Mammalian Societies Research Articles

Mandibular shape in the genus Marmota (Rodentia, Sciuridae): A preliminary analysis using outlines

Marmots are of prominent interest for sociobiologists studying mammal societies. They are also a fascinating group on which to test congruence between morphological information and molecular phylogeny and the possible occurrence of homoplasy in the evolution of the sciurid skeleton. To investigate marmot morphological relationships, an analysis of the outlines of the posterior region of the marmot mandible was performed using Elliptic Fourier analysis. Outgroup species belonging to other sciurid genera were also included, and the efficacy of this technique to discriminate taxa based on the morphology of this mandibular region was assessed. The mandible outlines led to a partial separation of the groups under study, but the phylogenetic signal seems to be weak compared to previous studies of the marmot mandible. Indeed, epigenetic influences acting on the posterior region of the mandible, an area of insertion of important masticatory muscles, may be a source of phenotypic variation that can mask the phylogenetic signal. However, interpretations must be made with caution as the posterior region of the mandible is an apparently suitable structure for outline analysis but the poor alignment of the outlines using standard elliptic Fourier methods made the study more complex than expected.

Kinship as a basis for alliance formation between male bottlenose dolphins, Tursiops truncatus, in the Bahamas

Alliances between reproductive males have been described in both cetacean and terrestrial mammal societies, and kin selection theory has often been invoked to explain these stable male coalitions. However, recent studies of bottlenose dolphins, Tursiops aduncus, in Australia suggest that mechanisms other than kinship are fundamental in the formation of male alliances. We supplemented skin biopsy sampling with the collection of faecal samples from individually recognized wild bottlenose dolphins, T.truncatus, to assess the role of kin selection in alliance membership in the northeast Bahamas. Stable alliances between pairs of males were identified based on association analyses of individual photoidentification data collected over 4 years. Molecular genetic analyses of tissue samples revealed highly significant correlations between patterns of association and both mitochondrial DNA haplotype identity and microsatellite relatedness, indicating that males within long-term alliances are more closely related than expected by chance. These data reinforce the high degree of plasticity previously reported within the genus Tursiops, and suggest that social and ecological differences between populations can markedly affect the role of kin selection in determining social alliances between male bottlenose dolphins.Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.

Reproductive skew among males in a female-dominated mammalian society

The purpose of this study was to document patterns of reproductive skew among male spotted hyenas (Crocuta crocuta), a species in which many normal mammalian sex roles are reversed. We used paternity determined from 12 microsatellite markers together with demographic and behavioral data collected over 10 years from a free-living population to document relationships among reproductive success (RS), social rank, and dispersal status of male hyenas. Our data suggest that dispersal status and length of residence are the strongest determinants of RS. Natal males comprise over 20% of the adult male population, yet they sire only 3% of cubs, whereas immigrants sire 97%. This reproductive advantage to immigrants accrues despite the fact that immigrants are socially subordinate to all adult natal males, and it provides a compelling ultimate explanation for primary dispersal in this species. High-ranking immigrants do not monopolize reproduction, and tenure accounts for more of the variance in male reproductive success than does social rank. Immigrant male hyenas rarely fight among themselves, so combat between rivals may be a relatively ineffectual mode of sexual selection in this species. Instead, female choice of mates appears to play an important role in determining patterns of paternity in Crocuta. Our data support a “ limited control” model of reproductive skew in this species, in which female choice may play a more important role in limiting control by dominant males than do power struggles among males.

Research Techniques in Animal Ecology: Controversies and Consequences

1. Hypothesis Testing in Ecology, by Charles J. Krebs2: A Critical Review of the Effects of Marking on the Biology of Vertebrates, by Dennis L. Murray and Mark R. Fuller3. Animal Home Ranges and Territories and Home Range Estimators, by Roger A. Powell4. Delusions in Habitat Evaluation: Measuring Use, Selection, and Importance, by David L. Garshelis5. Investigating Food Habits of Terrestrial Vertebrates, by John A. Litvaitis6. Detecting Stability and Causes of Change in Population Density, by Joseph S. Elkinton7. Monitoring Populations, by James P. Gibbs8. Modeling Predator--Prey Dynamics, by Mark S. Boyce9. Population Viability Analysis: Data Requirements and Essential Analyses, by Gary C. White10. Measuring the Dynamics of Mammalian Societies: An Ecologist's Guide to Ethological Methods, by David W. Macdonald, Paul D. Stewart, Pavel Stopka, and Nobuyuki Yamaguchi11. Modeling Species Distribution with GIS, by Fabio Corsi, Jan de Leeuw, and Andrew K. Skidmore

The evolution of superoxide dismutase (SOD) and catalase values in acute phase of myocardial infarction (MI)

