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Functional morphology is the study of relationships between morphology and organismal function. A simple inspection of animal diversity reveals a remarkable array of phenotypes and concomitant functions. For example, even within a single mammalian group (bats), one observes organisms consuming food of all types, such as blood, fruit, leaves, nectar, insects, and other animals. Accompanying this diversity in diet is a remarkable diversity in morphological structure ranging from vampire bats with fangs for making sharp incisions for drawing blood to leaf-eaters specialized for grinding and mastication. One also observes similar variation for different kinds of animal locomotion. Whereas some organisms have evolved wings for flight, such as in birds, bats, and flying insects, other species have evolved elongated hindlimbs for running or jumping, such as in some lizards and kangaroos. This diversity in form and function forms an essential template for functional morphologists because it provides the ''menu'' from which researchers can address how function relates to form. [ABSTRACT FROM PUBLISHER]

A chapter of the book "Forest Fare: Studying Food Webs in the Forest," by Julie K. Lundgren is presented. It explores the impact of the growing world population on animal ecology. It informs that the fragmentation of the undeveloped forestland threatens and endangers animals in the forest. It adds that animals that are sensitive to the daily activities of humans like noise, traffic, and lights.

A part of the book "Arctic Appetizers: Studying Food Webs in the Arctic," by Gwendolyn Hooks is presented. It explores the life of several species of ice algae, a type of phytoplankton, living in the Arctic. It offers information about the Arctic ice, which serves as a nursery for young zooplankton. It also describes the food cycle for living organisms in the Arctic Ocean.

The idea that kin selection plays a key role in the evolution of helping behavior is supported by evidence that in many cooperatively breeding vertebrates, helpers assist relatives. However, whether help is directed towards kin through an active kin-selection process or whether it is merely the result of passive coincidence, i.e., because the helpers normally remain on the natal territory where the recipients of help just happen to be relatives has been a long-standing debate. Moreover, the nature and evolution of active kin-discrimination mechanisms that may be used within cooperative breeding (and how these are influenced by the ecology of the species) have, until recently, received little attention. In this review, we discuss the roles of indirect and direct kin-recognition mechanisms on effective kin discrimination, with kin recognition defined in its broader sense as the differential treatment of conspecifics according to their genetic relatedness. In cooperative breeding species, indirect recognition based on spatial rules that reliably predict relatedness can result in effective kin-directed helping. However, direct recognition based on environmental or genetic cues should be able to provide more discriminating mechanisms of kin recognition. Environmentally determined recognition cues and templates could provide an effective means of kin recognition because cooperative breeders are characterized by extended associations with family on stable territories, philopatry, and high adult longevity. Examples of long-term studies that have investigated the use of kin-recognition mechanisms in cooperative breeding vertebrate species are discussed. While there is strong evidence that kin- recognition cues and templates, especially based on vocalizations, can be learned during a period of association with kin, there is no evidence for the use of genetically determined recognition cues or templates. How the ecology of a species may determine the nature and accuracy of the kin recognition mechanism that evolves, and how this will in turn determine the limits of adaptive behavior, is discussed. [ABSTRACT FROM AUTHOR]

The close kinship between helping workers and their sexual sisters in haplodiploid Hymenoptera is thought to have favored the evolution of sterile worker caste s and altruistic behavior in ants, bees, and wasps. Much research has therefore concentrated on elucidating the genetic structure of Hymenopteran societies. However, variation in kinship appears to be surprisingly unimportant in shaping some of the details of the social structure of insect societies. Instead, major features of the colony phenotype, such as worker number, queen number, reproductive skew, worker policing, and the pattern of allocation of resources towards colony growth or reproduction are more strongly affected by variation in ecological parameters, such as the availability of suitable nest sites for colony founding, resource abundance and the occurrence of social parasites. [ABSTRACT FROM AUTHOR]

Sociality has evolved predominantly in a few taxa within the animal kingdom. Even within the Hymenoptera, which are famous for their abundance and diversity of social life forms, eusocial species are very unevenly distributed among different families. Here we ask why within the superfamily Apoidea so few sphecid wasps but so many bees have become eusocial. We argue that the crucial difference between these two taxa is the type of resource provided for the progeny and that this has important consequences for the evolution of sociality. Sphecids provision brood cells with dead or paralyzed arthropods whereas bees gather pollen and nectar as larval food. In social Hymenoptera, workers are often smaller than the foundress es, since this saves some resources in particular at the beginning of the nest founding. However, the large size of the prey of sphecids requires a female to generate a certain minimum amount of power to bring the prey to the nest. Thus, small and/or weak females would not be successful at all and would not represent valuable helpers. In bees, however, small individuals are capable of gathering pollen at a comparatively high rate. Furthermore, the evolution of sociality might be facilitated if foundresses can save investment by providing sexuals and helpers only with the resources that are necessary for their respective task. Such a task-related investment for progeny might be much easier in bees than in sphecids, since the former can provide pollen of different plant species and different proportions of nectar whereas the latter cannot control the quality of the larval food to such an extent. The large size of the prey of sphecids has also enabled a unique strategy of oviposition for larval parasites. Flies and cuckoo wasps might oviposit on the prey while it is carried to the nest by a sphecid female. This "out-of-nest" parasitism cannot be countered by communal nesting, for example, making early steps of sociality less beneficial than in bees where this type of parasitism does not occur. We conclude that one of the most basic ecological features, the type of resource used for provisioning, might have far-reaching consequences for the evolution of sociality in the Hymenoptera. [ABSTRACT FROM AUTHOR]

