Dwarf Mongooses Research Articles

The Ancestral Carnivore Karyotype (2n = 38) Lives Today in Ringtails

Chromosome painting was used to investigate the conservation of high-resolution longitudinal 4',6-diamidino-2-phenylindole (DAPI)/G bands in Carnivore chromosomes. Cat (Felis catus) and raccoon dog (Nyctereutes procyonoides) painting probes were hybridized to the ringtail (Bassaricus astutus), dwarf mongoose (Helogale parvula), and Malagasy civet (Fossa fossa) to identify homologous chromosome elements. The patterns of chromosome segment homology among Carnivore species allowed us to reconstruct and propose the disposition of a high-resolution banded ancestral carnivore karyotype (ACK). Three bi-armed chromosomes consistently found among Caniformia species are represented as 6 homologous acrocentric chromosomes among Feliformia species of Carnivora. However, reexamination of the most basal of Feliformia species, the African palm civet Nandinia, revealed the presence of the 3 heretofore Caniformia bi-armed chromosomes. Because these 3 bi-armed chromosomes are found in both Caniformia and Feliformia lineages, they are presumed ancestral for all Carnivora, suggesting that the ACK chromosome number would be 38, rather than the previously supposed 42. Banded chromosomes of the ACK are used to evaluate the consistency between recently determined molecular phylogenetic relationships and postulated cytogenetic dynamics in the same Carnivore species.

Conflict over the timing of breeder replacement in vertebrate and invertebrate societies

Conflicts over reproduction are common in social groups, where they often result in more or less pronounced reproductive skew. Conflicts are greatest in groups of reproductively totipotent individuals where a single breeder of each sex monopolizes reproduction. Skew models investigate how reproduction is divided among group members, i.e. how the conflict is settled. Here, we investigate the conflict over the timing of breeder replacement.Using a genetic model we show that some non-breeding individuals should challenge the breeder under a wide set of conditions, rather than queue for a breeding vacancy. Consequently, societies of totipotent individuals may be the stage of an almost perpetual conflict between the breeder and helpful reproductives. However, the outcome of this conflict may be determined by non-breeding individuals that are not helpful reproductives (policing behaviours), or constrained by ecological conditions such as high costs of independent breeding or incest avoidance. We discuss our model in the light of skew models and model of matricide, and review the literature of highly skewed vertebrate and invertebrate societies of totipotent individuals (naked and Damaraland mole-rats, African wild dogs, dwarf mongooses, queenless ants, Polistine wasps). This cross-taxonomic review reveals that some non-breeders attempt to replace the breeder or position themselves so as to be able to do so when the opportunity arises, which supports the predictions of the model.

DOMINANCE, AGGRESSION, AND GLUCOCORTICOID LEVELS IN SOCIAL CARNIVORES

In social animals, reproductive success is often related to social dominance. In cooperatively breeding birds and mammals, reproductive rates are usually lower for social subordinates than for dominants, and it is common for reproduction in subordinates to be completely suppressed. Early research with captive animals showed that losing fights can increase glucocorticoid (GC) secretion, a general response to stress. Because GCs can suppress reproduction, it has been widely argued that chronic stress might underlie reproductive suppression of social subordinates in cooperative breeders. Contradicting this hypothesis, recent studies of cooperative breeders in the wild show that dominant individuals have elevated GCs more often than do subordinates. Here, I summarize relationships between rank, aggression, and GCs from field studies of 3 cooperatively breeding carnivores: the dwarf mongoose (Helogale parvula), the African wild dog (Lycaon pictus), and the gray wolf (Canis lupus). In all 3 species, GC levels are higher in dominants than in subordinates for 1 or both sexes. Higher GCs are associated with higher rates or severity of aggression in some cases, but not all. As studies have accumulated, the patterns observed in these carnivores are emerging as typical for cooperative breeders.

Social dominance, aggression and faecal glucocorticoid levels in a wild population of wolves, Canis lupus

Adrenal glucocorticoid (GC) secretion is an important component of the response to stress in vertebrates. A short-term increase in circulating GCs serves to redirect energy from processes that can be briefly curtailed without harm, allowing energy to be directed towards eliminating or avoiding the stressor. In contrast, prolonged elevation of GCs can cause a broad range of pathologies, including reproductive suppression. We examined whether social subordination in wolves leads to chronically elevated GC levels, and whether this ‘social stress’ causes reproductive suppression of subordinates in cooperatively breeding species. Behavioural and endocrine data collected over 2 years from three packs of free-living wolves in Yellowstone National Park did not support this hypothesis. GC levels were significantly higher in dominant wolves than in subordinates, for both sexes, in all packs, in both years of study. Unlike other cooperatively breeding carnivores (e.g. dwarf mongooses, Helogale parvula, and African wild dogs, Lycaon pictus), high GCs in dominant wolves were not associated with high rates of aggression or agonistic interaction. Aggression increased for wolves of all ranks during mating periods, accompanied by a significant rise in GC levels. If chronic elevation of GCs carries fitness costs, then social stress in wolves (and many other social species) is a cost of dominance, not a consequence of subordination. The specific behavioural correlates of dominance that affect GC levels appear to vary among species, even those with similar social systems.