Sexual violence occurring in the context of long-term heterosexual relationships, such as sexual intimidation, is widespread across human populations [1, 2, 3]. However, its evolutionary origins remain speculative because few studies have investigated the existence of comparable forms of sexual coercion in animals [4, 5], in which repeated male aggression toward a female provides the aggressor with delayed mating benefits [6]. Here, we test whether male aggression toward females functions as sexual coercion in wild chacma baboons (Papio ursinus). We found support for all three main predictions of the sexual coercion hypothesis [7]: male aggression (1) is greatest against cycling females, (2) is costly and represents the main source of injuries for cycling females, and (3) increases male mating success with their victims in the future. Detailed analysis of chronological sequences between aggression and matings ruled out other coercive mechanisms, such as short-term harassment and punishment, by showing that aggression and matings are temporally decoupled. This decoupling may explain why some forms of sexual violence have been largely overlooked in well-studied animal populations despite their likely impact on the fitness of both sexes. Finally, we found no support for alternative hypotheses such as a female preference for aggressive males [8, 9]. This new, detailed study of the forms and intensity of sexual intimidation in a wild primate suggests that it may be widespread across mammalian societies, with important implications for understanding the evolution of mate choice and sexual conflict in mammals, as well as the origins of human sexual violence.

Female-Headed Households and Female-Maintained Families: Are They Worth Targeting to Reduce Poverty in Developing Countries?

Controversy exists over whether to target public- and private-sector programs to female-headed households in developing countries in the attempt to combat poverty and social disadvantage. The issues related to the definition and measurement of female headship and the importance of the concept for development policy are discussed. A systematic review is then presented of the empirical evidence on the relation between female headship and poverty. If female-headed households tend to be poorer on average than other households headship should seriously be considered as a potentially useful criterion for targeting antipoverty interventions especially in developing countries where means testing is not feasible. The authors examine the potential costs and benefits of targeting female headship and review the experience of Chile one of the few countries which has targeted female headship through government intervention and the only one which has evaluation data available. The analysis of the project experience is used along with a review of the empirical evidence to answer the question of the desirability and efficiency of targeting female headship in order to reduce poverty in developing countries.

Loud calling in a female-dominated mammalian society: I. Structure and composition of whooping bouts of spotted hyaenas, Crocuta crocuta

In East Africa, spotted hyaenas live in highly structured, female-dominated social groups. They use a loud call, the whoop, for medium-and long-distance communication. Whoops are produced in bouts as a sequence of a variable number of discrete calls. Bouts may be composed of any combination of three structurally distinct types of whoops. Cubs, adult males and adult females differed in the composition of whooping bouts. Cubs also produced fewer calls per bout than adults, and adult males produced fewer calls per bout than adult females. Spotted hyaenas can probably recognize callers individually, since the structure of whoops of the same individual over a period of several years was stable, while variation between individuals could be impressive.

Loud calling in a female-dominated mammalian society: II. Behavioural contexts and functions of whooping of spotted hyaenas, Crocuta crocuta

Spotted hyaenas use a loud call, the whoop. In this study, whoops served three main functions: (1) to display identity; (2) to request support; and (3) to convey information about the location of the caller. An analysis of ontogenetic changes revealed a common functional framework of loud calling for cubs and adults. Cubs primarily whooped to provide information about their location and to request support, while adults mainly whooped to display their identity, males more so than females. Females whooped during agonistic encounters with other female clan members and clashes with neighbouring clans, when locating offspring and when rallying group members to defend communal resources. Whooping in males was mainly used for inter- and intra-sexual display. Self-advertisement (vocal display) was the most common function of whooping at the communal den. Both sexes displayed vocally, but males called at higher rates than females. High-ranking females displayed vocally at a higher rate than subordinates to assert their priority of access to kills in the clan's core range. Breeding females also whooped to deter potentially infanticidal non-clan members from approaching cubs at the communal den. Spotted hyaenas are polygynous, and male vocal display rates are an important component of inter-male competition. Display rates may also influence mate choice by the dominant and more aggressive females. Dominant males exerted more effort when whooping than subordinates by having higher display rates, more often using the energetically more costly type S whoop, and producing more calls per bout. All top ranked males are old, and have probably held long tenure in the clan. If females only mate with dominant males they may select mates on the basis of age, familiarity, display effort or a combination of these factors.

Social dynamics of mammals: Reproductive success, kinship and individual fitness

Apparent altruism, in which an individual seemingly decreases its evolutionary fitness by assisting others, can confer benefits if the individual assists kin. Thus, an animal can increase its total or inclusive fitness by producing offspring (direct fitness) and/or helping kin to reproduce (indirect fitness). Although kin selection has been suggested as the mechanism underlying the formation of mammalian societies, many species act as if they attempt to maximize the direct fitness component of their inclusive fitness.

