Search

Plants exchange a variety of information intra- and interspecifically by using various mediating cues. For example, plant individuals that are injured by herbivores release volatile chemicals, which induce receiver plants to express anti-herbivore resistance. Remarkably, some plant species were known to represent kin specificity in the response, where cues from a damaged individual induce a higher level of resistance in a kin receiver than in a non-kin receiver. Such higher sensitivity to warning cues from kin could be advantageous via two mechanisms. If each herbivore tends to attack plants with a certain genotype, plants should be more sensitive to warning cues from kin that share genetic properties. In addition, if herbivores successively attack the neighboring plant with a high probability, and if related plants tend to grow in close proximity, plants may be more sensitive to warning cues from neighboring kin under the presence of a trade-off between sensitivity to kin and non-kin. In the present study, we constructed a mathematical model including those mechanisms to investigate the evolutionary process of the higher sensitivity to warning cues from kin than sensitivities to cues from non-kin. According to the analysis of evolutionary dynamics, we revealed that both mechanisms could contribute, although higher sensitivity to cues from kin is more likely to evolve when the spatial range of competition is greater than the range of effective alarm cues. This result highlights the importance of the competition regime in the evolution of signaling among kin.

Kin discrimination, the differential treatment of conspecifics based on kinship, occurs across the tree of life, from animals to plants to fungi to bacteria. When kin and nonkin interact, the ability to identify kin enables individuals to increase their inclusive fitness by helping kin, harming nonkin, and avoiding inbreeding. For a given species, the strength of selection for kin discrimination mechanisms is influenced by demographic, ecological, and life-history processes that collectively determine the scope for discrimination and the payoffs from kin-biased behavior. In this review, we explore how these processes drive variation in kin discrimination across taxa, highlighting contributions of recent empirical, comparative, and theoretical work to our understanding of when, how, and why kin discrimination evolves. [ABSTRACT FROM AUTHOR]

In many taxa, young can recognize their parents using olfactory cues. Yet this possibility has been overlooked in birds, because they were long assumed to have a poor sense of smell. While evidence is growing that birds use odours to communicate, olfactory parent recognition has only been documented in two altricial bird species. Whether chicks of precocial species use olfaction to recognize parents is currently unknown. Parent recognition is particularly important in precocial species, as chicks leave the nest shortly after hatching, and may lose contact with their parents and encounter other conspecific adults. We conducted Y-maze trials in the wild to test whether chicks of a precocial shorebird, the white-fronted plover, Anarhynchus marginatus , can recognize parents via olfaction. We tested first whether chicks show a preference for the odour (preen oil) of an unfamiliar adult over a control (no odour), and second whether chicks show a preference for the odour of a parent over that of an unfamiliar adult. Plover chicks spent as much time with the odour of an unfamiliar adult as with the control, and as much time with the odour of a parent as with that of an unfamiliar adult. Therefore, we found no evidence that chicks react to the preen oil odour of a conspecific adult, nor that they can discriminate a parent using preen oil odours. It may be that chicks of this species can discriminate parental and foreign odours but that our experiment failed to detect it, that they rely on other (e.g. auditory) cues, or that they do not need to discriminate between parents and foreign conspecific adults. • Young can recognize their parents using olfactory cues in many taxa. • Plover chicks are precocial and could benefit from parent recognition. • Odour preferences of wild plover chicks were tested using a Y-maze in the field. • Plover chicks did not prefer parental odours (preen oil). • We found no evidence of olfactory parent recognition in white-fronted plovers. [ABSTRACT FROM AUTHOR]

Across taxa, breeding among close relatives is usually avoided because it incurs fitness costs to offspring. Incest is often averted through the dispersal of either sex from the natal area to breed. In some philopatric species, association among relatives extends into adulthood, and an ability to discriminate kin may be required for individuals to reduce inbreeding risk. Here, we aim to determine the mechanism of kin recognition for incest avoidance in the Damaraland mole-rat Fukomys damarensis, a cooperative breeder characterized by extreme reproductive skew. Pairs of opposite-sex adults were formed in the laboratory and, within pairs, genetic relatedness and degree of familiarity were manipulated through cross-fostering experiments. We found that unfamiliar pairs were more likely to engage in sexual behaviours and bred more successfully than familiar pairs, regardless of their genetic similarity. Females paired with unfamiliar males were also more likely to exhibit reproductive activation, characterized by increased levels of oestradiol and progesterone. This study shows that in Damaraland mole-rats, inbreeding avoidance can be achieved through a discrimination mechanism that relies on association during rearing, and that ovulation is induced by mating. This study advances our understanding of incest avoidance in species with constrained dispersal. [ABSTRACT FROM AUTHOR]

Many invasive plants can reproduce through both seeds and clonal growth. In habitats, interacting seedlings may originate from the same mother, and interacting ramets originating from the same plant may not be adjacent to each other in the stolon, particularly for vines that can show curved growth. However, in a homogeneous environment, how kinship and integration between adjacent/non-adjacent ramets affect plant growth and feedback with soil biota has been less studied. We address these questions using an invasive stoloniferous vine Mikania micrantha. We found that sibling groups and stranger groups did not differ in biomass production, root allocation and feedback with soil biota, indicating that kin recognition is unlikely in M. micrantha. For two-ramet stolon fragments in which interacting ramets were adjacent to each other, older ramets allocated more biomass to roots than younger ramets when integrated, particularly in comparison with disconnected ramets from different genotypes, indicating that a division of labor was induced. For four-ramet stolon fragments in which there were two unrooted ramets between the two rooted, interacting ramets, integration increased biomass allocation to roots, possibly because only two of the four ramets could absorb belowground resources and a lower shoot allocation decreased aboveground light competition. When inoculated with soil biota conditioned by the four-ramet integrated fragments, plants of M. micrantha also increased biomass allocation to roots. These results indicate that the distance between interacting ramets in the stolon may affect the integration effect and feedback with soil biota in clonal plants. [ABSTRACT FROM AUTHOR]

The improvement of performance and yield in both cultivar and species mixtures has been well established. Despite the clear benefits of crop mixtures to agriculture, identifying the critical mechanisms behind performance increases are largely lacking. We experimentally demonstrated that the benefits of rice cultivar mixtures were linked to relatedness‐mediated intraspecific neighbour recognition and discrimination under both field and controlled conditions. We then tested biochemical mechanisms of responses in incubation experiments involving the addition of root exudates and a root‐secreted signal, (–)‐loliolide, followed by transcriptome analysis. We found that closely related cultivar mixtures increased grain yields by modifying root behaviour and accelerating flowering over distantly related mixtures. Importantly, these responses were accompanied by altered concentration of signalling (–)‐loliolide that affected rice transcriptome profiling, directly regulating root growth and flowering gene expression. These findings suggest that beneficial crop combinations may be generated a‐priori by manipulating neighbour genetic relatedness in rice cultivar mixtures and that root‐secreted (–)‐loliolide functions as a key mediator of genetic relatedness interactions. The ability of relatedness discrimination to regulate rice flowering and yield raises an intriguing possibility to increase crop production. Summary statement: This study identified the role and mechanisms of relatedness‐mediated neighbour discrimination in the improvement of performance and yield in rice cultivar mixtures, and found root‐secreted (–)‐loliolide's role as a key component of rice response to neighbour genetic relatedness interactions. [ABSTRACT FROM AUTHOR]

