Oliver Schülke
Biographic Data
| ID | 96396 |
|---|---|
| NAME | Oliver Schülke |
| GIVEN NAMES | Oliver |
| FAMILY NAME | Schülke |
| SIGNATURE | SCHÜLKE O |
| AFFILIATIONS | German Primate Center |
| ORCID | 0000-0003-0028-9425 |
| VERIFIED | Yes |
| TOTAL WORKS | 34 |
| TOTAL CITATIONS | 46 |
| AUTHOR COUNT | 34 |
| EDITOR COUNT | 0 |
| FIRST PUBLICATION YEAR | 2001 |
| LATEST PUBLICATION YEAR | 2026 |
| H-INDEX | 4 |
Age‐Trajectory of Mother–Infant Relationships in Wild Assamese Macaques
Maternal care is ubiquitous in mammals, yet its degree and duration vary across taxa. In primates, mothers provide extended care for young and follow similar developmental transitions in the mother–infant relationship, yet at different paces of change. Since ecological pressures shape life‐history traits including female reproductive rate and timing of infant independence, research is needed on mother–infant relationships in wild populations expo…
Assessing Gestation and Fetal Sex in Wild Assamese Macaques Using Urinary Estrogen Analysis
In mammals, estrogens and progestogens are crucial for gestation, fetal development, and maternal preparation for parturition and lactation. Measuring these hormones allows for the diagnosis of pregnancy, estimation of pregnancy failures, and potentially prenatal sex determination. We evaluated urinary estrogen and progestogen metabolites as biomarkers for gestation detection and for their utility for fetal sex determination in wild Assamese maca…
The evolution of between-sex bonds in primates
Social bonds can be a way for individuals to gain access to crucial resources and services that cannot be taken by force and are therefore subject to leverage. Bonds between the sexes can provide access to services that are specific to the other sex. Females exert leverage over males in terms of mating access, males have leverage over females in terms of the service protection, and both sexes exert leverage over the other sex in terms of toleranc…
Bonobo mothers have elevated urinary cortisol levels during early but not mid or late lactation
In mammals, the costs of reproduction are biased towards females. Lactation is particularly energetically expensive, and behavioral and physiological data indicate that maternal effort during lactation induces energetic stress. Another source of stress in females is male aggression directed towards them when they are cycling. Evaluating the costs of reproduction in wild and mobile animals can be a challenging task, and requires detailed informati…
Developmental and environmental modulation of fecal thyroid hormone levels in wild Assamese macaques ( Macaca assamensis )
Thyroid hormones are key modulators of development, as well as mediators of environmental conditions, by regulating developmental processes and metabolism in primates. Hormone measurement in noninvasively collected samples, that is, feces and urine, is a valuable tool for studying the endocrine function of wildlife, and recent studies have demonstrated the feasibility of measuring thyroid hormones in fecal samples of zoo‐housed and wild nonhuman …
Toward Passive Acoustic Monitoring of Lemurs: Using an Affordable Open-Source System to Monitor Phaner Vocal Activity and Density
Developing new cost-effective methods for monitoring the distribution and abundance of species is essential for conservation biology. Passive acoustic monitoring (PAM) has long been used in marine mammals and has recently been postulated to be a promising method to improve monitoring of terrestrial wildlife as well. Because Madagascar’s lemurs are among the globally most threatened taxa, this study was designed to assess the applicability of an a…
Responsiveness of fecal immunoglobulin A to HPA‐axis activation limits its use for mucosal immunity assessment
The assessment of mucosal immunity as a component of animal health is an important aspect for the understanding of variation in host immunity, and its tradeoff against other life‐history traits. We investigated immunoglobulin A (IgA), the major type of antibody associated with mucosal immunity, in relation to changes in parasitic burden following anthelminthic treatment in noninvasively collected fecal samples in a semi‐free ranging group of Barb…
Fermented food consumption in wild nonhuman primates and its ecological drivers
OBJECTIVES: Although fermented food use is ubiquitous in humans, the ecological and evolutionary factors contributing to its emergence are unclear. Here we investigated the ecological contexts surrounding the consumption of fruits in the late stages of fermentation by wild primates to provide insight into its adaptive function. We hypothesized that climate, socioecological traits, and habitat patch size would influence the occurrence of this beha…
Female macaques compete for ‘power’ and ‘commitment’ in their male partners
The evolution of social philopatry in female primates
The transition from solitary life to sociality is considered one of the major transitions in evolution. In primates, this transition is currently not well understood. Traditional verbal models appear insufficient to unravel the complex interplay of environmental and demographic factors involved in the evolution of primate sociality, and recent phylogenetic reconstructions have produced conflicting results. We therefore analyze a theoretical model…
