Ecological Cues Research Articles

Electrophysiological Responses of Trissolcus japonicus, T. basalis, and T. oenone (Hymenoptera: Scelionidae) to Volatile Compounds Associated with New Zealand Stink Bugs (Hemiptera: Pentatomidae).

Parasitoid biological control agents rely heavily on olfaction to locate their hosts. Chemical cues associated with hosts and non-hosts are known to influence the expression of host preferences and host-specificity. A better understanding of how and why parasitoids attack some species and not others, based on volatile organic compounds associated with potential hosts, can provide key information on the parasitoid's host preferences, which could be applied to pre-release risk assessments for classical biological control agents. Electrophysiological techniques such as electroantennography (EAG) and GC-EAD (gas chromatography coupled with electroantennographic detection) are widely used to identify bioactive semiochemicals. But the application of these techniques to understanding how chemical ecological cues mediate parasitoid host specificity has not been as thoroughly explored. We conducted GC-EAD and EAG studies to identify olfactory-active compounds associated with adult females of nine stink bug species from Aotearoa/New Zealand on the antennae of three closely related parasitoid species: Trissolcus japonicus Ashmead, a pre-emptively (= proactively) approved biocontrol agent against brown marmorated stink bug; T. basalis (Wollaston), a biocontrol agent introduced against Nezara viridula L. in 1949; and T. oenone Johnson, a native Australasian pentatomid parasitoid. Eight compounds associated with stink bugs elicited antennal responses from all three parasitoids, and we were able to identify seven of these. (E)-2-hexenal, (E)-4-oxo-2-hexenal, (E)-2-octenal and (E)-2-decenal generally elicited stronger responses in the three parasitoids, while n-tridecane, n-dodecane, and (E)-2-decenyl acetate elicited weaker responses. We discuss how and why the results from electrophysiological experiments can be applied to non-target risk assessments within biological control programmes.

Response Plasticity of Drosophila Olfactory Sensory Neurons.

In insect olfaction, sensitization refers to the amplification of a weak olfactory signal when the stimulus is repeated within a specific time window. In the vinegar fly, Drosophila melanogaster, this occurs already at the periphery, at the level of olfactory sensory neurons (OSNs) located in the antenna. In our study, we investigate whether sensitization is a widespread property in a set of seven types of OSNs, as well as the mechanisms involved. First, we characterize and compare the differences in spontaneous activity, response velocity and response dynamics, among the selected OSN types. These express different receptors with distinct tuning properties and behavioral relevance. Second, we show that sensitization is not a general property. Among our selected OSN types, it occurs in those responding to more general food odors, while OSNs involved in very specific detection of highly specific ecological cues like pheromones and warning signals show no sensitization. Moreover, we show that mitochondria play an active role in sensitization by contributing to the increase in intracellular Ca2+ upon weak receptor activation. Thus, by using a combination of single sensillum recordings (SSRs), calcium imaging and pharmacology, we widen the understanding of how the olfactory signal is processed at the periphery.

The mycorrhizal symbiosis: research frontiers in genomics, ecology, and agricultural application.

Mycorrhizal symbioses between plants and fungi are vital for the soil structure, nutrient cycling, plant diversity, and ecosystem sustainability. More than 250 000 plant species are associated with mycorrhizal fungi. Recent advances in genomics and related approaches have revolutionized our understanding of the biology and ecology of mycorrhizal associations. The genomes of 250+ mycorrhizal fungi have been released and hundreds of genes that play pivotal roles in regulating symbiosis development and metabolism have been characterized. rDNA metabarcoding and metatranscriptomics provide novel insights into the ecological cues driving mycorrhizal communities and functions expressed by these associations, linking genes to ecological traits such as nutrient acquisition and soil organic matter decomposition. Here, we review genomic studies that have revealed genes involved in nutrient uptake and symbiosis development, and discuss adaptations that are fundamental to the evolution of mycorrhizal lifestyles. We also evaluated the ecosystem services provided by mycorrhizal networks and discuss how mycorrhizal symbioses hold promise for sustainable agriculture and forestry by enhancing nutrient acquisition and stress tolerance. Overall, unraveling the intricate dynamics of mycorrhizal symbioses is paramount for promoting ecological sustainability and addressing current pressing environmental concerns. This review ends with major frontiers for further research.