In this chapter, I discuss the ecology and evolution of helping in hover wasps (Stenogastrinae), a tropical group that is uniquely suited for experimental studies in the field. I first outline the ecological benefits of helping that have been tested for in hover wasps, such as insurance advantages and direct fitness for helpers. I then discuss explanations for individual variation in helping decisions -why only some female offspring become helpers; and why some helpers work harder than others. Most of the chapter focuses on the hairy-faced hover wasp, whose behavioral ecology is best known, but I also discuss reproductive skew and task allocation in other species, and draw comparisons with other wasps where appropriate. The chapter ends with a comparison of the ecology of helping in hover wasps and that in cooperatively breeding vertebrates. The conclusion is that although helping can be understood using Hamilton's inclusive fitness framework in both of these major taxa, the critical ecological factors differ fundamentally between them. [ABSTRACT FROM AUTHOR]

We integrate phylogenetic information with data on genetic relatedness, inbreeding, sex ratio s, reproductive skew, host-plant use, gall morphology, soldier defensive behavior, kleptoparasite pressure, and demography to evaluate hypotheses for the origin and evolution of soldier caste s in Australian gall thrips. Necessary and sufficient conditions for the single origin of thrips soldiers appear to include high relatedness and inbreeding, strong kleptoparasite pressure, small brood size, and long duration of the gall. However, only brood size and gall duration apparently changed (becoming smaller) concomitant to the origin of soldiers. Reproductive skew between the foundress and soldiers was relatively low at the origin of soldiers, but increased substantially along the lineage leading to two species, Kladothrips habrus and K. intermedius, that also exhibit a relatively high propensity for defense by soldiers. Analysis of the associations between genetic and ecological traits that resulted from the social-adaptive radiation of gall thrips with soldiers indicated that (1) fewer matings by foundress es, and less mating after dispersal, result in stronger local mate competition, higher relatedness (and a higher inbreeding coefficient) among soldier females, and a stronger female bias in dispersers, and (2) gall size apparently constrains the reproduction of soldiers, with less soldier reproduction favoring the evolution of more-effective, more-altruistic soldiers; moreover, when soldiers are more effective, fewer of them need be produced, leading to higher production of dispersers. Soldiers were apparently lost in two lineages, in both cases in conjunction with a shift to a phylogenetically divergent species of Acacia host plant. Our analyses demonstrate that the evolution of soldiers in thrips is driven by a combination of selective pressures at three levels: from host-plant, to conspecific interactions, to kleptoparasites. [ABSTRACT FROM AUTHOR]

All the chapters of this book highlight to some extent the importance of kinship in the evolution of social life throughout the animal kingdom. They also accentuate that variation in genetic relatedness alone is not sufficient to explain the occurrence or details in the organization of social life. A comparative summary of the ecological and demographic factors favoring social life reveals some striking patterns of correlated traits (sociality syndromes). Accordingly, three types of sociality can be distinguished: (i) Aphids, thrips, wood-dwelling termites and the naked mole rat are all groups of totipotent individuals without intensive alloparental care protected by altruistic defenders. They have a long-lasting bonanza-type resource and a safe nest that offers the opportunity of inheriting the natal breeding position. (ii) Social Hymenoptera and non-wood dwelling termites with sterile or subfertile workers are characterized by intensive, altruistic alloparental care that usually involves progressive food provisioning. (iii) Cooperatively breeding vertebrates and social Hymenoptera with totipotent workers (e.g., wasps and queenless ants) take an intermediate position between class (ii) and class (i). Helpers here can gain indirect fitness benefits through alloparental care as well as direct benefits through inheriting the breeding position or by founding an own nest. [ABSTRACT FROM AUTHOR]

Kin-selection theory provides an evolutionary framework for the analysis of the effects of genetic relatedness on animal social systems. The aim of this chapter is to review postulated causal relationships between kinship patterns and social systems in non-human primates. In this context it is crucial to distinguish between social organization, i.e., the size and composition of a social unit, and its social structure, i.e., the pattern of social interactions among the members of a social unit. Current theories about the determinants of primate social systems yield predictions about where and why relatives should live together. Results of the available studies of the genetic structure of primate societies indicate deviations in several cases from expected patterns, however. The socioecological model, which has been widely used to analyze and explain relationships among ecological, social and genetic factors, on the one hand, and social structure, on the other hand, has therefore presumably overestimated the effects of kinship on primate social systems. [ABSTRACT FROM AUTHOR]