The Effect of Dominance Rank on the Distribution of Different Types of Male–Infant–Male Interactions in Barbary Macaques (Macaca sylvanus)
Subtypes of aggression and their relation to anxiety in Barbary macaques
Human aggression can be differentiated into reactive aggression (RA), displayed in face of a real or perceived threat and associated with high levels of anxiety, and proactive aggression (PA), displayed to achieve a certain goal and linked to lower anxiety levels. To study the origins of these aggression subtypes and their relation to anxiety, we tested if both subtypes can be distinguished in a nonhuman primate species, characterized their occur…
Reproductive tolerance in male primates: Old paradigms and new evidence
Within social groups of primates, males commonly compete over reproduction, but they may also rely on cooperation with other males. Theory suggests that it may be adaptive for male primates to tolerate some reproduction by other males if reproductive tolerance fosters cooperation, particularly that dominant males yield so‐called reproductive concessions to subordinates to entice their cooperation. We review four recent studies that claimed to hav…
A first report of non-invasive adenovirus detection in wild Assamese macaques in Thailand
Opposite‐sex social bonding in wild Assamese macaques
In large multimale-multifemale primate groups, individual adult males and females may form close social relationships that extend beyond the mating context, a surprising finding for polygynandrous mammals. The patterns of these associations can be relatively stable across time. Here we investigate whether dyadic social relationships between the sexes transcend mere association in wild Assamese macaques and may be characterized as strong, equitabl…
Patterns and Consequences of Male–Infant Relationships in Wild Assamese Macaques (Macaca assamensis)
Male care for offspring is unexpected in polygynandrous mammals. Evidence from nonhuman primates, however, indicates not only the existence of stable male–immature associations in multimale–multifemale groups, but also male care in the form of protection from infanticidal attacks and conspecific harassment. Here, we investigate the relationship characteristics, dynamics, and consequences of male–immature associations in wild Assamese macaques, Ma…
Males matter: Increased home range size is associated with the number of resident males after controlling for ecological factors in wild A ssamese macaques
OBJECTIVES: There is increasing evidence of male resource defense during intergroup encounters in non-human primates. Only few studies showed a reproductive benefit of having more males in a group, and evidence only comes from territorial species, or from species with relatively small male group sizes where males are less prone to suffer from collective action problems. We investigated the effect of male group size on home range size and female r…
Feeding behavior and aggression in wild Siberut macaques ( Macaca siberu ) living under low predation risk
Investigating which factors influence feeding competition is crucial for our understanding of the diversity of social relationships. Socio-ecological models differ in their predictions whether predation risk directly influences feeding competition and which factors exactly predict contest competition. We investigated feeding competition in Siberut macaques (Macaca siberu), a species endemic to Siberut Island (West Sumatra, Indonesia). Siberut mac…
Personality structure and social style in macaques
Why regularities in personality can be described with particular dimensions is a basic question in differential psychology. Nonhuman primates can also be characterized in terms of personality structure. Comparative approaches can help reveal phylogenetic constraints and social and ecological patterns associated with the presence or absence of specific personality dimensions. We sought to determine how different personality structures are related …
Preliminary study of the genetic diversity of eastern Assamese macaques (Macaca assamensis assamensis) in Thailand based on mitochondrial DNA and microsatellite markers
Towards the non‐invasive assessment of MHC genotype in wild primates: Analysis of wild assamese macaque MHC‐DRB from fecal samples
The major histocompatibility complex (MHC) plays an important role in the immune response and may thus crucially affect an individual's fitness, relevant also for studies on evolutionary ecology and wildlife conservation. Detailed knowledge on the genomic organization, polymorphism and diversity of the MHC has a narrow taxonomic focus though and among macaques is only available for rhesus and long-tailed macaques-the species most commonly kept fo…
Mating Competition, Promiscuity, and Life History Traits as Predictors of Sexually Transmitted Disease Risk in Primates
Lack of Evidence for Energetic Costs of Mate-Guarding in Wild Male Assamese Macaques (Macaca assamensis)
The Absence of Grooming for Rank-Related Benefits in Female Assamese Macaques (Macaca assamensis)
Brief communication: Female fecal androgens prior to the mating season reflect readiness to conceive in reproductively quiescent wild macaques
