A wide range of species have been found to differentiate kin from nonkin. However, the ability to recognize kin, or the costs and benefits of discriminating kin from nonkin may depend on particular ...extrinsic environmental or intrinsic physiological conditions, resulting in context-dependent kin discrimination. North American red squirrels, Tamiasciurus hudsonicus, have previously been shown to be capable of discriminating the territorial calls of kin and nonkin. More recently, post hoc analysis of existing data suggested that kin discrimination might depend on the state of the caller (i.e. acute stress). Here we tested this hypothesis with independently collected data from a repeated-measures playback experiment and found no evidence in support of acute stress mediating kin discrimination. While squirrels were shown to register and respond to playbacks, exposure to a trapping/handling stressor in the caller had no effect on the receiver's response to the calls of kin and nonkin. Furthermore, we found no overall discrimination between the calls of kin and nonkin. These independently collected data instead suggest that the previous post hoc finding consistent with context-dependent kin discrimination was likely a spurious relationship associated with the data from which the post hoc hypothesis was generated rather than representing a real biological relationship. Our findings from this study emphasize the importance of testing post hoc hypotheses with independent experiments.
•We test whether acute stress enhances red squirrel kin discrimination of rattle calls.•We found no evidence of stress-mediated or general kin discrimination.•These findings falsify a previously posited hypothesis in the literature.•Kin discrimination in red squirrels may be more closely linked to food resources.
Studies of vocal kin recognition in avian species have typically tested responses to vocal signals based upon either familiarity (recognition via ‘learned associations’) or relatedness (recognition ...of genetic kin) but have rarely simultaneously tested for the effects of both. Here we examined vocal kin recognition in the cooperatively breeding southern pied babbler, Turdoides bicolor, using vocalizations from familiar kin, unfamiliar kin, familiar nonkin and unfamiliar nonkin in a playback experiment. We found limited support for recognition based upon familiarity: individuals appeared to be recognized from a period of prior association and associative learning. Focal birds (dominant females) discriminated familiar birds from unfamiliar birds, but discrimination was evident in only one of three behavioural response measures. Focal birds did not discriminate familiar kin from familiar nonkin, nor did they discriminate unfamiliar kin from unfamiliar nonkin, indicating no support for vocal recognition based on relatedness. The context of the experiment also affected discrimination, with focal birds reacting more strongly to calls from females (potential rivals) than to calls from males. Because familiarity in this species arises from the association of individuals in groups, and most groups comprise close kin, familiarity with group members offers a close proxy for kin recognition. While kin recognition systems based upon familiarity do not allow the identification of unfamiliar kin, the benefits of such recognition may be negligible in cooperatively breeding species that live in kin-based groups.
•Animals may recognize relatives because they are familiar with certain individuals.•Animals may recognize relatives through shared genetic heritage.•Pied babblers live in family-based groups and recognize familiar calls.•Pied babblers did not discriminate unfamiliar relatives from unfamiliar nonkin.•Recognition in pied babblers is based on familiarity and not genetic relatedness.
The phenomenon that organisms can distinguish genetically related individuals from strangers (i.e., kin recognition) and exhibit more cooperative behaviours towards their relatives (i.e., positive ...kin discrimination) has been documented in a wide variety of organisms. However, its occurrence in plants has been considered only recently. Despite the concerns about some methodologies used to document kin recognition, there is sufficient evidence to state that it exists in plants. Effects of kin recognition go well beyond reducing resource competition between related plants and involve interactions with symbionts (e.g., mycorrhizal networks). Kin recognition thus likely has important implications for evolution of plant traits, diversity of plant populations, ecological networks and community structures. Moreover, as kin selection may result in less competitive traits and thus greater population performance, it holds potential promise for crop breeding. Exploration of these evo‐ecological and agricultural implications requires adequate control and measurements of relatedness, sufficient replication at genotypic level and comprehensive measurements of performance/fitness effects of kin discrimination. The primary questions that need to be answered are: when, where and by how much positive kin discrimination improves population performance.