Microbes face many physical, chemical, and biological insults from their environments. In response, cells adapt, but whether they do so cooperatively is poorly understood. Here, we use a model social bacterium, Myxococcus xanthus, to ask whether adapted traits are transferable to naïve kin. To do so we isolated cells adapted to detergent stresses and tested for trait transfer. In some cases, strain-mixing experiments increased sibling fitness by transferring adaptation traits. This cooperative behavior depended on a kin recognition system called outer membrane exchange (OME) because mutants defective in OME could not transfer adaptation traits. Strikingly, in mixed stressed populations, the transferred trait also benefited the adapted (actor) cells. This apparently occurred by alleviating a detergent-induced stress response in kin that otherwise killed actor cells. Additionally, this adaptation trait when transferred also conferred resistance against a lipoprotein toxin delivered to targeted kin. Based on these and other findings, we propose a model for stress adaptation and how OME in myxobacteria promotes cellular cooperation in response to environmental stresses. [ABSTRACT FROM AUTHOR]

Kin recognition has been selected by natural selection because it can enhance the chances of cooperation among close relatives, but it could also be an accidental consequence of other life-history processes. In this study, we carried out experiments by using Asiatic toad tadpoles (Bufo gargarizans) to evaluate the hypothesis that: (1) individuals can use waterborne chemical cues or combine other possible cues to communicate kinship identity when exposed to kin during early ontogeny; (2) unfamiliar siblings (or familiar non-siblings) should have similar growth with unfamiliar non-siblings because the former is not able to identify their relatives (or may not consider familiar non-siblings as kin); (3) the familiar siblings may obtain a more equal resource share in populations of siblings, thus size variation is weak. The first and second predictions were partially better supported: kinship had a positive effect on tadpole growth, obtained larger mass at metamorphosis, and increased survival, but development time was longer than that of unfamiliar non-siblings. Further, the growth of unfamiliar siblings and familiar non-siblings was different from that of familiar siblings, suggesting that Asiatic toad tadpoles lose kin-recognition ability when isolated across the embryonic stage or may not be considered as siblings when exposed to water from non-sibling groups during early embryonic development. Thus, besides chemical cues, Asiatic toad tadpoles need to combine other possible modalities to communicate kinship identity. The third prediction was supported weakly. Therefore, our results suggest that exposure to kin during early embryonic development is essential for altering kin-recognition ability. More importantly, familiar sibling groups can be expected to develop slower and spend more time in the water, allowing more time for feeding and growth, which is consistent with kin selection theory, suggesting that natural selection should drive the evolution of mechanisms that minimize the competitive intensity between sibling groups. [ABSTRACT FROM AUTHOR]

Summary: Greenbeards are selfish genetic elements that make their bearers behave either altruistically towards individuals bearing similar greenbeard copies or harmfully towards individuals bearing different copies. They were first proposed by W. D. Hamilton over 50 yr ago, to illustrate that kin selection may operate at the level of single genes. Examples of greenbeards have now been reported in a wide range of taxa, but they remain undocumented in plants. In this paper, we discuss the theoretical likelihood of greenbeard existence in plants. We then question why the greenbeard concept has never been applied to plants and speculate on how hypothetical greenbeards could affect plant–plant interactions. Finally, we point to different research directions to improve our knowledge of greenbeards in plants. [ABSTRACT FROM AUTHOR]

Animals benefit from cannibalism via reduced competition for food sources or acquiring nutrition. When cannibalism occurs between kin, it is costly to individuals because of reduced inclusive fitness. Hence, animals should avoid cannibalism between kin. Because the chance that a cannibal would consume relatives can be affected by behaviours of predators and prey, it is crucial to study avoidance of cannibalism from the viewpoints of both predators and prey simultaneously. Here, we investigated avoidance of cannibalism by adult females and larvae of the predatory mite Gynaeseius liturivorus , focusing on their kinship. Adult female G. liturivorus protect their eggs against predators by remaining on oviposition sites, and do not feed on conspecific eggs, but do feed on larvae and juveniles. When adult females were kept with larvae, they fed more on nonoffspring larvae than on their own offspring. Newly hatched larvae dispersed from oviposition sites in the presence of nonmothers faster than in the presence of their mothers. These results suggest that adult females and larvae of G. liturivorus avoided cannibalism via kin recognition. • Cannibalism between kin individuals reduces their inclusive fitness. • Adult female predatory mites feed on more nonoffspring than offspring larvae. • Larvae disperse faster from hatching sites in the presence of nonmothers. • Adults and larvae avoid cannibalism via kin recognition. [ABSTRACT FROM AUTHOR]

Communication during parental care is important in the context of offspring defence and parent-offspring recognition. In aquatic environments, chemical communication is usually the most effective and plays different roles in parental behaviour in many groups of animals. Attending females of some Neotropical anurans (Leptodactylus) lead entire schools of tadpoles through the water. However, little is known about how attending females communicate with the tadpoles or whether this communication is mother-offspring specific. We therefore conducted behavioural experiments with Leptodactylus podicipinus to address these questions. Initially, we investigated how visual, tactile, and chemical stimuli from attending females affect the aggregation behaviour of tadpoles. Next, we compared the effects of the chemical stimulus from attending females with those from other conspecifics (non-attending females and males) on schooling behaviour. Finally, we tested whether tadpoles preferred to be aggregated next to familiar attending females instead of unfamiliar ones. Our results indicated that only the chemical stimulus from attending females, and not visual or tactile, increased the time that tadpoles remained aggregated. The chemical stimuli from non-attending females and males did not affect tadpoles' behaviour. However, contrary to our expectations, we did not find a school preference for familiar attending females. Our study is the first showing that chemical stimulus is important for mother-tadpole communication in a Leptodactylus species, playing a crucial role in tadpole aggregation and attraction. Future studies including other species should address the nature of the chemical compounds and their role, if any, in kin recognition in these frogs with aquatic maternal care. Significance statement: Parent-offspring communication is not well understood in anurans. Females of some frog species in the genus Leptodactylus protect and guide schools of tadpoles in aquatic habitats and tactile, chemical and visual communication may be involved. Through our experiments, we found that only chemical stimulus from attending females had a positive effect on tadpoles´ aggregation time and attraction, playing an important role in school cohesion. Additionally, there were no differences in tadpoles´ responses to chemical stimuli from familiar and unfamiliar females, which may increase tadpoles´ survival chances. In these cases, however, the costs and benefits for attending females and tadpoles are yet to be addressed. Although tactile and visual stimuli deserve more investigation, we showed that parent-offspring chemical communication in this frog species is effective, leading to school cohesion, consequently favouring protection of tadpoles by their mothers. [ABSTRACT FROM AUTHOR]

