The effects of body size, activity, and phylogeny on primate sleeping ecology

Abstract

Objectives Sleeping ecology plays a key integrative role in the primates' lives. Selecting an adequate sleeping site is therefore critical, but both extrinsic (e.g., predation, thermoregulation) and intrinsic factors (e.g., body size, circadian activity) need to be considered simultaneously. There is, however, a notable lack of comprehensive comparative analyses of sleeping ecology within primates. We explored the links among body size, circadian activity, and sleeping site choice in phylogenetically controlled comparative analyses across all major primate lineages. Materials and Methods We compiled published information on body size, circadian activity, and sleeping site choice of extant primates. We performed ancestral state reconstructions for the different sleeping sites and used comparative phylogenetic analyses to quantify associations between sleeping site preference, body size and circadian pattern. Results Comparative analyses across 390 species revealed that primate sleeping site usage was best predicted by circadian activity patterns. Nocturnal species were more likely to use tree holes and nests, whereas diurnal primates were more likely to sleep on trees. Ancestral reconstructions indicated a relative ambiguity among states for several nodes, especially within strepsirrhines, whereas “on trees” was the most likely sleeping site type within haplorrhines. Discussion The main intrinsic predictor of sleeping site choice in primates has links to two extrinsic factors: predation risk and thermoregulation. Thermoregulatory and anti‐predator benefits accrue for nocturnal species that rest in nests or tree holes. Body size only poses a constraint for shelter use in larger species. Comparative studies of resting ecology are integral for reconstructing primate evolution and for revealing complex adaptations in arboreal mammals.

phytools 2.0: an updated R ecosystem for phylogenetic comparative methods (and other things)

“…In particular, phylogenies and the comparative method have made recent appearances in studies on infectious disease epidemiology, virology, cancer biology, sociolinguistics, biological anthropology, molecular genomics, and community ecology, among other disciplines ( e.g. , Moura et al, 2016 ; Baele et al, 2018 ; Bentz et al, 2018 ; Beale et al, 2019 ; Bushman, McCormick & Sherrill-Mix, 2019 ; Sánchez-Busó et al, 2019 ; Valles-Colomer et al, 2019 ; Freitas et al, 2020 ; Jezovit et al, 2020 ; Blinkhorn & Grove, 2021 ; McLaughlin et al, 2022 ; Pepke & Eisenberg, 2022 ; Pozzi, Voskamp & Kappeler, 2022 ; Compton et al, 2023 ; Mifsud et al, 2023 ; Van Borm et al, 2023 , and many others).…”

phytools 2.0: An updated R ecosystem for phylogenetic comparative methods (and other things)

“…Phylogenetic comparative methods have also begun to be applied extensively outside of their traditional domain of evolutionary research. In particular, phylogenies and the comparative method have made recent appearances in studies on infectious disease epidemiology, virology, cancer biology, sociolinguistics, biological anthropology, molecular genomics, and community ecology, among other disciplines (e.g., Moura et al 2016; Baele et al 2018; Bentz et al 2018; Beale et al 2019; Bushman et al 2019; Sánchez-Busó et al 2019; Valles-Colomer et al 2019; Freitas et al 2020; Jezovit et al 2020; Blinkhorn and Grove 2021; McLaughlin et al 2022; Pepke and Eisenberg 2022; Pozzi et al 2022; Compton et al 2023; Mifsud et al 2023; Van Borm et al 2023, and many others).…”

Nocturnal selective pressures on the evolution of human musicality as a missing piece of the adaptationist puzzle

“…Despite the ongoing debate, this initial timeline of fire use is also considered to be aligned with the tree-to-ground nesting transition by the fully bipedal early Homo erectus ( Coolidge and Wynn, 2006 ; Wrangham, 2009 ; Samson and Nunn, 2015 ; Fruth et al, 2018 ). Nesting on the ground eliminates the danger of eventually falling out of the tree; the ground makes for a more stable nest enabling a more uninterrupted and efficient sleep, so much so that nesting on the ground or in lower branches happens sometimes in Chimpanzees when there is less predation risk ( Hernandez-Aguilar et al, 2013 ; Fruth et al, 2018 ; Pozzi et al, 2022 ). Thus, sleeping hidden in caves, probably protected by sentinels ( Samson and Nunn, 2015 ; Samson et al, 2017 ) capable of stone throwing (which appeared 2 Ma ago, Lombardo and Deaner, 2018 ) and by sporadic use of fire arguably, could have favored the tree-to-ground nesting in Homo erectus speeding sleep efficiency freeing nocturnal awake time.…”

“…Night-time happens every day (i.e., frequently and consistently), lasts roughly 12 h per day (i.e., long-lasting), and humans have been expanding into the nocturnal niche at least since the habitual use of fire (400–300 ka ago) (i.e., ancient/long-standing). The night-time exhibits a predictable selective landscape consisting of a collection of adaptive problems of varying magnitudes (e.g., predation and thermoregulation) ( Fruth et al, 2018 ; Pozzi et al, 2022 ). Expanding on Varella et al (2021) and Varella and Valentova (2023) and others (e.g., Putilov, 2014 ; Killin, 2017 ; Nowell, 2018 ), I propose that the six crucial specific and recurrent ancient adaptive challenges/opportunities faced by early hominins during awakening night-time were lack of luminosity, low temperatures, regrouping to cook before sleep, dangerousness, peak tiredness, and concealment of identity.…”

“…Indeed, social monogamy and small family-sized groups are consistent predictors of complex song in vocal communication across primates ( Haimoff, 1986 ; Geissmann, 2000 ; Schruth et al, 2021 ), and the majority of duetting primates are nocturnal or live across great distances in visually unreachable environments ( cf. Geissmann, 2000 ; Clink et al, 2020 ; Pozzi et al, 2022 ). Duetting songbirds also tend to be monogamous ( Geissmann, 2000 ).…”