Can plant distinguish genetically related individuals from strangers (kin recognition) and exhibit more cooperative behaviour towards their relatives (positive kin discrimination)? Having reviewed the 14 years of research on this issue, we conclude that the answer to this question is yes. Focusing on belowground interactions, we illustrate how this kin recognition involves reduced resource competition between related plants but may also involve interactions with symbionts (e.g., mycorrhizal networks). But the implications of kin recognition for evolution of plant traits, diversity of plant populations, ecological networks and community structures, as well as crop production, though widely suggested to be significant, still need to be explored. Addressing these outstanding questions requires approaches that quantify when, where and by how much positive kin discrimination improves population performance.
Nepotism and reciprocity are not mutually exclusive explanations for cooperation, because helping decisions can depend on both kinship cues and past reciprocal help. The importance of these two ...factors can therefore be difficult to disentangle using observational data. We developed a resampling procedure for inferring the statistical power to detect observational evidence of nepotism and reciprocity. We first applied this procedure to simulated data sets resulting from perfect reciprocity, where the probability and duration of helping events from individual A to B equalled that from B to A. We then assessed how the probability of detecting correlational evidence of reciprocity was influenced by (1) an increasing number of helping observations and (2) an increasing degree of simultaneous nepotism. Last, we applied the same analyses to empirical data on food sharing in common vampire bats, Desmodus rotundus, and allogrooming in mandrills, Mandrillus sphinx, and Japanese macaques, Macaca fuscata. We show that at smaller sample sizes, the effect of kinship was easier to detect and overestimated relative to the effect of reciprocal help. This bias in power was true in both empirical and simulated data, including when simulating perfect reciprocity and imperfect nepotism. We explain the causes and consequences of this difference in power for detecting the roles of kinship versus reciprocal help. When comparing the relative evidence for kin-biased help and reciprocal help, we suggest that researchers measure the relative reliability of both kinship bias and symmetry in the model by plotting the coefficients and their detection probability as a function of sampling effort. We provide R scripts to allow others to do this power analysis with their own data sets.
•Reciprocity could be based on a long-term social history more than recent events.•We developed an R script to infer power for detecting nepotism and reciprocity.•We applied this procedure to simulated and empirical cooperation networks.•Compared to kinship effects, symmetrical helping is harder to estimate.•Weak simultaneous nepotism makes even perfect reciprocity hard to detect.
Pathways to paternal care in primates Rosenbaum, Stacy; Silk, Joan B.
Evolutionary anthropology,
September/October 2022, Letnik:
31, Številka:
5
Journal Article
Recenzirano
Natural selection will favor male care when males have limited alternative mating opportunities, can invest in their own offspring, and when care enhances males' fitness. These conditions are easiest ...to fulfill in pair‐bonded species, but neither male care nor stable “breeding bonds” that facilitate it are limited to pair‐bonded species. We review evidence of paternal care and extended breeding bonds in owl monkeys, baboons, Assamese macaques, mountain gorillas, and chimpanzees. The data, which span social/mating systems and ecologies, suggest that there are multiple pathways by which conditions conducive to male care can arise. This diversity highlights the difficulty of making inferences about the emergence of male care in early hominins based on single traits visible in the fossil record. We discuss what types of data are most needed and the questions yet to be answered about the evolution of male care and extended breeding bonds in the primate order.
Crozier’s paradox suggests that genetic kin recognition will not be evolutionarily stable. The problem is that more common tags (markers) are more likely to be recognised and helped. This causes ...common tags to increase in frequency, eliminating the genetic variability that is required for genetic kin recognition. In recent years, theoretical models have resolved Crozier’s paradox in different ways, but they are based on very complicated multi-locus population genetics. Consequently, it is hard to see exactly what is going on, and whether different theoretical resolutions of Crozier’s paradox lead to different types of kin discrimination. I address this by making unrealistic simplifying assumptions to produce a more tractable and understandable model of Crozier’s paradox. I use this to interpret a more complex multi-locus population genetic model where I have not made the same simplifying assumptions. I explain how Crozier’s paradox can be resolved, and show that only one known theoretical resolution of Crozier’s paradox – multiple social encounters – leads without restrictive assumptions to the type of highly cooperative and reliable form of kin discrimination that we observe in nature. More generally, I show how adopting a methodological approach where complex models are compared with simplified ones can lead to greater understanding and accessibility.
