Cerebral lateralization is a ubiquitous trait documented throughout all the branches of the phyletic tree, including that of invertebrate species1-2. Brain asymmetries that occur at the individual-level (i.e., individuals show either a left or right bias) are associated with several computational advantages3-4; however, mounting evidence is collected in favour of population-level lateralization (i.e., most individuals show the bias toward the same direction)5 that has apparent disadvantages (e.g., the predictability of the individuals’ responses). The adaptive benefit in the alignment of asymmetries within a population could lie in the facilitation of cooperation and defence behaviours and hence, should be especially evident in gregarious species6-7. We tested this hypothesis by investigating the detour responses of two sister families of invertebrate species: the cockroach (Gromphadorhina portentosa), a wingless hexapod, and the crayfish (Procambarus clarkii) a crustacean that can colonize new niches walking outside the aquatic environment. Both species navigate using the antennae, display aggressive interactions with conspecifics and multisensory social signalling8-9, but cockroaches are considered gregarious while crayfish solitary. In a formally identical labyrinth, animals could explore subsequent compartments. After the alignment of the body through a narrow corridor, a central physical obstacle forced a left-right detour choice in order to enter the next compartment. Few animals of both species displayed an individual-level lateralization (3 of the 102 cockroaches; 55 of the 202 crayfish). However, no population-level bias was evident in cockroaches, whereas crayfish showed a slight but consistent rightward bias in line with what observed in other vertebrate species10. Motivational rather than social aspects can account for the observed species’ differences. Whilst cockroaches were extremely fast and their navigational goal was to find a sheltered place where to hide, crayfish explored systematically and slowly the environment in order to find a physical discontinuity where to engage in burrowing activity.
Mind the obstacle: Lateralization of detour behaviour in two invertebrate species
CHIANDETTI, CINZIA
2016-01-01
Abstract
Cerebral lateralization is a ubiquitous trait documented throughout all the branches of the phyletic tree, including that of invertebrate species1-2. Brain asymmetries that occur at the individual-level (i.e., individuals show either a left or right bias) are associated with several computational advantages3-4; however, mounting evidence is collected in favour of population-level lateralization (i.e., most individuals show the bias toward the same direction)5 that has apparent disadvantages (e.g., the predictability of the individuals’ responses). The adaptive benefit in the alignment of asymmetries within a population could lie in the facilitation of cooperation and defence behaviours and hence, should be especially evident in gregarious species6-7. We tested this hypothesis by investigating the detour responses of two sister families of invertebrate species: the cockroach (Gromphadorhina portentosa), a wingless hexapod, and the crayfish (Procambarus clarkii) a crustacean that can colonize new niches walking outside the aquatic environment. Both species navigate using the antennae, display aggressive interactions with conspecifics and multisensory social signalling8-9, but cockroaches are considered gregarious while crayfish solitary. In a formally identical labyrinth, animals could explore subsequent compartments. After the alignment of the body through a narrow corridor, a central physical obstacle forced a left-right detour choice in order to enter the next compartment. Few animals of both species displayed an individual-level lateralization (3 of the 102 cockroaches; 55 of the 202 crayfish). However, no population-level bias was evident in cockroaches, whereas crayfish showed a slight but consistent rightward bias in line with what observed in other vertebrate species10. Motivational rather than social aspects can account for the observed species’ differences. Whilst cockroaches were extremely fast and their navigational goal was to find a sheltered place where to hide, crayfish explored systematically and slowly the environment in order to find a physical discontinuity where to engage in burrowing activity.File | Dimensione | Formato | |
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