Identification of Cuticular and Web Lipids of the Spider Argiope bruennichi

Emerging evidence shows that the cuticular and silk lipids of spiders are structurally more diverse than those of insects, although only a relatively low number of species have been investigated so far. As in insects, such lipids might play a role as signals in various contexts. The wasp spider Argiope bruennichi has probably the best investigated chemical communication system within spiders, including the known structure of the female sex pheromone. Recently we showed that kin-recognition in A. bruennichi could be mediated through the cuticular compounds consisting of hydrocarbons and, to a much larger proportion, of wax esters. By use of mass spectrometry and various derivatization methods, these were identified as esters of 2,4-dimethylalkanoic acids and 1-alkanols of varying chain lengths, such as tetradecyl 2,4-dimethylheptadecanoate. A representative enantioselective synthesis of this compound was performed which proved the identifications and allowed us to postulate that the natural enantiomer likely has the (2R,4R)-configuration. Chemical profiles of the silk and cuticular lipids of females were similar, while male cuticular profiles differed from those of females. Major components of the male cuticular lipids were tridecyl 2,4-dimethyl-C17-19 alkanoates, whereas those of females were slightly longer, comprising tridecyl 2,4-dimethyl-C19-21 alkanoates. In addition, minor female-specific 4-methylalkyl esters were detected.

Kin Recognition in Plants: Did We Learn Anything From Roots?

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.

Permissive aggregative group formation favors coexistence in yeast

ABSTRACTIn Saccharomyces cerevisiae, the FLO1 gene encodes flocculins that lead to formation of multicellular flocs, that offer protection to the constituent cells. Flo1p was found to preferentially bind to fellow cooperators compared to defectors lacking FLO1 expression, resulting in enrichment of cooperators within the flocs. Given this dual function in cooperation and kin recognition, FLO1 has been termed a ‘green beard gene’. Because of the heterophilic nature of Flo1p binding however, we hypothesize that kin recognition is permissive and depends on the relative stability of FLO1+/flo1− versus FLO1+/FLO1+ bonds, which itself can be dependent on environmental conditions and intrinsic cell properties. We combine single cell measurements of adhesion strengths, individual cell-based simulations of cluster formation and evolution, and in vitro flocculation experiments to study the impact of relative bond stability on defector exclusion as well as benefit and stability of cooperation. We hereto vary the relative bond stability by changing the shear flow rate and the inherent bond strength. We identify a marked trade-off between both aspects of the green beard mechanism, with reduced relative bond stability leading to increased kin recognition, but at the expense of decreased cluster sizes and benefit of cooperation. Most notably, we show that the selection of FLO1 cooperators is negative-frequency dependent, which we directly attribute to the permissive character of the Flo1p bond. Taking into account the costs associated to FLO1 expression, this asymmetric selection results in a broad range of ecological conditions where coexistence between cooperators and defectors is stable. Although the kin recognition aspect of the FLO1 ‘green beard gene’ is thus limited and condition dependent, the negative-frequency dependency of selection can conserve the diversity of flocculent and non-flocculent phenotypes ensuring flexibility towards variable selective pressures.

Acquisition of a Learned Operant and Critical Flicker-Fusion Rate in the Tuatara (Sphenodon spp.)

<p>Scientific investigation of the sensory world and behavior of the tuatara is limited. This study incorporates both ecological and psychological perspectives to test learning and visual perception using a novel operant technique and flicker-fusion rates to measure visual discrimination in tuatara. We posed four main questions: (1) can a reliable method examine learning and visual perception in tuatara?, (2) what is the critical flicker-fusion (CFF) rates for tuatara and how does it relate to motion detection ability?, (3) can stimulus control be transferred to a Y-maze from an open field arena?, and (4) what are the implications for behavioral ecology, conservation, and species welfare? Tuatara (Sphenodon punctatus) were trained using an operant conditioning procedure with food reinforcement to respond to discriminative stimuli (S+) of various flicker-fusion rates, and ignore a non-discriminative stimulus (S-). Tuatara discriminated CFF rates between 2.65-45.61 Hz, but not at 65.09 Hz. The upper threshold between 45.61-65.09 Hz is comparable to other mammalian, avian, and herpetological species. Tuatara demonstrated a learning capacity for acquisition of an operant task as well as cognitive development for learning and memory strategies. Visual discrimination is important to tuatara and may facilitate behavioral responses to many context-dependent ecological processes (i.e., predator/prey/kin recognition, mate selection, environmental discrimination, optimal foraging strategies, and communication). By understanding the importance of visual stimuli, the study provides a better perspective of the tuatara natural sensory world. Additionally, a reliable method was established that can be used for more comprehensive psychophysical experiments to further access visual perception and learning in all reptiles, with the potential to examine other sensory mechanisms such as audition, chemoreception, and tactility.</p>

Acquisition of a Learned Operant and Critical Flicker-Fusion Rate in the Tuatara (Sphenodon spp.)

