Linking cognition to ecology in wild sympatric mouse lemur species

Abstract

Cognitive abilities covary with both social and ecological factors across animal taxa. Ecological generalists have been attributed with enhanced cognitive abilities, but which specific ecological factors may have shaped the evolution of which specific cognitive abilities remains poorly known. To explore these links, we applied a cognitive test battery (two personality, ten cognitive tests; n = 1104 tests) to wild individuals of two sympatric mouse lemur species ( n = 120 Microcebus murinus, n = 34 M. berthae ) varying in ecological adaptations but sharing key features of their social systems. The habitat and dietary generalist grey mouse lemurs were more innovative and exhibited better spatial learning abilities; a cognitive advantage in responding adaptively to dynamic environmental conditions. The more specialized Madame Berthe's mouse lemurs were faster in learning associative reward contingencies, providing relative advantages in stable environmental conditions. Hence, our study revealed key cognitive correlates of ecological adaptations and indicates potential cognitive constraints of specialists that may help explain why they face a greater extinction risk in the context of current environmental changes.

Retaining memory after hibernation: Performance varies independently of activity levels in wild grey mouse lemurs

“…After females emerged from hibernation, we retested the same individuals to assess memory retention of the learned stimulus–reward associations. We predicted no sex difference in learning of the association tasks before hibernation, as previously reported as part of another study (Henke‐von der Malsburg et al, 2021 ). Instead, considering the assumed reduced neurological processes during hibernation, we predicted variation in memory retention after hibernation in accordance with sex‐specific activity levels during the dry season.…”

“…We briefly restrained newly captured individuals with .6 μl ketamine (50 mg/ml) per 1 g body mass to mark them with a subdermally implanted PIT tag (Trovan, Usling, Germany). We took standard morphometric measures, such as body mass, bizygomatic breadth, body and tail length, as well as tail circumference from all individuals that were captured for the first time in the respective field season (Eberle & Kappeler, 2002 ; Henke‐von der Malsburg et al, 2021 ). In addition to these targeted captures for experimental animals, we conducted monthly captures to assess population dynamics and general activity levels (Eberle & Kappeler, 2002 ).…”

“…Individuals were fed daily with small insects and banana pieces after testing and had ad libitum access to water. After a maximum of three nights, we released individuals at their capture site at dusk (Henke‐von der Malsburg et al, 2021 ). Nine subjects had to be recaptured to complete the pre‐hibernation learning sessions because they failed to learn the tasks within three nights.…”

“…We focused on adult individuals that already participated in other experimental tasks in previous studies (Henke-von der Malsburg et al, 2021;Huebner et al, 2018) to reduce a potential bias toward greater general testing experience, although all subjects were naïve to the discrimination tasks of the present study. We only tested individuals that were motivated and voluntarily participated in the experiments (Henke-von der Malsburg et al, 2021;Henke-von der Malsburg & Fichtel, 2018). To account for potential self-selection, we controlled for individual variation in exploration and neophilia that may affect discrimination performance or memory (Dougherty & Guillette, 2018;Griffin et al, 2015;Guido et al, 2017).…”

Stressfulness of the Design Influences Consistency of Cognitive Measures and Their Correlation With Animal Personality Traits in Wild Mice (Mus Musculus)

“…A causality between cognition and tness is hard to determine, but several correlations have been found 2,4,54 suggesting that such a relationship exists. In addition to that, some studies found differences in cognition between populations or related species with different ecology that could be adaptive 38,59 .…”