Lateralisation of escape responses in the stripe-faced dunnart, Sminthopsis macroura (Dasyuridae: Marsupialia)

Abstract

Although lateralisation has been observed in many vertebrate species, marsupials have been neglected in the study of lateralisation. We investigated the behavioural responses of the stripe-faced dunnart (Sminthopsis macroura) to a mechanical model of a snake approaching into the monocular (left and right) or the binocular visual field. The snake model was presented to 30 adult subjects. The behavioural responses and the latency to react to the stimulus were scored. Reactivity was calculated by pooling scores for retreat, startle, ears back, and orientation. Retreat tended to be the most common of these responses. Approach of the snake into the dunnarts' left monocular visual field elicited a significantly higher reactivity compared to approach into the right or binocular visual field. Half of the animals did not respond in the 60 seconds allocated when the stimulus approached on their right side, whereas only seven did not respond when the stimulus approached on the left, and ten when the stimulus was presented binocularly. These results are consistent with the right hemisphere's known specialisation for controlling fear and escape responses. Our results suggest that marsupials are lateralised in a way similar to other vertebrates.

The costs of hemispheric specialization in a fish

“…The literature contains many other examples of remarkable left -right differences in the behavioural response. For example, toads, chicks and dunnarts differ in their promptness to react to a predator depending on the visual hemifield in which it appears (Lippolis et al 2002(Lippolis et al , 2005Dharmaretnam & Rogers 2005), and mosquitofish make closer cooperative predator inspection when predator and shoalmates are seen with the correspondingly preferred eye (De Santi et al 2001). Gelada baboons and Anolis lizards are more likely to attack a conspecific on one side than the other (Deckel 1995;Casperd & Dunbar 1996), and side biases are shown by toads, chicks and pigeons in food detection (Vallortigara et al 1998;Diekamp et al 2005).…”

Australian Lungfish <i>(Neoceratodus forsteri)</i>: A Missing Link in the Evolution of Complementary Side Biases for Predator Avoidance and Prey Capture

“…In other words, the right side of the brain is in control. This function of the right hemisphere seems to have been conserved throughout vertebrate evolution as it is also present in the predator-avoidance responses of fish [Bisazza et al, 1997a, b], toads [Lippolis et al, 2002] and the marsupial, Sminthopsis macroura [Lippolis et al, 2005].…”

Intraspecific competition and coordination in the evolution of lateralization

“…This hypothesis recognizes that brain asymmetries manifest themselves in behaviour, and thus may have fitness consequences in interactions with other organisms. For instance, vigilance behaviour and escape responses elicited by predators often show lateral biases (Lippolis et al 2002(Lippolis et al , 2005Vallortigara & Rogers 2005). We have studied this idea in a game-theoretical model considering group-living prey subjected to predation (Ghirlanda & Vallortigara 2004;Vallortigara 2006).…”