Sleep patterns, daytime predation, and the evolution of diurnal sleep site selection in lorisiforms

Abstract

65sleep and sleep site selection, a comparative approach is required (Elgar, Pagel and Harvey, 1988; 66 Lesku, Roth II, Amlaner and Lima, 2006;Rattenborg, Martinez-Gonzalez and Lesku, 2009). Sleep can 67 comprise more than 50% of a primate's activity budget (Campbell and Tobler, 1984 79that are self-constructed or constructed by other species. Use of nests (either self-constructed or made in 80 tree holes or hollows) and platforms as sleep sites is common among strepsirhines and great apes, and, 81 presumably, the earliest humans (Sabater, Veá and Serrallonga, 1997;Bearder et al., 2003; Fultz, Brent, 82 Breaux and Grand, 2013;Samson and Shumaker, 2015b), but are rarely used by other haplorhines. 83Samson and Nunn (2015) distinguished these assembled nests, on the basis that for larger primates, tree 84 hollows would not be a viable sleeping option, and suggest that ancestral Paleocene and Eocene 85primates probably had galago-like fixed point nest use. Since most monkeys do not use nests, nest use 86 must have evolved multiple times. To be able to infer potential sleep site patterns in early primates (i.e. 87the ones for which only morphological data are available), we also must examine how body size, forelimb 88 to hindlimb ratio, and hand dexterity combine to assist living primates in their sleep site choices (Covert, 89 2002; Gebo and Dagosto, 2004). 4To examine the question further, Kappeler (1998) Rasmussen (1986) and Ehrlich and MacBride, (1989)]. 98Regarding the paucity of field data on many primate taxa, he urged further research of wild primates to 99 understand better the evolution of sleep site selection. 105In the twenty-first century, substantial taxonomic changes have occurred for both the African and Asian 106 lorisiforms. First, the dwarf galagos of the genus Galagoides were recognized as a polyphyletic clade 107 (Pozzi et al., 2015), and now are comprised of Galagoides (western and central Africa) and Paragalago 108(eastern Africa). Paragalago is a sister taxon to the genus Galago, and Galagoides and is a sister taxon 109 to the clade containing Sciurocheirus, Otolemur, Paragalago and Galago (Masters et al., 2017 132These data can be used as a basis to understanding ancestral sleep behavior of primates that can help to 133 inform sleep patterns that occurred later in primate evolution. 135 MATERIAL AND METHODS 136We follow the taxonomy of Nekaris 174To gain insight into sleep patterns and the presence of fragmented sleep in the lorisiforms, we compiled 175 data on when individuals entered and exited sleep sites. From selected sites, we added information on 176 pre-or post-dusk waking and pre-or post-dawn sleeping. We added observations of sleep during the 177 night or non-sleep behavior during the day. 178We examined evidence of predation on lorisiforms and highlight those instances where the events 179 occurred while the animal was asleep, or where we could reasonably infer that predation had taken place 180 during the daytime. We excluded predation events by nocturnal p...

Sleeping Site Selection in the Nocturnal Northern Lesser Galago (Galago senegalensis) Supports Antipredator and Thermoregulatory Hypotheses

“…are "marathon sleepers", spending a much greater time asleep than diurnal primates do (Nunn et al 2010). The importance of a safe sleeping site is therefore paramount in nocturnal primates, but detailed information on the sleeping behavior of many species in Asia and mainland Africa is unavailable (Bearder et al 2003;Svensson et al 2018).…”

“…Small, arboreal, nocturnal primates are estimated to be predated on at a greater rate than other primate groups (Hart 2007) but reports of predation on nocturnal primates are scarce (Burnham et al 2012;Hart 2007). Known predators of nocturnal primates include snakes, felids, nonfelid carnivores, raptors, and other primates including humans (Burnham et al 2012;Svensson et al 2018). Nocturnal primates may be especially vulnerable to predation during the daytime (Butynski 1982;Pruetz and Bertolani 2007); therefore a level of crypsis is required when sleeping (Bearder et al 2002;Burnham et al 2012;Nekaris and Bearder 2011;Svensson et al 2018).…”

“…Galagos are nocturnal, arboreal strepsirrhine primates distributed across sub-Saharan Africa, comprising six genera: Euoticus, Galago, Galagoides, Otolemur, Paragalago, and Sciurocheirus. Taxa vary in sleeping behavior and ecology (Svensson et al 2018), but generally, galagos sleep in groups with variable membership during the day and forage alone at night (Bearder 1999;Bearder and Doyle 1974;Bearder et al 2003;Charles-Dominique 1977;Harcourt and Nash 1986), with particular sleeping sites used repeatedly by different individuals (Bearder et al 2003). Galago nests, built by a number of species within the Galagoides, Galago, and Otolemur genera, are usually leaf and twig, open platform constructions within thorny trees, presumably to provide protection from predators (Bearder et al 2003).…”

“…In addition, Galago spp. and the thick-tailed galago (Otolemur crassicaudatus) use tree cavities, dense tangles of vegetation, and branches as sleeping sites (Bearder et al 2003;Svensson et al 2018). Some species sleep in areas of dense forest canopy and understory cover (e.g., Allen's squirrel galago, Sciurocheirus alleni; and elegant needle-clawed galago, Euoticus elegantulus: Laurance et al 2008).…”

“…Reptiles such as snakes (Svensson et al 2018), and raptors such as Verreaux's eagle (Aquila verreauxii: Baker 2013, given in Svensson et al 2018) and hawks (Ambrose and Butynski, given in Svensson et al 2018), are either observed or suspected predators of galago species. Genets (Genetta spp.)…”