Dominance, reproduction and survival in banded mongooses: towards an egalitarian social system?

The banded mongoose, Mungos mungo, is a social species that forms multimale and multifemale family groups. Earlier studies suggest these family groups are relatively egalitarian with small differences in reproductive opportunities among individuals of different rank. In contrast, previous studies of other social mongooses have focused on species with more despotic control of reproduction (meerkats, Suricata suricatta, dwarf mongooses, Helogale parvula). In these species, the distribution of reproductive opportunities amongst individuals of different rank has met the predictions of reproductive skew theory: dominant individuals accrue greater reproductive benefits than subordinates, with subordinates breeding less often than dominants. In this paper we test how well two predictions of reproductive skew theory explain variance in measures of reproductive effort, and its correlates, in a wild population of banded mongooses in Queen Elizabeth National Park, Uganda. We measure dominance rank in males and females, and we investigate whether individuals of higher social rank accrue greater benefits than subordinates in terms of survival and reproduction. Banded mongoose dominance hierarchies showed linearity, but low reproductive skew. Rank was not significantly correlated with age. Furthermore, there were only small effects of dominance rank on nutritional levels, and no effects on reproduction and survival, suggesting that banded mongoose societies are indeed relatively egalitarian. No evidence of reproductive suppression was found and other forms of reproductive control were not observed. However, we do not exclude the possibility of increased reproductive competition in circumstances of higher ecological constraints. These findings show that reproductive skew theory is equally useful in explaining variation in reproduction in societies with low reproductive skew, as it is in explaining the allocation of reproductive effort in despotic social systems.

Developing New Metrics for the Investigation of Animal Vocalizations

Abstract An increasing body of evidence shows that non-human animal languages maybe far more complex than previously assumed. Semantic content in animal alarm calls has been found in the vocalizations of vervet monkeys, some types of ground squirrels, dwarf mongooses, chickens, and Gunnison’s prairie dogs. This paper presents a classification system that provides important evidential support to earlier work on prairie dog communications. It does so using an entirely different system of analysis and a more fully automated experimental procedure. Furthermore, the application of fuzzy logic led to the development of a new system of metrics that can be used to investigate the difficult issues of how information is encoded in animal vocalizations and the level of linguistic complexity of those vocalizations.

Life at the Top: Animals Pay the High Price of Dominance

In the wild, dominant animals stress out their subordinates, according to textbook studies. But recent studies show the top dogs—as well as top dwarf mongooses, baboons, and other animals—have the highest levels of cortisol, a stress hormone. And habitually high cortisol levels may cost them years off their lives.

Pregnancy, oestrogens and future reproductive success in Serengeti dwarf mongooses

Pregnancy, oestrogens and future reproductive success in Serengeti dwarf mongooses

Inclusive fitness and reproductive strategies in dwarf mongooses

Abstract Dwarf mongooses (Helogale parvula) are small, communally breeding carnivores found in woodland and tree-savanna throughout Africa. Within a pack, socially subordinate mongooses do not normally breed, yet they invariably participate in all aspects of parental care. The primary alternative to tolerating reproductive suppression is dispersal, which shortens the wait for dominance and breeding. Here, we calculate the annual inclusive fitness payoffs to the dispersing and nondispersing strategies for males and females of ages one to seven, using data from a 14-year study in Serengeti National Park, Tanzania. Factors with effects on inclusive fitness included relatedness to pack mates before and after dispersal, the effect of help on recipients' reproductive success, the probability of dispersing successfully, the probability of attaining dominance, and reproductive success after attaining dominance. All of these factors differed between male and female dwarf mongooses. We compared the contributions of direct and indirect fitness to the total fitness of mongooses pursuing each of the strategies, across a range of ages. In our population, dispersal and nondispersal both yielded direct and indirect payoffs at most ages. For dispersers of both sexes, direct fitness was the primary component of total fitness but indirect fitness was substantial for young (< 2 years old) dispersers. For nondispersers of both sexes, indirect fitness was the major component of total fitness among young mongooses (up to 2 or 3 years), but direct fitness was the major component among older mongooses. By comparing the inclusive fitness payoffs for the two strategies, we determined the range of ages at which dispersal should be favored for each sex. These comparisons correctly predicted that males should be more dispersive than females at all ages, and that males should disperse over a broader range of ages.