Mixed Patterns of Intergenerational DNA Methylation Inheritance in Acropora.

For sessile organisms at high risk from climate change, phenotypic plasticity can be critical to rapid acclimation. Epigenetic markers like DNA methylation are hypothesized as mediators of plasticity; methylation is associated with the regulation of gene expression, can change in response to ecological cues, and is a proposed basis for the inheritance of acquired traits. Within reef-building corals, gene-body methylation (gbM) can change in response to ecological stressors. If coral DNA methylation is transmissible across generations, this could potentially facilitate rapid acclimation to environmental change. We investigated methylation heritability in Acropora, a stony reef-building coral. Two Acropora millepora and two Acropora selago adults were crossed, producing eight offspring crosses (four hybrid, two of each species). We used whole-genome bisulfite sequencing to identify methylated loci and allele-specific alignments to quantify per-locus inheritance. If methylation is heritable, differential methylation (DM) between the parents should equal DM between paired offspring alleles at a given locus. We found a mixture of heritable and nonheritable loci, with heritable portions ranging from 44% to 90% among crosses. gBM was more heritable than intergenic methylation, and most loci had a consistent degree of heritability between crosses (i.e. the deviation between parental and offspring DM were of similar magnitude and direction). Our results provide evidence that coral methylation can be inherited but that heritability is heterogenous throughout the genome. Future investigations into this heterogeneity and its phenotypic implications will be important to understanding the potential capability of intergenerational environmental acclimation in reef building corals.

Evolutionary divergence of developmental plasticity and learning of mating tactics in Trinidadian guppies.

Behavioural plasticity is a major driver in the early stages of adaptation, but its effects in mediating evolution remain elusive because behavioural plasticity itself can evolve. In this study, we investigated how male Trinidadian guppies (Poecilia reticulata) adapted to different predation regimes diverged in behavioural plasticity of their mating tactic. We reared F2 juveniles of high- or low-predation population origins with different combinations of social and predator cues and assayed their mating behaviour upon sexual maturity. High-predation males learned their mating tactic from conspecific adults as juveniles, while low-predation males did not. High-predation males increased courtship when exposed to chemical predator cues during development; low-predation males decreased courtship in response to immediate chemical predator cues, but only when they were not exposed to such cues during development. Behavioural changes induced by predator cues were associated with developmental plasticity in brain morphology, but changes acquired through social learning were not. We thus show that guppy populations diverged in their response to social and ecological cues during development, and correlational evidence suggests that different cues can shape the same behaviour via different neural mechanisms. Our study demonstrates that behavioural plasticity, both environmentally induced and socially learnt, evolves rapidly and shapes adaptation when organisms colonize ecologically divergent habitats.

A Literature Review on Availability Heuristic Implicated in Different Fields

Decision-makers involved in economic activities are faced with the constraints of a complex environment and with the limitations of their cognitive ability. In other words, people are bounded rational. Therefore, psychological factors affect people's judgments and decisions under uncertainty, including the availability heuristic. The availability heuristic refers to that people judge the probability of event according to the ease of recalling the instances. It was first proposed by Tversky and Kahneman, and is an ecological cue that people often use in making decisions. Although the availability heuristic has received a lot of attention, there is still a lack of systematic research literature on the mechanism of availability heuristic and its application in real life. This essay aims to investigate the origin and definition of availability heuristic, and then identify the underlying mechanism as well as the determinants of the availability heuristic to explain how the availability heuristic is applied in the cooperation relationship, financial markets and consumer behavior in real world.

Collective synchrony of mating signals modulated by ecological cues and social signals in bioluminescent sea fireflies.

Individuals often employ simple rules that can emergently synchronize behaviour. Some collective behaviours are intuitively beneficial, but others like mate signalling in leks occur across taxa despite theoretical individual costs. Whether disparate instances of synchronous signalling are similarly organized is unknown, largely due to challenges observing many individuals simultaneously. Recording field collectives and ex situ playback experiments, we describe principles of synchronous bioluminescent signals produced by marine ostracods (Crustacea; Luxorina) that seem behaviorally convergent with terrestrial fireflies, and with whom they last shared a common ancestor over 500 Mya. Like synchronous fireflies, groups of signalling males use visual cues (intensity and duration of light) to decide when to signal. Individual ostracods also modulate their signal based on the distance to nearest neighbours. During peak darkness, luminescent 'waves' of synchronous displays emerge and ripple across the sea floor approximately every 60 s, but such periodicity decays within and between nights after the full moon. Our data reveal these bioluminescent aggregations are sensitive to both ecological and social light sources. Because the function of collective signals is difficult to dissect, evolutionary convergence, like in the synchronous visual displays of diverse arthropods, provides natural replicates to understand the generalities that produce emergent group behaviour.

