The Development of Anxiety and Exploration in Two Species of the African Striped Mouse Rhabdomys.

Genes and the environment interact to produce complex, environmentally relevant behaviors. We tested whether the behavior of two sister species of striped mice originating from different habitats (semi-arid Rhabdomys pumilio and grassland R. bechuanae) are modulated by the early social rearing environment. We cross-fostered pups between the species, and at adulthood tested their exploratory behavior and anxiety in open field and novel object tests, and a plus maze. We expected that the early social rearing environment would alter the phenotype of both species. Regardless of treatment, R. bechuanae were more exploratory and slightly less anxious than R. pumilio. However, fostered individuals of both species showed no changes in exploratory and anxiety responses. Thus there may be a genetic influence on behavioral development, or the early rearing environments of R. pumilio and R. bechuanae are not sufficiently different to alter behavior.

Environmental correlates of exploratory behavior and anxiety in three African striped mouse (Rhabdomys) taxa occurring in different habitats and contexts.

Species or populations are locally adapted to the environments they occupy because of different selection pressures. Our study considers behavioral differences in rodents originating from environments with different levels of overhead cover. We investigated exploratory behavior and anxiety in 4 populations of the African striped mouse Rhabdomys, in South Africa, from different environments: R. pumilio from a semi-desert; R. bechuanae and R. d. dilectus, which were sympatric in the central grasslands; and another allopatric R. d. dilectus occurred in the northern grasslands. We tested all individuals in 5 standard laboratory tests: light-dark, startle response, open field and novel object tests, and the plus maze. In a principle components analysis, R. pumilio and the central grassland R. dilectus grouped together, and R. bechuanae and the allopatric R. dilectus grouped together, but there was some overlap between populations. Univariate analyses showed population-level differences in exploration and anxiety. R. pumilio and the central R. d. dilectus were more exploratory and less anxious than R. bechuanae and the allopatric R. d. dilectus. The behavior of R. pumilio (more exploratory and less anxious) reflects the open environments it occupies in nature, whereas the allopatric R. d. dilectus and R. bechuanae were less exploratory and more anxious reflecting the closed habitats they occupy. The similarity between R. pumilio and the central R. d. dilectus cannot be explained by habitat and might be related to the effects of coexistence between central grassland R. d. dilectus and R. bechuanae, which may potentially alter the behavior of one or both species. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Anxiety and exploratory behavior in the African striped mouse, Rhabdomys, taxa are partially modified by the physical rearing environment.

The environment may modulate genetic influences on behavioral expression. We investigated whether the physical rearing environment modulates anxiety and exploratory behavior in four populations, representing three species, of the striped mouse Rhabdomys. One population originated from an arid, open habitat and the others from grassy, covered habitats, and two species occurred in sympatry. We raised captive individuals of all populations in treatments that simulated cover or no cover for two generations and investigated the behavior of resulting adults in an open-field, light-dark and startle response tests. We expected that, when raised without cover, the arid population would be less anxious and more exploratory than grassland populations, but found the opposite in the open-field test only. We also expected that all individuals would be anxious and less exploratory when raised under cover, which was the case for anxiety in a light-dark test, but individuals from the no cover treatment were more anxious in the open-field test. Only one population × treatment interaction was detected in which the arid population was least exploratory. Therefore, the physical rearing environment had less of an influence than phylogeny on the development of anxiety and exploration in Rhabdomys.