Social Organization of Lepilemur ruficaudatus

We characterize the spatial organization of red-tailed sportive lemurs (Lepilemur ruficaudatus) as a key aspect of their social organization and social system. Sportive lemurs are small (<1000 g), nocturnal and folivorous primates endemic to Madagascar. We studied a population of 57 individually-marked individuals in Kirindy Forest, western Madagascar, between 1995 and 2001. We radio-tracked 20 males and 26 females of the marked population to obtain detailed information on the size and location of their home ranges. Census data and morphometric measurements provided complementary data sets. Males and females occupied small (<1 ha) home-ranges. Long-term records from 9 individuals revealed home-range stability over several years. In 4 cases home ranges overlapped extensively with that of one member of the opposite sex; in 2 cases, a spatial association of 1 male and 2 females occurred. However, home ranges overlapped very little with neighboring individuals of both sexes. During the study period, spatially associated individuals used on average 5.6 sleeping trees within 117 days, but they spent on average only about every fourth night together. The data suggest that home ranges in red-tailed sportive lemurs are exclusively used by pairs or trios and that the modal social organization of red-tailed sportive lemurs is pair-living.     

Spatiotemporal distribution of individuals as an indicator for the social system of Lepilemur sahamalaza

Primate social systems are highly diverse, complicating the classification of particularly elusive species that are difficult to observe. The spatial distribution of individuals over time is a critica lindicator for the social organization and long‐term studies are important to establish patterns of social interactions. In recent years, species of the cryptic, nocturnal sportive lemurs of the genus Lepilemur were found to live in pairs in which a single male and a single female share and defend a mutual home range. The present study aimed to forward research into this underrepresented genus by determining the social organization and structure of the Sahamalaza sportive lemur, L. sahamalaza. We collected 773.15 hr of behavioral and GPS data during a period of 10 months (between 2015 and 2016) on 14 individuals: eight females and six males. There was no evidence of pair‐specific home range use as intra‐ and intersexual home range overlap was high. No pattern of social interactions between focal individuals could be distinguished despite high range overlap. Individuals met and interacted infrequently, resulting in an interaction rate of 0.32 interactions/hr. Sleeping associations between adult individuals were never observed. While both sexes had access to multiple potential mating partners, range sizes or ranging distances did not increase in mating periods. Overall, the social system of Sahamalaza sportive lemurs exhibits aspects of a solitary social organization and structure with potential for the polygamous mating system. These findings underline the importance of detailed social ecology studies that can provide the basis for understanding potential environmental influences on social system variability of closely related species.     

Determinants of Pair‐Living in Red‐Tailed Sportive Lemurs (Lepilemur ruficaudatus)

Pair‐living and a monogamous mating strategy are rare and theoretically unexpected among mammals. Nevertheless, about 10% of primate species exhibit such a social system, which is difficult to explain in the absence of paternal care. In this study, we investigated the two major hypotheses proposed to explain the evolution of monogamy in mammals, the female defence hypothesis (FDH) and the resource defence hypothesis (RDH), in red‐tailed sportive lemurs (Lepilemur ruficaudatus), a nocturnal primate from Madagascar. We analysed behavioural data from eight male–female pairs collected during a 24‐mo field study to illuminate the determinants of pair‐living in this species. Male and female L. ruficaudatus were found to live in dispersed pairs, which are characterised by low cohesion and low encounter rates within a common home range. Social interactions between pair partners were mainly agonistic and characterised by a complete absence of affiliative interactions – body contact was only observed during mating. During the short annual mating season, males exhibited elevated levels of aggression towards mates, as well as extensive mate guarding and increased locomotor activity. In addition, males were exclusively responsible for the maintenance of proximity between pair partners during this period, and they defended their territories against neighbouring males but not against females. Together, these results point towards the importance of female defence in explaining pair‐living in L. ruficaudatus. We discuss the spatial and temporal distribution of receptive females in relation to the female defence strategies of males and suggest possible costs that prevent male red‐tailed sportive lemurs from defending more than one female.     

