Kin recognition in Aleochara bilineata could support the kinship theory of genomic imprinting

Genomic imprinting corresponds to the differential expression of a gene according to its paternal or maternal origin. The kinship theory of genomic imprinting proposes that maternally or paternally inherited genes may be in conflict over their effects on kin differently related along the paternal or maternal line. Most examples supporting the kinship theory of imprinting deal with competition between offspring for maternal resources. However, genomic imprinting may also explain differential behavioral expression toward kin whenever sibs are more related to each other via one parental sex than the other. Unfortunately, nothing is currently known about imprinting associated with a behavioral phenotype in insects. Here we report the first evidence of such a maternally imprinted behavior. We show that the solitary parasitoid larvae of Aleochara bilineata Gyll (Coleoptera; Staphylinidae), which avoid superparasitizing their full sibs, also avoid their cousins when they are related to them through their father, but not when they are related to them through their mother. A genetic kin recognition mechanism is proposed to explain this result and we conclude that genomic imprinting could control the avoidance of kin superparasitism in this species and have a profound influence on decision-making processes.     

Factor of familiarity in sibling recognition in golden hamsters

Male hamsters, reared with their siblings and non-siblings, were tested for their exploratory behavior of conspecific in the 4th and 8th week after their birth. During the tests, a familiar sibling, an unfamiliar sibling, a familiar non-sibling and an unfamiliar non-siblings was presented in a choice box. Subjective distance among these testing animals was measured using the caseV of Thurston's paired-comparison test. The hamsters spent more time with the unfamiliar animals than with the familiar ones. Although biological relation (sibling or non-sibling) had a significant effect in the 4th-week test, only the familiarity determined the investigatory behavior in the 8th-week test. These results suggest sibling recognition based on learning in hamsters.     

Kin recognition and the 'armpit effect': evidence of self-referent phenotype matching

In species with multiple paternity or maternity, animals may best assess their relatedness to unfamiliar conspecifics by comparing their own phenotype(s) with those of unidentified individuals. Yet whether animals can recognize kin through self-matching is controversial. Because golden hamsters (Mesocricetus auratus) mate multiply and can produce multiply sired litters, they were tested for their ability to use self-matching for kin recognition. Hamsters that were reared only with non-kin since birth responded differentially to odours of unfamiliar relatives and non-relatives. Postnatal association with kin was not necessary for this discrimination. Prenatal learning was unlikely because of delayed production and perception of social odours. To our knowledge, this is the first demonstration that a vertebrate can use its own phenotype for kin-recognition purposes without prior experience with kin. By using itself as a referent, rather than its siblings or parents, a golden hamster may be better able to direct nepotism towards the most appropriate individuals. Kin discrimination via self-inspection may be especially important in nepotistic contexts (to identify most closely related conspecifics), whereas inclusion of the phenotypes of close kin as referents may be favoured in mate-choice contexts (to identify all related individuals).     

Individual recognition in salamanders: Cloacal odours

Male red-backed salamanders (Plethodon cinereus) were studied to determine the origin of the chemical cues allowing for individual odour recognition between conspecifics. Individual males showed a preference for substrates with their own faecal and cloacal odours rather than those marked by unfamiliar conspecific males. This discriminatory ability did not depend on recent differences in food consumed. These scent marks might be used to define breeding territories in the field.     

Kin recognition in rattlesnakes

Snakes are often regarded as the least social of all vertebrate groups, but this assumption stems from the fact that they are secretive and difficult to observe in nature, rather than direct evidence. Recent studies have revealed a surprising degree of social complexity in snakes. Here, I examine the ability of captive-raised timber rattlesnakes (Crotalus horridus) to recognize siblings by measuring the mean separation distance and frequency of contact between pairs of individuals housed together. The results show that female siblings associate more closely with each other than nonsibling pairs. Previous studies have shown that timber rattlesnakes occupying the same hibernacula have higher relatedness than snakes using neighbouring hibernacula, and frequently form social aggregations. Rattlesnakes exhibit other characteristics consistent with advanced sociality, including group defence, conspecific alarm signals and maternal defence of young. These findings reinforce the notion that, rather than being solitary and asocial, some snake species may form family groups.     

Kin recognition: evidence that humans can perceive both positive and negative relatedness

The evolution of spite entails actors imposing costs on 'negative' relatives: those who are less likely than chance to share the actor's alleles and therefore more likely to bear rival alleles. Yet, despite a considerable body of research confirming that organisms can recognize positive relatives, little research has shown that organisms can recognize negative relatives. Here, we extend previous work on human phenotype matching by introducing a cue to negative relatedness: negative self-resembling faces, which differ from an average face in the opposite direction to the way an individual's own face differs from the average. Participants made trustworthiness and attractiveness judgements of pairs of opposite-sex positive and negative self-resembling faces. Analyses revealed opposing effects of positive and negative self-resembling faces on trustworthiness and attractiveness judgements. This is the first clear evidence that humans are sensitive to negative relatedness cues, and suggests the potential for the adaptive allocation of spiteful behaviour.     

