Biology subjects

Reichert, M. S.

Publications and source records attributed to Reichert, M. S..

12 recordsLinked to original sources

bioRxiv2025

Exploring the Winner-Loser Effect on Emotion in Crickets

Individual variation in behavioral traits, commonly referred to as personality, is exhibited in numerous animal species, including invertebrates. The specific personality trait of exploration tendency may be affected by positive/optimistic or negative/pessimistic emotional states. Animal contests can induce these emotions, as winning against ones opponent increases optimism, while losing causes pessimism; these states can then affect behavior in other contexts. Previous studies demonstrate that house crickets (Acheta domesticus) experience this winner-loser effect in fights, thus we investigated if a crickets exploratory behavior is influenced by the outcome of its contest. We predicted that after a fight, winners would exhibit increased exploratory behavior due to an optimistic emotional state, while losers would show decreased exploratory behavior due to a pessimistic emotional state. Exploration tendency was measured as an individuals latency to exit a shelter. Crickets then participated in an aggression contest, with opponents chosen to be smaller or larger so that focal individuals either won (n=33) or lost (n=31), respectively. Latency to exit was again measured after the contest, as well as 48 h later to examine the persistence of winner-loser effects on exploration behavior over extended time periods. Latencies for control crickets (n=40) were measured at the same time points, but controls did not engage in a fight. In one of two years, winning crickets latency times decreased following the contest, while losing crickets latency times were not significantly affected. This suggests that individuals emotional states were changed by the experience of winning a fight, which affected exploration tendencies, while losing a fight does not have an effect on exploration tendency. These data on invertebrate emotions have important implications for human health by allowing for future studies on the mechanisms behind mental states.

animal behavior and cognition↗

bioRxiv2025

Social connections, group size and fine-scale manipulations of social stability shape learning, scrounging and foraging rate in wild great tits

The social environment provides both opportunities and challenges for foragers. How multiple components of sociality and foraging interact simultaneously is poorly understood, while experimental manipulation of sociality within wild foraging groups is rare. We tested whether production learning, scrounging, and foraging rate are associated with individual social network metrics and manipulated social stability in mixed species flocks of wild birds. First, individuals were randomly allowed access to, and learned to forage primarily from, one of five feeders. Thereafter, we performed two reversals, manipulating social connections by either assigning birds to a new feeder along with all others assigned to their previous feeder (stable treatment) or reassigning each bird individually (unstable treatment). Most of the effects observed were context dependent but in general we found that: i) Learning was slower in the stable treatment, for individuals with higher weighted degree, and in smaller flocks; ii) Scrounging was higher in the stable treatment, increased with weighted degree, but decreased with flock size; and iii) Foraging rate was predicted only by weighted degree. Our findings demonstrate the complex and dynamic nature of the relationship between sociality and foraging and suggest that selection for group living is more nuanced than usually recognized.

animal behavior and cognition↗

bioRxiv2024

The Amphibian Genomics Consortium: advancing genomic and genetic resources for amphibian research and conservation

Amphibians represent a diverse group of tetrapods, marked by deep divergence times between their three systematic orders and families. Studying amphibian biology through the genomics lens increases our understanding of the features of this animal class and that of other terrestrial vertebrates. The need for amphibian genomic resources is more urgent than ever due to the increasing threats to this group. Amphibians are one of the most imperiled taxonomic groups, with approximately 41% of species threatened with extinction due to habitat loss, changes in land use patterns, disease, climate change, and their synergistic effects. Amphibian genomic resources have provided a better understanding of ontogenetic diversity, tissue regeneration, diverse life history and reproductive modes, anti-predator strategies, and resilience and adaptive responses. They also serve as essential models for studying broad genomic traits, such as evolutionary genome expansions and contractions, as they exhibit the widest range of genome sizes among all animal taxa and possess multiple mechanisms of genetic sex determination. Despite these features, genome sequencing of amphibians has significantly lagged behind that of other vertebrates, primarily due to the challenges of assembling their large, repeat-rich genomes and the relative lack of societal support. The emergence of long-read sequencing technologies, combined with advanced molecular and computational techniques that improve scaffolding and reduce computational workloads, is now making it possible to address some of these challenges. To promote and accelerate the production and use of amphibian genomics research through international coordination and collaboration, we launched the Amphibian Genomics Consortium (AGC, https://mvs.unimelb.edu.au/amphibian-genomics-consortium) in early 2023. This burgeoning community already has more than 282 members from 41 countries. The AGC aims to leverage the diverse capabilities of its members to advance genomic resources for amphibians and bridge the implementation gap between biologists, bioinformaticians, and conservation practitioners. Here we evaluate the state of the field of amphibian genomics, highlight previous studies, present challenges to overcome, and call on the research and conservation communities to unite as part of the AGC to enable amphibian genomics research to "leap" to the next level.