An extensive body of research exists on androgen secretion in males. Although androgens are also known to drive patterns of female reproductive physiology and behavior, little attention has been paid to these “male” hormones in females. Here, we examined female fecal androgen excretion in strictly seasonally breeding wild Assamese macaques ( Macaca assamensis ) and tested the hypothesis that changes in premating season fecal androgens vary with f…
Reproductive and Life History Parameters of Wild Female Macaca assamensis
Information on basic reproductive parameters and life-history traits is crucial for the understanding of primate evolution, ecology, social behavior, and reproductive strategies. Here, we report 4 yr of data on reproductive and life-history traits for wild female Assamese macaques (Macaca assamensis) at Phu Khieo Wildlife Sanctuary, northeastern Thailand. During 2 consecutive reproductive seasons, we investigated reproductive behavior and sexual …
Social Relationships in Free-Ranging Male Macaca arctoides
Macaque social relationships differ greatly between species. Based on captive studies that focus mainly on females, researchers have classified stumptail macaque (Macaca arctoides) social relationships as tolerant, as indicated by a high rate of affiliation, frequent aggression, and symmetrical conflicts. To accumulate more data on male social relationships, which are relatively understudied, and to generate comparative data, we investigated male…
Fermented food consumption in wild nonhuman primates and its ecological drivers
OBJECTIVES: Although fermented food use is ubiquitous in humans, the ecological and evolutionary factors contributing to its emergence are unclear. Here we investigated the ecological contexts surrounding the consumption of fruits in the late stages of fermentation by wild primates to provide insight into its adaptive function. We hypothesized that climate, socioecological traits, and habitat patch size would influence the occurrence of this beha…
Patterns and Consequences of Male–Infant Relationships in Wild Assamese Macaques (Macaca assamensis)
Male care for offspring is unexpected in polygynandrous mammals. Evidence from nonhuman primates, however, indicates not only the existence of stable male–immature associations in multimale–multifemale groups, but also male care in the form of protection from infanticidal attacks and conspecific harassment. Here, we investigate the relationship characteristics, dynamics, and consequences of male–immature associations in wild Assamese macaques, Ma…
Evolution of Pair-Living in Phaner furcifer
The evolution of social philopatry in female primates
The transition from solitary life to sociality is considered one of the major transitions in evolution. In primates, this transition is currently not well understood. Traditional verbal models appear insufficient to unravel the complex interplay of environmental and demographic factors involved in the evolution of primate sociality, and recent phylogenetic reconstructions have produced conflicting results. We therefore analyze a theoretical model…
Males matter: Increased home range size is associated with the number of resident males after controlling for ecological factors in wild A ssamese macaques
OBJECTIVES: There is increasing evidence of male resource defense during intergroup encounters in non-human primates. Only few studies showed a reproductive benefit of having more males in a group, and evidence only comes from territorial species, or from species with relatively small male group sizes where males are less prone to suffer from collective action problems. We investigated the effect of male group size on home range size and female r…
Personality structure and social style in macaques
Why regularities in personality can be described with particular dimensions is a basic question in differential psychology. Nonhuman primates can also be characterized in terms of personality structure. Comparative approaches can help reveal phylogenetic constraints and social and ecological patterns associated with the presence or absence of specific personality dimensions. We sought to determine how different personality structures are related …
Lack of Evidence for Energetic Costs of Mate-Guarding in Wild Male Assamese Macaques (Macaca assamensis)
Toward Passive Acoustic Monitoring of Lemurs: Using an Affordable Open-Source System to Monitor Phaner Vocal Activity and Density
Developing new cost-effective methods for monitoring the distribution and abundance of species is essential for conservation biology. Passive acoustic monitoring (PAM) has long been used in marine mammals and has recently been postulated to be a promising method to improve monitoring of terrestrial wildlife as well. Because Madagascar’s lemurs are among the globally most threatened taxa, this study was designed to assess the applicability of an a…
The Effect of Dominance Rank on the Distribution of Different Types of Male–Infant–Male Interactions in Barbary Macaques (Macaca sylvanus)
Mating Competition, Promiscuity, and Life History Traits as Predictors of Sexually Transmitted Disease Risk in Primates
The Absence of Grooming for Rank-Related Benefits in Female Assamese Macaques (Macaca assamensis)
Brief communication: Female fecal androgens prior to the mating season reflect readiness to conceive in reproductively quiescent wild macaques