Avian vs mammalian societies, as viewed from socio-ecological analysis

This paper was first planned in 1971 and was written in 1975 (marking the author's age of 60th) to compare avian and mammalian based on socio-ecological and -ethological analyses, independently of Wilson's Sociobiology (1975); with the following contents:I sociology1. Animal societies: its two viewpointsa. Phenotypic sociology b. Functional sociology2. Animal societies: its functional analysis3. Animal societies: its evolutiona. Origin and functional evolution b. Phenotypic evolutionII. Avian and mammalian societies1. Comparative characteristics2. Evolutionary retrospects3. Distributional property4. Life diversificationa. Mammalian b. Avian5. Behavioral diversificationa. Brain structure b. Brain function c. Instincts and intelligence b. Instinctive grades: 1) Physiological (individual or maintenance) behaviors 2) Social behaviors (a) Instinctive reflex beh. (= IRM) (Primary inst. beh.) b) Instinctive responding beh. (Secondary inst. beh.) c) Mental instinct-controlling beh. (Tertiary inst. beh.) d) Psychological reflex beh. (Spiritual shock beh.) e) Mental instinct-suppressing beh. (reductive inst. beh.) f) Learning g) Imprinting h) Tool-using i) Coopreative behaviorIII. Social development1. Flock-vs family-base life2. Dominance and leadership3. Individual and population (groups)4. Group-making propertya. Avian group life: 1) Family group 2) Areal group 3) Group territory 4) Colonyb. Mammalian group life c. Human group life5. On group selectionIV. PostscriptThe avian and mammalian societies, despite common general physiology, have evolved toward basically aerial-diurnal and terrestrial-nocturnal contrasted lives.The avian society is aberrantly specialized and could be neglected from the quadrupedal evolutionary line leading to mammalian society, but the avian flock-based, monogamous social structure with sexual cooperative division of work and the mammalian mother-filial family-based, polygynous, despotic and graded social structure, are compounded in the human society, which, beside this biological social base, is put under artificial restraint and constraint of laws, religions, ideologies of nations (or races). With this contradictions, the world human societies inevitably contiune their cooperative efforts, but with endless competition.

Mammalian social systems: Structure and function

Mammalian societies are complex socio-ecological systems controlled by the interactions of numerous internal constraints and external factors. We present a simple model describing these systems functionally in terms of the adaptive behavioural strategies for resource exploitation, predation avoidance and mating and rearing of young to maturity shown by the individuals that comprise them. The relations between species-specific limitations on the range of potential individual social behaviour and the environmental variables to which the system is responsive are analysed and hypotheses from correlational and analytical field studies examined. We advocate the continued development of sophisticated systems-analytical approaches to societal analysis taking into account the contrasting informational provenance of factors of different types. This is preferred to either an over-emphasis on environmental determination or excessively formalised neo-darwinian modelling based on assumptions from genetics and selection theory alone.

Social organization and the environment: Aspects of contemporary social ethology

Summary 1. A major development within the ethology of the last decade focusses attention upon the relations between social behaviour, ecology and population dynamics. This field may be termed ‘social ethology’ following an early but neglected usage of the term by Waxweiler at the start of the century. 2. Contemporary social ethology comprises three interdependent perspectives, socio-ecology, socio-demography and the study of social processes within natural and experimental groups. 3. In socio-ecology recent studies reveal that close correlations exist between the forms of avian and mammalian social organizations and their respective ecological niches. In particular the adaptive significance of certain mammalian societies comprising, on the one hand, multimale reproductive units and, on the other, those made up of one-male and all-male units is discussed and explanatory hypotheses derived from primate and ungulate data briefly considered. 4. In socio-demography research suggests that socially mediated mortality is of greater significance in the density-dependent control of bird and mammal numbers than had formerly been thought. The relations between ecological factors extrinsic to and social factors intrinsic to a social organization may be modelled in the form of open adaptive cybernetic systems rather than expressed in terms of analogies to closed mechanical or physiological systems. 5. Studies of social processes in non-human primate groups suggest that some form of role analysis may prove heuristic. The relations between dominance status, affiliative and kinship relations, social subterfuge and competition-contingent cooperation are discussed in an attempt to outline the dynamics of social change within relatively stable group structures. 6. ‘Human ethology’ seems at present to lack adequate definition as an academic discipline. Social ethology may provide the essential biological basis for future research in this area.

Group Formation Determined by Social Behavior; A Comparative Study of Two Mammalian Societies

Group Formation Determined by Social Behavior; A Comparative Study of Two Mammalian Societies