Time filter

Source Type

Dammhahn M.,Leibniz Institute for Primate Research
Proceedings. Biological sciences / The Royal Society | Year: 2012

Despite increasing interest, animal personality is still a puzzling phenomenon. Several theoretical models have been proposed to explain intraindividual consistency and interindividual variation in behaviour, which have been primarily supported by qualitative data and simulations. Using an empirical approach, I tested predictions of one main life-history hypothesis, which posits that consistent individual differences in behaviour are favoured by a trade-off between current and future reproduction. Data on life-history were collected for individuals of a natural population of grey mouse lemurs (Microcebus murinus). Using open-field and novel-object tests, I quantified variation in activity, exploration and boldness for 117 individuals over 3 years. I found systematic variation in boldness between individuals of different residual reproductive value. Young males with low current but high expected future fitness were less bold than older males with high current fecundity, and males might increase in boldness with age. Females have low variation in assets and in boldness with age. Body condition was not related to boldness and only explained marginal variation in exploration. Overall, these data indicate that a trade-off between current and future reproduction might maintain personality variation in mouse lemurs, and thus provide empirical support of this life-history trade-off hypothesis.

Luhrs M.L.,University of Gottingen | Kappeler P.M.,University of Gottingen | Kappeler P.M.,Leibniz Institute for Primate Research
Behavioral Ecology and Sociobiology | Year: 2013

In hypercarnivorous species, females have large spatial requirements to meet their nutritional needs, and food competition among females is intense. As a result, females are typically solitary and territorial, and solitary males compete for access to dispersed females. Yet, largely anecdotal reports indicate that facultative male sociality may be more common in solitary carnivores than previously thought. We studied spatial interactions among fossas (Cryptoprocta ferox), Madagascar's largest carnivore, using simultaneous GPS tracking of 13 adult individuals to determine patterns of sex-specific spatial distribution and sociality. Male home ranges were larger than those of females, male home ranges overlapped more with those of other males than those of females with other females. Whereas some males were solitary, a subset of adult males was found to have very high home range overlap, high rates of co-location within <50 m, low minimum inter-individual distances, and significantly positive "dynamic interaction". These associated dyads sometimes, but not always, were close relatives. The fact that solitary and associated males coexist in this population raises interesting questions concerning constraints and flexibility of social tolerance. This study yielded preliminary indications that female distribution appears to be primarily structured by resource competition, whereas male sociality seems to depend on demographic chance events, yet unknown proximate determinants of social tolerance, and it is associated with somatic and reproductive advantages. Male associations among carnivores are therefore more widespread and appear to be based on a wider range of factors than previously thought. © 2013 Springer-Verlag Berlin Heidelberg.

Dammhahn M.,Leibniz Institute for Primate Research | Soarimalala V.,British Petroleum | Goodman S.M.,British Petroleum
Biotropica | Year: 2013

Unraveling the mechanisms facilitating species coexistence in communities is a central theme in ecology. Species-rich tropical mammal communities provide excellent settings to explore such mechanisms as they often harbor numerous congeneric species with close phylogenetic relationships. Explicit tests for the mechanisms that allow syntopic occurrence in these assemblages, however, is often hampered because of the difficulty in obtaining detailed ecological data on the organisms making up the community. Using stable nitrogen and carbon ratios of hair samples, we examine whether trophic niche differentiation and microhabitat segregation explain the coexistence of 21 small mammal species at a montane humid forest site in eastern Madagascar. Overall, the community was trophically diverse and covered wide isotopic space. This diversity was based on: (1) a multi-layered trophic community structure with mainly frugivorous-granivorous rodents (subfamily Nesomyinae) as primary consumers and insectivorous tenrecs (family Tenrecidae) as secondary and tertiary consumers; (2) trophic segregation of rodents and tenrecs with the latter occupying different microhabitats; and (3) a dense and regular packing of species in the community. The 12 locally occurring Microgale shrew tenrecs (subfamily Oryzorictinae) showed high trophic redundancy, but were maximally spaced from each other within the trophic space covered by the genus. Results of stable isotope analysis suggest that in combination the differentiation of microhabitats and trophic niches explain the coexistence of small mammals in this community. Congeneric species appeared to be under more intense competition compared with non-congeneric species and their coexistence can only partly be explained by trophic and microhabitat niche segregation. © 2012 The Authors Journal compilation © 2012 by The Association for Tropical Biology and Conservation.

Vuarin P.,CNRS Mechanical Adaptation and Evolution | Dammhahn M.,Leibniz Institute for Primate Research | Henry P.-Y.,CNRS Mechanical Adaptation and Evolution
Functional Ecology | Year: 2013

Phenotypic flexibility is a major mechanism in compensating climate-driven changes in resource availability. Heterotherms can use daily torpor to overcome resource shortages and adverse environmental conditions. The expression of this adaptive energy-saving strategy varies among individuals, but the factors constraining individual flexibility remain largely unknown. As energy availability depends on individual stores and/or on the ability to acquire food, the propensity and flexibility in torpor use are expected to be constrained by body condition and/or size, respectively. The aim of this study was to test whether the dependency of torpor depth on air temperature was constrained by body condition and/or body size in a small heterothermic primate, the grey mouse lemur (Microcebus murinus). During the onset of the dry season, we monitored air temperature as well as skin temperatures of 14 free-ranging individuals (12 females, two males) of known body mass and size. Unexpectedly, torpor depth depended as much on air temperature as on body condition and size. Fatter, or larger, mouse lemurs underwent deeper torpor than smaller, or leaner, ones. Individual reaction norms of torpor depth to air temperature also revealed that the propensity to undergo deep torpor and the flexibility in torpor depth were enhanced by large body size and high body condition, whereas small, lean individuals remained normothermic. Our study illustrates that alternative physiological strategies to overcome temperature constraints co-occur in a population, with body size and condition being key determinants of the energy conservation strategy that an individual can launch. © 2013 The Authors. Functional Ecology © 2013 British Ecological Society.

Brameier M.,Leibniz Institute for Primate Research
BMC Research Notes | Year: 2010

Background. MicroRNAs (miRNAs) are negative regulators of gene expression in multicellular eukaryotes. With the recently completed sequencing of three primate genomes, the study of miRNA evolution within the primate lineage has only begun and may be expected to provide the genetic and molecular explanations for many phenotypic differences between human and non-human primates. Findings. We scanned all three genomes of non-human primates, including chimpanzee (Pan troglodytes), orangutan (Pongo pygmaeus), and rhesus monkey (Macaca mulatta), for homologs of human miRNA genes. Besides sequence homology analysis, our comparative method relies on various postprocessing filters to verify other features of miRNAs, including, in particular, their precursor structure or their occurrence (prediction) in other primate genomes. Our study allows direct comparisons between the different species in terms of their miRNA repertoire, their evolutionary distance to human, the effects of filters, as well as the identification of common and species-specific miRNAs in the primate lineage. More than 500 novel putative miRNA genes have been discovered in orangutan that show at least 85 percent identity in precursor sequence. Only about 40 percent are found to be 100 percent identical with their human ortholog. Conclusion. Homologs of human precursor miRNAs with perfect or near-perfect sequence identity may be considered to be likely functional in other primates. The computational identification of homologs with less similar sequence, instead, requires further evidence to be provided. © 2010 Brameier; licensee BioMed Central Ltd.

Discover hidden collaborations