Mate preference based on relatedness may evolve in response to costs and benefits of inbreeding avoidance. Whereas mating with closely related individuals can have negative fitness consequences due ...to inbreeding depression, it may simultaneously be favoured by inclusive fitness benefits. Variation in the fitness payoff shaped by benefits of inbreeding may even lead to preference for mating with kin. We investigated this hypothesis in the social spider Stegodyphus dumicola, a cooperative species in which reproduction occurs among siblings within the group, premating dispersal is lacking and infrequent encounters with unrelated individuals result in homozygous genetic lineages. We tested whether female mate choice is influenced by male relatedness by pairing females with males that differ in the degree of genetic relatedness, namely nest members, non-nest members from the same population and non-nest members from allopatric populations. We recorded premating (male rejections, latency to mating) and mating (copulation duration and interruptions) behaviours. Females showed no preference for partners on the basis of their relatedness during the premating phase, as frequencies of rejections and successful matings did not differ markedly in encounters with nest and non-nest members. This suggests that selection on discriminatory mechanisms may be weakened or lost in species with inbreeding tolerance and in which relatedness between interacting individuals is very high and variance in relatedness extremely low. Unrelated males from the geographically distant population experienced longer copulations than males from the same population. We interpret this finding as depicting a possible scenario of a between-population reproductive barrier or functional incompatibility, which may be the mechanism causing lower fitness in between-population crosses previously documented in these populations.
•Benefits of inbreeding may lead to mate preference for kin.•Social spiders inbreed due to lack of dispersal and within nest matings.•Our study shows that females do not prefer partners based on their relatedness.•Selection on kin recognition mechanisms may be relaxed in this system.
Abstract
Reproductive sharing in animal groups with multiple breeders, insects and vertebrates alike, contains elements of both conflict and cooperation, and depends on both relatedness between ...co-breeders, as well as their internal and external conditions. We studied how queens of the ant Formica fusca adjust their reproductive efforts in response to experimental manipulations of the kin competition regime in their nest. Queens respond to the presence of competitors by increasing their egg laying efforts, but only if the competitors are highly fecund and distantly related. Such a mechanism is likely to decrease harmful competition among close relatives. We demonstrate that queens of Formica fusca fine-tune their cooperative breeding behaviors in response to kinship and fecundity of others in a remarkably precise and flexible manner.
Ant societies may contain multiple queens competing over reproduction. In the ant, Formica fusca, queens adjust their egg laying effort to kinship of their nestmates. Our experiments show that queens increase their egg laying rate when exposed to odors of a highly fecund second queen, but only when this queen is not close kin. When exposed to odors of a highly fecund close relative, queens decrease their egg laying in order to decrease competition.
Abstract
Group-living animals are faced with the challenge of sharing space and local resources amongst group members who may be either relatives or non-relatives. Individuals may reduce the ...inclusive fitness costs they incur from competing with relatives by either reducing their levels of aggression toward kin, or by maintaining physical separation between kin. In this field study, we used the group-living cichlid Neolamprologus multifasciatus to examine whether within-group aggression is reduced among group members that are kin, and whether kin occupy different regions of their group’s territory to reduce kin competition over space and local resources. We determined the kinship relationships among cohabiting adults via microsatellite genotyping and then combined these with spatial and behavioral analyses of groups in the wild. We found that aggressive contests between group members declined in frequency with spatial separation between their shelters. Female kin did not engage in aggressive contests with one another, whereas non-kin females did, despite the fact these females lived at similar distances from one another on their groups’ territories. Contests within male–male and male–female dyads did not clearly correlate with kinship. Non-kin male-male and male–female dyads lived at more variable distances from one another on their territories than their corresponding kin dyads. Together, our study indicates that contests among group members can be mediated by relatedness in a sex-dependent manner. We also suggest that spatial relationships can play an important role in determining the extent to which group members compete with one another.
Group-living animals must share space and resources with group mates, who can be either kin or non-kin, and it is often unclear how competitive or cooperative group members should be. In a group-living cichlid, we show that co-habiting females are less aggressive to their female kin (relative to non-kin) despite living at equivalent distances to one another. This pattern was not detected among co-habiting males, revealing that kin-directed social behavior can differ between the sexes.
PDF
