Kin Recognition Research Articles

Kin discrimination in cannibalism by a predatory mite, Amblyseius herbicolus (Chant) (Acari: Phytoseiidae)

Kin recognition has been widely observed across the animal kingdom. Individuals discriminate and treat conspecifics differently in relation to their genetic relatedness to increase their inclusive fitness (i.e. their own reproductive success and that of their relatives) and to avoid adverse influences from inbreeding. Although most studies on kin recognition have focused on group-living species, this behaviour can also be adaptive in solitary species.

Social context during ontogeny affects cannibalism and kin recognition of the predatory mite Amblyseius herbicolus at different life stages.

Cannibalism is commonly found among phytoseiids at almost all mobile life stages. The avoidance of kin cannibalism in the presence of non-kin has been observed in a limited number of phytoseiid species. However, studies examining kin recognition by individuals at different life stages are limited. Early experience with conspecifics can alter individuals' social behaviour at later stages. In this study, we examined the influence of ontogenetic isolation on cannibalism and kin recognition by the predatory mite Amblyseius herbicolus (Chant) (Acari: Phytoseiidae) at different life stages. In a choice test, A. herbicolus protonymphs, deutonymphs, pre-ovipositional adults, and ovipositional adults were used as predators, and larvae (siblings vs. non-siblings) were given as prey. Two rearing treatments were applied to the predators to generate different social experience during ontogeny: reared in isolation or in pairs with ad libitum mixed stages of Carpoglyphus lactis (Acari: Carpoglyphidae). Social experience with siblings during ontogeny significantly reduced the cannibalism rate. Despite the social experience during ontogeny, protonymphs, deutonymphs, and pre-ovipositional adults did not discriminate siblings from non-siblings during cannibalism. The discrimination behaviour between siblings and non-siblings of A. herbicolus occurred after adults became ovipositional. We hypothesize that A. herbicolus adults could learn the characteristics of their larvae through the contact with and assessment of their eggs during oviposition. The result of this study shows that kin discrimination could be phase-specific. Future studies can investigate if contact with non-kin (or non-sibling) eggs and subsequently hatching larvae can influence the discrimination ability of ovipositional adults.

Sibling competition for food and kin selection in nestlings of a colonial raptor

Kin selection theory predicts that individual progeny members, in species where offspring share depreciable parental care, should increasingly attempt to monopolize resources provided by the parents as their relatedness to brood competitors declines. Although the level of relatedness among broodmates is often variable in vertebrates, whether it affects within-brood competition dynamics has seldom been studied. We tested this prediction in nestlings of the lesser kestrel, Falco naumanni , a cavity-nesting colonial raptor that can breed in high-density colonies, where nestlings often move between nearby nests, generating mixed parentage among broodmates. Pairs of nestlings composed of either unrelated, unfamiliar individuals or siblings were experimentally forced to compete for food. Nestlings stole prey more frequently when competing with an unrelated, unfamiliar competitor than when competing with a sibling. This finding adds to the limited evidence that rivalry among broodmates is affected by their relatedness, suggesting that kin recognition and kin selection may play an important role in determining individual competitive strategies and care allocation in multiparous species. • Coloniality favours the occurrence of mixed kinship broods. • Competition for food should differ between siblings and unrelated offspring. • We tested this prediction in mixed kinship lesser kestrel broods. • Prey thefts were more frequent when competitors were unrelated. • Kin selection affects competitive behaviour in altricial avian offspring.

Mandrill mothers associate with infants who look like their own offspring using phenotype matching.

