive (LR) strain display longer retention of a conditioned response, and tend to show proactive behaviors such as enhanced aggression, social dominance, and rapid resumption of feed intake after stress. Differences in brain monoamine neurochemistry have also been reported in these lines. In comparative studies, experiments with the lizard Anolis carolinensis reveal connections between monoaminergic activity in limbic structures, proactive behavior in novel environments, and the establishment of social status via agonistic behavior. Together these observations suggest that within-species diversity of physiological, behavioral and cognitive correlates of stress responsiveness is maintained by natural selection throughout the vertebrate sub-phylum.
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Machnik, M., Hegger, I., Kietzmann, M., Thevis, M., Guddat, S., & Schanzer, W. (2007). Pharmacokinetics of altrenogest in horses. J Vet Pharmacol Ther, 30(1), 86–90.
Abstract: The Federation Equestre Internationale has permitted the use of altrenogest in mares for the control of oestrus. However, altrenogest is also suspicious to misuse in competition horses for its potential anabolic effects and suppression of typical male behaviour, and thus is a controlled drug. To investigate the pharmacokinetics of altrenogest in horses we conducted an elimination study. Five oral doses of 44 mug/kg altrenogest were administered to 10 horses at a dose interval of 24 h. Following administration blood and urine samples were collected at appropriate intervals. Altrenogest concentrations were measured by liquid chromatography-tandem mass spectrometry. The plasma levels of altrenogest reached maximal concentrations of 23-75 ng/mL. Baseline values were achieved within 3 days after the final administration. Urine peak concentrations of total altrenogest ranged from 823 to 3895 ng/mL. Twelve days after the final administration concentrations were below the limit of detection (ca 2 ng/mL).
Keywords: Administration, Oral; Animals; Chromatography, Liquid/veterinary; Doping in Sports/prevention & control; Horses/*metabolism; Male; Mass Spectrometry/veterinary; Progesterone Congeners/administration & dosage/blood/*pharmacokinetics/urine; Reproducibility of Results; Substance Abuse Detection/veterinary; Trenbolone/administration & dosage/*analogs & derivatives/blood/pharmacokinetics/urine
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Giraldeau, L. - A., Lefebvre, L., & Morand-Ferron, J. (2007). Can a restrictive definition lead to biases and tautologies? Behav. Brain Sci., 30(4), 411–412.
Abstract: We argue that the operational definition proposed by Ramsey et al. does not represent a significant improvement for students of innovation, because it is so restrictive that it might actually prevent the testing of hypotheses on the relationships between innovation, ecology, evolution, culture, and intelligence. To avoid tautological thinking, we need to use an operational definition that is taxonomically unbiased and neutral with respect to the hypotheses to be tested.
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Vervaecke, H., Stevens, J., Vandemoortele, H., Sigurjönsdöttir, H., & De Vries, H. (2007). Aggression and dominance in matched groups of subadult Icelandic horses (Equus caballus). J. Ethol., 25(3), 239–248.
Abstract: Abstract We studied sex differences in the nature of aggression and dominance behaviour in two newly formed groups of 1-year-old Icelandic horses. One herd contained nine geldings, the other nine mares. The groups were matched with regard to dominance-determining traits such as age, weaning age, composition of native herd, social experience, genetic origin, body condition and maternal dominance status. High-ranking individuals of both sexes were more aggressive, high-ranking males were older, and high-ranking females had a better body condition. Frequencies of aggressions were similar in both groups. The mares reacted significantly more by showing submission upon an aggression rather than by not responding or by escalating the aggression. For the geldings, this difference was not observed due to a lower tendency to submit. A linear dominance hierarchy was found in both groups. David`s scores provided additional information regarding cardinal rank distances and were used to calculate steepness of hierarchies. The female hierarchy was somewhat steeper compared to the male hierarchy, suggesting somewhat lower despotism among males. This was mainly a consequence of the lower unidirectionality in male submission. Male contests occurred predominantly between dyads at top and mid positions, suggesting a low degree of acceptance of the hierarchy.
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Tibbetts, E. A., & Dale, J. (2007). Individual recognition: it is good to be different. Trends. Ecol. Evol, 22(10), 529–537.
Abstract: Individual recognition (IR) behavior has been widely studied, uncovering spectacular recognition abilities across a range of taxa and modalities. Most studies of IR focus on the recognizer (receiver). These studies typically explore whether a species is capable of IR, the cues that are used for recognition and the specializations that receivers use to facilitate recognition. However, relatively little research has explored the other half of the communication equation: the individual being recognized (signaler). Provided there is a benefit to being accurately identified, signalers are expected to actively broadcast their identity with distinctive cues. Considering the prevalence of IR, there are probably widespread benefits associated with distinctiveness. As a result, selection for traits that reveal individual identity might represent an important and underappreciated selective force contributing to the evolution and maintenance of genetic polymorphisms.
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Kraft, C. N., Urban, N., Ilg, A., Wallny, T., Scharfstadt, A., Jager, M., et al. (2007). [Influence of the riding discipline and riding intensity on the incidence of back pain in competitive horseback riders]. Sportverletz Sportschaden, 21(1), 29–33.