genomics↗

bioRxiv2023

Unravelling effects of fine-scale changes within wild-bird flocks on sociality

O_LISocial structure and individual sociality impact a wide variety of behavioural and ecological processes. Although it is well known that changes in the physical and social environment shape sociality, how perturbations govern sociality at a fine spatial scale remains poorly understood. By applying automated experimental treatments to RFID-tracked wild great tits (Parus major) in a field experiment, we examined how individual social network metrics changed when food resources and social stability were experimentally manipulated at the within-group spatial scale. C_LIO_LIFirst, we examined how individual sociality responds when food resources changed from a dispersed distribution (50m apart) to a clustered distribution (1m apart). Second, we tested how sociality changed when individuals were restricted to feeding in a manner that mimics assortative behaviour within flocks. Third, we tested the effects of experimentally manipulating the stability of these social groupings. Finally, we returned the feeders to the original dispersed distribution to test whether effects carried over. C_LIO_LIRepeatability analyses showed consistent differences among individuals in their social phenotypes across the various manipulations; dyadic association preferences also showed consistency. Nevertheless, average flock size and social centrality measures increased after the food was clustered. Some of these metrics changed further when birds were then forced to feed from only one of the five clustered feeders. There was some support for group stability at individual feeders also impacting individual social network metrics: increase in flock size was more pronounced in the stable than the unstable group. Most of the differences in sociality were maintained when the food distribution returned to the dispersed pattern, and this was caused primarily by the change in resource distribution rather than the social manipulation. C_LIO_LIOur results show that perturbations in the access to resources and social group stability can change sociality at a surprisingly fine spatial scale. These small-scale changes could arise through a variety of mechanisms, including assortative positioning within groups due to, for instance, similarity among individuals in their preferences for different resource patches. Our results suggest that small-scale effects could lead to social processes at larger scales and yet are typically overlooked in social groups. C_LI

animal behavior and cognition↗

bioRxiv2022

Partitioning variance in a signaling trade-off under sexual selection reveals among-individual covariance in trait allocation

Understanding the evolution of traits subject to trade-offs is challenging because phenotypes can (co)vary at both the among- and within-individual levels. Among-individual covariation indicates consistent, possibly genetic, differences in how individuals resolve the trade-off, while within-individual covariation indicates trait plasticity. There is also the potential for consistent among-individual differences in behavioral plasticity, although this has rarely been investigated. We studied the sources of (co)variance in two characteristics of an acoustic advertisement signal that trade off with one another and are under sexual selection in the gray treefrog, Hyla chrysoscelis: call duration and call rate. We recorded males on multiple nights calling spontaneously and in response to playbacks simulating different competition levels. Call duration, call rate, and their product, call effort, were all repeatable both within and across social contexts. Call duration and call rate covaried negatively, and the largest covariance was at the among-individual level. There was extensive plasticity in calling with changes in social competition, and we found some evidence for among-individual variance in call rate plasticity. The significant negative among-individual covariance in trait values is perpendicular to the primary direction of sexual selection in this species, indicating potential limits on the response to selection.

animal behavior and cognition↗

bioRxiv2022

Individual variation in the avian gut microbiota: the influence of host state and environmental heterogeneity

The gut microbiome has important consequences for fitness, yet the complex, interactive nature of ecological factors that influence the gut microbiome has scarcely been investigated in natural populations. We sampled the gut microbiota of wild great tits (Parus major) at different life stages and across multiple conifer and mixed woodland fragments, allowing us to evaluate multiple factors that relate to within-individual gut microbiota acquisition, including habitat type, nest position and life history traits. The gut microbiota varied with both environment and life-history in ways that were largely dependent on age. Notably, it was the nestling, as opposed to the adult gut microbiota that was most sensitive to ecological variation, pointing to a high degree of developmental plasticity. Individual nestling differences in gut microbiota were consistently different (repeatable) from one to two weeks of life, driven entirely by the effect of sharing the same nest. Our findings point to important early developmental windows in which the gut microbiota are most sensitive to environmental variation and suggest reproductive timing, and hence parental quality or food availability, interact with the microbiome.

ecology↗

bioRxiv2021

Inhibitory control performance is repeatable across years and contexts in a wild bird population

Inhibitory control is one of several cognitive mechanisms required for self-regulation, decision making and attention towards tasks. Linked to a variety of maladaptive behaviours in humans, inhibitory control is expected to influence behavioural plasticity in animals in the context of foraging, social interaction, or responses to sudden changes in the environment. One widely used cognitive assay, the detour task, putatively tests inhibitory control. In this task, subjects must avoid impulsively touching transparent barriers positioned in front of food, and instead access the food by an alternative but known route. Recently it has been suggested that the detour task is unreliable and measures factors unrelated to inhibitory control, including motivation, previous experience and persistence. Consequently, there is growing uncertainty as to whether this task leads to erroneous interpretations about animal cognition and its links with socio-ecological traits. To address these outstanding concerns, we designed a variant of the detour task for wild great tits (Parus major) and deployed it at the nesting site of the same individuals across two spring seasons. This approach eliminated the use of food rewards, limited social confounds, and maximised motivation. We compared task performance in the wild with their performance in captivity when tested using the classical cylinder detour task during the non-breeding season. Task performance was temporally and contextually repeatable, and none of the confounds had any significant effect on performance, nor did they drive any of the observed repeatable differences among individuals. These results support the hypothesis that our assays captured intrinsic differences in inhibitory control. Instead of throwing the detour task out with the bathwater, we suggest confounds are likely system and experimental-design specific, and that assays for this potentially fundamental but largely overlooked source of behavioural plasticity in animal populations, should be validated and refined for each study system.