Within the family of African mole-rats (Bathyergidae) there is a range of lifestyles from strictly solitary to eusocial. This variation correlates strongly with numerous ecological factors providing evidence in support of an ecological basis for the evolutionary inception and maintenance of sociality in mole-rats. Furthermore, recent studies on the relatedness of individuals both within and between neighboring colonies of social mole-rats suggest that previous arguments that expounded the importance of relatedness to the evolution of sociality were misleading. A close look at arguably the only eusocial mammal known to science, the naked mole-rat, provides a unique opportunity to study the similarities in the selective environment of insects and mammals without the associated phylogenetic noise of a close common ancestry. In addition, striking examples of convergent evolution between naked molerats and eusocial insects provides insight into why there are so few eusocial vertebrates. [ABSTRACT FROM AUTHOR]

Horses (Equidae ) are believed to clearly demonstrate the links between ecology and social organization. Their social cognitive abilities enable them to succeed in many different environments, including those provided for them by humans, or the ones domestic horses encounter when escaping from their human care takers. Living in groups takes different shapes in equids. Their aggregation and group cohesion can be explained by Hamilton's selfish herd theory. However, when an individual joins and to which group it joins appears to be an active individual decision depending on predation pressure, intra group harassment and resource availability. The latest research concerning the social knowledge horses display in eavesdropping experiments affirms the need for an extension of simple herd concepts in horses for a cognitive component. Horses obviously realize the social composition of their group and determine their own position in it. The horses exceedingly flexible social behavior demands for explanations about the cognitive mechanisms, which allow them to make individual decisions. "Ecology conditions like those that favour the evolution of open behavioural programs sometimes also favour the evolution of the beginnings of consciousness, by favouring conscious choice. Or in other words, consciousness originates with the choice that are left open by open behavioural programs." Popper (1977) [ABSTRACT FROM AUTHOR]

Termites (Isoptera) belong to the classical eusocial insects and their resemblance to ant colonies is so striking that they are commonly known as ‘white ants'. However, the termites evolved social life independently, long before the ants. Their different ancestry also is reflected in several fundamental differences in the organization of the colonies. This chapter aims at summarizing the state-of-the-art in termite research and comparing the results with other social invertebrate and vertebrate systems in an attempt to reveal common principles underlying social evolution. First, I provide an overview of termites' biology and classification. I continue with a summary on the ‘hunt' for a genetical explanation of the evolution of termite' eusociality. Using a case study, I summarize ecological factors favoring cooperation in a lower termite and show the relevance of these results for other termite species. Based on these results I outline the potential evolutionary transitions in termite eusociality. Finally, I compare the driving forces in termites with those in cooperatively breeding vertebrates and offer a potential explanation why eusociality rarely evolved in vertebrates, despite often strikingly similar ecological pressures in both groups. [ABSTRACT FROM AUTHOR]

Social aphids are an ideal animal group in which to demonstrate the relative importance of ecological versus genetic factors in the evolution of sociality for several reasons: (1) Since aphids are clonal, the genetics of a colony is starkly simple (the aphids are either from the same clone or they are not) and, in principle, easy to measure; (2) Because good phylogeni es are available for several aphid taxa and there is clear evidence that there have been more independent origins of sociality in aphids than in any other social clade, it is possible to test for associations between ecological factors and the evolution of sociality; (3) Recent developments, in the understanding of the mechanism of the proximate control of soldier development, in the genetic basis of sociality, and in models of social evolution, make the social aphids an ideal group for experimental work on the evolution of social behavior; (4) The social aphids are of special ecological interest because they include the only organisms that have evolved sterile castes in societies that do not occupy some kind of nest (the secondary-host generations of the Hormaphidinae). The ecological context of altruism in social aphids has been shown to be quite intricate since it is now clear that colony defense is not the only costly behavior that they perform: they also have vital roles in keeping the colony clean, migrating to new colonies, and repairing their nest. Numerous ecological factors are highly pertinent in aphid social evolution including (1) the fact that all social aphids have at some stage in their life cycle a valuable and defensive fortress in the form of a plant gall, (2) population size and density, (3) birth rate, (4) the level of exposure to specialized predation, and (5) variation in the level of tending provided by ants. Kin selection in social aphids has given rise not only to a range of elaborate adaptations in behavior and morphology but also to impressive short-term flexibility in social investment. For example, in species that have specialized defenders that can mature to make a direct contribution to their colony's fitness, defense investment can be increased both through heightened production of defenders at birth and prolongation of the defender stage. We demonstrate that ecological factors are essential in any attempt to understand the role of kin selection in the evolution of social behavior in a group of organisms: ecology determines the extent to which groups consist of related individuals and the context in which these individuals can give and receive help. [ABSTRACT FROM AUTHOR]

