Revealing the behavioural ecology of the elusive hairy-eared dwarf lemur (Allocebus trichotis)

In this study we followed hairy-eared dwarf lemurs (Allocebus trichotis), a small nocturnal strepsirrhine primate, using radio-tracking during a one year study. Our aim was to clarify the behavioural ecology of the species and in particular to determine habitat use, social organisation and seasonal activity cycle. We conducted field work between January and December 2007 in the Analamazaotra Special Reserve, Andasibe, central eastern Madagascar. After capturing and measuring eleven individuals, we followed two males and two females for eight months and two additional females for three months. Adults weighed about 77 g, measured 13-14 cm and had a 12-15 cm tail. The much larger home range of Allocebus trichotis compared to other Cheirogaleidae (mean: 15 ha (MCP), 5 ha (kernel)) could be due to the highly insectivorous diet or the use of patchily distributed gum-trees. Each focal animal used four or five different tree holes and shared these with conspecifics and occasionally with white-tailed tree rats (Brachytarsomys albicauda). Tree holes were in living trees with average diameters at breast height of 32 cm, at median heights of 7 m. Tree holes could have antipredator and thermoregulatory functions and might be a limiting resource. Hairy-eared dwarf lemurs mainly used the small branch niche, five to ten meters above ground. Their diet was gummivore-insectivore. We propose a dispersed pair-bonded multi-male/multi-female social system with a monogamous or slightly promiscuous mating system. During the colder drier season, most animals decreased activity and entered periods of daily torpor, especially the heavier ones. The mating season probably lasted from October to December with births between December and February. Although this study presents crucial data on a rare nocturnal species, its small sample sizes call for additional research. Continued efforts are needed to assess the conservation status of this Data Deficient species. Fortunately, this and recent studies prove the feasibility of research on small nocturnal strepsirrhine primates in the eastern rainforests of Madagascar

Concatenation and Concordance in the Reconstruction of Mouse Lemur Phylogeny: An Empirical Demonstration of the Effect of Allele Sampling in Phylogenetics

The systematics and speciation literature is rich with discussion relating to the potential for gene tree/species tree discordance. Numerous mechanisms have been proposed to generate discordance, including differential selection, longbranch attraction, gene duplication, genetic introgression, and/or incomplete lineage sorting. For speciose clades in which divergence has occurred recently and rapidly, recovering the true species tree can be particularly problematic due to incomplete lineage sorting. Unfortunately, the availability of multilocus or “phylogenomic” data sets does not simply solve the problem, particularly when the data are analyzed with standard concatenation techniques. In our study, we conduct a phylogenetic study for a nearly complete species sample of the dwarf and mouse lemur clade, Cheirogaleidae. Mouse lemurs (genus, Microcebus) have been intensively studied over the past decade for reasons relating to their high level of cryptic species diversity, and although there has been emerging consensus regarding the evolutionary diversity contained within the genus, there is no agreement as to the inter-specific relationships within the group. We attempt to resolve cheirogaleid phylogeny, focusing especially on the mouse lemurs, by employing a large multilocus data set. We compare the results of Bayesian concordance methods with those of standard gene concatenation, finding that though concatenation yields the strongest results as measured by statistical support, these results are found to be highly misleading. By employing an approach where individual alleles are treated as operational taxonomic units, we show that phylogenetic results are substantially influenced by the selection of alleles in the concatenation process. Includes supplementary materials

Social variables exert selective pressures in the evolution and form of primate mimetic musculature

Mammals use their faces in social interactions more so than any other vertebrates. Primates are an extreme among most mammals in their complex, direct, lifelong social interactions and their frequent use of facial displays is a means of proximate visual communication with conspecifics. The available repertoire of facial displays is primarily controlled by mimetic musculature, the muscles that move the face. The form of these muscles is, in turn, limited by and influenced by phylogenetic inertia but here we use examples, both morphological and physiological, to illustrate the influence that social variables may exert on the evolution and form of mimetic musculature among primates. Ecomorphology is concerned with the adaptive responses of morphology to various ecological variables such as diet, foliage density, predation pressures, and time of day activity. We present evidence that social variables also exert selective pressures on morphology, specifically using mimetic muscles among primates as an example. Social variables include group size, dominance ‘style’, and mating systems. We present two case studies to illustrate the potential influence of social behavior on adaptive morphology of mimetic musculature in primates: (1) gross morphology of the mimetic muscles around the external ear in closely related species of macaque (Macaca mulatta and Macaca nigra) characterized by varying dominance styles and (2) comparative physiology of the orbicularis oris muscle among select ape species. This muscle is used in both facial displays/expressions and in vocalizations/human speech. We present qualitative observations of myosin fiber‐type distribution in this muscle of siamang (Symphalangus syndactylus), chimpanzee (Pan troglodytes), and human to demonstrate the potential influence of visual and auditory communication on muscle physiology. In sum, ecomorphologists should be aware of social selective pressures as well as ecological ones, and that observed morphology might reflect a compromise between the demands of the physical and the social environments

Defining the Low End of Primate Social Complexity: The Social Organization of the Nocturnal White-Footed Sportive Lemur (Lepilemur leucopus)