An extensive body of research exists on androgen secretion in males. Although androgens are also known to drive patterns of female reproductive physiology and behavior, little attention has been paid to these “male” hormones in females. Here, we examined female fecal androgen excretion in strictly seasonally breeding wild Assamese macaques ( Macaca assamensis ) and tested the hypothesis that changes in premating season fecal androgens vary with f…
Brief communication: Fecal androgen excretion and fetal sex effects during gestation in wild assamese macaques ( Macaca assamensis )
In placental mammals, pregnancy usually is associated with an increase in maternal androgens, which may significantly impact fetal growth and differentiation, and affect postnatal development and behavior. Owing to their slow life histories and challenging social conditions, determination of maternal androgens and potential interference effects of fetal androgen production are of particular interest in wild primates. However, androgen production …
Differential energy budget and monopolization potential of harem holders and bachelors in hanuman langurs ( Semnopithecus entellus ): Preliminary results
The demographic structure in the Hanuman langur ( Semnopithecus entellus ) population of Jodhpur is extreme, in that some single males monopolize harems with, on average, 25 adult females. It has been proposed that extratroop males, which live in all‐male bands, inhabit low‐quality habitats and suffer from reduced food provisioning and longer daily travel distances. To compare the resulting energetic consequences for harem holders and bachelors, …
Big times for dwarfs: Social organization, sexual selection, and cooperation in the Cheirogaleidae
Evolution of Pair-Living in Phaner furcifer
The importance of ingestion rates for estimating food quality and energy intake
Testing ecological or socioecological models in primatology often requires estimates of individual energy intake. It is a well established fact that the nutrient content (and hence the energy content) of primate food items is highly variable. The second variable in determining primate energy intake, i.e., the ingestion rate, has often been ignored, and few studies have attempted to estimate the relative importance of the two predictors. In the pr…
Male reproductive skew, paternal relatedness, and female social relationships
Female social relationships among primates are thought to be shaped by socio‐ecological factors and phylogenetic constraints. We suggest that patterns of paternal relatedness among females influence measures of social tolerance that have been used to classify species into different social relationship categories. As kin support and kin preference have only been measured for matrilineal kin and related individuals exchange less aggression and have…
Social Relationships in Free-Ranging Male Macaca arctoides
Macaque social relationships differ greatly between species. Based on captive studies that focus mainly on females, researchers have classified stumptail macaque (Macaca arctoides) social relationships as tolerant, as indicated by a high rate of affiliation, frequent aggression, and symmetrical conflicts. To accumulate more data on male social relationships, which are relatively understudied, and to generate comparative data, we investigated male…
Social Bonds Enhance Reproductive Success in Male Macaques
Reproductive and Life History Parameters of Wild Female Macaca assamensis
Information on basic reproductive parameters and life-history traits is crucial for the understanding of primate evolution, ecology, social behavior, and reproductive strategies. Here, we report 4 yr of data on reproductive and life-history traits for wild female Assamese macaques (Macaca assamensis) at Phu Khieo Wildlife Sanctuary, northeastern Thailand. During 2 consecutive reproductive seasons, we investigated reproductive behavior and sexual …
Brief communication: Fecal androgen excretion and fetal sex effects during gestation in wild assamese macaques ( Macaca assamensis )
In placental mammals, pregnancy usually is associated with an increase in maternal androgens, which may significantly impact fetal growth and differentiation, and affect postnatal development and behavior. Owing to their slow life histories and challenging social conditions, determination of maternal androgens and potential interference effects of fetal androgen production are of particular interest in wild primates. However, androgen production …
The Absence of Grooming for Rank-Related Benefits in Female Assamese Macaques (Macaca assamensis)
Brief communication: Female fecal androgens prior to the mating season reflect readiness to conceive in reproductively quiescent wild macaques
An extensive body of research exists on androgen secretion in males. Although androgens are also known to drive patterns of female reproductive physiology and behavior, little attention has been paid to these “male” hormones in females. Here, we examined female fecal androgen excretion in strictly seasonally breeding wild Assamese macaques ( Macaca assamensis ) and tested the hypothesis that changes in premating season fecal androgens vary with f…
