On heights and plains: How rodents from different habitats cope with three-dimensional environments?

Abstract

Dwelling in a specific habitat requires adaptation to the habitat physical and biological properties in order to maximize fitness. Adaptations that are manifested in the organization of behavior in time and space reflect how the environment is perceived and utilized. Testing species from different habitats in the same laboratory environment can uncover the differences in their behavior and their adaptations to specific habitats. The question posed in this study is that of how two rodent species, one occupying flatlands (Tristram’s jird; Meriones tristrami) and the other occupying structured rocky habitats (common spiny mouse; Acomys dimidiatus), differ in the way that they explore the same three-dimensional laboratory environment. Individuals of these two species were introduced into an arena with a five-level ziggurat in the center, and their behavior was followed for 60 min. We found that both species preserved the typical spatiotemporal rodents’ behavior of establishing a home-base—a location that is a terminal from which they set out to explore the environment. However, the jirds, which live in flatlands, mainly travelled on the arena floor and the lower levels of the ziggurat; while, in contrast, the spiny mice, which live in rocky habitats and are used to climbing, mostly remained and travelled on the ziggurat, with some of them hardly descending to the arena floor. We suggest that the distinction in spatial behavior between the two species reflects their different motor abilities, different depth perception, and different umvelt (perceived world), in accordance with their different natural habitats.

Rodents Prefer Going Downhill All the Way (Gravitaxis) Instead of Taking an Uphill Task

“…Similarly, we found that sand rats and rats that dwell and forage in complex habitats were also biased towards the lower sectors [ 8 , 10 ]. This differed, however, in rocky habitat dwellers, the spiny mice, which preferred the upper sectors [ 9 ], whereas the flatland-dweller jirds preferred lower sectors and moved away from cliffs and upper sectors [ 9 , 10 ]. The bias towards descent rather than ascent has usually been interpreted in terms of energy cost.…”

“…Some of these studies focused on flying, swimming or swinging (e.g., bats [ 3 , 4 , 5 ]; fish [ 6 ]), while others focused on surface-bounded animals that in the real world may encounter sloping terrain, bushes, rocks, trees, and other forms of vertical structures. Studying the spatial behavior of surface-bounded animals indicated that they seem to display an attraction to the lower sectors and to horizontal surfaces [ 7 , 8 , 9 , 10 , 11 ]. However, some rodents also have climbing skills that are related to their habitat requirements [ 12 ].…”

“…Specifically, Tristram’s jird ( Meriones tristrami ) a rodent species that resembles the Mongolian gerbil and similarly inhabits flatlands refrained from establishing its home-base at the perimeter cliffs of the apparatus and instead settled in the center [ 10 ]. When placed on a level pyramid, jirds soon descended to the floor, established there their home base, and traveled mainly on the floor or on the lower level of the pyramid [ 9 ]. In contrast, when the common spiny mice ( Acomys dimidiatus ), which dwell and forage among rocks and boulders, were placed on the level pyramid, they spent most of the time on it and seldom reached the floor [ 9 ].…”

“…When placed on a level pyramid, jirds soon descended to the floor, established there their home base, and traveled mainly on the floor or on the lower level of the pyramid [ 9 ]. In contrast, when the common spiny mice ( Acomys dimidiatus ), which dwell and forage among rocks and boulders, were placed on the level pyramid, they spent most of the time on it and seldom reached the floor [ 9 ]. This variability among different species in their response to three-dimensional environments illustrates the need for comparative studies that incorporate variation in anatomy, style of locomotion, and habitats, required in order to differentiate the general from the species-specific patterns in spatial behavior [ 25 , 26 ].…”

Snakes on a slope: strong anti-gravitactic responses and differential habitat use in the Saharan horned viper ( Cerastes cerastes ) in the Negev desert

“…This may facilitate three-dimensional navigation by receiving balanced vestibular cues [ 25 ] or help to avoid unbalanced muscular activity [ 19 ]. Additionally, the species' natural habitat plays a role in their reaction to the slope: species that live naturally in a complex environment are better at vertical exploration than those that live on plains [ 26 ]. Some species are also inclined to go down or up the slope—gravitaxis or anti-gravitaxis, respectively [ 24 , 27 , 28 ].…”