Kin Recognition

A few species of mammals produce group-specific vocalisations that are passed on by learning, but the function of learned vocal variation remains poorly understood. Resident killer whales live in stable matrilineal groups with repertoires of seven to 17 stereotyped call types. Some types are shared among matrilines, but their structure typically shows matriline-specific differences. Our objective was to analyse calls of nine killer whale matrilines in British Columbia to test whether call similarity primarily reflects social or genetic relationships. Recordings were made in 1985-1995 in the presence of focal matrilines that were either alone or with groups with non-overlapping repertoires. We used neural network discrimination performance to measure the similarity of call types produced by different matrilines and determined matriline association rates from 757 encounters with one or more focal matrilines. Relatedness was measured by comparing variation at 11 microsatellite loci for the oldest female in each group. Call similarity was positively correlated with association rates for two of the three call types analysed. Similarity of the N4 call type was also correlated with matriarch relatedness. No relationship between relatedness and association frequency was detected. These results show that call structure reflects relatedness and social affiliation, but not because related groups spend more time together. Instead, call structure appears to play a role in kin recognition and shapes the association behaviour of killer whale groups. Our results therefore support the hypothesis that increasing social complexity plays a role in the evolution of learned vocalisations in some mammalian species.

Besides its immunological function of self/non-self discrimination the major histocompatibility complex (MHC) has been recognized as a possible source of individual specific body odors. Dating back to speculations on the role of the extraordinary polymorphism of the MHC as background of an individual chemosensory identity and to early observations of MHC-dependent mate choice in inbred strains of mice, systematic experimental studies revealed a first evidence for H-2 related body odors in this species. Meanwhile a large number of animal studies with rodents and a series of field studies and experiments with humans have extended our knowledge of MHC-related odor signals and substantiated the hypothesis of immunogenetic associated odor types. These results suggest that the most prominent feature of the MHC, its extraordinary genetic diversity, seems in part to be selectively maintained by behavioral mechanisms which operate in contemporary natural populations. The high degree of heter...

Kin recognition is a critical element to kin cooperation, and in vertebrates, it is primarily based on associative learning. Recognition of socially unfamiliar kin occurs rarely, and it is reported only in vertebrate species where promiscuity prevents recognition of first-order relatives. However, it is unknown whether the recognition of socially unfamiliar kin can evolve in monogamous species. Here, we investigate whether genetic relatedness modulates aggression among group members in Siberian jays (Perisoreus infaustus). This bird species is genetically and socially monogamous and lives in groups that are formed through the retention of offspring beyond independence, and the immigration of socially unfamiliar nonbreeders. Observations on feeders showed that genetic relatedness modulated aggression of breeders towards immigrants in a graded manner, in that they chased most intensely the immigrant group members that were genetically the least related. However, cross-fostering experiments showed that breeders were equally tolerant towards their own and cross-fostered young swapped as nestlings. Thus, breeders seem to use different mechanisms to recognize socially unfamiliar individuals and own offspring. As Siberian jays show a high degree of nepotism during foraging and predator encounters, inclusive fitness benefits may play a role for the evolution of fine-scale kin recognition. More generally, our results suggest that fine-graded kin recognition can evolve independently of social familiarity, highlighting the evolutionary importance of kin recognition for social species.

Cooperation and conflict are inevitable consequences whenever a group of individuals get together, be they groups of self-replicating molecules or groups of warring nations. This paper gives an overview of my research using the tropical primitively eusocial paper wasp Ropalidia marginata, aimed at understanding the factors that modulate cooperation and conflict in an insect society. Hamilton's rule provides an excellent theoretical framework not only for investigating the role of genetic relatedness in modulating the levels of cooperation and conflict, as has been done so extensively in the last 30 years, but also for focussing on other factors, when genetic relatedness may be relatively unimportant. Polyandry or multiple mating by queens of R. marginata and serial polygyny or the frequent change in queens, breakdown the genetic asymmetries created by haplodiploidy and make it genetically less advantageous to be a worker, than theoretically expected. Intra-colony kin recognition abilities appear not to be so well developed as to facilitate nepotism in the face of intra-colony genetic variability. Artificial colonies with highly elevated levels of genetic variability appear to be indistinguishable from natural colonies. We have therefore investigated the possibility that social behaviour in insect societies is at least in part mutualistic. The response of wasps to alien conspecifics in the context of their nestS and outside, suggest that factors other than genetic relatedness such as inter-individual assessments, facilitated by impressive cognitive abilities, may play a significant role in modulating the levels of cooperation and conflict.

Colonial identity in social insects is based on nestmate recognition which is mediated through cuticular substances. Although this is considered to be distinct from kin recognition, it is possible that through evolution the signal mediating kinship was replaced by the signal mediating "nestmateship". Cuticular hydrocarbons in Cataglyphis niger are responsible for modifying the ant's aggressive behavior and are considered to

"Social behaviour in spiders is rare: of the 39 000 species of spiders known, only 23 are considered to be cooperatively social. Delena cancerides is a social species of the huntsman spider that is endemic to Australia. This species is virtually unique among social spiders, having evolved social behaviour in the absence of a snare web. It is thought that this form of social behaviour in D. cancerides has evolved via the sub-social route, that is, the extension of an ancestrally occurring period of maternal care and the delayed dispersal of juveniles. Most social spiders show no aggression towards non-kin conspecifics, prompting suggestions that spiders cannot recognize kin; however, D. cancerides individuals are highly aggressive towards conspecifics introduced from outside their own colony. In order to determine whether selective aggression in D. cancerides has its basis in kin recognition, tolerance behaviour was assessed in the context of kinship and size. We observed that, in general, juveniles preferred to starve than engage in cannibalism of any conspecifics, related or not. However, where cannibalism did occur, non-kin were preferentially eaten, indicating that this species is clearly capable of kin recognition. Size thresholds were also established, below which juveniles are tolerated by adults and above which aggressive interactions leading to death occur. We conclude that kin recognition and juvenile dispersal explain the
uncharacteristically high levels of genetic polymorphism in this species."

Kin recognition in social insects In two very well known papers in 1964, W. D. Hamilton proposed a genetical theory for the evolution of altruistic and other social behaviour, a theory which is now known as kin selection. Hamilton's ideas were rapidly appreciated and widely applied (Wilson, 1971). Yet, at least for the next 15 year~:; we had no clue as to how animals assessed kinship or genetic relatedness amongst themselves. This situation has now changed and the ability to discriminate kin from non-kin has been reported not only in ants, bees and wasps but also in marine invertebrates. isopods, fishes, frogs, toads, birds and a variety of mammalian species (Gadagkar, 1985).

Kin recognition requires the ability to discriminate between one’sowngenetic relatives and non-relatives.
There are two mechanisms that aid in kin discrimination: phenotype matching and familiarity. Dogs
may be a good model for assessing these mechanisms as dogs are a promiscuous social species with a
keen sense of smell. Domestic dogs of both sexes were presented with two scents (close kin, distantkin)
and preference was assessed through three measures (latency to approach, number of visits, time
spent). Experiment 1 explored the possibility of phenotype matching as subjects had no contact with
sires, whose scent was presented alongside a control male’s scent. Experiment 2 explored recognition
of siblings raised with the subjects and then separated at seven weeks of age. Whereas female dogs in
this experiment did not show a statistically significant preference, male dogs showed a preference for
distant-kin when presented with sire and female sibling samples.