Social organization,survival, and dispersal of cape foxes (Vulpes chama) in South Africa

We monitored 20 cape foxes (Vulpes chama) to determine the social organization, survival, and dispersal of this species on two sites in South Africa from 2005 to 2008. Cape foxes were socially monogamous and territorial, with annual home ranges of mated pairs (n = 8) overlapping 80% on average, compared to a mean overlap of 3% between foxes in adjacent ranges. At least 2 pairs remained associated for >1 breeding season, and both sexes exhibited strong site fidelity, as home ranges in consecutive years overlapped 58–98%. Members of mated pairs never foraged together, however they used the same or nearby (<100 m apart) day rests 81% of the time when pups were 0–4 months of age, but only 28% of the time during other months of the year. Dispersal was male biased, as all juvenile males (n = 6) dispersed when 9–11.5 months old, whereas 3 of 4 juvenile females remained philopatric as either breeders or non-breeding associates. At least 6 foxes bred as yearlings (3 F, 3 M), indicating cape foxes have high reproductive potential. Two adult females maintained their territories after their mates died, whereas two adult males dispersed soon after their mates died, indicating cape foxes likely have a female-based social organization. Annual survival was 0.64, and predation from larger carnivores, primarily black-backed jackals (Canis mesomelas), was responsible for 71% of mortalities. Our results provided empirical support for previous hypotheses regarding the relationship between body size and life-history patterns in Canidae, as several ecological parameters of cape foxes were similar to that of other small (<6 kg) canid species, especially Vulpes species inhabiting arid and semi-arid environments.     

SmTRC1, a novel Schistosoma mansoni DNA transposon, discloses new families of animal and fungi transposons belonging to the CACTA superfamily

Background

The number of species within the Malagasy genus Lepilemur and their phylogenetic relationships is disputed and controversial. In order to establish their evolutionary relationships, a comparative cytogenetic and molecular study was performed. We sequenced the complete mitochondrial cytochrome b gene (1140 bp) from 68 individuals representing all eight sportive lemur species and most major populations, and compared the results with those obtained from cytogenetic studies derived from 99 specimens.

Results

Interspecific genetic variation, diagnostic characters and significantly supported phylogenetic relationships were obtained from the mitochondrial sequence data and are in agreement with cytogenetic information. The results confirm the distinctiveness of Lepilemur ankaranensis, L. dorsalis, L. edwardsi, L. leucopus, L. microdon, L. mustelinus, L. ruficaudatus and L. septentrionalis on species level. Additionally, within L. ruficaudatus large genetic differences were observed among different geographic populations. L. dorsalis from Sahamalaza Peninsula and from the Ambanja/Nosy Be region are paraphyletic, with the latter forming a sister group to L. ankaranensis.

Conclusion

Our results support the classification of the eight major sportive lemur taxa as independent species. Moreover, our data indicate further cryptic speciation events within L. ruficaudatus and L. dorsalis. Based on molecular data we propose to recognize the sportive lemur populations from north of the Tsiribihina River, south of the Betsiboka River, and from the Sahamalaza Peninsula, as distinct species.     

Estrous phase alters social behavior in a polygynous but not a monogamous Peromyscus species

The social organization of rodent species determines behavioral patterns for both affiliative and agonistic encounters. The neuropeptide oxytocin has been implicated in the mediation of social behavior; however, variability in both neuropeptide expression and social behavior within a single species indicates an additional mediating factor. The purpose of the present comparative study was to investigate social behaviors in naïve mixed-sex pairs of monogamous Peromyscus californicus and polygynous Peromyscus leucopus. We identified substantial inter- and intra-specific variability in the expression of affiliative and agonistic behaviors. Although all P. californicus tested engaged in frequent and prolonged intervals of social contact and rarely engaged in aggressive behaviors, P. leucopus exhibited significant variability in both measures of social behaviors. The naturally occurring differences in social behavior displayed by P. leucopus vary across the estrous cycle, and correspond to hypothalamic oxytocin, as well as circulating oxytocin and glucocorticoid concentrations. These results provide evidence for a rhythm in social behavior across the estrous cycle in polygynous, but not monogamous, Peromyscus species.     

