Biology subjects

Jaeggi, A. V.

Publications and source records attributed to Jaeggi, A. V..

3 recordsLinked to original sources

bioRxiv2025

Developmental trajectories of cognitive traits in meerkats match socio-ecological demands

Understanding cognitive development is fundamental for explaining variation in adult cognitive phenotypes, and thus the processes driving cognitive evolution. The ontogeny of cognitive traits is likely influenced by both population-wide pressures, such as ecological demands, and individual-specific factors, including early life experiences. To properly investigate cognitive variation, we must therefore identify species-level developmental trajectories and individual variation from normative ontogeny. We studied the ontogeny of three cognitive traits--inhibition control, spatial cognition, and physical problem-solving skills--in 28 wild meerkats (Suricata suricatta) from eight litters (seven groups). Our longitudinal study followed individuals from early life to nutritional independence and into sub-adulthood. We found that rates of development (learning curves) varied among traits, reflecting the timing of socio-ecological pressures in this species. Performance of cognitive traits did not correlate over ontogeny nor at specific time points, suggesting independent processes underlying each measured trait. While the development of inhibitory control appeared conserved, that of spatial cognition and physical problem-solving showed substantive individual differences. Furthermore, only physical problem-solving showed consistency in performances over time, emerging near nutritional independence, reflecting its ecological importance early in life. Future research should determine the drivers of individual developmental variation and how such differences translate into fitness consequences.

animal behavior and cognition↗

bioRxiv2025

Pair-Living Emerged Early in Placental Mammals

It is widely assumed that the first placental mammals were solitary. This assumption has been used as the default in previous comparative studies, but has never been tested independently. Here, we compiled a comprehensive database by reviewing over 14,000 primary peer-reviewed publications on the social organization of the 5,386 extant placental mammal species. We found empirical data for 738 species across 1,478 populations: 354 populations were primarily solitary, 241 populations pair-living and 878 populations group-living. Notably, 383 species (52%) and 580 populations (39%) exhibited intra-specific variation in social organization. Using a Bayesian phylogenetic framework that incorporates intra-specific variation, we show that the ancestral placental mammal - living approximately 160 to 100 million years ago - was not exclusively solitary, but likely displayed intraspecific variation. Pair-living was predicted to account for approximately 26% of ancestral social organisation. Our analysis found that ecology and life history of extant solitary and pair-living mammals was very similar and different from those of group-living mammals. Our results revise prevailing theories of mammalian social evolution, revealing that pair-living emerged early, shifting the focus of mammalian social evolution from the origins of pair-living to the origins of group-living.

evolutionary biology↗

bioRxiv2019

Intraspecific variation in Artiodactyla social organisation: A Bayesian phylogenetic multilevel analysis of detailed population-level data

Understanding inter-specific variation in social systems is a major goal of behavioural ecology. Previous comparative studies of mammalian social organisation produced inconsistent results, possibly because they ignored intra-specific variation in social organisation (IVSO). The Artiodactyla have been the focus of many comparative studies as they occupy a wide diversity of habitats and exhibit large variation in life history patterns as well as other potential correlates of social organisation. Here we present the first systematic data on IVSO among Artiodactyla, infer their ancestral social organisation, and test whether habitat, sexual dimorphism, seasonal breeding, and body size predict inter- and intraspecific variation in social organisation. We found data on social organisation for 110 of 226 artiodactyl species, of which 74.5% showed IVSO. Using Bayesian phylogenetic multilevel models, the ancestral artiodactyl population was predicted to have a variable social organisation with significantly higher probability (0.77, 95% CI 0.29-1.00) than any non-variable form (i.e. solitary, pair-living, group-living). Greater sexual dimorphism and smaller body size both predicted more IVSO; smaller body size also predicted a higher likelihood of pair-living. Our results challenge the long-held assumption that ancestral Artiodactyla were pair-living and strongly imply that taking IVSO into account is crucial for understanding mammalian social evolution.

animal behavior and cognition↗