We review the historical development of theory on the evolution and ecology of cooperation. Darwin launched this topic of inquiry with a surprisingly modern discussion of how fitness could be derived from both personal reproduction (direct fitness) and the reproduction of family (indirect fitness), and the anarchist Petr Kropotkin forever wove ecology into sociobiology with his book on Mutual Aid. From there, an eccentric group of protagonists took the helm and developed theories of social evolution with clear (although sometimes implicit) links to ecology. Here we provide a summary of the foundational theory, including Hamilton's rule, neighbormodulated fitness, inclusive fitness, and levels of selection; discuss the classification and semantics of social behaviors; and give a brief overview of the various mechanisms that have been invoked to explain cooperation. Recently, models have emerged that frame the evolution of cooperation in an explicitly ecological context, including the theories of reproductive skew, cooperation in viscous populations, and the tragedy of the commons. In particular, rates and patterns of dispersal strongly influence fitness, the costs and benefits of sociality, and genetic relatedness in social groups. This is an exciting time for ecological sociobiology and there is a great need for studies that combine careful natural history with social evolutionary theory. [ABSTRACT FROM AUTHOR]

In 1935, 101 cane toads, B. marinus, were introduced into north Queensland, Australia in an attempt to control the greyback cane beetle, Dermolepida albohirtum, a pest of sugar cane fields. The cane toad was, however, completely unable to control the beetles and itself became a successful pest. Since their arrival, cane toads have been implicated in the population declines of many native frog species and mammalian and reptilian predators. These effects are through predation, competition and the toxic secretions produced by the toad, poisoning potential predators. While the toxic nature of their secretions has been long known, only a part of the chemical complexity of the secretion has been identified to a molecular level. Our study aims to look at how diverse the chemical composition of cane toad skin secretions is, as well as its variability across life-history stages, between individuals and also whether different populations of toads may show differences in their chemistry. Beyond this, the chemical ecology of the toad, which probably includes pheromonal communication, may offer opportunities for control of this pest. [ABSTRACT FROM AUTHOR]

Preliminary investigations have been conducted to identify the chemical composition of carpal gland secretions from feral pigs in the lowland tropical rainforest of NE Australia. Carpal glands are located along the inner part of the front legs and their secretion may be distributed to the surrounding vegetation and bedding sites. Secretions were collected from the external surface of the glands by swabbing with filter paper discs. Compounds were then extracted in distilled ether and analysed by capillary gas chromatography. Secretions from boars and reproductive females contained more compounds than those from non-reproductive females. Only seventeen compounds were found in the secretions collected from boars and reproductive females, while one compound was only present in secretions from reproductive females. In boars compounds were at higher concentrations than in reproductive females. Lowest concentrations were found in non-reproductive females. Boars and reproductive females have more compounds with a higher molecular weight than non-reproductive females. The similarity in the chemical composition of carpal gland secretions from boars and reproductive females may be responsible for the same response that these animals trigger in conspecifics, i.e. avoidance behaviour. Further investigations will focus on the potential these secretions may have as repellents in feral pig control. [ABSTRACT FROM AUTHOR]

Olfactory stimuli are frequently integrated into zoo enrichment programs. This ‘olfactory enrichment' can stimulate reproduction or naturalistic behaviour, enhance enclosure exploration, or reduce inactivity. However, not all scents achieve their desired goals, and can in fact bring about undesirable behaviour such as increased levels of stereotypy. Few attempts have been made to quantify the impact of introducing olfactory stimuli to zoo enclosures, and there are inherent difficulties when designing, implementing and evaluating olfactory enrichment. Firstly, it is difficult without appropriate chemical analyses to anticipate what information a scent conveys, and therefore whether it will be received as an excitatory or aversive stimulant. Second, more practical difficulties are encountered. Consideration needs to be given to (i) the choice of scent used, its relevance and motivation, (ii) how to present the scent in time and space, (iii) individual variation in response rates and neophobia (fear of novelty) to scents, and finally (iv) the health implications linked to the use of olfactory stimuli. This paper reviews the olfactory stimuli used in zoos as enrichments and their reported effects. Practical suggestions are made to encourage and stimulate more empirical quantification of olfactory stimulation in zoo animals. [ABSTRACT FROM AUTHOR]

Small mammals are subject to predation from mammalian, avian and reptilian predators. There is an obvious advantage for prey species to detect the presence of predators in their environment, enabling them to make decisions about movement and foraging behavior based on perceived risk of predation. One technique commonly exploited to assess this risk is to use the odours of the faeces and/or urine of their predators to determine presence/absence and the length of time since a predator passed through an area. I examined the effect of faecal odours from marsupial and eutherian predators, and a native reptilian predator, on the behavior of three endemic Australian rodent species (the Fawn-footed Melomys Melomys cervinipes, the Bush Rat Rattus fuscipes and the Giant White-tailed Rat Uromys caudimaculatus) in rainforest remnants on the Atherton Tableland, North Queensland, Australia. Infrared camera traps were used to assess visit rates of rodents to odour stations containing faecal and control odours. Rodents avoided odour stations containing predator faeces, but did not avoid herbivore or control odours. The responses of the three prey species differed: in the late wet season U. caudimaculatus avoided predator odours, while R. fuscipes and M. cervinipes did not. In contrast, in the late dry season all three species avoided odour stations containing predator odours. I speculate that these differential responses may result from variations in life history traits between the species. [ABSTRACT FROM AUTHOR]