Pair-specific usage of sleeping sites and their implications for social organization in a nocturnal Malagasy primate, the Milne Edwards' sportive lemur (Lepilemur edwardsi)

Safe sleeping sites may be a limited resource crucial for survival. In order to investigate their potential significance for social organization in nocturnal primates, we analyzed the spatial distribution of daily sleeping sites, their characteristics, their usage, and sleeping group compositions in the nocturnal Milne Edwards' sportive lemur during a 6-month field study in the dry deciduous forest of northwestern Madagascar. Sexes did not differ either in body size or in body mass. Sleeping sites were used almost exclusively by adult male-female pairs. Individuals showed a high sleeping-site fidelity limited to 2-3 different sleeping sites in close vicinity during the whole study period. Most females showed a higher fidelity to one distinct sleeping site than their male partners. Sleeping groups consisted of one adult male and one adult female and remained stable in composition over the whole study period. Exclusive pair-specific usage of sleeping sites suggests sleeping site related territoriality of male-female pairs, perhaps influenced by inter- and intrasexual resource competition. Results give first insights into the distribution patterns and social organization of this species. They imply dispersed monogamy for the Milne Edwards' sportive lemur, with sleeping sites as a potentially restricted and defendable resource.     

Social organization of Galagos in Kenyan coastal forests: II. Galago garnettii

The social organization of Galago garnettii was studied for the first time and the study included data from two different sites in the coastal forests of Kenya. A combination of mark-recapture and radio-tracking techniques was used to investigate patterns of inter- and intrasexual home range overlap. Patterns of range use were established by radio tracking focal individuals. Adult females of different ages shared highly overlapping ranges, while like-aged females showed little range overlap. Females matured and had their first infants in their natal ranges. Adult males' ranges were larger than those of females and overlapped them extensively. Resident adult males showed little range overlap with each other, unless they were of different ages. Turnover of males was frequent in both populations. Males probably dispersed from their natal ranges. Adults rarely slept together. The social organization of G. garnettii is relatively similar to that of the closely related G. crassicaudatus of southern Africa but contrasts with that of its sympatric congener, G. zanzibaricus. The differences and similarities between these three species are discussed in relation to diet and body size.     

Resting metabolic rates of Lepilemur ruficaudatus

Seventeen sportive lemurs (Lepilemur ruficaudatus) were captured in a dry, deciduous forest in western Madagascar, and the resting metabolic rates were measured. According to the data, resting metabolic rates of Lepilemur ruficaudatus are among the lowest of mammalian folivores recorded so far. © 1996 Wiley-Liss, Inc.     

Food Resource Characteristics in Two Nocturnal Lemurs with Different Social Behavior: Avahi occidentalis and Lepilemur edwardsi

I present results from a comparative field study on the feeding behavior of the gregarious Avahi occidentalis and the solitary-but-social Lepilemur edwardsi to evaluate hypotheses relating to social organization and food resources. While Avahi and Lepilemur are both nocturnal, have comparable body weights and positional behaviors, and are both folivorous, they differ in their social organization. Therefore, they present an ideal model for assessing food resource characteristics through comparisons of food selection in both species with regard to forest composition. The monogamous Avahi tend to select under-represented resources. They are repeatedly exploited, which suggests that their location must be known. It is worthwhile and probably imperative to defend those resources. Such defense imposes ranging limitations on male Avahi. Females may prefer familiar mates that will share their knowledge of resource location and defend the resources. A stable monogamous pattern could be the optimal strategy. In contrast, food selection by Lepilemur is based on common resources to a higher degree, but they show a lower degree of exploitation. Lepilemur males would be less restricted and could potentially opt for a different strategy, e.g., a dispersed harem. It is unclear whether this strategy is realized or not. I discuss other possible correlates of monogamy—infanticide protection, predation avoidance—but the gregarious pattern in Avahi may best be seen as a retention, and its nocturnal activity as a secondary adaptation.     

