Summary: Guttridge et al. (2009)

Sharks are often seen to associate in groups, but the structure (composition and organization) of these groups is unknown. Guttridge et al. (2009) aimed to quantify the social preferences of juvenile lemon sharks Negaprion brevirostris that live in close association with heterospecific nurse sharks Ginglymostoma cirratum. Juvenile lemon sharks associated with conspecifics in binary choice field experiments. Guttridge et al. (2009) found that 2-3 year old lemon sharks preferred groups of size-matched individuals and associated with conspecifics more than with heterospecifics. Their study provides further information on group-joining decisions and suggest that active mechanisms play a role in shark group formation and structure. Furthermore, shark associations provide opportunities for investigating social learning and cooperation in these fish.

Summary: Kim et al. (2011)

Gene-environment interactions influence the evolution of begging displays in bird chicks. The strength (intensity) of within-brood sibling competition, one mechanism thought to influence evolution of begging display, can cause begging behaviour to vary in response to environmental conditions experienced by offspring. Kim et al. (2011) broke down the the begging display of yellow-legged gull (Larus michahelis)chicks into 2 different functional components: 1) pecks (associated with pee calls) = begging for food; and 2) chatter calls = attention-seeking behaviour. They found, using a begging test, that males and chicks in poor-body condition begged at higher rates, while chicks from male-biased broods begged less frequently. Furthermore, chicks from larger broods begged more frequently. Their results suggest that chicks adjust their individual begging efforts to the strength of of sibling competition, if begging is costly. They also found that genetic origin had a significant effect on the frequency of chatter calls, but not on begging. Frequency of chatter calls also varied with sex, chick order within a brood and body condition. Kim et al. (2011) suggest that chatter calls can be subject to evolution under directional selection and that different begging components may have evolved through different evolutionary pathways.

Summary: Dormann et al. (2010)

It has been suggested that closely related species share similar climate niches. To test this hypothesis, Dormann et al. (2010) used distribution data for 140 European mammal species, together with climate, land cover and topographical data (to fit species distribution models) in order to derive an estimate of the mammals realised climate niches and to investigate their degree of overlap. They compared climate niche overlap of species pairs and found that closely related species differed in their climate niches, but display high climate niche distances. Dormann et al. (2010) interpret this finding as a strong interspecific competitive constraint on the fundamental niche. Their results imply a flexibility of realised climate niches that are independent of phylogenetic distance. Furthermore, the suggest that climate niche models may not be particularly useful for the prediction of future mammal distributions.

Summary: Hilário & Ferrari (2010)

Infanticide is a common phenomenon, usually caused by polygynous males taking over a harem with unrelated infants. Hilário & Ferrari (2010) describe rwo incidences of infanticide in a free-ranging group of
buffy-head marmosets (Callithrix flaviceps) in 2008, the first observed incidence in this species. Over a 10-day period, 4 females within the group gave birth, with the infanticides occurring on the third and sixth days. The perpetrator in the first incident was unknown, but the socially dominant breeding female is likely to have caused both as she was observed ingesting the second infant's head. The behaviour appears typical of marmosets in general. The strategy of the socially dominant breeding female attacking offspring of subordinates is likely aimed at reducing competition for caregivers.

Summary: Bartsch et al. (2010)

The hippocampus is an important structure for the processing of place learning tasks and topographical memory. Cells in the cormu ammonis 1 (CA1) sector of the hippocampus in rodents and primates have been shown to play an important part in place learning, specifically with regards to navigation and consolidation of spatial memory. However, it is unknown what role these cells play in the human hippocampus. Transient global amnesia (TGA) is a rare, self-limiting dysfunction of the hippocampus. Using a virtual Morris water maze, Bartsch et al. (2010) investigated 14 patients with TGA (selective and focal lesions in the CA1 sector of the hippocampus) to determine the role of CA1 cells in place learning. All individuals showed a profound impairment in place learning, with lesion size and TGA duration correlated with decreased performance. Bartsch et al. (2010) results indicate that, like rodents and primates, cells in this area of the hippocampus (CA1) play an important in place learning in humans.