In hamsters and inbred mice, pheromone-containing chemosensory signals originating from the animal's own species (conspecific) and other species (heterospecific) produce differential patterns of immediate early gene (IEG = Fos/FRAs) expression in the medial amygdala. In males of both species, conspecific stimuli, regardless of gender or putative function, activated neurons in both anterior and posterior medial amygdala (MeA, MeP). With heterospecific stimuli, MeA was activated but MeP appeared to be suppressed. MeP neurons expressing GABA-receptor were selectively suppressed by heterospecific stimuli at the same time as the GABAergic caudal intercalated nucleus (ICNc) of the amygdala was activated, suggesting suppression of MeP by ICN. We propose that information on conspecific chemosignals with preprogrammed meaning (pheromones) is analyzed by MeP neurons, probably influenced by gonadal steroid status. Information about heterospecific stimuli that activate anterior medial amygdala via the vomeronasal organ appears to have restricted access to MeP. Signals from conspecific males that are potentially threatening elicit different patterns of activation in MeP than other conspecific signals. In hamsters, male flank gland secretion activates predominantly GABA-immunoreactive neurons and mainly in ventral MeP (MePv). Male mouse urine also activates predominantly MePv in mice. This region responds to predator odors in rats and is reported to do so in mice. These findings, with other data, support a division of labor in medial amygdala according to the reproductive or defense-related potential of the stimuli. There is some evidence for a convergence of information on conspecific and heterospecific threatening stimuli but, so far, the details are not entirely consistent. In our experiments with hamsters and mice, stimuli from potential predators (cat urine, cat collar) like other heterospecific stimuli, activated MeA and not MeP. Others studying mice found activation in ventral MeA (MeAv) during male-male interactions and in MePv by cat collar stimuli. Since the submission of this paper we have also found activation in mouse MePv by stronger cat collar stimuli (see note at end of text). [ABSTRACT FROM AUTHOR]

Squamata reptiles are often divided in two major groups based on the main sensory modality that they use: the chemical/visual and the visual taxa. Although Liolaemus lizards belong to the visual taxon Iguania, I show that they may depend heavily on chemosignals in many different aspects of their life. The combined information from Liolaemus and other "visual genera" that use chemosignals, urges us to reconsider the classical dichotomous segregation of Squamata in terms of sensory modality. In addition, further work is also necessary to understand the role of chemical signals in "visual" lizards. [ABSTRACT FROM AUTHOR]

Tongue-flicking is a sensory-gathering behavior used by snakes to deliver odorants to the vomeronasal organ. In the present study we provide a detailed description of environmental control and motor patterns of tongue-flicking in garter snakes, Thamnophis sirtalis. Tongue-flicks were monitored during prey extract trailing, foraging, delivery of air-borne odors and in an open field. Tongue-flick rates increased during airborne odor delivery and as a function of prey extract concentration during trailing, as previously reported. Motivation and prey consumption appeared to modify tongue-flick patterns since 1. tongue-flick rates were higher under foraging conditions than in an open field where no prior prey consumption had occurred and no prey odors were present; and 2. tongue-flick rates were elevated after prey consumption. The number of oscillations and the duration of tongue extensions were significantly reduced following tongue-substrate touches, suggesting that tongue contact with the substrate is the immediate stimulus for tongue retraction. [ABSTRACT FROM AUTHOR]

Fourteen premature infants (born at 30-33 weeks gestational age) were tested for their responses to the odours of different categories of human breast milk that are commonly available in intensive care nurseries: viz. their own mother's fresh and frozen milk, and frozen / pasteurized donor milk. Freezing reduced, but did not eliminate the stimulating effect of breast milk odour. The pattern of results obtained at 36 weeks post-conceptual age suggests that preterm infants may recognize the odour of their own mother's milk, and/or pasteurisation reduces the salience of milk odour. Breast milk odour elicits heightened sucking activity, which could have a positive effect on the development of breastfeeding behaviour. [ABSTRACT FROM AUTHOR]

Milk and the nipples of mammalian females have long been known to release attraction in conspecific newborns. This applies also to humans, in whom breast odour cues control infant state and directional responses. Such cues from the whole breast as well as from the isolated areola delay crying onset and stimulate positive orientation and oral actions in infants. Native secretions from areolar glands are especially salient to newborns in which they intensify oral-facial actions and respiration. Thus, odorous compounds from areolar glands may be in a position to play a role, among many other determinants, in establishing the processes pertaining to milk production, transfer and intake by infants. [ABSTRACT FROM AUTHOR]