Genetic Differentiation among Natural Populations of Lepilemur ruficaudatus

We studied the genetic differentiation of five populations of red-tailed sportive lemur Lepilemur ruficaudatus by means of allozyme variability and RAPD polymorphisms in order to test whether the Tsiribihina River separates the distribution areas of Lepilemur ruficaudatus and and L. edwardsi. Genetic data as well as the karyotype of a male individual clearly indicate that the Andramasay Forest in the north of Tsiribihina River is inhabited by Lepilemur ruficaudatus and not by L. edwardsi. We propose that the distribution of the two species are separated by the Manambolo River. However, the northernmost population of Lepilemur ruficaudatus inhabiting the Andramasay Forest is gentically differentiated from those that inhabit the dry forest in the south of Tsiribihina River.     

Use of space and home range characteristics of Lepilemur mittermeieri,an endangered sportive lemur endemic to the Ampasindava peninsula,north‐west Madagascar

Lepilemur mittermeieri, a little‐studied sportive lemur of north‐west Madagascar, endemic to the Ampasindava Peninsula, faces habitat loss through forest degradation and rapid fragmentation. Understanding its habitat requirement is the first step toward preservation of this threatened forest‐dependent species. In this study, we gathered data on the use of space and home range characteristics of L. mittermeieri. We studied individuals from early March to the end of June 2015 and 2016, in three sites of the Ampasindava peninsula. We radio‐tracked 15 individuals to obtain detailed information on the size and location of home ranges (around 450 hr of tracking). Direct observation and morphometric measurements provided additional data sets. Both kernel density estimation (KDE) and minimum convex polygon (MCP) methods yielded similar home range sizes (an average of 2.01 ha with KDE method and 1.96 ha with MCP method). We did not find differences in home range size between males and females, with respect to forest type or proximity to the forest edge. Home ranges overlapped and individuals showed low levels of territoriality. We highlighted a sexually‐dimorphic trait: males have longer upper canine than females. Our results constitute the first set of ecological information on Lepilemur mittermeieri and could be the basis for a conservation strategy for this endangered species with a very small distribution area.     

Variation in the Social Systems of Extant Hominoids: Comparative Insight into the Social Behavior of Early Hominins

The observed social systems of extant apes and humans suggest that the common ancestral state for Miocene hominoids was living in multimale–multifemale groups that exhibited a tendency to fission and fusion in response to ecological and/or social variables. The Hominoidea share a set of social commonalities, notably a social niche that extends beyond kin and beyond the immediate social group, as well as extensive intraspecific flexibility in social organization. We propose that an essential feature of hominoid evolution is the shift from limited plasticity in a generalized social ape to expanded behavioral plasticity as an adaptive niche. Whereas in most nonhominoid primates variability and flexibility take the shape of specific patterns of demographic flux and interindividual relationships, we can consider behavioral flexibility and plasticity as a means to an end in hominoid socioecological landscapes. In addition, the potential for innovation, spread, and inheritance of behavioral patterns and social traditions is much higher in the hominoids, especially the great apes, than in other anthropoid primates. We further suggest that this pattern forms a basis for the substantial expansion of social complexity and adaptive behavioral plasticity in the hominins, especially the genus Homo. Our objectives in this article are threefold: 1) summarize the variation in the social systems of extant hominoid taxa; 2) consider the evolutionary processes underlying these variations; and 3) expand upon the traditional socioecological model, especially with respect to reconstructions of early hominin social behavior. We emphasize a central role for both ecological and social niche construction, as well as behavioral plasticity, as basal hominoid characteristics. Over evolutionary time these characteristics influence the patterns of selection pressures and the resulting social structures. We propose that a mosaic of ecological and social inheritance patterns should be considered in the reconstruction of early hominin social systems.     

