Prosimian juvenile mortality in zoos and primate centers

I review literature on juvenile mortality of captive prosimians in order to evaluate the available information on captive breeding. Juvenile mortality includes abortion, premature mortality, stillbirth, and death of the unweaned young. Prosimian juvenile mortality ranges between 25 and 45% in captive populations. It is generally lower in the Lemuroidea, particularly the Cheirogaleidae, than in the Lorisoidea. Mortality is particularly high in the Lorisinae. Most mortality, including a high stillbirth rate, occurs on the first day and during the first 10 days thereafter. Stress, maternal neglect and traumatic insults, not infrequently linked to each other, are the most frequently reported causes of death. The percentage of congenital malformations tends to be high in some colonies. Sex of the infant and parity seem to be important risk factors for juvenile mortality, whereas litter size does not appear to be important. Based on few data, wild- caught females appear to have higher breeding success than those born in captivity. Synchronized births in lemuroids and isolated births in Galagoare more likely to result in successfully weaned infants.     

Parallel episodes of phyletic dwarfism in callitrichid and cheirogaleid primates

The Callitrichidae are the smallest anthropoids, whereas the Cheirogaleidae include the smallest of all primates. Using species‐level analyses, we show that these are derived conditions; both neonatal and adult body mass decreased in a gradual, phyletic manner in parallel across callitrichids, and across cheirogaleids. We identify lineages with particularly rapid decreases and highlight the pygmy marmoset, Callithrix pygmaea, as a phenotypic outlier. The life‐history traits associated with body‐mass reduction in each clade suggest that the convergent evolution of small body size was achieved by changes in different ontogenetic stages. Body‐size reduction in callitrichids appears to be almost exclusively due to alterations in prenatal growth rate, whereas body‐size reduction in cheirogaleids may have been largely due to reduced duration of growth phases. Finally, we use these results to discuss some of the debates surrounding the evolution of Homo floresiensis and suggest potential parallels between the evolution of H. floresiensis and callitrichids.     

Isolation of new microsatellite markers and application in four species of mouse lemurs (Microcebus sp.)

We report the development of 13 new microsatellite markers for mouse lemurs (Microcebus sp.). Two markers were isolated from the fat tailed dwarf lemur (Cheirogaleus medius) and 11 from the grey mouse lemur (Microcebus murinus). A total of 561 individuals from four different species of mouse lemurs was genotyped with the newly developed markers. All markers showed Mendelian inheritance in 21 families of mouse lemurs. All markers show polymorphism in several species of mouse lemurs and seven amplified in C. medius. Among these new markers are the first 10 published for M. berthae and the first 11 for M. griseorufus.     

Physiological ecology of cheirogaleid primates: variation in hibernation and torpor

Torpor (i.e. the reduction of body temperature and metabolic rate for less than 24 h) and hibernation (i.e. torpor phases longer than 24 h) are among the most extreme adaptations to seasonality in primate habitats. Although widespread among mammals, this form of extreme thermoregulation is rare among primates and is reported only for species of the cheirogaleid family. Understanding their physiological ecology is crucial for many aspects of cheirogaleid socioecology like their social organization and their mating systems. This paper first provides an overview of published information on hibernation and torpor and identifies a patchy distribution for the occurrence of hibernation across genera, species and populations. Based on a review of published studies from the wild and from captivity, we then propose a possible explanation for variation in hibernation behavior among Microcebus species and populations. Accordingly, the amount of energy that can be saved during torpor early in the lean dry season, which is determined by the minimum ambient temperature will be decisive. Only where temperatures are low, early dry season torpor bouts will be long enough to save enough energy to build up fat reserves for longer bouts of hibernation. Finally, we summarize information on the causal factors for the occurrence of hibernation by analyzing sex differences within populations. Further physiological studies on other cheirogaleid species are needed to identify the phylogenetic origin of hibernation in primates.     

Environmental drivers of Cheirogaleidae population density: Remarkable resilience of Madagascar’s smallest lemurs to habitat degradation

AimGlobal animal populations are in decline due to destruction and degradation of their natural habitat. Understanding the factors that determine the distribution and density of threatened animal populations is therefore now a crucial component of their study and conservation. The Cheirogaleidae are a diverse family of small‐bodied, nocturnal lemurs that are widespread throughout the forests of Madagascar. However, many cheirogaleid lemurs are now highly threatened with extinction and the environmental factors that determine their distribution and population density are still little known. Here, I investigated the environmental drivers of Cheirogaleidae population density at genus level.LocationVarious forest sites across Madagascar.MethodsI investigated how six environmental variables affect Cheirogaleidae population density at the genus level via random‐effect meta‐analyses. I then used a generalized linear mixed‐effects model to identify the primary predictors of Cheirogaleidae population density. Finally, I investigated how the population density of this family of lemurs varies between protected and unprotected areas of Madagascar via a GLM analysis.ResultsMy results indicate that the relationships between the tested environmental factors and population density are genus‐specific among the Cheirogaleidae. Rather remarkably, the density of Microcebus appears to have a profoundly positive relationship with anthropogenic disturbance and a negative relationship with forest cover, a finding that is also reflected by larger population densities within unprotected areas in comparison with localities within Madagascar''s protected area network.Main ConclusionsThe results of this study are highly encouraging for the conservation of the Cheirogaleidae and highlight the remarkable resilience of these lemurs to habitat degradation and anthropogenic activity. However, this study also outlines the dearth of knowledge that we have for many species, and why these data are urgently needed to understand the biogeography and ecology of threatened animal populations and implement successful conservation.