Behavioral discrimination of kin is a key process structuring social relationships in animals. In this study, we provide evidence for discrimination towards non-kin by third-parties through a mechanism of phenotype matching. In mandrills, we recently demonstrated increased facial resemblance among paternally related juvenile and adult females indicating adaptive opportunities for paternal kin recognition. Here, we hypothesize that mandrill mothers use offspring's facial resemblance with other infants to guide offspring's social opportunities towards similar-looking ones. Using deep learning for face recognition in 80 wild mandrill infants, we first show that infants sired by the same father resemble each other the most, independently of their age, sex or maternal origin, extending previous results to the youngest age class. Using long-term behavioral observations on association patterns, and controlling for matrilineal origin, maternal relatedness and infant age and sex, we then show, as predicted, that mothers are spatially closer to infants that resemble their own offspring more, and that this maternal behavior leads to similar-looking infants being spatially associated. We then discuss the different scenarios explaining this result, arguing that an adaptive maternal behavior is a likely explanation. In support of this mechanism and using theoretical modeling, we finally describe a plausible evolutionary process whereby mothers gain fitness benefits by promoting nepotism among paternally related infants. This mechanism, that we call 'second-order kin selection', may extend beyond mother-infant interactions and has the potential to explain cooperative behaviors among non-kin in other social species, including humans.

Amblyseius herbicolus mothers prefer to oviposit near eggs of non-kin in the absence of prey Carpoglyphus lactis (Acari: Phytoseiidae, Carpoglyphidae)

Many animal species can recognise and discriminate conspecifics differing in their genetic relatedness. The discrimination of kin from non-kin or more distantly related kin can benefit individuals with increased inclusive fitness and avoid adverse influences from inbreeding. A preference by mothers to oviposit near their own or closely related eggs rather than ovipositing near non-kin or distantly related eggs has been observed in several phytoseiids, possibly to reduce cannibalism and allow imprinting between siblings. The phytoseiid Amblyseius herbicolus reluctantly cannibalise kin (i.e. siblings or offspring) in the presence of non-kin or more distantly related kin. This study investigated the oviposition preference of A. herbicolus females when provided with two sites, each containing either their own eggs or eggs laid by non-kin. The influence of food on such oviposition site preference is largely unknown in phytoseiids. Thus, we also examined the oviposition site choice of A. herbicolus females in the presence and absence of its prey Carpoglyphus lactis eggs. Our results demonstrated a significant influence of prey on the oviposition site preference of A. herbicolus: adults preferred to oviposit near eggs of non-kin in the absence of prey but showed no preference when C. lactis eggs were present at both sites. We suggest that A. herbicolus females preferred to oviposit near eggs of non-kin in the absence of prey to possibly avoid kin cannibalism during food stress.

Involvement of Flagellin in Kin Recognition between Bacillus velezensis Strains.

Kin discrimination in nature is an effective way for bacteria to stabilize population cooperation and maintain progeny benefits. However, so far, the research on kin discrimination for Bacillus still has concentrated on "attack and defense" between cells and diffusion-dependent molecular signals of quorum sensing, kin recognition in Bacillus, however, has not been reported. To determine whether flagellar is involve in the kin recognition of Bacillus, we constructed Bacillus velezensis SQR9 assembled with flagellin of its kin and non-kin strains, and performed a swarm boundary assay with SQR9, then analyzed sequence variation of flagellin and other flagellar structural proteins in B. velezensis genus. Our results showed that SQR9 assembled with flagellin of non-kin strains was more likely to form a border phenotype with wild-type strain SQR9 in swarm assay than that of kin strains, and that non-kin strains had greater variation in flagellin than kin strains. In B. velezensis, these variations in flagellin were prevalent and had evolved significantly faster than other flagellar structural proteins. Therefore, we proposed that flagellin is an effective tool partly involved in the kin recognition of B. velezensis strains. IMPORTANCE Kin selection plays an important role in stabilizing population cooperation and maintaining the progeny benefits for bacteria in nature. However, to date, the role of flagellin in kin recognition in Bacillus has not been reported. By using rhizospheric Bacillus velezensis SQR9, we accomplished flagellin region interchange among its related strains, and show that flagellin acts as a mediator to distinguish kin from non-kin in B. velezensis. We demonstrated the polymorphism of flagellin in B. velezensis through alignment analysis of flagellin protein sequences. Therefore, it was proposed that flagellin was likely to be an effective tool for mediating kin recognition in B. velezensis.