Subordinate reproduction in dwarf mongooses

Abstract. Dwarf mongooses, Helogale parvula, are group-living carnivores in which the oldest male and female dominate reproduction, while subordinates tolerate reproductive suppression and provide care for the offspring of the oldest pair. Subordinates of both sexes, however, mate and subordinate females occasionally become pregnant. In addition, a model of 'power-sharing' in social groups (Vehrencamp 1983, Anim. Behav., 31, 667-682) predicts that dominant individuals should cede some fitness to subordinates, particularly older, higher-ranking individuals not closely related to the dominants, in order to retain them within the group. Human multilocus probes (Jeffreys' 33.15 and 33.6) were used to 'fingerprint' dwarf mongooses from nine different packs in the Serengeti National Park, Tanzania. The results demonstrate that subordinates of both sexes obtain direct fitness: 24% of young had subordinate fathers, while 15% had subordinate mothers. Multiple paternity can occur within a single female's litter. Those subordinates that reproduced were of high social rank and tended to be distantly related to the same-sex dominant, as predicted by Vehrencamp's model. The number of yearlings produced by subordinate females was similar to that predicted by the model. Subordinate males father a relatively high proportion of offspring given their frequency of mating, while subordinate females mate relatively more often than they produce offspring, consistent with previously inferred differences between the mechanisms of male and female reproductive suppression (Creel et al. 1992, Anim. Behav., 43, 231-245). Even though DNA analyses indicate that subordinates produced a substantial proportion of young born in this population, the magnitude of direct fitness obtained by subordinates was still low compared with the magnitude of indirect fitness obtained by helping.

Death and disappearance: estimating mortality risks associated with philopatry and dispersal

Models dealing with the relationship of inbreeding to dispersal, the evolution of cooperative breeding, and the adaptive significance of reproductive suppression all involve a parameter describing die probability that emigration ends in death. Surprisingly, estimates of this parameter (or equivalently, of the probability of dispersing successfully) are virtually absent from the literature. There are formidable difficulties in estimating dispersal risk by direct observation of emigrants, but we contend that many investigators have already collected demographic information that can be used to estimate it indirectly. The root problem is that the proportion of the population diat emigrates from its natal group or home range, e, is not generally observable. Nevertheless, for each value of e diere is only one possible survival rate of emigrants (st) and of philopatric animals (sf) diat can explain the overall survival rate. For study sites Uiat are neither sources nor sinks, we describe a graphical framework within which census data and behavioral observations can be used to place bounds on e, s,, and sp. We use data from a Serengeti population of the dwarf mongoose (HelogaU parvula) to illustrate how different types of data and assumptions allow us to construct better estimates of these parameters. For dwarf mongooses, die approach reveals unexpected differences in dispersal risk among sex and age classes.

Dwergmuishondjies en die betekenis van Golgota? Enkele teologiese en ekologiese perspektiewe

Dwarf mongooses and the meaning of Golgotha? Some theological and ecological perspectivesDuring the previous eight years we have taken notice of growing theological reflection on the ecological meaning of God, creation and re-creation. It seems that an holistic view of God, man and environment in a balanced coherence leads to a level-headed environment ethics. In this contribution the question is discussed whether Christianity with its exclusive views on man have not contributed to the harmful affliction of the ecological consciousness by subordinating the place and meaning of creation to salvation.

Aggression, Reproduction, and Androgens in Wild Dwarf Mongooses: A Test of the Challenge Hypothesis

Aggression, Reproduction, and Androgens in Wild Dwarf Mongooses: A Test of the Challenge Hypothesis

Lipid components in anal scent sacs of three mongoose species (Helogale parvula, Crossarchus obscurus, Suricata suricatta)

Anal sac secretions of three social mongoose species (Helogale parvula, Crossarchus obscurus, andSuricata suricatta) were chemically analyzed by means of gas chromatography-mass spectrometry. Compounds with high molecular weights (greater than 250) were found to distinguish the three species. Differences in composition suggest a possible species-specific role in scent marking. MaleH. parvula had vitamin E present in the anal sac, whereas it was absent in the females. This suggests a possible sex-specific function of vitamin E inH. parvula. No differences in chemical composition were found between male and femaleS. suricatta. Ten compounds were found in femaleC. obscurus that were not present in the male.

Behavioural and endocrine mechanisms of reproductive suppression in Serenge dwarf mongooses

Behavioural, demographic and endocrine data were collected from a wild population of dwarf mongooses, Helogale parvula, in Serengeti National Park, Tanzania. The data show that subordinate females are reproductively suppressed by a complex of endocrine and behavioural mechanisms, while subordinate males are reproductively suppressed primarily by behavioural mechanisms. Subordinate females have (1) low baseline oestrogen levels, (2) low mating rates, and (3) low peak oestrogen levels during mating periods. Subordinate males (1) have low mating rates, and (2) are the recipients of increased aggression during mating periods, but (3) have androgen levels indistinguishable from those of dominants, both during and away from mating periods. Mechanistic differences between the sexes suggest that the selection pressures favouring reproductive suppression may also differ between the sexes.