Among mammals, rabbits (Oryctolagus cuniculus) show unusually limited maternal care and only nurse for a few minutes once each day. Successful suckling depends on pheromonal cues on the mother's ventrum, which release a stereotyped and distinctive pattern of nipple-search behaviour in the young, and which have been termed the nipple-search pheromone. The present report summarizes what is currently known about this unusually effective chemical signal and compares this with information in more recent reports of a rabbit mammary pheromone thought to achieve the same function. We draw attention to anomalies in the present state of knowledge regarding the nature and action of these two sets of chemical signals, and thus to the continuing uncertainty as to the chemical nature and source of the cues governing nipple-search behaviour, and thus successful suckling, in the newborn rabbit. [ABSTRACT FROM AUTHOR]

Lactating female rabbits (Oryctolagus cuniculus) nurse once daily for 5 min. The pups are thus forced to localize the nipples quickly. The females emit multiple chemosignals to guide them, among which are common odors derived from dietary aromas and one identified pheromone. Thus, the mammary pheromone (MP) released in rabbit milk is highly behaviorally active: it is a potent releaser of suckling-related behaviors in pups. The MP also acts as a strong reinforcer for early odor learning. Both of these functions of the MP are active right after birth and are thus in a position to play a central role in neonatal adaptation. However, the releasing function and the reinforcing functions of the MP follow different time-courses, suggesting that they are controlled by different underlying mechanisms. These data illustrate how a same chemical signal can carry distinct functions in a newborn mammal. [ABSTRACT FROM AUTHOR]

Females of many species choose to mate with relatively unrelated males in order to ensure outbred, heterozygous offspring. There is some evidence to suggest that the MHC is involved in mate choice decisions, either because MHC heterozygous offspring are more resistant to disease, or because the highly detectable odours associated with this region allow it to act as a marker of general inbreeding. To determine which role the MHC plays it is necessary to disentangle this region from the genetic background, a requirement which has generally proven difficult to achieve. We argue that the emphasis on MHC's role in mate choice has resulted in other potential markers of inbreeding being neglected, and discuss the evidence for MHC disassortative mating, the interaction with genetic background, and a possible role for alternative markers of inbreeding. [ABSTRACT FROM AUTHOR]

Many terrestrial mammals, including voles, self-groom when they encounter odors of opposite-sex conspecifics. Voles also spend different amounts of time self-grooming when they are exposed to odors of reproductively active and reproductively quiescent opposite-sex conspecifics, suggesting that self-grooming may be involved in the behaviors that support reproduction. If self-grooming is affected by the reproductive condition of the donor and the groomer, it is also likely that their ages will influence the amount of time that the groomer will self-groom. The objective of this paper was to test the hypothesis that age of the groomer and the scent donor affects the amount of time that meadow voles, Microtus pennsylvanicus, spend self-grooming when exposed to bedding scented by opposite-sex conspecifics. Older males (12-13 mo-old) spent more time self-grooming than younger males did (2-3 mo-old and 8-9 mo-old) when they were exposed to odors of 2-3 mo-old and 8-9 mo-old female voles. Younger males spent similar amounts of time self-grooming in response to odors of 2-3 mo-old, 8-9 mo-old, and 12-13 mo-old female voles. Female voles, independent of their age, spent more time self-grooming in response to odors of 12-13 mo-old males relative to 2-3 mo-old and 8-9 mo-old males. These data demonstrate that voles discriminate between the odors of different age opposite-sex conspecifics and adjust the amount of time they self-groom when exposed to them. The data augment the view that self-grooming is a specialized form of olfactory communication between the sexes. [ABSTRACT FROM AUTHOR]

The ability to recognize familiar conspecifics appears to be widespread among vertebrates and influences a variety of behavioural interactions including mate selection. Female choice of males has been shown to vary according to male familiarity, but interestingly in some species this favours familiar males, while in others unfamiliar males are preferred. Preference for unfamiliar partners might result from the attempt to minimise inbreeding costs by avoiding mating with individuals encountered during development, or with those sharing relatedness cues. Conspecifics that are familiar through prior mating experience might be avoided in species that benefit from a promiscuous mating system, again resulting in preference for unfamiliar mates. Conversely, familiar mates may be favoured in monogamous species where formation of a pair bond is important for parental investment, and when familiarity provides an opportunity for females to assess the quality and compatibility of potential mates. Thus different types of familiarity may have differing effects on mate choice, with the direction of preference being determined by other aspects of life history, such as the likelihood of inbreeding, the importance of polyandry, and the role of social dominance and territoriality in reproductive success. [ABSTRACT FROM AUTHOR]

Even in rodents, there is no clear evidence of the existence of sexual pheromones mediating instinctive intersexual attraction. In this review we discuss previous results of our group indicating that female mice reared in the absence of male-derived chemosignals are ‘attracted' by some components of male-soiled bedding, presumably detected by the vomeronasal organ. In contrast, male odors (olfactory stimuli) only acquire attractiveness by means of their association with the innately ‘attractive' vomeronasal-detected pheromones. These ‘attractive' male pheromones are rewarding to adult females, since they induce conditioned preference for a place where they are repeatedly presented to the females. Pheromone reward seems independent of the dopaminergic neurotransmission in the tegmento-striatal pathway, and uses mechanisms and circuits apparently different to those of other natural reinforcers. [ABSTRACT FROM AUTHOR]