Group-living animals sometimes cooperatively protect their offspring against predators. This behavior is observed in a wide range of taxa but, to the best of our knowledge, this is the first report of its occurrence in arthropods that are not eusocial. Adult female predatory mites Gynaeseius liturivorus protect their eggs against egg predators, the predatory mite species Neoseiulus californicus. In the field, several adult female G. liturivorus were often found on the same plant structures such as folded leaves. We tested whether these females might protect their eggs cooperatively, focusing on kinship between the females. When two adult female G. liturivorus were kept in the absence of egg predators, their reproduction was not affected by their kinship. The presence of egg predators reduced the number of G. liturivorus eggs. However, reproduction of two G. liturivorus sisters was higher than that of two non-sisters. Together, sisters guarded the oviposition site longer than non-sisters. We further tested if non-sisters increased egg guarding by having developed together from eggs to adults and found no such effect. Although it remains unclear how adult female G. liturivorus recognize conspecifics as kin or sisters, our results suggest that G. liturivorus sisters reduced predation on their offspring by cooperatively guarding their eggs. [ABSTRACT FROM AUTHOR]

Analyses of animal social networks have traditionally been conducted on species that exhibit social behaviors such as group living, whereas relatively less work has been done on species that are thought of as solitary, are cryptic, and that communicate through scent-marking cues. We employed noninvasive fecal genetic sampling, conducted from March 2015 to February 2016, to identify individuals of one such species, the giant panda (Ailuropoda melanoleuca), across a study population in southwestern China. We then used spatiotemporal proximity thresholds to infer scent mark–based association networks and conduct social network analyses of the population. Results show social clustering in which cluster members preferentially associated with each other. Genetic relatedness was a positive predictor of associations outside the mating season but a negative predictor of associations in the mating season (Mar–Jun), potentially indicating a behavioral change that would reduce risk of inbreeding and kin competition that we term "kin-space recognition." Our findings suggest that associations between individuals in species generally thought of as solitary may be widespread and dependent on complex behavior. [ABSTRACT FROM AUTHOR]

Abstract Plants exchange a variety of information intra‐ and interspecifically by using various mediating cues. For example, plant individuals that are injured by herbivores release volatile chemicals, which induce receiver plants to express anti‐herbivore resistance. Remarkably, some plant species were known to represent kin specificity in the response, where cues from a damaged individual induce a higher level of resistance in a kin receiver than in a non‐kin receiver. Such higher sensitivity to warning cues from kin could be advantageous via two mechanisms. If each herbivore tends to attack plants with a certain genotype, plants should be more sensitive to warning cues from kin that share genetic properties. In addition, if herbivores successively attack the neighboring plant with a high probability, and if related plants tend to grow in close proximity, plants may be more sensitive to warning cues from neighboring kin under the presence of a trade‐off between sensitivity to kin and non‐kin. In the present study, we constructed a mathematical model including those mechanisms to investigate the evolutionary process of the higher sensitivity to warning cues from kin than sensitivities to cues from non‐kin. According to the analysis of evolutionary dynamics, we revealed that both mechanisms could contribute, although higher sensitivity to cues from kin is more likely to evolve when the spatial range of competition is greater than the range of effective alarm cues. This result highlights the importance of the competition regime in the evolution of signaling among kin.

Mating with close kin can have considerable negative fitness consequences, which are expected to result in selective pressure for inbreeding avoidance mechanisms, such as dispersal, mate choice and post-copulatory biases. Captive studies have suggested that inbreeding avoidance through mate choice is far less widespread than expected and may be absent where other mechanisms already limit inbreeding. However, few studies have examined multiple mechanisms of inbreeding avoidance simultaneously, particularly in the wild. We use 13 years of detailed dispersal, copulation and paternity data from mountain gorillas to examine inbreeding avoidance. We find that partial dispersal of both sexes results in high kinship in multimale groups, but that copulations between close kin occur 40% less than expected. We find strong kin discrimination in mate choice, with significant avoidance of maternal kin but more limited avoidance of paternal kin. We find no evidence for post-copulatory inbreeding avoidance. Our analyses support familiarity-based mechanisms of kin identification and age-based avoidance that limits mating between fathers and daughters in their natal group. Our findings demonstrate that multiple complementary mechanisms for inbreeding avoidance can evolve in a single species and suggest that inbreeding avoidance through mate choice may enable more flexible dispersal systems to evolve. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Communication through airborne volatile organic compounds (VOCs) and root exudates plays a vital role in the multifarious interactions of plants. Common ragweed (Ambrosia artemesiifolia L.) is one of the most troublesome invasive alien species in agriculture. Below- and aboveground chemical interactions of ragweed with crops might be an important factor in the invasive species' success in agriculture. In laboratory experiments, we investigated the contribution of intra- and interspecific airborne VOCs and root exudates of ragweed to its competitiveness. Wheat, soybean, and maize were exposed to VOCs emitted from ragweed and vice versa, and the adaptation response was measured through plant morphological and physiological traits. We observed significant changes in plant traits of crops in response to ragweed VOCs, characterized by lower biomass production, lower specific leaf area, or higher chlorophyll contents. After exposure to ragweed VOCs, soybean and wheat produced significantly less aboveground dry mass, whereas maize did not. Ragweed remained unaffected when exposed to VOCs from the crops or a conspecific. All crops and ragweed significantly avoided root growth toward the root exudates of ragweed. The study shows that the plant response to either above- or belowground chemical cues is highly dependent on the identity of the neighbor, pointing out the complexity of plant–plant communication in plant communities. [ABSTRACT FROM AUTHOR]

Eusocial insect colonies are vulnerable to exploitation by egg‐laying workers arising either as natal reproductive workers or as non‐natal reproductive 'drifting' workers (intraspecific social parasites). Worker egg‐laying is potentially costly to the colony, but queens and workers can counter its costs via egg eating (queen or worker policing). Bumblebee colonies exhibit egg laying by both natal and non‐natal workers: natal workers collectively lay more eggs but do so only after a specific point in the colony cycle, the 'competition point', whereas non‐natal workers potentially lay eggs throughout the colony cycle. These features create a special opportunity to investigate whether policing of worker‐laid eggs is context‐dependent (i.e. depends on worker origin of eggs and/or colony stage). We introduced artificial egg cells containing eggs laid by either natal or non‐natal workers into colonies of the bumblebee Bombus terrestris both before and after their competition points and observed the fate of introduced egg cells and eggs. In both colony stages, the majority of introduced egg cells and eggs were policed, demonstrating that policing was not activated only after the competition point. However, in the pre‐competition point stage alone, a smaller proportion of non‐natal workers' eggs (15%) remained after 20 h compared to the proportion of natal workers' eggs remaining (24%). More effective policing of non‐natal workers' eggs early in the colony cycle potentially represents an adaptive, context‐dependent response to the stage in the cycle when all worker‐laid eggs are normally unrelated to the natal colony. [ABSTRACT FROM AUTHOR]

