Abstract: Research on mate choice has primarily focused on preferences for quality indicators, assuming that all individuals show consensus about who is the most attractive. However, in some species, mating preferences seem largely individual-specific, suggesting that they might target genetic or behavioral compatibility. Few studies have quantified the fitness consequences of allowing versus preventing such idiosyncratic mate choice. Here, we report on an experiment that controls for variation in overall partner quality and show that zebra finch (Taeniopygia guttata) pairs that resulted from free mate choice achieved a 37% higher reproductive success than pairs that were forced to mate. Cross-fostering of freshly laid eggs showed that embryo mortality (before hatching) primarily depended on the identity of the genetic parents, whereas offspring mortality during the rearing period depended on foster-parent identity. Therefore, preventing mate choice should lead to an increase in embryo mortality if mate choice targets genetic compatibility (for embryo viability), and to an increase in offspring mortality if mate choice targets behavioral compatibility (for better rearing). We found that pairs from both treatments showed equal rates of embryo mortality, but chosen pairs were better at raising offspring. These results thus support the behavioral, but not the genetic, compatibility hypothesis. Further exploratory analyses reveal several differences in behavior and fitness components between “free-choice” and “forced” pairs.

Abstract: <p>Although previous studies of horses have investigated their facial expressions in specific contexts, e.g. pain, until now there has been no methodology available that documents all the possible facial movements of the horse and provides a way to record all potential facial configurations. This is essential for an objective description of horse facial expressions across a range of contexts that reflect different emotional states. Facial Action Coding Systems (FACS) provide a systematic methodology of identifying and coding facial expressions on the basis of underlying facial musculature and muscle movement. FACS are anatomically based and document all possible facial movements rather than a configuration of movements associated with a particular situation. Consequently, FACS can be applied as a tool for a wide range of research questions. We developed FACS for the domestic horse (<italic>Equus caballus</italic>) through anatomical investigation of the underlying musculature and subsequent analysis of naturally occurring behaviour captured on high quality video. Discrete facial movements were identified and described in terms of the underlying muscle contractions, in correspondence with previous FACS systems. The reliability of others to be able to learn this system (EquiFACS) and consistently code behavioural sequences was high?and this included people with no previous experience of horses. A wide range of facial movements were identified, including many that are also seen in primates and other domestic animals (dogs and cats). EquiFACS provides a method that can now be used to document the facial movements associated with different social contexts and thus to address questions relevant to understanding social cognition and comparative psychology, as well as informing current veterinary and animal welfare practices.</p>

Abstract: The proliferation of genetically modified mouse models has exposed phenotypic variation between investigators and institutions that has been challenging to control1-5. In many cases, the microbiota is the presumed culprit of the variation. Current solutions to account for phenotypic variability include littermate and maternal controls or defined microbial consortia in gnotobiotic mice6,7. In conventionally raised mice, the microbiome is transmitted from the dam2,8,9. Here we show that microbially–driven dichotomous fecal IgA levels in WT mice within the same facility mimic the effects of chromosomal mutations. We observed in multiple facilities that vertically-transmissible bacteria in IgA-Low mice dominantly lowered fecal IgA levels in IgA-High mice after cohousing or fecal transplantation. In response to injury, IgA-Low mice showed increased damage that was transferable by fecal transplantation and driven by fecal IgA differences. We found that bacteria from IgA-Low mice degraded the secretory component (SC) of SIgA as well as IgA itself. These data indicate that phenotypic comparisons between mice must take into account the non-chromosomal hereditary variation between different breeders. We propose fecal IgA as one marker of microbial variability and conclude that cohousing and/or fecal transplantation enables analysis of progeny from different dams.

Abstract: Use of the right hand by humans for speech-related hand gestures, writing and throwing exemplifies motoric asymmetry. There are reports of asymmetry in many other animal species, including reports of left preference in emotional responsivity, spontaneous behaviour and the trained performance of the horse, Equus ferus caballus. The present study used the novel approach of using judges' scores to examine asymmetry in an equestrian event. The study analysed the scores of five judges evaluating the reining performance of 482, three-year-old American Quarter Horses competing in a major competition. Reining requires that the horses perform the manoeuvres of spin, circle and stop directed to either the left or right and symmetrical performance is featured in the judging criteria. The scores were sensitive to performance level, sex and manoeuvre, but there was no evidence of a population asymmetry in the left vs. right direction of the manoeuvres. The results are discussed in relation to need of using a large number of subjects in measuring asymmetry, the expression of individual vs. population asymmetry as a function of morphological and behavioural measures, and the influence of behavioural training on asymmetry.

Abstract: Previous empirical work on animal social learning has found that many species lack the ability to learn entire action sequences solely through reliance on social information. Conversely, acquiring action sequences through asocial learning can be difficult due to the large number of potential sequences arising from even a small number of base actions. In spite of this, several studies report that some primates use action sequences in the wild. We investigate how social information can be integrated with asocial learning to facilitate the learning of action sequences. We formalize this problem by examining how learners using temporal difference learning, a widely applicable model of reinforcement learning, can combine social cues with their own experiences to acquire action sequences. The learning problem is modeled as a Markov decision process. The learning of nettle processing by mountain gorillas serves as a focal example. Through simulations, we find that the social facilitation of component actions can combine with individual learning to facilitate the acquisition of action sequences. Our analysis illustrates that how even simple forms of social learning, combined with asocial learning, generate substantially faster learning of action sequences compared to asocial processes alone, and that the benefits of social information increase with the length of the action sequence and the number of base actions.