Mate recognition is an essential component of successful reproductive behavior, and in rodent species, is primarily guided by the perception of social odors in the environment. Importantly, there is substantial evidence that species or sexual odor preferences may be regulated by early olfactory experience, although considerable variability in the plasticity of these behaviors has been observed. The current chapter summarizes what is known regarding the role of early olfactory experience in the development of adult odor preferences, synthesizing data across species, sex, and behavioral paradigms. [ABSTRACT FROM AUTHOR]

In this chapter, we review recent data about the involvement of both the main and the accessory olfactory system in mate recognition and the control of sexual behavior in mice. Whereas the main olfactory system seems to play a central role in mate recognition in both male and female mice, clear sex differences emerge with regard to which olfactory system plays a more important role in the control of sexual behavior. Indeed, the main but not the accessory olfactory system seems to be more important in regulating sexual behavior in male mice, whereas in female mice, the accessory olfactory system seems to play a critical role in the control of mating. Olfaction is of primary importance for social recognition in mammals, including mice. Thus mice use odors to distinguish sex, social or reproductive status of conspecifics (Brennan and Zufall 2006; Brown 1979). In addition, odors have been shown to facilitate the display of sexual behavior (e.g. Thompson and Edwards 1972) and to induce neuroendocrine responses (e.g. pregnancy block in female mice; Brennan and Keverne 1997). [ABSTRACT FROM AUTHOR]

Vaginal marking is a reproductively-oriented scent marking response, in which female Syrian hamsters deposit vaginal secretions in response to odor cues from male conspecifics. Converging lines of evidence suggest that vaginal marking functions as a solicitational signal, or an advertisement of a female's impending sexual receptivity. Although vaginal marking is commonly used as an assay of proceptivity, the neural control of vaginal marking remains largely unknown. In this chapter, we will review the existing literature on vaginal marking, synthesizing evidence from behavioral, endocrine, and neuroanatomical studies that indicate targets for the neural control of vaginal marking. Lastly, we will describe preliminary data from our laboratory that suggests a possible neural circuit for the descending control of vaginal marking in female Syrian hamsters. [ABSTRACT FROM AUTHOR]

She-males are male garter snakes that elicit courtship behavior from other males during the breeding season. Initially thought to consist of a small sub-set of males which retained their attractive nature throughout the breeding season, recent behavioral data suggests that most, if not all, males undergo a period of ‘she-maleness' upon first emerging from winter hibernation before losing their attractive nature shortly after emergence. Utilizing behavioral experiments and chemical analyses, we sought to discern whether newly-emerged male red-sided garter snakes (Thamnophis sirtalis parietalis) display a pheromone profile similar to the female sexual attractiveness pheromone. Sequestered in the skin lipids of females and responsible for triggering male courtship behavior, this pheromone has been previously linked with long-term she-maleness in this species. Results from courtship trials demonstrated that newly-emerged males are attractive to other males, although not to the same degree as females. Subsequent chemical analyses of skin lipids from females and newly-emerged males showed no quantitative or qualitative difference in the components constituting the sexual attractiveness pheromone. Thus, it appears that the majority of males in this species emerge with a female-like pheromone profile and subsequent physiological changes, yet to be identified, are responsible for the short- vs. long-term nature of this phenomenon. [ABSTRACT FROM AUTHOR]

Plethodontid (lungless) salamanders have evolved an unusual pheromone delivery system in which the male courtship pheromone is applied to the skin of the female, apparently diffusing through the mucosal-rich epithelia into her superficial capillary system. In Desmognathus ocoee, a plethodontid salamander that uses the diffusion mode of pheromone delivery, we conducted a behavioural bioassay to test a 20-25 kDa molecular weight fraction of the male courtship pheromone: this fraction was effective in increasing female receptivity. The principal component of the D. ocoee pheromone fraction was identified as a 25 kDa protein that had significant sequence similarity with the precursor of a newt reproductive pheromone (a decapeptide termed sodefrin). We termed the principal protein component in the D. ocoee pheromone "Sodefrin Precursor-like Factor" (SPF). SPF also occurs in other plethodontid salamanders, including species of Plethodon, Aneides and Eurycea. Across these species, SPF is a highly variable protein that bears the signature of positive selection. The presence of SPF in distantly related genera suggests that the sodefrin precursor gene has been retained as a courtship signal throughout the evolutionary radiation of plethodontid salamanders. [ABSTRACT FROM AUTHOR]