Plants exhibit differential behaviours through changes in biomass development and distribution in response to environmental cues, which may impact crops uniquely. We conducted a mesocosm experiment in pots to determine the root and shoot behavioural responses of wheat, T. aestivum. Plants were grown in homogeneous or heterogeneous and heavily or lightly fertilized soil, and alone or with a neighbour of the same or different genetic identity (cultivars: CDC Titanium, Carberry, Glenn, Go Early, and Lillian). Contrary to predictions, wheat did not alter relative reproductive effort in the presence of neighbours, more nutrients, or homogenous soil. Above and below ground, the plants' tendency to use potentially shared space exhibited high levels of plasticity. Above ground, they generally avoided shared, central aerial space when grown with neighbours. Unexpectedly, nutrient amount and distribution also impacted shoots; plants that grew in fertile or homogenous environments increased shared space use. Below ground, plants grown with related neighbours indicated no difference in neighbour avoidance. Those in homogenous soil produced relatively even roots, and plants in heterogeneous treatments produced more roots in nutrient patches. Additionally, less fertile soil resulted in pot-level decreases in root foraging precision. Our findings illustrate that explicit coordination between above- and belowground biomass in wheat may not exist. [ABSTRACT FROM AUTHOR]

Triphysaria is a facultative parasitic plant in the Orobanchaceae that parasitizes the roots of a wide range of host plants including Arabidopsis, Medicago, rice and maize. The important exception to this broad host range is that Triphysaria rarely parasitize other Triphysaria. We explored self and kin recognition in Triphysaria versicolor and showed that exudates collected from roots of host species, Arabidopsis thaliana and Medicago truncatula, induced haustorium development when applied to the roots of Triphysaria seedlings in vitro while those collected from Triphysaria did not. In mixed exudate experiments, Triphysaria exudates did not inhibit the haustorium-inducing activity of those from host roots. Interestingly, when roots of Triphysaria seedlings were treated with either horseradish peroxidase or fungal laccase, the extracts showed haustorium-inducing factor (HIF) activity, suggesting that Triphysaria roots contain the proper substrates for producing HIFs. Transgenic Triphysaria roots overexpressing a fungal laccase gene TvLCC1 showed an increased responsiveness to a known HIF, 2,6-dimethoxy benzoquinone (DMBQ), in developing haustoria. Our results indicate kin recognition in Triphysaria is associated with the lack of active HIFs in root exudates. Treatment of Triphysaria roots with enzymatic oxidases activates or releases molecules that are HIFs. This study shows that exogenously applied oxidases can activate HIFs in Triphysaria roots that had no previous HIF activity. Further studies are necessary to determine if differential oxidase activities in host and parasite roots account for the kin recognition in haustorium development.

Despite increasing evidence of kin recognition in natural and crop plants, there is a lack of knowledge of kin recognition in herbicide-resistant weeds that are escalating in cropping systems. Here, we identified a penoxsulam-resistant barnyardgrass biotype with the ability for kin recognition from two biotypes of penoxsulam-susceptible barnyardgrass and normal barnyardgrass at different levels of relatedness. When grown with closely related penoxsulam-susceptible barnyardgrass, penoxsulam-resistant barnyardgrass reduced root growth and distribution, lowering belowground competition, and advanced flowering and increased seed production, enhancing reproductive effectiveness. However, such kin recognition responses were not occurred in the presence of distantly related normal barnyardgrass. Root segregation, soil activated carbon amendment, and root exudates incubation indicated chemically-mediated kin recognition among barnyardgrass biotypes. Interestingly, penoxsulam-resistant barnyardgrass significantly reduced a putative signaling (–)-loliolide production in the presence of closely related biotype but increased production when growing with distantly related biotype and more distantly related interspecific allelopathic rice cultivar. Importantly, genetically identical penoxsulam-resistant and -susceptible barnyardgrass biotypes synergistically interact to influence the action of allelopathic rice cultivar. Therefore, kin recognition in plants could also occur at the herbicide-resistant barnyardgrass biotype level, and intraspecific kin recognition may facilitate cooperation between genetically related biotypes to compete with interspecific rice, offering many potential implications and applications in paddy systems. [ABSTRACT FROM AUTHOR]

In this study, we explored the potential contribution of the gut microbiome to reproductive isolation in tunnelling dung beetles, using Onthophagus taurus (Schreber, 1759) and its sister species O. illyricus (Scopoli, 1763) as a model system (Coleoptera: Scarabaeidae: Scarabaeinae: Onthophagini). Gut microbiota play critical roles in normative development of these beetles, and are vertically inherited via a maternally derived faecal pellet called the pedestal. We first compared the developmental outcomes of individuals reared with pedestals derived from either the same or the sister species (Self and Cross inoculation treatments, respectively). We then crossed the resulting adult O. taurus in three combinations (Self female X Self male; Self female X Cross male; Cross female X Self male). We predicted that if the vertically transmitted gut microbiome plays a role in reproductive isolation by facilitating species recognition, the Self X Self line would have improved reproductive outcomes compared to the lines in which partners had mismatched gut microbiomes. Instead, we found that between‐partner concordance of maternally transmitted gut microbiota resulted in fewer offspring, and that this reduction was due to partial pre‐copulatory isolation as evidenced by reduced sperm transfer in the Self X Self line. This pattern is consistent either with microbiome‐mediated familiarity/kin recognition, or with absence of mate choice in crosses with mismatched microbiomes. We discuss our results in the light of recent research on the influence of extracellular microbial symbionts over insects' mating preferences. [ABSTRACT FROM AUTHOR]