Seed Morpho-Anatomy and Germination Enhancement of the Australian Native Species Lomandra longifolia Labill. and L. hystrix (R.Br.) L.R. Fraser & Vickery

Lomandra species are an important understory component of many Australian native ecosystems, contributing to the floristic richness and stabilizing soils. However, a limited understanding of their germination biology currently hinders their efficient use in seed-based restoration and ornamental plant production. The present study investigated Lomandra longifolia and L. hystrix diaspore morpho-anatomy and evaluated different mechanical and/or chemical treatments (nicking, leaching, smoke water and gibberellic acid [GA3]) and under light or dark conditions to enhance germination. Embryos of both species were small and linear with a low embryo to seed ratio (<0.45). Germination rates of both species were significantly hastened by leaching seeds in running water for 36 h as compared to a non-leached seed. The results suggest that pre-treating both Lomandra species by leaching could maximize the effectiveness of seed used by resulting in faster, more uniform and, therefore, reliable germination of these species. Finally, seeds of L. longifolia had low final germination (<40%), with a high presence of viable but dormant seeds. The ecological cues that promote germination in nature for both species should be further examined.

Effect of victim relatedness on cannibalistic behaviour of ladybird beetle, Cheilomenes sexmaculata Fabricius (Coleoptera: Coccinellidae)

Cannibalism is taxonomically widespread and has a large impact on the individuals’ fitness and population dynamics. Thus, identifying how the rates of cannibalism are affected by different ecological cues is crucial for predicting species evolution and population dynamics. In current experiment, we investigated how victim relatedness affects the cannibalistic tendencies of different life stages of ladybird, Cheilomenes sexmaculata, which is highly cannibalistic. We provided larval instars and newly emerged adults of C. sexmaculata with a choice of sibling, half-sibling and non-sibling conspecific eggs as victim of cannibalism. First victim cannibalised and latency to cannibalise were observed along with total number of victims cannibalised after 24 h. First preference of victim did not differ with life stages of the cannibals though the number of victims cannibalized did increase with advancement in stage. Percent egg cannibalism also varied significantly with life stage and victim relatedness. First and second instars tend to cannibalise more percentage of sibling and non-sibling eggs while third instars cannibalised more percentage of non-sibling eggs; fourth instars and adults on the other hand cannibalised highest percentage of eggs irrespective of their relatedness. Insignificant effect of victim relatedness was observed on latency to cannibalise eggs, though it varied significantly with the cannibal’s life stage. Shortest latency to cannibalise was recorded for first instars and longest for adults and second instars. In conclusion, kin recognition and avoidance of cannibalism is stage-specific, with fourth instar and newly emerged adults being less discriminatory as compared to early stages owing to increased evolutionary survival pressure.

Light modulates Drosophila lifespan via perceptual systems independent of circadian rhythms.

Across taxa, sensory perception modulates aging in response to important ecological cues, including food, sex, and danger. The range of sensory cues involved, and their mechanism of action, are largely unknown. We therefore sought to better understand how one potential cue, that of light, impacts aging in Drosophila melanogaster. In accordance with recently published data, we found that flies lived significantly longer in constant darkness. Extended lifespan was not accompanied by behavioral changes that might indirectly slow aging such as activity, feeding, or fecundity, nor were circadian rhythms necessary for the effect. The lifespans of flies lacking eyes or photoreceptor neurons were unaffected by light kept at normal housing conditions, and transgenic activation of these same neurons was sufficient to phenocopy the effects of environmental light on lifespan. The relationship between light and lifespan was not correlated with its intensity, duration, nor the frequency of light-dark transitions. Furthermore, high-intensity light reduced lifespan in eyeless flies, indicating that the effects we observed were largely independent of the known, non-specific damaging effects associated with light. Our results suggest that much like other environmental cues, light may act as a sensory stimulus to modulate aging.