Infanticide by a Male Milne-Edwards' Sportive Lemur (Lepilemur edwardsi) in Ampijoroa,NW-Madagascar

During a long-term field study on the behavioral ecology and communication of a population of the monogamous Milne-Edwards' sportive lemur (Lepilemur edwardsi) in NW-Madagascar, we recorded for the first time an infanticide in a nocturnal lemur. A male newcomer killed the infant of a female whose male partner had left her recently. Both the social-pathology and the sexual-selection hypotheses may explain infanticidal behavior in Lepilemur edwardsi.     

Out of Sight but Not Out of Mind? Behavioral Coordination in Red-Tailed Sportive Lemurs (<Emphasis Type="Italic">Lepilemur ruficaudatus</Emphasis>)

Many animals are organized into social groups and have to synchronize their activities to maintain group cohesion. Although activity budgets, habitat constraints, and group properties may impact on behavioural synchrony, little is known regarding how members of a group reach a consensus on the timing of activities such as foraging bouts. Game theory predicts that pair partners should synchronize their activities when there is an advantage of foraging together. As a result of this synchronization, differences in the energetic reserves of the two players develop spontaneously and the individual with lower reserves emerges as a pacemaker of the synchrony. Here, we studied the behavioral synchrony of pair-living, nocturnal, red-tailed sportive lemurs (Lepilemur ruficaudatus). We observed 8 pairs continuously for ≥1 annual reproductive cycle in Kirindy Forest, Western Madagascar. During focal observations, one observer followed the female of a pair and, simultaneously, another observer followed the male. We recorded the location and behavioral state of the focal individual every 5 min via instantaneous sampling. Although behavioral synchrony of pair partners appeared to be due mainly to endogenous activity patterns, they actively synchronized when they were in visual contact (<10 m). Nevertheless, red-tailed sportive lemurs benefit from synchronizing their activity only for 15% of the time, when they are close together. The lack of an early warning system for predators and weak support for benefits via social information transfer in combination with energetic constraints may explain why red-tailed sportive lemurs do not spend more time together and thus reap the benefits of behavioral synchrony.     

The Effects of Climate Seasonality on Behavior and Sleeping Site Choice in Sahamalaza Sportive Lemurs, <Emphasis Type="Italic">Lepilemur sahamalaza</Emphasis>

Temperature, rainfall, and resource availability may vary greatly within a single year in primate habitats. Many primate species show behavioral and physiological adaptations to this environmental seasonality, including changes to their diets and activity. Sahamalaza sportive lemurs (Lepilemur sahamalaza) inhabit the northwest of Madagascar and have been studied only during the dry, colder period of the year. We investigated potential effects of climate seasonality on this species by collecting behavioral data between October 2015 and August 2016, encompassing both the warmer wet and the colder dry seasons. We collected 773.15 hours of behavioral data on 14 individual sportive lemurs to investigate year-round activity budgets, ranging behavior, and sleeping site locations. Additionally we recorded temperature and rainfall data at our study site to describe the environmental conditions during the study period. The study individuals significantly decreased their time spent traveling and increased their time spent resting in the dry season compared to the wet season. Although home range size and path lengths did not differ over the study period, sleeping locations were significantly different between seasons as the lemurs focused on more confined areas in colder periods. Overall, the results indicate that Sahamalaza sportive lemur behavior varies with season, in line with reports for other primates.     