Whereas other species of sportive lemurs (genus Lepilemur) have been described as living in dispersed pairs, which are characterized by spatial overlap but a lack of affinity or affiliation between one adult male and female, existing reports on the social organization of the white-footed sportive lemur (Lepilemur leucopus) are conflicting, describing them as either living in dispersed one-male multifemale systems or pairs. We conducted this study in the spiny forest of Berenty Reserve, southern Madagascar, to clarify the social organization and to characterize the level of social complexity of this species. We combined 1530 h of radio-telemetry and behavioral observations over a period of 1 yr to describe the spatiotemporal stability, size, and interindividual overlap of individual home ranges as well as interindividual cohesiveness. Results revealed low intra- and high intersexual home range overlap. Although most of the social units identified consisted of dispersed pairs (N = 5), males were associated with two adult females in two cases. Furthermore, members of a social unit were never observed to groom each other or to share a daytime sleeping site, and Hutchinson’s and Doncaster’s dynamic interaction tests indicated active avoidance between pair partners. Low cohesiveness together with extremely low rates of social interactions therefore arguably places Lepilemur leucopus at the low end of primate social complexity

Tammar wallabies (Macropus eugenii) associate safety with higher levels of nocturnal illumination

Moonlight is commonly reported to increase the time nocturnal animals allocate to antipredator vigilance and to affect space use patterns because predation risk increases as a function of light intensity. The majority of studies reporting moon-light effects have been conducted on small-body sized mammals which are relatively vulnerable to a variety of predators. Moonlight effects were studied experimentally on a mid-sized mammal, the tammar wallaby (Macropus eugenii), a macropodid marsupial. Four groups of six adult female wallabies were observed for 6 days during each of three moon phases (no moon, quarter moon and full moon). In addition to natural illumination, wallabies were exposed to 2 days each of three artificial light treatments (no light, red light, white light) during each moon phase treatment. Subjects were videotaped at night with an image intensifier affixed to a video camera. Time budgets were calculated from the video record, and later analyzed in a repeated-measures factorial ANOVA. There was no effect of natural moonlight on time allocation, suggesting that wallabies had no endogenous cycle associated with moonlight. There were effects of artificial illumination and of the experimental group on time allocation. Wallabies tended to forage more and allocate less time to antipredator vigilance under the two light treatments, suggesting that, unlike previous studies on a variety of other taxa, they associated safety with increased illumination. We speculate that differences among groups might reflect the different seasons over which wallabies were studied. Results suggest that the nocturnally active tammar wallaby exercises caution in the dark.14 page(s

Tree Hole Utilisation by the Hairy-Eared Dwarf Lemur (Allocebus trichotis) in Analamazaotra Special Reserve

In this study we describe tree hole characteristics and use by the hairy-eared dwarf lemur (Allocebus trichotis) to determine habitat needs, potential functions of tree holes and sleeping group composition. We radio-tracked 6 adult individuals between April and November 2007 in the Analamazaotra Special Reserve. Tree holes were 1–9 m high (median: 7 m), in living trees measuring 26–54 cm in diameter at breast height (median: 32 cm), and could be a limiting resource. Each individual used 4 or 5 tree holes and had high nest fidelity. Animals most often slept socially in mixed-sex groups of 2–6 individuals and occasionally shared a tree hole with white-tailed tree rats (Brachytarsomys albicauda). We identified two sleeping groups: one composed of 2 adult males, 2 adult females and 2 juveniles; one composed of at least 2 adult females and 2 juveniles. Although tree holes were generally group exclusive, some intergroup sleeping was observed. Tree holes could have antipredator and thermoregulatory functions. Further research into sleeping hole availability, nest use and the degree of niche separation or competition between sympatric Cheirogaleidae and other tree hole users (e.g. endemic rodents) is needed to assess better the conservation needs of these species.</jats:p

De impact van SARS-CoV-2-pandemie op Belgische revalidatiecentra

The severe acute respiratory syndrome coro-navirus 2 (SARS-CoV-2) pandemic has a sig-nificant impact on the organisation and func-tioning of a rehabilitation centre. The main priority is to halt the spread of this virus in the community and in rehabilitation patients and caregivers, using infection prevention precau-tions. Nevertheless, a rehabilitation facility remains responsible to provide a continuity of care for outpatients as well as inpatients. This article discusses the situation and the approach of a sizeable Belgian rehabilitation centre, Alge-meen Ziekenhuis Delta, to obtain a rationalized and more homogeneous policy.De „severe acute respiratory syndrome coronavirus 2”-pandemie (SARS-CoV-2) heeft een grote invloed op de organisatie en de werking van de revalidatiecentra. De eerste prioriteit is uiteraard het beperken van een snelle verspreiding van het virus, door middel van preventieve maatregelen bin-nen de maatschappij, maar ook bij de revalidanten en de zorgverstrekkers. Niettemin blijft een reva-lidatiedienst verantwoordelijk voor de continuïteit van de zorg, zowel voor de gehospitaliseerde, de ambulante, als voor de multidisciplinair revaliderende patiënten. Dit artikel beschrijft de situatie in en de aanpak van een groot Belgisch revalidatiecentrum, het Algemeen Ziekenhuis Delta, om tot een beredeneerd en een meer uniform beleid te kunnen komen