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Table S2

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Table S2

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Dataset S1

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Dataset S1

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Table S1

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Table S1

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Dataset S2

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Dataset S2

A thelytokous predatory mite is more cannibalistic towards distant kin.

Kin recognition has been widely observed in various taxa. Cannibalism avoidance may be a strong driver for the evolution of kin recognition, as it may avoid a reduction in inclusive fitness. Kin recognition has recently been observed in a generalist phytoseiid, Amblyseius herbicolus (Acari: Phytoseiidae). This study experimentally examined the degree of relatedness needed between prey larvae and cannibal adults of A. herbicolus for the occurrence of kin discrimination. The adults were individually placed in enclosed arenas with two prey, a daughter and a more distant related larva, to observe their cannibalizing choice. The adults of A. herbicolus did not discriminate between close relatives (daughter versus niece) but preferably cannibalized more distant kin (i.e., first and second cousins once removed). Phenotype matching and familiarization seem prominent as recognition mechanisms used by A. herbicolus adults. The effect of learning on kin recognition through prior contact in A. herbicolus requires further investigation. Studies on other adaptive functions of kin recognition of A. herbicolus, such as cooperation and parental care, may provide meaningful insights.

A plant growth model to test for changes in plant–plant interaction over a growing season: the case of kin competition

Kin recognition and kin selection have long been known to occur in animals where they shape altruistic behavior towards relatives. More recently, studies have found that kin recognition and altered behavior towards kin can also occur in plants. However, inferring the underlying mechanism responsible for variation in plant performance in experimental studies is challenging as often, results can be explained by alternative and non‐exclusive mechanisms such as niche differences, kin competition avoidance and genetic variation in growth rate and competitive ability. Plant–plant interactions may change with the life stage of plants, and competition is often most intense towards the end of plants growing season. However, changes in plant–plant interaction intensity across plants life cycle are rarely considered in kin interaction studies. Here, we adapt a model of plant growth over time modified to specifically include effects of kin and non‐kin competition. The model decompose competitive interactions at different stages during plant growth from initial growth to the end of the growing season. It estimates genotype specific variation in growth rate, and how sensitive individual genotypes are to competition from neighbors. Furthermore, it estimates size asymmetry among plants accounting for both variation in growth rate, neighbor relatedness and resource variation (here water availability). We use this model to analyze the results from a competition experiment where plants grew in mini‐populations with neighbor plants that were either kin or non‐kin. We find that when applied to our experiments, this approach can disentangle kin effects from other effects caused by genotypic variation in growth rate and competitive response to neighbors, and thus significantly help to detect whether plants exhibit kin‐cooperative behavior.

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Figure S9

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Figure S9

Kin Discrimination Modifies Strain Distribution, Spatial Segregation, and Incorporation of Extracellular Matrix Polysaccharide Mutants of Bacillus subtilis Strains into Mixed Floating Biofilms.

