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Variable social organization is ubiquitous in Artiodactyla and probably evolved from pair-living ancestors


Jaeggi, A V; Miles, M I; Festa-Bianchet, M; Schradin, C; Hayes, L D (2020). Variable social organization is ubiquitous in Artiodactyla and probably evolved from pair-living ancestors. Proceedings of the Royal Society of London, Series B: Biological Sciences, 287(1926):20200035.

Abstract

Previous studies to understand the evolution of interspecific variation in mammalian social organization (SO; composition of social units) produced inconsistent results, possibly by ignoring intraspecific variation. Here we present systematic data on SO in artiodactyl populations, coding SO as solitary, pair-living, group-living, sex-specific or variable (different kinds of SOs in the same population). We found that 62% of 245 populations and 83% of species (83/100) exhibited variable SO. Using Bayesian phylogenetic mixed-effects models, we simultaneously tested whether research effort, habitat, sexual dimorphism, breeding seasonality or body size predicted the likelihood of different SOs and inferred the ancestral SO. Body size and sexual dimorphism were strongly associated with different SOs. Contingent on the small body size (737 g) and putative sexual monomorphism of the earliest fossil artiodactyl, the ancestral SO was most likely to be pair-living (probability = 0.76, 95% CI = 0-1), followed by variable (p = 0.19, 95% CI = 0-0.99). However, at body size values typical of extant species, variable SO becomes the dominant form (p = 0.74, 95% CI = 0.18-1.00). Distinguishing different kinds of 'variable' highlights transitions from SOs involving pair-living to SOs involving solitary and/or group-living with increasing body size and dimorphism. Our results support the assumption that ancestral artiodactyl was pair-living and highlight the ubiquity of intraspecific variation in SO.

Abstract

Previous studies to understand the evolution of interspecific variation in mammalian social organization (SO; composition of social units) produced inconsistent results, possibly by ignoring intraspecific variation. Here we present systematic data on SO in artiodactyl populations, coding SO as solitary, pair-living, group-living, sex-specific or variable (different kinds of SOs in the same population). We found that 62% of 245 populations and 83% of species (83/100) exhibited variable SO. Using Bayesian phylogenetic mixed-effects models, we simultaneously tested whether research effort, habitat, sexual dimorphism, breeding seasonality or body size predicted the likelihood of different SOs and inferred the ancestral SO. Body size and sexual dimorphism were strongly associated with different SOs. Contingent on the small body size (737 g) and putative sexual monomorphism of the earliest fossil artiodactyl, the ancestral SO was most likely to be pair-living (probability = 0.76, 95% CI = 0-1), followed by variable (p = 0.19, 95% CI = 0-0.99). However, at body size values typical of extant species, variable SO becomes the dominant form (p = 0.74, 95% CI = 0.18-1.00). Distinguishing different kinds of 'variable' highlights transitions from SOs involving pair-living to SOs involving solitary and/or group-living with increasing body size and dimorphism. Our results support the assumption that ancestral artiodactyl was pair-living and highlight the ubiquity of intraspecific variation in SO.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Evolutionary Medicine
Dewey Decimal Classification:610 Medicine & health
Scopus Subject Areas:Life Sciences > General Biochemistry, Genetics and Molecular Biology
Life Sciences > General Immunology and Microbiology
Physical Sciences > General Environmental Science
Life Sciences > General Agricultural and Biological Sciences
Language:English
Date:13 May 2020
Deposited On:18 May 2020 07:53
Last Modified:29 Jul 2020 15:11
Publisher:Royal Society Publishing
ISSN:0962-8452
OA Status:Closed
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1098/rspb.2020.0035
PubMed ID:32370675

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