Abstract: INTRODUCTION: The connection between morphologic changes of the spine and the intensity of training has been assessed for a number of sport activities. The influence of horseback riding on the spine has only rarely been evaluated. The aim of our study was to evaluate to what degree horseback riders suffer from back pain and whether there is an association between this parameter and the category i. e. the intensity of horseback riding. Furthermore we wanted to judge whether riding may have a positive effect on pre-existent back pain. METHODS: 508 horseback riders (63.2 % females; 36.8 % males) competing in either dressage, showjumping or vaulting were interviewed using a questionnaire. Apart from biometric data, the intensity with which riding was performed and the localisation and intensity (VAS) of back pain was assessed. Furthermore, in the case of existing back pain, riders were asked whether different riding disciplines and paces changed the intensity of pain. RESULTS: 300 dressage riders (59.1 %), 188 showjumpers (37.0 %) and 20 vaulters (3.9 %) with an average age of 33.5 Jahre (12 – 77 years) were questioned. The incidence of back pain was 72.5 %. A significant correlation between back pain and riding discipline respectively gender or riding level could not be found. Discrepancies in VAS-score for dressage riders (3.95 +/- 0.13), show jumpers (4.10 +/- 0.16) and vaulters (3.76 +/- 0.5) were marginal and not significant (p > 0.05). Overall 58.7 % resp. 15.2 % reported to have pain in the lumbar i.e cervical spine. Despite the fact that a large fraction of dressage riders claimed to have problems in these spine areas with 57.7 % resp. 68.8 %, this finding was not significant compared to the other riding disciplines. While 61.6 % of dressage riders reported an improvement of their back pain when riding, this was only the case in 40.9 % of show jumpers. CONCLUSION: Compared to the general population, a high incidence of back pain is found among riders. A significant correlation between the intensity of riding or the riding discipline and frequency or severity of back pain could not be found. For riders with pre-existent back pain the pace “walk” seems to have a positive influence on pain intensity.
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Lusseau, D. (2007). Evidence for social role in a dolphin social network. Evol. Ecol., 21(3), 357–366.
Abstract: Abstract Social animals have to take into consideration the behaviour of conspecifics when making decisions to go by their daily lives. These decisions affect their fitness and there is therefore an evolutionary pressure to try making the right choices. In many instances individuals will make their own choices and the behaviour of the group will be a democratic integration of everyone’s decision. However, in some instances it can be advantageous to follow the choice of a few individuals in the group if they have more information regarding the situation that has arisen. Here I provide early evidence that decisions about shifts in activity states in a population of bottlenose dolphin follow such a decision-making process. This unshared consensus is mediated by a non-vocal signal, which can be communicated globally within the dolphin school. These signals are emitted by individuals that tend to have more information about the behaviour of potential competitors because of their position in the social network. I hypothesise that this decision-making process emerged from the social structure of the population and the need to maintain mixed-sex schools.
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Rankin, D. J., Lopez-Sepulcre, A., Foster, K. R., & Kokko, H. (2007). Species-level selection reduces selfishness through competitive exclusion. Journal of Evolutionary Biology, 20(4), 1459–1468.
Abstract: Abstract Adaptation does not necessarily lead to traits which are optimal for the population. This is because selection is often the strongest at the individual or gene level. The evolution of selfishness can lead to a .tragedy of the commons., where traits such as aggression or social cheating reduce population size and may lead to extinction. This suggests that species-level selection will result whenever species differ in the incentive to be selfish. We explore this idea in a simple model that combines individual-level selection with ecology in two interacting species. Our model is not influenced by kin or trait-group selection. We find that individual selection in combination with competitive exclusion greatly increases the likelihood that selfish species go extinct. A simple example of this would be a vertebrate species that invests heavily into squabbles over breeding sites, which is then excluded by a species that invests more into direct reproduction. A multispecies simulation shows that these extinctions result in communities containing species that are much less selfish. Our results suggest that species-level selection and community dynamics play an important role in regulating the intensity of conflicts in natural populations.
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Shrader, A. M., Kerley, G. I. H., Kotler, B. P., & Brown, J. S. (2007). Social information, social feding, and competition in group-living goats (Capra hircus). Behav. Ecol., 18(1), 103–107.
Abstract: There are both benefits (e.g., social information) and costs (e.g., intraspecific competition) for individuals foraging in groups. To ascertain how group-foraging goats (Capra hircus) deal with these trade-offs, we asked 1) do goats use social information to make foraging decisions and 2) how do they adjust their intake rate in light of having attracted by other group members? To establish whether goats use social information, we recorded their initial choice of different quality food patches when they were ignorant of patch quality and when they could observe others foraging. After determining that goats use social information, we recorded intake rates while they fed alone and in the presence of potential competitors. Intake rate increased as the number of competitors increased. Interestingly, lone goats achieved an intake rate that was higher than when one competitor was present but similar to when two or more competitors were present. Faster intake rates may allow herbivores to ingest a larger portion of the available food before competing group members arrive at the patch. This however, does not explain the high intake rates achieved when the goats were alone. We provide 2 potential explanations: 1) faster intake rates are a response to greater risk incurred by lone individuals, the loss of social information, and the fear of being left behind by the group and 2) when foraging alone, intake rate is no longer a trade-off between reducing competition and acquiring social information. Thus, individuals are able to feed close to their maximum rate.
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J. Keay-Bright, J. B. (2007). The influence of land management on soil erosion in the Sneeuberg Mountains, Central Karoo, South Africa. Land Degradation & Development, 18(4), 423–439.
Abstract: Farm practices in the Sneeuberg Mountains, Karoo, South Africa are examined to assess their contribution to the development of the observed gullies and badlands. Data from the literature is augmented by interviews with local farmers and measurements in the field. Changes in stocking rates, grazing systems and technological advances are assessed for their impact on soil erosion, vegetation cover and species composition. The possibility of natural and managed rehabilitation of badland areas is discussed, as are future prospects for farm management in the Sneeuberg. The findings suggest that high stock numbers and less benign management practices in the 19th century and the early 20th century underlie much of the degradation seen today. Copyright – 2007 John Wiley & Sons, Ltd.
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