Walking the line: Investigating biophysical characteristics related to wildlife use of linear features

AbstractHabitat restoration is a necessary component of wildlife conservation in anthropogenic landscapes. To ensure restoration initiatives achieve the desired effects on wildlife communities, it is useful to investigate how animals use landscape features. Understanding the relationships between wildlife use and ecological cues provides specific and measurable targets that can be used to measure restoration success.In western Canada, linear feature networks formed by seismic lines, pipelines and roads have altered the boreal forest landscape and resulted in population declines for woodland caribou. Restoration is aimed at supporting caribou recovery by deterring linear feature use by caribou predators and ungulate competitors. Information on how linear feature characteristics facilitate or deter wildlife use supports restoration initiatives by providing specific targets for restoration.Here, we used wildlife track and sign data to investigate biophysical characteristics related to the use of linear features by canines, bears, deer, elk and moose in caribou ranges of west‐central and north‐western Alberta and British Columbia. We built generalized linear mixed models consistent with three hypotheses that could explain likely mechanisms for use: (1) ease of movement, (2) risk avoidance and (3) resource availability (prey and forage).Moose, deer, elk and bears were more likely to use linear features with either human or game trails. Bears and canines were less likely to use seismic lines with greater lateral vegetation cover and taller vegetation, respectively. Moose, deer and elk were more likely to use linear features with a greater cover of ungulate forage taxa such as willow, birch, sedges and forbs.These results suggest that restoration focusing on trails, online vegetation structure and online vegetation type should deter predators and ungulate prey species to the overall benefit of caribou. Our study corroborates the findings of other research recommending structural and functional restoration using high‐intensity line blocking and vegetative regeneration. We provide specific targets for linear feature restoration to assist in prioritization according to restoration objectives, which translates to a broader goal of linking local‐level restoration actions to landscape‐level conservation goals. This approach to restoration has implications for any major system experiencing anthropogenic landscape change.

Examining ecological harshness cues and anticipated food scarcity on food preferences

To solve the adaptive problem of food uncertainty, humans have evolved cognitive mechanisms for preferring energy dense foods which are sensitive to ecological cues. In the current studies, ecological cues were used to determine if individuals alter their preferences for energy dense foods when exposed to safe, resource scarce, or violent ecological cues. In addition, the Anticipated Food Scarcity Scale (AFSS) was used to assess overall dispositional responses to food instability. Study 1 used a between-within subjects design, and the findings showed that individuals were more likely to prefer high-caloric foods compared to low-caloric foods, regardless of ecological scenario. In Study 2, using a within-subjects design, individuals’ preferences for food were moderated by anticipated food scarcity, where food preferences were higher when in a safe compared to a resource scarce ecology. The studies show that energy dense foods are preferred overall and anticipating food scarcity is associated with those ratings at the individual level, when considering food in a safe ecological scenario.

Perceived Mate Scarcity Leads to Increased Willingness to Mate Poach

ABSTRACT Mate poaching, where an individual attempts to attract a pair-bonded individual, is a risky mating tactic. Yet, it is surprisingly common. Although many studies have investigated individual differences in mate poaching, few have examined potentially relevant ecological factors, such as mate availability. In this study, 254 unmated North American adults were primed with either perceived mate scarcity or abundance, and subsequently completed measures of fear of being single, intrasexual competitiveness, and attitudes toward mate poaching. Results from a sequential mediation model revealed that men and women primed with mate scarcity held a more positive attitude toward mate poaching relative to those primed with mate abundance, and that this link was mediated by an induced fear of being single and intrasexual competitiveness. Our results suggest that mate poaching is a facultative adaptation of human mating psychology driven by intrasexual competitiveness that is activated in response to environments of low mate availability. It highlights the need for researchers to consider ecological cues when studying individual variation in mate poaching behavior.