Preliminary study of the genetic diversity of eastern Assamese macaques (Macaca assamensis assamensis) in Thailand based on mitochondrial DNA and microsatellite markers
Towards the non‐invasive assessment of MHC genotype in wild primates: Analysis of wild assamese macaque MHC‐DRB from fecal samples
The major histocompatibility complex (MHC) plays an important role in the immune response and may thus crucially affect an individual's fitness, relevant also for studies on evolutionary ecology and wildlife conservation. Detailed knowledge on the genomic organization, polymorphism and diversity of the MHC has a narrow taxonomic focus though and among macaques is only available for rhesus and long-tailed macaques-the species most commonly kept fo…
Mating Competition, Promiscuity, and Life History Traits as Predictors of Sexually Transmitted Disease Risk in Primates
Lack of Evidence for Energetic Costs of Mate-Guarding in Wild Male Assamese Macaques (Macaca assamensis)
Feeding behavior and aggression in wild Siberut macaques ( Macaca siberu ) living under low predation risk
Investigating which factors influence feeding competition is crucial for our understanding of the diversity of social relationships. Socio-ecological models differ in their predictions whether predation risk directly influences feeding competition and which factors exactly predict contest competition. We investigated feeding competition in Siberut macaques (Macaca siberu), a species endemic to Siberut Island (West Sumatra, Indonesia). Siberut mac…
Personality structure and social style in macaques
Why regularities in personality can be described with particular dimensions is a basic question in differential psychology. Nonhuman primates can also be characterized in terms of personality structure. Comparative approaches can help reveal phylogenetic constraints and social and ecological patterns associated with the presence or absence of specific personality dimensions. We sought to determine how different personality structures are related …
Opposite‐sex social bonding in wild Assamese macaques
In large multimale-multifemale primate groups, individual adult males and females may form close social relationships that extend beyond the mating context, a surprising finding for polygynandrous mammals. The patterns of these associations can be relatively stable across time. Here we investigate whether dyadic social relationships between the sexes transcend mere association in wild Assamese macaques and may be characterized as strong, equitabl…
Patterns and Consequences of Male–Infant Relationships in Wild Assamese Macaques (Macaca assamensis)
Male care for offspring is unexpected in polygynandrous mammals. Evidence from nonhuman primates, however, indicates not only the existence of stable male–immature associations in multimale–multifemale groups, but also male care in the form of protection from infanticidal attacks and conspecific harassment. Here, we investigate the relationship characteristics, dynamics, and consequences of male–immature associations in wild Assamese macaques, Ma…
Males matter: Increased home range size is associated with the number of resident males after controlling for ecological factors in wild A ssamese macaques
OBJECTIVES: There is increasing evidence of male resource defense during intergroup encounters in non-human primates. Only few studies showed a reproductive benefit of having more males in a group, and evidence only comes from territorial species, or from species with relatively small male group sizes where males are less prone to suffer from collective action problems. We investigated the effect of male group size on home range size and female r…
A first report of non-invasive adenovirus detection in wild Assamese macaques in Thailand
Reproductive tolerance in male primates: Old paradigms and new evidence
Within social groups of primates, males commonly compete over reproduction, but they may also rely on cooperation with other males. Theory suggests that it may be adaptive for male primates to tolerate some reproduction by other males if reproductive tolerance fosters cooperation, particularly that dominant males yield so‐called reproductive concessions to subordinates to entice their cooperation. We review four recent studies that claimed to hav…
The Effect of Dominance Rank on the Distribution of Different Types of Male–Infant–Male Interactions in Barbary Macaques (Macaca sylvanus)
Subtypes of aggression and their relation to anxiety in Barbary macaques
Human aggression can be differentiated into reactive aggression (RA), displayed in face of a real or perceived threat and associated with high levels of anxiety, and proactive aggression (PA), displayed to achieve a certain goal and linked to lower anxiety levels. To study the origins of these aggression subtypes and their relation to anxiety, we tested if both subtypes can be distinguished in a nonhuman primate species, characterized their occur…
Female macaques compete for ‘power’ and ‘commitment’ in their male partners
Biology (32 works) · Primate Behavior and Ecology (31 works) · Animal Behavior and Reproduction (24 works) · Ecology (23 works) · Animal Vocal Communication and Behavior (17 works) · Demography (16 works) · Zoology (16 works) · Population (13 works) · Animal ecology (12 works) · Psychology (11 works)