In vertebrates, little is known of kin recognition systems and their plasticity. Even in well-studied anuran larvae (tadpoles), the determinants and effects of prior experience have not been clarified. This study evaluates the plasticity of kin and conspecific discrimination in tadpoles of the Japanese montane brown frog Rana ornativentris. We raised tadpoles under two different sibship conditions: the pure line, comprising only siblings, and the mixed line, comprising both siblings and non-siblings. The association preference by a subject tadpole to unfamiliar ("stimulus") tadpoles was assessed through binary-choice tests using a 2 × 2 × 2 factorial design among each kinship line (pure and mix), subject ontogeny/size (early stage/small and late-stage/large), and stimuli ontogeny/size. Contrary to our expectations, kin preference was confirmed only in early developmental small tadpoles from mixed line, and only with a small stimulus. Furthermore, tadpoles from mixed line did not exhibit size preference for unrelated conspecifics. These results suggest that different prior associations have modulated kin templates along tadpole ontogeny and that the presence of non-kin would enhance the learning of kin/non-kin. This study provides the first example that plasticity of kin recognition affects not only kin-biased association but also conspecific recognition along ontogeny in tadpoles. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Communication through airborne volatile organic compounds (VOCs) and root exudates plays a vital role in the multifarious interactions of plants. Common ragweed (Ambrosia artemesiifolia L.) is one of the most troublesome invasive alien species in agriculture. Below- and aboveground chemical interactions of ragweed with crops might be an important factor in the invasive species’ success in agriculture. In laboratory experiments, we investigated the contribution of intra- and interspecific airborne VOCs and root exudates of ragweed to its competitiveness. Wheat, soybean, and maize were exposed to VOCs emitted from ragweed and vice versa, and the adaptation response was measured through plant morphological and physiological traits. We observed significant changes in plant traits of crops in response to ragweed VOCs, characterized by lower biomass production, lower specific leaf area, or higher chlorophyll contents. After exposure to ragweed VOCs, soybean and wheat produced significantly less aboveground dry mass, whereas maize did not. Ragweed remained unaffected when exposed to VOCs from the crops or a conspecific. All crops and ragweed significantly avoided root growth toward the root exudates of ragweed. The study shows that the plant response to either above- or belowground chemical cues is highly dependent on the identity of the neighbor, pointing out the complexity of plant–plant communication in plant communities.

ABSTRACT 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.

Infanticide is widespread across the animal kingdom, but the physiological drivers of infanticide versus care or neglect are relatively unexplored. Here, we identified salient environmental and physiological antecedents of infanticide in the mimic poison frog ( Ranitomeya imitator ), a biparental amphibian in which female parents feed their tadpoles unfertilized eggs. Specifically, we explored potential environmental cues influencing infant-directed behavior by evaluating changes in the frequency of food provisioning and tadpole mortality after either cross-fostering tadpoles between family units or displacing tadpoles within the terraria of their parents. We found that changes in offspring location reduce care and increase infanticide. Specifically, parents fed their displaced offspring less and, in some instances, tadpole mortality increased. We also investigated whether care and infanticide were related to changes in steroid hormone concentrations in an unfamiliar setting. Infanticide of fertilized eggs and hatchlings in the new territory included cannibalism and was associated with lower testosterone concentrations, but not with changes in corticosterone. Overall, our results support earlier findings that familiarity with offspring location drives parental investment in poison frogs, while indicating an association between low androgen levels and infanticidal behavior in an amphibian.

Plants exhibit differential behaviours through changes in biomass development and distribution in response to environmental cues, which may impact crops uniquely. We conducted a mesocosm experiment in pots to determine the root and shoot behavioural responses of wheat, T. aestivum. Plants were grown in homogeneous or heterogeneous and heavily or lightly fertilized soil, and alone or with a neighbour of the same or different genetic identity (cultivars: CDC Titanium, Carberry, Glenn, Go Early, and Lillian). Contrary to predictions, wheat did not alter relative reproductive effort in the presence of neighbours, more nutrients, or homogenous soil. Above and below ground, the plants’ tendency to use potentially shared space exhibited high levels of plasticity. Above ground, they generally avoided shared, central aerial space when grown with neighbours. Unexpectedly, nutrient amount and distribution also impacted shoots; plants that grew in fertile or homogenous environments increased shared space use. Below ground, plants grown with related neighbours indicated no difference in neighbour avoidance. Those in homogenous soil produced relatively even roots, and plants in heterogeneous treatments produced more roots in nutrient patches. Additionally, less fertile soil resulted in pot-level decreases in root foraging precision. Our findings illustrate that explicit coordination between above- and belowground biomass in wheat may not exist.

Kin recognition might help plants decrease competitive cost and improve inclusive fitness with close genes; thus it might interact with environmental factors to affect communities. Whether and how various factors, such as the genetic distance of neighbors, environmental stressors, or the way a plant recognizes its neighbors, might modify plant growth strategies remains unclear. To answer these questions, we conducted experiments in which ramets of a clonal plant, Glechoma longituba, were grown adjacent to different genetically related neighbors (clone kin / close kin / distant kin) in different nutrient conditions (high / medium / low), or with only root exudates from pre-treatment in culture solution. By comparing competitive traits, we found that: (1) kin recognition in G. longituba was enhanced with closer genetic distance; (2) the outcomes of kin recognition were influenced by the extent of nutrient shortage; (3) kin recognition helped to alleviate the nutrient shortage effect; (4) kin recognition via root exudates affected only below-ground growth. Our results provide new insights on the potential for manipulating the outcome of kin recognition by altering neighbor genetic distance, nutrient conditions and recognition ways. Moreover, kin recognition can help plants mitigate the effects of nutrient shortage, with potential implications in agricultural research. [ABSTRACT FROM AUTHOR]

Cannibalism is a commonly found behaviour in the animal kingdom. The biggest concern of cannibalism is that it reduces the inclusive fitness of the cannibals by eliminating close relatives. Kin recognition is a strategy used by many cannibals to benefit from cannibalism without the cost of reducing their inclusive fitness by eating close relatives. Most members of the family Phytoseiidae are cannibalistic. Previous studies suggest that specialist phytoseiids practice kin recognition, while generalists use species recognition or discrimination due to the diet specification and frequent intraspecific interactions. We examined whether kin recognition is used by a type‐III generalist phytoseiid, Amblyseius herbicolus (Chant) (Acari: Phytoseiidae). The cannibalistic adults with different hunger levels (0‐, 24‐ and 48‐hr starvation) were given a choice of kin and a non‐kin larva. Kin recognition of A. herbicolus was affected by the hunger level. Adults not starved before the test significantly preferred cannibalizing non‐kin larva. Conversely, adults starved for 24 and 48 hr showed no statistically significant preference between kin and non‐kin larvae. Furthermore, the latency reflected hunger level, where not starved adults had the most prolonged latency, while adults starved for 24 and 48 hr had intermediate and shortest latency. This study suggests A. herbicolus use innate recognition mechanisms to avoid kin cannibalism since the adults and larvae had no prior association before the experiment. The effect of familiarization on kin recognition in A. herbicolus should be further investigated. [ABSTRACT FROM AUTHOR]