Relatedness modulates density‐dependent cannibalism rates in Drosophila

Abstract Cannibalism is taxonomically widespread and can have large impacts on individual fitness and population‐level processes. As such, identifying how cannibalism rates vary in response to ecological cues is important for predicting species evolution and population dynamics. In this study, we aimed to identify several eco‐evolutionary factors that affect cannibalism rate and measure how they interacted with one another. To do this, we conducted two experiments using complimentary methods to measure how cannibalism rates varied among larval Drosophila melanogaster and Drosophila simulans in response to changes in conspecific relatedness, social familiarity and density. We found that larvae were more likely to cannibalise non‐related larval victims in both species, and that this effect increased at high densities in D. simulans. We found no evidence that Drosophila larvae use social familiarity to assess relatedness. Finally, in D. melanogaster, cannibalistic larvae prefer to cannibalise larvae that are being attacked by a greater number of conspecifics, implying that cues linked to conspecific abundance encourage cooperative cannibalism. By showing that cannibalism frequency in Drosophila spp. is sensitive to relatedness and several other factors, we reveal the complex relationship between cannibalism frequency and species ecology. Also, by showing that the effect of relatedness on cannibalism frequency is density dependent, we advance the current understanding of how ecological variables interact to affect kin selection. A free Plain Language Summary can be found within the Supporting Information of this article.

Neuroendocrine regulation of pubertal suppression in the naked mole-rat: What we know and what comes next

Puberty is a key developmental milestone that marks an individual’s maturation in several ways including, but not limited to, reproductive maturation, changes in behaviors and neural organization. The timing at which puberty occurs is variable both within individuals of the same species and between species. These variations can be aligned with ecological cues that delay or suppress puberty. Naked mole-rats are colony-living rodents where reproduction is restricted to a few animals; all other animals are pubertally-suppressed. Animals removed from suppressive colony cues can reproductively mature, presenting the unique opportunity to study adult-onset puberty. Recently, we found that RFRP-3 administration sustains pubertal delay in naked mole-rats removed from colony. In this review, we explore what is known about regulators that control puberty onset, the role of stress/social status in pubertal timing, the status of knowledge of pubertal suppression in naked mole-rats and what comes next.

β-Ionone: Its Occurrence and Biological Function and Metabolic Engineering.

β-Ionone is a natural plant volatile compound, and it is the 9,10 and 9′,10′ cleavage product of β-carotene by the carotenoid cleavage dioxygenase. β-Ionone is widely distributed in flowers, fruits, and vegetables. β-Ionone and other apocarotenoids comprise flavors, aromas, pigments, growth regulators, and defense compounds; serve as ecological cues; have roles as insect attractants or repellants, and have antibacterial and fungicidal properties. In recent years, β-ionone has also received increased attention from the biomedical community for its potential as an anticancer treatment and for other human health benefits. However, β-ionone is typically produced at relatively low levels in plants. Thus, expressing plant biosynthetic pathway genes in microbial hosts and engineering the metabolic pathway/host to increase metabolite production is an appealing alternative. In the present review, we discuss β-ionone occurrence, the biological activities of β-ionone, emphasizing insect attractant/repellant activities, and the current strategies and achievements used to reconstruct enzyme pathways in microorganisms in an effort to to attain higher amounts of the desired β-ionone.

Socioecological conditions predict degu social instability and provide limited cues to forecast subsequent breeding conditions

Permanent changes in group membership may result in detrimental fitness effects on both group residents and immigrants. Factors associated with this form of social instability are rarely documented. We used a 15-year dataset on degus, a social and short-lived species, to test the hypothesis that physical condition and socioecological factors experienced during breeding are associated with social instability in terms of group individual membership (hypothesis 1). We also tested the hypothesis that these factors represent potential cues for individuals to predict social instability conditions during subsequent breeding (i.e., exhibiting autocorrelation) (hypothesis 2). Social instability in degu group membership was ubiquitous. Social instability increased with increasing ectoparasite load but decreased with increasing food abundance, increasing degu density, increasing mean minimum temperature, and increasing number of female group members. Of these conditions, degu density during winter exhibited autocorrelation. Finally, overall predictability of ecological conditions varied from low to high within a 5–6-year period. These findings indicate that socioecological conditions experienced by the breeding adults and their developing offspring predict within-year social instability (hypothesis 1) and provide some limited cues to individuals to predict similar conditions during the subsequent breeding event (hypothesis 2). Permanent changes in the adult composition of social groups (social instability) can have significant impacts on the fitness of group members. Determining the ecological and social conditions associated with social instability and whether individuals can anticipate social instability in adulthood can inform socioecological theory. In the communally rearing rodent, Octodon degus, social instability during breeding is ubiquitous and impacts the fitness of adult males and females differently. We determined that social instability in degu groups during breeding is associated with local ecological conditions (ambient temperature, ectoparasite loads, abundance of food, population density) and the social environment (number of adult females). Of the ecological variables, only population density exhibited autocorrelation. These results are important because they imply limited ecological cues available for the offspring to anticipate social instability conditions as adults.