Human body odour is individually specific and several lines of evidence suggest that to some extent it is under genetic control. There are however numerous other sources of variation, commonly labelled as environmental factors, which are the main aim of this paper. These include: 1) reproductive status, 2) emotional state, 3) diet and 4) diseases. We primarily focus on axillary and genital odours as they have been proposed to have communicative function. We prelusively conclude that a specific diet and some diseases have major impact on variations in human body odour. [ABSTRACT FROM AUTHOR]

Humans produce temporarily stable, genetically mediated odour signatures and possess the ability to recognise, discriminate and identify other people through the sense of smell. The capability of self, gender, kin and non-kin odour recognition plays a role in social interactions. It seems that despite the stability of olfactory cues, the hedonic quality of body odour may vary over time. [ABSTRACT FROM AUTHOR]

The function of scent marking varies not only between species, but also among different age/sex classes within the same species. We conducted a longitudinal study of 26 free-living spotted hyenas to describe the ontogeny of anal gland scent marking (‘pasting') in this species. Males increased the proportional abundance of overmarking between cub and subadult periods, while female pasting remained consistent throughout early development. Pasting was sexually dimorphic in that male cubs pasted more frequently than female cubs, and male subadults countermarked more often than their female peers. By examining the anal pouches of 113 anaesthetized individuals, we also determined that spotted hyenas do not consistently produce paste until their third year. In light of these findings, the potential functions of pasting by juvenile hyenas were discussed. [ABSTRACT FROM AUTHOR]

The spotted hyena (Crocuta crocuta) is a territorial carnivore that lives in highly structured social groups called clans. Individuals of both sexes produce scent in a prominent anal scent gland. Gas-chromatographic analysis of 13 fatty acids and esters in scent profiles from 45 individuals belonging to three social groups demonstrated sufficient variation to suggest that odour may permit individual olfactory recognition. Further, anal scent secretions from members of the same clan are more similar to each other than those from different clans, consistent with the idea of a social group odour. We describe a mechanism involving both scent pasting and dry-pasting behaviour to explain how a group odour label may be concocted from individual scent secretions and how this group label is spread among members of a clan. [ABSTRACT FROM AUTHOR]

Male Saccopteryx bilineata possess a sac-like organ for the storage and display of odoriferous secretion in their front wing membrane. Since males use the scent in agonistic and courtship activities, and compose it from different secretions of distinct sources, like saliva, urine and gland secretion, we hypothesized that multiple information is encoded in the male scent-profile. We expected that the odour profile of males varies seasonally, giving information on male reproductive status. In addition, the odour profile ought to vary between individuals, thus providing the possibility for individual recognition. We repeatedly collected samples from wing-sac liquids of 20 male S. bilineata in five Costa Rican colonies during the mating and non-mating season. Samples were analysed by gas chromatography coupled to mass spectrometry to compare wing-sac contents. Wing-sac odours included various substances such as carboxylic acids, terpenoids and aromatic compounds. Male scent profiles varied (1) between seasons in the relative amount of tetradecanoic and octadecanoic acid, and (2) between individuals in the relative amount of two species-specific substances. These results suggest that the wing-sac liquid of male S. bilineata is indeed a composite trait and may be useful for the simultaneous transfer of multiple information. [ABSTRACT FROM AUTHOR]

Within a limited time after mating, exposure of female rodents to the scent of an unfamiliar conspecific male results in pregnancy termination. Since its discovery in mice, pregnancy block (or the ‘Bruce Effect') has been confirmed in several other murine and microtine rodent species. Adaptive explanations for this behaviour have traditionally focused on advantages to the blocking male, but the suggested benefits to females remain controversial. Consideration of potential female benefits and the implications of female advantage in pregnancy block suggest that this behaviour could evolve with little or no reference to male advantage, and may represent a potential reproductive cost to stud males. [ABSTRACT FROM AUTHOR]

The ability of animals to recognise and discriminate individual conspecifics is a vital feature of mammalian social systems. Genes of the major histocompatibility complex (MHC) have long been recognised to play an important role in influencing chemosensory cues of individual identity. In particular, the profile of urinary volatiles of mice has been related to MHC type, although a mechanism to explain this link has remained obscure. This article aims to review recent developments, which have revealed a new class of MHC-associated chemosignals. These are nine-amino acid peptide ligands bound by MHC class I molecules, which are presented at the cell surface for immune surveillance. In addition to this immune function, these peptides have been found to elicit highly sensitive and specific responses in sensory neurons of both the main olfactory and vomeronasal systems. They have also been shown to convey information about strain identity in biologically relevant contexts. Hence it now appears that there are multiple systems for signalling MHC identity, with distinct features that are likely to be adapted for use in different behavioural contexts. [ABSTRACT FROM AUTHOR]

Sexual orientation influences human olfactory function. Following a brief review of the biological basis of homosexuality, this chapter explores exactly how olfactory function varies as a result of sexual orientation. Three separate areas of research are considered: recent studies on the neural processing of social odorants by heterosexuals and homosexuals; the influence of sexual orientation on the production and perception of body odours; and the influence of female sexual orientation on menstrual synchrony. [ABSTRACT FROM AUTHOR]