Abstract Sexually reproducing organisms face a strong selective pressure to find a mate and ensure reproduction. An important criterion during mate‐selection is to avoid closely related individuals and subsequent potential fitness costs of resulting inbred offspring. Inbreeding avoidance can be active through kin recognition during mate choice, or passive through differential male and female‐biased sex ratios, which effectively prevents sib‐mating. In addition, sex allocation, or the resources allotted to male and female offspring, can impact mating and reproductive success. Here, we investigate mate choice, sex ratios, and sex allocation in dispersing reproductives (alates) from colonies of the termite Cubitermes tenuiceps. Termites have a short time to select a mate for life, which should intensify any fitness consequences of inbreeding. However, alates did not actively avoid inbreeding through mate choice via kin recognition based on genetic or environmental cues. Furthermore, the majority of colonies exhibited a female‐biased sex ratio, and none exhibited a male‐bias, indicating that differential bias does not reduce inbreeding. Sex allocation was generally female‐biased, as females also were heavier, but the potential fitness effect of this costly strategy remains unclear. The bacterium Wolbachia, known in other insects to parasitically distort sex allocation toward females, was present within all alates. While Wolbachia is commonly associated with termites, parasitism has yet to be demonstrated, warranting further study of the nature of the symbiosis. Both the apparent lack of inbreeding avoidance and potential maladaptive sex allocation implies possible negative effects on mating and fitness.

Despite increasing evidence of kin recognition in natural and crop plants, there is a lack of knowledge of kin recognition in herbicide-resistant weeds that are escalating in cropping systems. Here, we identified a penoxsulam-resistant barnyardgrass biotype with the ability for kin recognition from two biotypes of penoxsulam-susceptible barnyardgrass and normal barnyardgrass at different levels of relatedness. When grown with closely related penoxsulam-susceptible barnyardgrass, penoxsulam-resistant barnyardgrass reduced root growth and distribution, lowering belowground competition, and advanced flowering and increased seed production, enhancing reproductive effectiveness. However, such kin recognition responses were not occurred in the presence of distantly related normal barnyardgrass. Root segregation, soil activated carbon amendment, and root exudates incubation indicated chemically-mediated kin recognition among barnyardgrass biotypes. Interestingly, penoxsulam-resistant barnyardgrass significantly reduced a putative signaling (–)-loliolide production in the presence of closely related biotype but increased production when growing with distantly related biotype and more distantly related interspecific allelopathic rice cultivar. Importantly, genetically identical penoxsulam-resistant and -susceptible barnyardgrass biotypes synergistically interact to influence the action of allelopathic rice cultivar. Therefore, kin recognition in plants could also occur at the herbicide-resistant barnyardgrass biotype level, and intraspecific kin recognition may facilitate cooperation between genetically related biotypes to compete with interspecific rice, offering many potential implications and applications in paddy systems.

From inbreeding avoidance to kin‐selected cooperation, social behaviours are frequently reliant on kin recognition. However, kin recognition mechanisms are costly to evolve and currently not very well understood. Recent evidence suggests that, by altering their host's odour, gut and other host‐associated microorganisms may provide a promising avenue for understanding kin recognition. In Drosophila melanogaster, kin recognition can mediate mate choice, sexual conflict and larval competition/cooperation, underscoring its important functional role. As is commonly the case, kin recognition in this species depends on both familiarity (i.e. shared rearing environment) and relatedness, and seems to rely mainly on body odours determined by cuticular hydrocarbons. Here, we investigated the degree to which larval rearing environment and relatedness (full‐sibs versus unrelated) determine co‐variation between gut microbiota and cuticular hydrocarbons in D. melanogaster. We found that rearing environment strongly determined microbiota composition and cuticular hydrocarbon profiles, but that these effects were independent from each other. In contrast, relatedness did not influence microbiota composition, but had a strong influence on microbiota diversity, which in turn covaried significantly with cuticular hydrocarbon profiles. Our results show that, in D. melanogaster, odours may convey information about both familiarity and relatedness via an interaction between: 1) direct effects of the rearing environment on cuticular hydrocarbons and 2) indirect effects of relatedness on cuticular hydrocarbons via gut microbiota diversity. [ABSTRACT FROM AUTHOR]

Cooperation involving shared resource systems is prone to 'the tragedy of the commons', where individuals act in their own self‐interest to exploit the resource in a manner that is detrimental to the common good of all group members. Directing cooperation towards kin provides a solution to this problem and predicts the differential performance depending on the relatedness of group members. In subsocial spiders, juveniles live in transient groups that cooperate in hunting and communal feeding. Prey capture is costly in terms of risk of injury and investment of venom and digestive enzymes, and therefore presents a situation where individuals may attempt to avoid costly interactions and exploit the resource acquired by other group members. We tested the prediction that individuals differentiate participation and/or investment in cooperative prey capture and extra‐oral digestion (injection of digestive enzymes into prey prior to the initiation of extraction of nutrients) in response to the relatedness of group members with whom they interact, in the subsocial spider Stegodyphus africanus. The performance of groups and interactions over prey attack in groups of either related or mixed kin spiderlings were determined over a period of 4 weeks. We show that kin groups attack the prey significantly faster, recruit individuals to form feeding groups faster, extract prey body mass more efficiently and experience less antagonistic interactions than groups of mixed relatedness, which ultimately translates into an elevated growth rate. These results indicate that related individuals are more willing to take risks and invest in communal digestion when foraging with kin, as predicted by inclusive fitness theory as a solution to the tragedy of the commons. [ABSTRACT FROM AUTHOR]

Sociality in animals depends on identification and recognition of conspecifics and social interactions can be a key driving force in ecological processes. We capitalized on the environmentally dependent sociality and unique reproductive strategy of the self-fertilizing mangrove rivulus (Kryptolebias marmoratus) to disentangle the influence of relatedness and familiarity on conspecific recognition. We also compared the importance of vision and chemosensation as primary phenotypic sensory cues in distinguishing individual fish and prey. Using lab-reared, isogenic rivulus, we presented a focal fish with the choice between two conspecifics (related and/or familiar). We determined that there was no clear impact of relatedness on short term association preferences in the two isogenic lineages we tested. Rather, rivulus preferentially associated with unrelated, familiar individuals over unrelated, unfamiliar individuals. Next, we used both isogenic lab lineages and wild-caught rivulus to determine the primary sensory modality involved in recognition by measuring aggressive behavior while manipulating the type of sensory information (visual and chemosensory) available during binary association trials. Our data indicate that this mangrove fish uses primarily visual cues and familiarity templates for mediating social interactions, contributing to the growing body of knowledge on recognition systems in fishes. Significance statement: Social relationships depend on the assessment of potential partners. We know that fishes can discriminate among individuals; however, how they recognize each other is more complex. We capitalized on the unique social behavior and reproductive strategy of a small mangrove fish to determine if they preferentially recognize related individuals, familiar individuals, or a combination of the two. We also asked if they used vision and/or smell as their primary mode of recognition. Here, we show that these fish prefer to associate with familiar yet unrelated individuals, possibly because there are more direct benefits associating with fish they have previously encountered. We also concluded that these fish use vision over smell to recognize other individuals even in murky mangrove water. Social behaviors are likely to change as a result of environmental change. Thus, understanding how fish recognize each other has important implications for their conservation and how they will respond to environmental challenges. [ABSTRACT FROM AUTHOR]