Hybrid Behavior-Genetic Models of the Confounding Gene-Environment Correlations in the Development of Life History Strategy: Two Convergent Approaches

Traditional theories of development and evolutionary developmental psychology propose that early environmental experiences shape an individual’s developmental trajectory. According to the Adaptive Calibration Model (ACM), for example, calibration of speed of life history strategy to ecological cues encountered during development contributes to behavior that is conditionally adaptive to the organism’s environment. These theories emphasize the role of environmental influences and typically do not use designs that control potential genetic confounds. To address this methodological problem, the current study used a genetically informative design to test whether the phenotypic associations of parental instability and abuse with a slow life history factor were confounded by common genetic factors. We analyzed twin and singleton data from the Midlife in the United States (MIDUS) Survey using two convergent structural equation modeling approaches. Both approaches suggest that, when accounting for shared genetic variance across instability, abuse, and slow life history, some hypothesized environmental pathways between the early environmental measures and slow life history were not required. Once genetic factors were controlled, only parental instability was directly related to slow life history, while other hypothesized environmental pathways were non-significant. This suggests that developmental models that emphasize environmental and contextual pathways should control for possible genetic confounds.

Seed‐enhancement combinations improve germination and handling in two dominant native grass species

The use of native grasses for both restoration and commercial purposes is becoming increasingly important globally. Many native grasses have limited success in seed‐based restoration (e.g. post‐mine rehabilitation) and commercial industries (e.g. agriculture) due to poor seed germination and handling. Seed‐enhancement technologies can assist in overcoming these barriers. This study aimed to use combinations of seed enhancements to overcome the germination and handling challenges in two dominant Australian native grass species with demand in restoration and commercial industries (Triodia wiseana C.A Gardner and Rytidosperma caespitosum [Gaudich.] Connor & Edgar). Selected enhancements included hydropriming (including inoculation with karrikinolide [KAR1]), flash flaming, and seed coating. Combinations of these seed enhancements allowed improvements in both germination (by up to 55% and 18% for T. wiseana and R. caespitosum, respectively) and floret geometry (flowability, as measured through a mechanized seeder, improved by up to 6‐fold and 17‐fold for T. wiseana and R. caespitosum, respectively), with the order of enhancement application being important. The responses of each species to enhancements corresponded with key biological processes and ecological cues required for recruitment events in nature, such as fire and rainfall events. Triodia wiseana germination was driven by fire‐related cues (i.e. KAR1, flaming), while R. caespitosum germination was highest in response to moisture‐related cues (i.e. hydro‐priming). Responses to seed enhancements (and combinations of) may have implications for the management and scaled use of the targeted species. This can assist in improving the restoration and commercial success of the study species, and potentially other grasses with germination and handling challenges, into the future.

Ethnobotanical Knowledge Encoded in Weenhayek Oral Tradition

Stories that reference plants occur throughout Indigenous oral traditions. It is widely recognized among local and academic knowledge holders that such stories store and transmit valuable ethnobotanical knowledge. However, there has been little detailed investigation of the quantity and kinds of information conveyed or the ways in which this information is encoded in oral texts. In this paper, we explore in detail the nature of this transmitted ethnobotanical knowledge, investigating the extent to which stories encode and convey information useful for identifying, locating, harvesting, processing, and predicting availability of important plant resources. Using an existing collection of traditional narratives from the Weenhayek of the Bolivian Gran Chaco, we searched for stories about wild plants and plant products. This search yielded a sample of 40 narratives, which were analyzed for the presence of information about plant characteristics, associated ecological cues, habitat and distribution, management, extraction and processing, availability, uses, and worldview (i.e., prescriptions and proscriptions related to plant management, extraction, processing, or use). Results are discussed in light of the constraints imposed by human attentional and memory systems, and their implications for knowledge storage and transmission.