The Round-Eared Sengi and the Evolution of Social Monogamy: Factors that Constrain Males to Live with a Single Female

Animal dispersion in space and time results from environmental pressures, and affects the outcome of a species' social organization. When females are solitary, males may either roam or be pair-living. We studied possible environmental influences affecting the social organization of the round-eared sengi ( Macroscelides proboscideus ) in a semi-desert in South Africa, using trapping and radio-tracking across 2.5 yr. Adult sex ratios did not deviate from 1:1 and we found no indication of sexual dimorphism in body mass. Females maintained exclusive areas, which had little overlap (<4%) with neighbouring females (NF), and males overlapped predominately only with the home range of single females. Generally, inter- and intra-sexual overlap with neighbouring individuals was low (3–6%) for both sexes, indicating territoriality and pair-living. Pairs were perennial and territories were maintained year-round. However, males generally maintained much larger areas than females, which were sensitive to population density. Male space use appeared to be primarily limited by the presence of neighbouring males. Female home ranges were smaller-sized despite changes in population density, possibly for energetic efficiency. Some paired males attempted to take over widowed females, but shifted back to their original home range following the intrusion of an un-paired male. We conclude that social monogamy is the predominant social organization in round-eared sengis in a semi-desert that may have resulted from females living solitarily in small exclusive territories, balanced sex ratios, and from a low variation of body mass between males.     

Intraspecific Variation in Home Range Overlap with Habitat Quality: A Comparison among Brown Bear Populations

We developed a conceptual model of spatial organization in vertebrates based upon changes in home range overlap with habitat quality. We tested the model using estimates of annual home ranges of adult females and densities for 30 populations of brown bears (Ursus arctos) in North America. We used seasonality as a surrogate of habitat quality, measured as the coefficient of variation among monthly actual evapotranspiration values for areas in which study populations were located. We calculated home range overlap for each population as the product of the average home range size for adult females and the estimated population density of adult females. Home range size varied positively with seasonality; however, home range overlap varied with seasonality in a nonlinear manner. Areas of low and high seasonality supported brown bears with considerable home range overlap, but areas of moderate seasonality supported brown bears with low home range overlap. These results are consistent with behavioural theory predicting a nonlinear relationship between food availability and territoriality.     

Woodland fragmentation affects space use of Eurasian red squirrels

When habitats become fragmented, variation in patch size and quality are expected to impose changes on the spacing pattern and social organization of animal populations. General theory predicts different possible responses including shrinking home ranges (fission response), increasing range overlap (fusion) and incorporation of multiple patches in the home range (expansion response) as fragmentation increases. We studied space use and social organization in a metapopulation of red squirrels (Sciurus vulgaris) in 15 woodland fragments differing in size and tree species composition. Home ranges and core areas of males were larger than females, and fragmentation had different and complex effects on the spacing pattern of both sexes. In food-supplemented patches, high densities led to increased intra-sexual overlap. In linear-shaped patches, squirrels used smaller home ranges and core areas and had lower male–male and male–female overlap levels, independent of patch quality or size. Home range and core area size of males increased with patch size, and male core areas overlapped extensively those of other males and females. Hence males seemed to show a fission response only in some patches. In contrast, home range and core area size of females was not related with patch size, but decreased with habitat quality, supporting predictions of a fusion response and intra-sexual defense of food-based core areas. Hence, where patch size and shape strongly affected space use of male red squirrels, social organization of females was only affected in small, food-supplemented patches, suggesting that the basic spatio-social organization of adult females is very resistant to fragmentation.     

Dispersal,inbreeding avoidance and reproductive success in white-footed mice

The dispersion pattern of 360 juvenile white-footed mice, Peromyscus leucopus, from 158 matings was monitored to determine whether dispersal was sufficient to prevent close inbreeding. Dispersal was male-biased with 20% of the daughters remaining in their natal home ranges. Dispersal of sons was not ‘forced’ by adult males, but may have been influenced by the presence of their mothers. One mother-son and five father-daughter pairs had overlapping home ranges during the breeding season, but the maximum number of matings among close relatives was three of 135 (2·2%). Dispersal of juvenile males was sufficient to keep close inbreeding at a minimum. Dispersal did not result from reproductive competition. Pregnant and post-lactating females frequently moved to new home ranges. The reproductive success of immigrants was the same as that of natal residents.