Effects of Laboratory Housing on Exploratory Behaviour, Novelty Discrimination and Spatial Reference Memory in a Subterranean, Solitary Rodent, the Cape Mole-Rat (Georychus capensis)

Abstract

A large number of laboratory and field based studies are being carried out on mole-rats, both in our research group and others. Several studies have highlighted the development of adverse behaviours in laboratory animals and have emphasised the importance of enrichment for captive animals. Hence we were interested in evaluating how laboratory housing would affect behavioural performance in mole-rats. We investigated exploratory behaviour, the ability to discriminate between novel and familiar environments and reference memory in the solitary Cape mole-rat ( Georychus capensis ). Our data showed that both wild and captive animals readily explore open spaces and tunnels. Wild animals were however more active than their captive counterparts. In the Y maze two trial discrimination task, wild animals failed to discriminate between novel and familiar environments, while laboratory housed mole-rats showed preferential spatial discrimination in terms of the length of time spent in the novel arm. The performance of the laboratory and wild animals were similar when tested for reference memory in the Y maze, both groups showed a significant improvement compared to the first day, from the 3rd day onwards. Wild animals made more mistakes whereas laboratory animals were slower in completing the task. The difference in performance between wild and laboratory animals in the Y-maze may be as a result of the lower activity of the laboratory animals. Laboratory maintained Cape mole-rats show classic behaviours resulting from a lack of stimulation such as reduced activity and increased aggression. However, they do display an improved novelty discrimination compared to the wild animals. Slower locomotion rate of the laboratory animals may increase the integration time of stimuli, hence result in a more thorough inspection of the surroundings. Unlike the captive animals, wild animals show flexibility in their responses to unpredictable events, which is an important requirement under natural living conditions.

Distributional range, ecology, and mating system of the Cape mole-rat (Georychus capensis) family Bathyergidae

“…Body masses for all animals, as well as males and females separately, fall within the range reported by previous authors (e.g., Du Toit et al 1985;Taylor et al 1985;Bennett et al 2006;Hagenah and Bennett 2012;Oosthuizen et al 2013). Body mass is significantly correlated with age (r = 0.76) and growth continues after maturity (Taylor et al 1985).…”

“…The sex ratio in G. capensis is biased towards females (also see the sampling of Oosthuizen et al 2013 for a similar pattern) -a consequence of the mating system (Greenwood 1980) which may influence male reproductive variables through differences in the amount of polyandrous matings (Hettyey and Roberts 2006). Together with this, there is no size dimorphism between the sexes and male animals do not have fat padding around the neck as observed in the two Bathyergus species, suggesting less competition for female acquisition (Scantlebury et al 2006).…”

Temperament, Plasticity, and Emotions in Defensive Behaviour of Paca (Mammalia, Hystricognatha)

“…During the novel-environment phase of the MDTB, pacas scoring low on the “restless” temperament dimension spent more time roaming and raising forelegs, which are exploratory behaviour patterns also observed in other rodent species when in unfamiliar surroundings (e.g., Rattus norvegicus and Georychus capensis [ 73 ]). In contrast, individuals judged as more “restless” spent more time eating grass, which we considered to be an abnormal behaviour for the species.…”

From Mice to Mole-Rats: Species-Specific Modulation of Adult Hippocampal Neurogenesis

“…Despite the relatively uniform habitat of the sealed tunnel systems, the difference in tunnel length and complexity appears to be sufficient stimulation to induce learning differences in the different species. Damaraland mole-rats with longer and more complex burrow systems, show superior learning abilities compared to the solitary Cape mole-rat (Costanzo et al, 2009 ; Oosthuizen et al, 2013 ), Oosthuizen, unpublished data). The enhanced learning abilities of Damaraland mole-rats are associated with more proliferating cells compared to Cape mole-rats (Amrein et al, 2014 ; Oosthuizen and Amrein, 2016 ).…”