<p>Scientific investigation of the sensory world and behavior of the tuatara is limited. This study incorporates both ecological and psychological perspectives to test learning and visual perception using a novel operant technique and flicker-fusion rates to measure visual discrimination in tuatara. We posed four main questions: (1) can a reliable method examine learning and visual perception in tuatara?, (2) what is the critical flicker-fusion (CFF) rates for tuatara and how does it relate to motion detection ability?, (3) can stimulus control be transferred to a Y-maze from an open field arena?, and (4) what are the implications for behavioral ecology, conservation, and species welfare? Tuatara (Sphenodon punctatus) were trained using an operant conditioning procedure with food reinforcement to respond to discriminative stimuli (S+) of various flicker-fusion rates, and ignore a non-discriminative stimulus (S-). Tuatara discriminated CFF rates between 2.65-45.61 Hz, but not at 65.09 Hz. The upper threshold between 45.61-65.09 Hz is comparable to other mammalian, avian, and herpetological species. Tuatara demonstrated a learning capacity for acquisition of an operant task as well as cognitive development for learning and memory strategies. Visual discrimination is important to tuatara and may facilitate behavioral responses to many context-dependent ecological processes (i.e., predator/prey/kin recognition, mate selection, environmental discrimination, optimal foraging strategies, and communication). By understanding the importance of visual stimuli, the study provides a better perspective of the tuatara natural sensory world. Additionally, a reliable method was established that can be used for more comprehensive psychophysical experiments to further access visual perception and learning in all reptiles, with the potential to examine other sensory mechanisms such as audition, chemoreception, and tactility.</p>

No evidence that relatedness or familiarity modulate male harm in wild Drosophila melanogaster

Sexual selection frequently promotes the evolution of aggressive behaviours that help males compete against their rivals, but which may harm females and hamper their fitness. Kin selection theory predicts that optimal male-male competition levels can be reduced when competitors are more genetically related to each other than to the population average, contributing to resolve this sexual conflict. Work in Drosophila melanogaster has spearheaded empirical tests of this idea, but studies so far have been conducted in lab-adapted populations in homogeneous rearing environments that may hamper kin recognition, and used highly skewed sex ratios that may fail to reflect average natural conditions. Here, we performed a fully factorial design with the aim of exploring how rearing environment (i.e. familiarity) and relatedness affect male-male aggression, male harassment, and overall male harm levels in a natural population of Drosophila melanogaster, under more natural conditions. Namely, we: a) manipulated relatedness and familiarity so that larvae reared apart were raised in different environments, as is common in the wild, and b) studied the effects of relatedness and familiarity under average levels of male-male competition in the field. We show that, contrary to previous findings, groups of unrelated-unfamiliar males were as likely to fight with each other and harass females than related-familiar males, and that overall levels of male harm to females were similar across treatments. Our results suggest that the role of kin selection in modulating sexual conflict is yet unclear in Drosophila melanogaster, and call for further studies that focus on natural populations and realistic socio-sexual and ecological environments.

Cooperatively breeding banded mongooses do not avoid inbreeding through familiarity-based kin recognition

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.

Identification of Cuticular And Web Lipids of The Spider Argiope Bruennichi

Emerging evidence shows that the cuticular and silk lipids of spiders are structurally more diverse than those of insects, although only a relatively low number of species have been investigated so far. As in insects, such lipids might play a role as signals in various context. The wasp spider Argiope bruennichi has probably the best investigated chemical communication system within spiders, including the known structure of the female sex pheromone. Recently we showed that kin-recognition in A. bruennichi is mediated through the cuticular compounds consisting of hydrocarbons and to a much larger proportion of wax esters. By use of MS and various derivatization methods these esters were identified here to be esters of 2,4-di­methyl­alkanoates with varying chain length and 1-alkanols, such as tetradecyl 2,4‑di­methyl­hepta­decanoate. A representative enantioselectively synthesis to this compound was performed which proved the identifications and allowed to postulate the natural enantiomer to have (2R,4R)-configuration. Cuticular profiles of the silk and cuticula of females were similar, while male cuticular profiles differed quantitatively from those of females. In addition, minor female specific 4-methylalkyl esters were detected.

Sex or cannibalism: Polyphenism and kin recognition control social action strategies in nematodes

Resource polyphenisms, where single genotypes produce alternative feeding strategies in response to changing environments, are thought to be facilitators of evolutionary novelty. However, understanding the interplay between environment, morphology, and behavior and its significance is complex. We explore a radiation of Pristionchus nematodes with discrete polyphenic mouth forms and associated microbivorous versus cannibalistic traits. Notably, comparing 29 Pristionchus species reveals that reproductive mode strongly correlates with mouth-form plasticity. Male-female species exhibit the microbivorous morph and avoid parent-offspring conflict as indicated by genetic hybrids. In contrast, hermaphroditic species display cannibalistic morphs encouraging competition. Testing predation between 36 co-occurring strains of the hermaphrodite P. pacificus showed that killing inversely correlates with genomic relatedness. These empirical data together with theory reveal that polyphenism (plasticity), kin recognition, and relatedness are three major factors that shape cannibalistic behaviors. Thus, developmental plasticity influences cooperative versus competitive social action strategies in diverse animals.

Family-specific chemical profiles provide potential kin recognition cues in the sexually cannibalistic spider Argiope bruennichi

Kin recognition, the ability to detect relatives, is important for cooperation, altruism and also inbreeding avoidance. A large body of research on kin recognition mechanisms exists for vertebrates and insects, while little is known for other arthropod taxa. In spiders, nepotism has been reported in social and solitary species. However, there are very few examples of kin discrimination in a mating context, one coming from the orb-weaver Argiope bruennichi . Owing to effective mating plugs and high rates of sexual cannibalism, both sexes of A. bruennichi are limited to a maximum of two copulations. Males surviving their first copulation can either re-mate with the current female (monopolizing paternity) or leave and search for another. Mating experiments have shown that males readily mate with sisters but are more likely to leave after one short copulation as compared with unrelated females, allowing them to search for another mate. Here, we ask whether the observed behaviour is based on chemical cues. We detected family-specific cuticular profiles that qualify as kin recognition cues. Moreover, correlations in the relative amounts of some of the detected substances between sexes within families indicate that kin recognition is likely based on subsets of cuticular substances, rather than entire profiles.