Summary: Stamatakis & Stuber (2012)

Negative reward-related information is carried to the ventral portion of the middle brain (including the rostromedial tegmental nucleus) via projections of the lateral habenula. Stamatakis & Stuber (2012) studied the behavioural complications of selective activation of this particular pathway in the brain in mice. They found that aversive stimuli increased the excitatory drive of the lateral habenula, which resulted in conditioned, passive and active behavioural avoidance of the aversive stimulus. The activity of these projections to the midbrain is thus aversive, and functions to negatively reinforce behavioural response.

Summary: Markham et al. (2012)

Social species benefit from group living, however, social groups must also compete for resources with other groups. Competition can be a major driver influencing a group's movements and space use and has the potential to shape the evolution of sociality. Markham et al. (2012) investigated the ecological factors influencing baboon Papio cynocephalus group dominance, with a specific focus on what spatial features influence dominance and what occurs when a group is defeated. They found that the number of adult males in a group predicted which group would win a direct conflict, but they also found that a group's intensity of use of areas associated with the encounter location also predicted a win, over a longer time period (9-12 months). Losing groups  used the area surrounding the encounter location less, possibly incurring short-term costs associated with reduced access to resources. Markham et al.'s (2012) study highlights the importance of inter-group competition on social group space use.

Summary: Kronfeld-Schor et al. (2013)

The circadian "clock" is the body's internal mechanism for keeping track of time. This "clock" is driven by an individual's physiology and it influences an animal's behaviour on a daily basis. Alterations to environmental light conditions results in the natural time-keeping rhythms to become entrained to particular light-dark (day-night) cycles. The circadian system consists of molecular, cellular, tissue and organismal levels, and how these levels contribute to an individuals behaviour is quite well understood. The shortcomings of these studies relate to the species studied, typically those that are standard laboratory species that have been maintained in captivity (so called "model" organisms). Kronfeld-Schor et al. (2013) suggest that to understand the evolutionary significance of the circadian clock, we need to study a variety of species from multiple taxonomic groups that display a diversity in activity patterns (e.g. diurnal, nocturnal, cathemeral, crepuscular). In a special feature of the Proceedings of the Royal Society of London B, Kronfeld-Schor et al. (2013) highlight seven papers that attempt to explore the adaptive significance of the circadian clock, with the reviews including the influence of moonlight, latitude, evolutionary history, sociality, temporal niche specialization, annual variation and post-transcriptional mechanisms. These seven papers demonstrate the complexity, as well as the diversity, of the circadian system.