ABSTRACT Mycobacteria mediate horizontal gene transfer (HGT) by a process called distributive conjugal transfer (DCT) that is mechanistically distinct from oriT-mediated plasmid transfer. The transfer of multiple, independent donor chromosome segments generates transconjugants with genomes that are mosaic blends of their parents. Previously, we had characterized contact-dependent conjugation between two independent isolates of Mycobacterium smegmatis. Here, we expand our analyses to include five independent isolates of M. smegmatis and establish that DCT is both active and prevalent among natural isolates of M. smegmatis. Two of these five strains were recipients but exhibited distinct conjugal compatibilities with donor strains, suggesting an ability to distinguish between potential donor partners. We determined that a single gene, Msmeg0070, was responsible for conferring mating compatibility using a combination of comparative DNA sequence analysis, bacterial genome-wide association studies (GWAS), and targeted mutagenesis. Msmeg0070 maps within the esx1 secretion locus, and we establish that it confers mycobacterial self-identity with parallels to kin recognition. Similar to other kin model systems, orthologs of Msmeg0070 are highly polymorphic. The identification of a kin recognition system in M. smegmatis reinforces the concept that communication between cells is an important checkpoint prior to DCT commitment and implies that there are likely to be other, unanticipated forms of social behaviors in mycobacteria. IMPORTANCE Conjugation, unlike other forms of HGT, requires direct interaction between two viable bacteria, which must be capable of distinguishing between mating types to allow successful DNA transfer from donor to recipient. We show that the conjugal compatibility of Mycobacterium smegmatis isolates is determined by a single, polymorphic gene located within the conserved esx1 secretion locus. This gene confers self-identity; the expression of identical Msmeg0070 proteins in both donor-recipient partners prevents DNA transfer. The presence of this polymorphic locus in many environmental mycobacteria suggests that kin identification is important in promoting beneficial gene flow between nonkin mycobacteria. Cell-cell communication, mediated by kin recognition and ESX secretion, is a key checkpoint in mycobacterial conjugation and likely plays a more global role in mycobacterial biology.

Aims: Kin recognition has been used to explain plant interactions among siblings. However, the phenotypic-based measurements have drawn various results, and the mechanism of plant kin recognition remains unclear. Here, we tested plant kin recognition based on plant nitrogen (N) use efficiency induced by the rhizosphere effect, plant growth performance and fitness. Methods: Glycine max (L.) Merr. was planted pairwise either with siblings or with non-siblings (strangers). Several characteristics, including plant height, specific leaf area (SLA), plant biomass, fitness, chlorophyll content, and plant N use efficiency (NUE) were measured. The root exudation rates of carbon (C) and N, soil microbial biomass C (MBC) and N, and the abundance of functional genes, as well as soil archaeal, bacterial, and fungal abundance, were quantified. Results: Significant increases in plant height, seed and shoot biomass, chlorophyll content, and NUE were observed in G. max plants living with siblings compared to strangers, suggesting that plant kin recognition results in superior growth and fitness. The root exudation rate of C was significantly higher in individuals living with siblings than with strangers. The input of C from root exudates further induced the rhizosphere effect, enhancing the soil MBC and increasing the abundance of soil archaea and soil ammonia-oxidizing archaea (AOAs). Plants living with siblings increased NUE for enriched available N in soil, and increased aboveground growth and fitness compared to those living with strangers for G. max. Conclusions: The rhizosphere effect on soil microbes and N turnover triggered by the root exudates depend on the neighbor's identity and could be a potential underground feedback mechanism for plant kin recognition. [ABSTRACT FROM AUTHOR]

Mating is an important process in bumblebees that could affect queen diapause survival and offspring reproduction. Both queens and males could influence mating failure. Here, we used the indigenous bumblebee Bombus lantschouensis to evaluate the mating interactions of males and gynes. The effects of kin recognition and males and gynes from multiple colonies on mating latency, mating duration, and the mating success rate were investigated. The results showed that gynes mated with related males had a longer mating latency than those mated with unrelated males (42.88 ± 3.8 min and 24.15 ± 2.5 min, respectively, P < 0.05) and that the mating success rate was significantly higher in unrelated groups than in related groups (49.29 ± 4.1% and 36.74 ± 2.6%, respectively, P < 0.05). However, no preference for related or unrelated males was observed in the mixed mating groups (mating success rate 30.63 ± 3.1% and 30.73 ± 2.4%, respectively, P > 0.05). Interestingly, the occurrence of males from multiple sources significantly increased the mating success rate (one colony 39.1 ± 4.2% to four colonies 60.05 ± 5.7%, P < 0.05). Nonetheless, an increase in the number of gyne sources had no effect on the mating success rate (one colony 39.50 ± 4.9% to four colonies 43.52 ± 5.7%, P > 0.05). Mating latency was significantly more influenced by males and gynes from multiple colonies than by kin relationship, male number, and gyne number (P < 0.05). In conclusion, there is no evidence that the bumblebee B. lantschouensis can recognize kin relationships before mating. The presence of males and gynes from multiple colonies can influence mating latency. Moreover, males from multiple colonies can significantly enhance mating success, which has implications for bumblebee ecological conservation and artificial mass rearing. [ABSTRACT FROM AUTHOR]

Abstract During intrasexual competition, individuals of the same sex compete for access to breeding sites and mating partners, often accompanied by aggressive behavior. Kin selection theory predicts different kin‐directed social interactions ranging from cooperation to aggression depending on the context and the resource in question. Kin competition reducing indirect fitness might be avoided by actively expelling relatives from territories and by showing higher aggression against kin. The West‐African cichlid Pelvicachromis taeniatus is a monogamous cave breeder with males occupying and defending breeding sites against rivals. This species is capable of kin recognition and shows kin‐preference during juvenile shoaling and mate choice. However, subadults of P. taeniatus seem to avoid the proximity of same‐sex kin. In the present study, we examined territorial aggression of territory holders against intruding related and unrelated males as well as intruder's behavior. We observed higher aggression among related competitors suggesting that related males are less tolerated as neighbors. Avoidance of intrasexual competition with relatives might increase indirect fitness of males in monogamous species.

Kin recognition, manifesting through various traits such as changes in root or shoot growth, has been documented in several species of plants. Identifying this phenomenon in plants has intrinsic value itself, understanding why plants recognize kin and how it might benefit them evolutionarily has been of recent interest. Here we explore studies regarding nutrient and resource allocation in regard to kin recognition as well as discuss how kin recognition is involved in multispecies interactions with an emphasis on how plant roots are involved in these processes. Future directions of this research are also discussed.