Kin recognition in social bees

Kin recognition in social insects has become a central issue in sociobiology because studies of the recognition abilities of social insects provide a test of kin selection theory. W.D. Hamilton(1) formalized kin selection theory by showing how individuals can gain fitness by increasing the reproductive output of relatives (kin). The social interactions of individuals, or groups, should be influenced by the genetic structure of the population. The ability to recognize kin can increase the adaptive value of social behavior by modulating it according to genetic relationship. From this, the specific prediction emerges: if individuals can distinguish among others with which they interact on the basis of the degree to which they are related, then behavior should be biased preferentially toward more closely related reproductive individuals.     

Kin recognition in embryonic damselfishes

Predator‐induced mortality rates are highest in early life stages; therefore, early recognition of threats can greatly increase survival chances. Some species of coral reef fishes have been frequently found to recruit back to their natal reefs; in this instance, there is a high chance of juveniles encountering their siblings, among other kin, after hatching. Kin recognition plays an important ecological role in that it allows individuals to protect genetically similar relatives, and hence increase their inclusive fitness. By observing changes in heart rates, we demonstrated that embryos of two damselfish species, Acanthochromis polyacanthus and Amphiprion melanopus, not only possess recognition of kin and damage‐released alarm odours, but also react to them in a graded manner. Such refined olfactory capabilities in embryonic stage organisms (seven and eleven days after fertilisation) suggest identification of threats may provide survival advantages post‐hatching, such as the informed choice of low risk habitats at settlement. To our knowledge this is the first time that kin recognition has been identified in embryos of any species.     

Mammalian social odours: attraction and individual recognition

Mammalian social systems rely on signals passed between individuals conveying information including sex, reproductive status, individual identity, ownership, competitive ability and health status. Many of these signals take the form of complex mixtures of molecules sensed by chemosensory systems and have important influences on a variety of behaviours that are vital for reproductive success, such as parent-offspring attachment, mate choice and territorial marking. This article aims to review the nature of these chemosensory cues and the neural pathways mediating their physiological and behavioural effects. Despite the complexities of mammalian societies, there are instances where single molecules can act as classical pheromones attracting interest and approach behaviour. Chemosignals with relatively high volatility can be used to signal at a distance and are sensed by the main olfactory system. Most mammals also possess a vomeronasal system, which is specialized to detect relatively non-volatile chemosensory cues following direct contact. Single attractant molecules are sensed by highly specific receptors using a labelled line pathway. These act alongside more complex mixtures of signals that are required to signal individual identity. There are multiple sources of such individuality chemosignals, based on the highly polymorphic genes of the major histocompatibility complex (MHC) or lipocalins such as the mouse major urinary proteins. The individual profile of volatile components that make up an individual odour signature can be sensed by the main olfactory system, as the pattern of activity across an array of broadly tuned receptor types. In addition, the vomeronasal system can respond highly selectively to non-volatile peptide ligands associated with the MHC, acting at the V2r class of vomeronasal receptor. The ability to recognize individuals or their genetic relatedness plays an important role in mammalian social behaviour. Thus robust systems for olfactory learning and recognition of chemosensory individuality have evolved, often associated with major life events, such as mating, parturition or neonatal development. These forms of learning share common features, such as increased noradrenaline evoked by somatosensory stimulation, which results in neural changes at the level of the olfactory bulb. In the main olfactory bulb, these changes are likely to refine the pattern of activity in response to the learned odour, enhancing its discrimination from those of similar odours. In the accessory olfactory bulb, memory formation is hypothesized to involve a selective inhibition, which disrupts the transmission of the learned chemosignal from the mating male. Information from the main olfactory and vomeronasal systems is integrated at the level of the corticomedial amygdala, which forms the most important pathway by which social odours mediate their behavioural and physiological effects. Recent evidence suggests that this region may also play an important role in the learning and recognition of social chemosignals.     

Experimental visceral leishmaniasis in golden hamsters

As a result of a long passage of L. donovani isolate on golden hamsters (21 passages were observed), in transplanting the agent from animals with a distinct clinical picture there was formed a highly virulent strain "G" of L. donovani for this species of animals. The weight arrest and then body mass losses were the most early signs of the disease. Parasites were regularly accumulated in spleen and liver and to a less extent in bone marrow. The main manifestations of visceral leishmaniasis in hamsters are cachexia, lienal syndrome, polyglandular deficiency on the background of hypoplasia of lymphoid tissue and defects of the system of monocytic phagocytes. Such symptom-complex can be a result of neuroendocrine deficiency during visceral leishmaniasis. Pathohistological picture of experimental visceral leishmaniasis is similar to that of man, so L. donovani infection in hamsters can serve as a model for studies of different medical and biological aspects of leishmaniasis.     

