Lateralized Function Without Lateralization

Abstract

In many vertebrates, the right hemisphere/left visual field is used to process information about threats while the left hemisphere/right visual field is used to process information about conspecifics. This is referred to as hemispheric lateralization. But prey that are too predictable in their response to predators could have reduced survival. We studied hemispheric lateralization in yellow-bellied marmots (Marmota flaviventer), a social rodent that falls prey to a variety of terrestrial and aerial predators. We first asked if they have lateralized responses to a predatory threat. We then asked if the eye that they used to assess risk influenced their perceptions of risk. We recorded the direction marmots were initially looking and then walked towards them at 0.5 m/s. We recorded the distance that they responded to our experimental approach by looking, the eye with which they looked at us, and the distance at which they fled (i.e., flight initiation distance; FID). We found that marmots had no eye preference with which they looked at an approaching threat. Furthermore, the population was not comprised of individuals that responded in consistent ways. However, we found that marmots who looked at the approaching person with their left eye had larger FIDs suggesting that risk assessment was influenced by they eye with which they used when assessing risk. These findings are consistent with selection to make prey less predictable for their predators, despite lateralized function.