ABSTRACTMicroorganisms in nature form multicellular groups called biofilms. In biofilms, bacteria embedded in the extracellular matrix (ECM) interact intensely due to their proximity. Most studies have investigated genetically homogeneous biofilms, leaving a gap in knowledge on genetically heterogeneous biofilms. Recent insights show that a Gram-positive model bacterium, Bacillus subtilis, discriminates between strains of high (kin) and low (nonkin) genetic similarity, reflected in merging (kin) and boundaries (nonkin) between swarms. However, it is unclear how kinship between interacting strains affects their fitness, the genotype assortment, and incorporation of the mutant lacking the main structural ECM polysaccharide (EpsA-O) into floating biofilms (pellicles). We cultivated Bacillus subtilis strains as mixtures of isogenic, kin, and nonkin strain combinations in the biofilm-promoting minimal medium under static conditions, allowing them to form pellicles. We show that in nonkin pellicles, the dominant strain strongly reduced the frequency of the other strain. Segregation of nonkin mixtures in pellicles increased and invasion of nonkin EpsA-O-deficient mutants into pellicles decreased compared to kin and isogenic floating biofilms. Kin and isogenic strains had comparable relative frequencies in pellicles and showed more homogenous cell mixing. Overall, our results emphasize kin discrimination as a social behavior that shapes strain distribution, spatial segregation, and ECM mutant ability to incorporate into genetically heterogenous biofilms of B. subtilis.IMPORTANCE Biofilm communities have beneficial and harmful effects on human societies in natural, medical, and industrial environments. Bacillus subtilis is a biotechnologically important bacterium that serves as a model for studying biofilms. Recent studies have shown that this species engages in kin discriminatory behavior during swarming, which may have implications for community assembly, thus being of fundamental importance. Effects of kin discrimination on fitness, genotype segregation, and success of extracellular matrix (ECM) polysaccharide (EpsA-O) mutant invasion into biofilms are not well understood. We provide evidence that kin discrimination depends on the antagonism of the dominant strain against nonkin by using environmental strains with determined kin types and integrated fluorescent reporters. Moreover, this antagonism has important implications for genotype segregation and for when the bacteria are mixed with ECM producers. The work advances the understanding of kin-discrimination-dependent bacterial sociality in biofilms and its role in the assembly of multicellular groups.

Flagellin partly involved in kin recognition between Bacillus velezensis strains-Supplemental Table S1

Flagellin partly involved in kin recognition between Bacillus velezensis strains-Supplemental Table S1

Flagellin partly involved in kin recognition between Bacillus velezensis strains-Supplemental Dataset S1

Flagellin partly involved in kin recognition between Bacillus velezensis strains-Supplemental Dataset S1

Flagellin partly involved in kin recognition between Bacillus velezensis strains-Supplemental Dataset S2

Flagellin partly involved in kin recognition between Bacillus velezensis strains-Supplemental Dataset S2

Flagellin partly involved in kin recognition between Bacillus velezensis strains-Supplemental Table S2

Flagellin partly involved in kin recognition between Bacillus velezensis strains-Supplemental Table S2

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Figure S8

Involvement of flagellin in kin recognition between Bacillus velezensis strains Supplemental Material Figure S8

Volatile-Mediated Induced and Passively Acquired Resistance in Sagebrush (Artemisia tridentata)

Plants produce a diversity of secondary metabolites including volatile organic compounds. Some species show discrete variation in these volatile compounds such that individuals within a population can be grouped into distinct chemotypes. A few studies reported that volatile-mediated induced resistance is more effective between plants belonging to the same chemotype and that chemotypes are heritable. The authors concluded that the ability of plants to differentially respond to cues from related individuals that share the same chemotype is a form of kin recognition. These studies assumed plants were actively responding but did not test the mechanism of resistance. A similar result was possible through the passive adsorption and reemission of repellent or toxic VOCs by plants exposed to damage-induced plant volatiles (DIPVs). Here we conducted exposure experiments with five chemotypes of sagebrush in growth chambers; undamaged receiver plants were exposed to either filtered air or DIPVs from mechanically wounded branches. Receiver plants exposed to DIPVs experienced less herbivore damage, which was correlated with increased expression of genes involved in plant defense as well as increased emission of repellent VOCs. Plants belonging to two of the five chemotypes exhibited stronger resistance when exposed to DIPVs from plants of the same chemotypes compared to when DIPVs were from plants of a different chemotype. Moreover, some plants passively absorbed DIPVs and reemitted them, potentially conferring associational resistance. These findings support previous work demonstrating that sagebrush plants actively responded to alarm cues and that the strength of their response was dependent on the chemotypes of the plants involved. This study provides further support for kin recognition in plants but also identified volatile-mediated associational resistance as a passively acquired additional defense mechanism in sagebrush.