Spontaneous lactation is an adaptive result of pseudopregnancy

Lactation is almost exclusively associated with pregnancy and giving birth. Although lactation can be induced without a preceding pregnancy in some species, this requires exogenous hormones, artificially intense or extended suckling or both. Spontaneous lactation, lactation by females that have neither been pregnant nor experimentally manipulated, is extremely unusual among eutherians. Among nondomesticated animals, spontaneous lactation has been observed repeatedly only in the dwarf mongoose Helogale parvula. We report here spontaneous lactation by free-living dwarf mongooses using data on urinary oestrogen conjugate concentrations (n = 560, 65 females) and body weight (n = 3,096, 25 females) from a population in Serengeti National Park, Tanzania. We use demographic data from this population to demonstrate that spontaneous lactation, and thus the endocrine phenomena that induce it, increase the evolutionary fitness of lactating females.

Group size, survival, reproduction, and routes to breeding in dwarf mongooses

Survival and reproduction in a marked population of dwarf mongooses, Helogale parvula, were studied for a period of 13 years in the Serengeti National Park, Tanzania. Dwarf mongooses live in packs with a mean size of 8·9 containing a dominant breeding pair, usually, the oldest individuals. Survivorship of both juveniles and adults is positively related to pack size. Packs containing eight (the median) or more members raised twice as many offspring to yearling status as did smaller packs. Most males and many females became breeders following emigration from their natal packs. Of emigrants that attained breeding status, most (both males and females) did so by founding new packs. Males sometimes became breeders by emigrating with other males and ousting male breeders in another group. Many females and some males waited to succeed alphas of the same sex in their natal packs. The median age class when alpha status was attained (3 years old) and when breeding tenure ended (5 years old) was the same in both sexes, but females that became breeders following emigration attained alpha status earlier than those that attained status in their natal packs.

Exhibit for the Dwarf mongooseHelogale parvula: at London Zoo

Exhibit for the Dwarf mongoose<i>Helogale parvula</i>: at London Zoo

Behavioural Parameters of Vigilance in the Dwarf Mongoose: Social Acquisition of a Sex-Biased Role

Dwarf mongooses live in matriarchal family groups and possess a highly complex coordinated vigilance system. Parameters of vigilance bchaviour such as guarding duration, frequency, sequence, cues mediating guard orientation and exchange, number of guards present and fidelity to guarding sites are described for wild groups and compared, where appropriate, with data from captive ones to determine whether vigilance becomes modified after generations in captivity. Wild and captive groups showed little difference in basic guarding behaviour. Vigilant animals utilise a complex system of vocalisations to indicate predator presence, these varying with the type of predator sighted and mediating group response, which differs with predator type. Guarding is performed almost exclusively by subordinate males in both captive and wild groups. Vigilance behaviour is absent in naive hand-raised animals kept either singly or in pairs and put together in a group at approximately 1 year old. It develops normally, however, in the young of groups containing experienced adults. Several of its characteristic behavioural parameters are postulated as being acquired during juvenile/adult association at guarding sites. The implications of these findings are discussed.

A motivational analysis of object play in juvenile dwarf mongooses ( Helogale undulata rufula)

The dwarf mongoose ( Helogale undulata rufula) has a play vocalization, a short pulse at the 2-kHz level which is repeated at a rate of 3 to 12 or more pulses/s during the entire play period. The repetition rate is indicative of motivation intensity. This motivational study on object play shows that: (1) play becomes fragmented prior to termination; (2) motivation changes during a session fall into three different patterns all terminating at a ‘set point’ or ‘sollwert’; (3) the behaviour patterns performed during play show little sequencing related to original context but are causally different from those of exploration and have ‘optimum intensities’; (4) more limbs employed in object manipulation indicate higher intensity irrespective of the original non-play context of the behaviour pattern concerned; and (5) high intensity is coupled with more behaviour patterns performed per time interval. Hand-reared isolates show a delay in the appearance of play in ontogeny in comparison with pair-raised animals and their play contains a higher frequency of patterns bringing the object into close bodily contact. Play is considered as being a behaviour pattern complex with its own motivation which, through its performance, may compensate for motivational deficits or surpluses, a set point or sollwert replacing a consummatory act. Behaviour patterns from other behavioural contexts are taken over and reordered with regard to different rules, hence the apparent lack of sequencing. A threshold of general excitation associated with stimulus input is postulated as regulating the time of appearance of play in ontogeny, not maturational factors, and it may be used to compensate for specific stimulatory deficits occurring during ontogeny.