Benefits conferred to animals living in groups may be greater if groups are formed by relatives rather than non-relatives, because cooperating with relatives increases the probability of their own genes being passed on to group offspring (inclusive fitness). Non-social aggregations are formed in response to environmental characteristics, while social aggregations are formed from the attraction among individuals. The attraction or repulsion between individuals is mediated by recognition mechanisms, which mediate important ecological processes and behaviours. Here, we conducted laboratory experiments to test if tadpoles of two sympatric bufonids, Rhinella icterica and R. ornata, are able to recognise siblings. We collected eggs of the two species in the field and raised them in laboratory settings, according to three different methods: siblings and non-siblings reared in separated containers; siblings and non-siblings reared in the same container separated by a plastic net; and eggs from the same spawn reared separately, each one in an individual container. Later, we tested if tadpoles could choose between groups of siblings and non-siblings. The results indicate that tadpoles of neither species were able to discriminate between siblings and non-siblings, regardless of the rearing methods. Therefore, kinship is less important than environmental factors in tadpole aggregation behaviour of these species, and it may be dependent on the balance between costs and benefits. Our results can be used as a start point to better understand tadpole aggregation behaviour and recognition mechanisms in these species. [ABSTRACT FROM AUTHOR]

Costs of parental care can include increased physical, physiological, and behavioral demands and reduced prospects for future reproduction. Therefore, animals may benefit from recognizing and discriminating their own offspring during the period of infant care to ensure that they provide care only to their own young. Differences in offspring discrimination between mothers and fathers may arise due to differences in the amount of parental care they provide. In mammals, mothers bear the costs of gestation and lactation, while fathers do not; therefore, we might expect that in mammal species in which both parents provide parental care, mothers will show greater levels of offspring discrimination than fathers. In the present study, we examined possible sex differences in offspring discrimination in the biparental, monogamous California mouse (Peromyscus californicus) across the lactational period. On postpartum days (PPD) 3, 7, 16, and 28, parents were housed individually in a test cage and presented simultaneously with two wire mesh balls, one containing their own pup and the other containing an unrelated pup. On individual test days, parents behaved similarly toward the two balls. Fathers, but not mothers, showed significant changes in latencies to approach and interact with the non-kin ball across test days, but no clear pattern was observed. Fathers also approached the non-kin ball more frequently than mothers when pups reached weaning age (PPD 28). Thus, fathers may show increased interest in unrelated young as their offspring become independent. [ABSTRACT FROM AUTHOR]

The wood‐feeding cockroach Panesthia angustipennis spadica Shiraki (Blaberidae) lives in a tunnel of decayed logs and is considered as gregarious species. However, decayed logs are distributed in a forest in clumps, and woody tunnels in decaying logs provide a semi‐enclosed environment for nymphs. We performed laboratory experiments to determine whether first‐ and second‐instar nymphs of P. angustipennis spadica show gregariousness in small spaces like woody tunnels. We also compared the aggregation intensity of sibling groups and mixed groups in the second instar. The laboratory experiments demonstrated that both the first‐ and second‐instar nymphs show gregariousness, with no difference in aggregation behavior regardless of kin relatedness. These results suggest that non‐kin‐based gregariousness may help to maintain colonies of P. angustipennis spadica that contain individuals derived from multiple families in a field. [ABSTRACT FROM AUTHOR]

In species that live in family groups, such as cooperative breeders, inbreeding is usually avoided through the recognition of familiar kin. For example, individuals may avoid mating with conspecifics encountered regularly in infancy, as these likely include parents, siblings, and closely related alloparents. Other mechanisms have also been reported, albeit rarely; for example, individuals may compare their own phenotype to that of others, with close matches representing likely relatives ("phenotype matching"). However, determinants of the primary inbreeding avoidance mechanisms used by a given species remain poorly understood. We use 24 years of life history and genetic data to investigate inbreeding avoidance in wild cooperatively breeding banded mongooses (Mungos mungo). We find that inbreeding avoidance occurs within social groups but is far from maximised (mean pedigree relatedness between 351 breeding pairs = 0.144). Unusually for a group-living vertebrate, we find no evidence that females avoid breeding with males with which they are familiar in early life. This is probably explained by communal breeding; females give birth in tight synchrony and pups are cared for communally, thus reducing the reliability of familiarity-based proxies of relatedness. We also found little evidence that inbreeding is avoided by preferentially breeding with males of specific age classes. Instead, females may exploit as-yet unknown proxies of relatedness, for example, through phenotype matching, or may employ postcopulatory inbreeding avoidance mechanisms. Investigation of species with unusual breeding systems helps to identify constraints against inbreeding avoidance and contributes to our understanding of the distribution of inbreeding across species. Significance statement: Choosing the right mate is never easy, but it may be particularly difficult for banded mongooses. In most social animals, individuals avoid mating with those that were familiar to them as infants, as these are likely to be relatives. However, we show that this rule does not work in banded mongooses. Here, the offspring of several mothers are raised in large communal litters by their social group, and parents seem unable to identify or direct care towards their own pups. This may make it difficult to recognise relatives based on their level of familiarity and is likely to explain why banded mongooses frequently inbreed. Nevertheless, inbreeding is lower than expected if mates are chosen at random, suggesting that alternative pre- or post-copulatory inbreeding avoidance mechanisms are used. [ABSTRACT FROM AUTHOR]

Nonhuman primates don't have formal kinship systems, but genetic relatedness shapes patterns of residence, behavior, mating preferences, and cognition in the primate order. The goal of this article is to provide insight about the ancestral foundations on which the first human kinship systems were built. In order for evolution to favor nepotistic biases in behavior, individuals need to have opportunities to interact with their relatives and to be able to identify them. Both these requirements impose constraints on the evolution of kinship bonds in primate species. For nonhuman primates and many other mammals, maternal care generates close ties between mothers and offspring and among littermates. For species in which mother–offspring bonds extend beyond weaning, associations with the mother also generate familiarity among siblings of different ages. For species with female philopatry, mother–offspring ties provide the foundation for lifelong relationships between mothers and daughters, and dense matrilineal kin networks. However, several factors constrain the development of kinship bonds in nonhuman primates. First, dispersal strategies, which are designed to reduce inbreeding, bias kinship networks in favor of the philopatric sex. Second, hostile relationships between groups mean that kin ties are usually severed when individuals move from one group to another. Third, in species with polygynandrous mating systems, uncertainty about paternity and restricted periods of male reproductive monopoly limit the scope for development of ties among fathers and offspring, paternal siblings, or extended paternal kin networks. In this article, I explore the impact of these factors on the evolution of ancestral human kinship systems. [ABSTRACT FROM AUTHOR]