Kin recognition in a social spider

Social spiders accept immigrant spiders into their kin-based groups, suggesting that spiders cannot recognise kin and may lose inclusive fitness benefits. A field and two laboratory experiments on Diaea ergandros, a social crab spider, demonstrated that younger and older instar D. ergandros do discriminate siblings, but potential benefits were variable and not equally distributed. First, proportional survival was greater in large groups regardless of the within-group relatedness, so accepting immigrants increases probability of group survival (although relatedness was more important among smaller groups). Second, juvenile D. ergandros ate unrelated spiders instead of siblings when starved, so immigrants might represent a food reserve in times of food shortage. Third, subadult resident, sibling females cannibalised unrelated, immigrant females and their brothers instead of immigrant males when starved, suggesting that subadult female spiders may maximise outbreeding opportunities. These benefits provide selective pressure for groups to accept immigrants, but as benefits are realised differentially, conflict and cooperation will exist within spider groups similar to that shown in other group-living taxa.     

Kin recognition in an annual plant

Kin recognition is important in animal social systems. However, though plants often compete with kin, there has been as yet no direct evidence that plants recognize kin in competitive interactions. Here we show in the annual plant Cakile edentula, allocation to roots increased when groups of strangers shared a common pot, but not when groups of siblings shared a pot. Our results demonstrate that plants can discriminate kin in competitive interactions and indicate that the root interactions may provide the cue for kin recognition. Because greater root allocation is argued to increase below-ground competitive ability, the results are consistent with kin selection.     

Nestmate recognition in social wasps: the origin and acquisition of recognition odours

Laboratory studies of nestmate recognition in gynes (potential queens) of the social wasp, Polistes fuscatus, indicate that recognition odours have both a heritable and an environmental component. In addition, both endogenous odours (acquired as brood) and adult-acquired odours appear to mediate nestmate recognition. Heritable and environmental, as well as endogenous and adult-acquired recognition odours, are not additive in their effect on tolerance, suggesting a ‘cue similarity threshold’ model of recognition rather than a model that postulates tolerance continuouusly increasing with increasing degree of similarity between the learned and perceived cue. Young gynes (1·7–71·8 h after emergence) clearly possess recognition odours and there is no evidence that the age of a young gyne affects its expression of recognition odours. The failure of a wasp, isolated from its natal nest at emergence, to recognize its nestmates is due to the disruption of its learning of recognition odours, not to its acquisition of recognition odours. Gynes appear not to learn recognition odours directly from themselves. Young gynes deprived of the opportunity to learn recognition odours from their natal nest treat all gynes as nestmates, regardless of relatedness. This latter result, together with additional evidence, suggests that the ontogeny of nestmate recognition ability involves the development of intolerance to unfamiliar odours rather than the development of tolerance to familiar odours.     

Cholera toxin: mitogen for Harderian glands of golden hamsters

1. Within 2 days, a single injection of 10 micrograms cholera toxin induces a 6-20-fold increase in mitotic activity in the Harderian glands of male and female golden hamsters. 2. Neither hypophysectomy nor ovariectomy had any influence on this response. 3. The cellular proliferation does not appear to involve cAMP nor is it the result of stress, nor a release from an early mitotic block. 4. Nuclear polyploidy increases within a few hours after treatment. 5. DNA density per unit area increases within 24 hr and is maintained for at least 3 days.     

Kin recognition: knowing who's boss in wasp colonies

Paper wasps recognise the dominant individual in their colony and surrender reproduction to this alpha individual. Contrary to expectations her dominance status is not signalled by a chemical indicator of fertility.     

Kin and kinship psychology both influence cooperative coordination in Yasawa,Fiji

Genes shared through common ancestry are among the oldest social bonds. Despite these ancient roots, humans often co-opt the psychology of genetic relatedness and extend it to genetically unrelated others through culturally-acquired kinship systems. We investigate how genealogical relatedness and kinship norms might mutually support or oppose each other within a known kin network in Yasawa, Fiji. Yasawans' reliance on intensive, kin-based cooperation for daily life makes Yasawan kinship an interesting test case to compare the effects of genealogy and kinship norms. Confirming qualitative ethnographic claims, we find that Yasawan kin terms can be described in two dimensions of respect/closeness and joking/authority. Individual players use different strategies for genealogical relatives and non-relatives by making economic game choices that are increasingly beneficial to partners who share a higher percentage of genes through common ancestry. However, pairs of players are most successful in coordinating their game choices despite conflicting self-interests based upon kinship norms relevant to hierarchy. Thus, while genealogical relatedness may boost generosity, the extra behavioral structuring from kinship norms facilitates more productive but difficult coordinated action even when communication is not possible.