animal behavior and cognition↗

bioRxiv2021

No reproductive benefits of dear enemy recognition in a territorial songbird

Territorial animals often respond less aggressively to neighbours than strangers. This dear enemy effect is hypothesized to be adaptive by reducing unnecessary aggressive interactions with non-threatening individuals. A key prediction of this hypothesis, that individual fitness will be affected by variation in the speed and the extent to which individuals reduce their aggression towards neighbours relative to strangers, has never been tested. We used a series of song playbacks to measure the change in response of male great tits to a simulated establishment of a neighbour on an adjacent territory during early stages of breeding, as an assay of individuals tendencies to form dear enemy relationships. Males reduced their approach to the speaker and sang fewer songs on later playback repetitions. However, only some males exhibited dear enemy behaviour by responding more strongly to a subsequent stranger playback, and when the playback procedure was repeated on a subset of males, there was some indication for consistent differences among individuals in the expression of dear enemy behaviour. We monitored nests and analysed offspring paternity to determine male reproductive success. Individuals that exhibited dear enemy behaviour towards the simulated neighbour did not suffer any costs associated with loss of paternity, but there was also no evidence of reproductive benefits, and no net effect on reproductive fitness. The general ability to discriminate between neighbours and strangers is likely adaptive, but benefits are probably difficult to detect because of the indirect link between individual variation in dear enemy behaviour and reproductive fitness, and because of the complex range of mechanisms affecting relations with territorial neighbours.

animal behavior and cognition↗

bioRxiv2020

Inhibitory control, personality, and manipulated ecological conditions influence foraging plasticity in the great tit

O_LIOrganisms are consistently under selection to respond effectively to a diversity of, sometimes rapid, changes in their environment. Behavioural plasticity can allow individuals to do so instantaneously, but why individuals vary in this respect is poorly understood. Although personality and cognitive traits are often hypothesised to influence plasticity, the effects reported are highly inconsistent, which we hypothesise is because ecological context is usually not considered. C_LIO_LIHere we explore the roles of individual cognitive and personality variation - assayed using standard tasks for inhibitory control, a measure of self-control, and reactive-proactive personality axis (RPPA), respectively - in driving foraging plasticity, and asked how these effects varied across two experimentally manipulated ecological contexts: food value and predation risk. C_LIO_LIAfter great tits (Parus major) had initially been trained to retrieve high value food hidden in sand, they were then simultaneously offered the hidden food and an alternative food choice on the surface, that was either high or low value. Their choices were further examined under high and low perceived predation risk treatments. Individuals choices were classified in terms of whether they continued to forage on the hidden but familiar food source, or instead switched to the new visible food source. We defined the latter option as the plastic response. C_LIO_LIOur assays captured consistent differences among individuals in foraging behaviour. Both inhibitory control and exploration influenced whether birds switched from the familiar but hidden food source to the new alternative visible food on the surface. These effects depended on the relative value of the food items available and on the perceived level of predation risk, but also on the time scale over which the response was measured. C_LIO_LIOur results demonstrate how an executive cognitive function and one specific personality axis can simultaneously influence plasticity in a key functional behaviour. That their effects on foraging were primarily observed as interactions with food value or predation risk treatments also suggest that the population level consequences of behavioural mechanisms, such as these, may only be revealed across key ecological conditions or gradients. C_LI

animal behavior and cognition↗

bioRxiv2020

A time-lagged association between the gut microbiome, nestling growth and nestling survival in wild great tits

O_LINatal body mass is a key predictor of viability and fitness in many animals. While variation in body mass and therefore juvenile viability may be explained by genetic and environmental factors, emerging evidence points to the gut microbiota as an important factor influencing host health. The gut microbiota is known to change during development, but it remains unclear whether the microbiome predicts fitness, and if it does, at which developmental stage it affects fitness traits. C_LIO_LIWe collected data on two traits associated with fitness in wild nestling great tits (Parus major): weight and survival to fledging. We characterised the gut microbiome using 16S rRNA sequencing from nestling faeces and investigated temporal associations between the gut microbiome and fitness traits across development at day 8 (D8) and day 15 (D15) post-hatching. We also explored whether particular microbial taxa were indicator species that reflected whether nestlings survived or not. C_LIO_LIThere was no link between mass and microbial diversity on D8 or D15. However, we detected a time-lagged relationship where weight at D15 was negatively associated with the microbial diversity at D8, controlling for weight at D8, therefore reflecting relative weight gain over the intervening period. C_LIO_LIIndicator species analysis revealed that specificity values were high and fidelity values were low, suggesting that indicator taxa were primarily detected within either the survived or not survived groups, but not always detected in birds that either survived or died. Therefore these indicator taxa may be sufficient, but not necessary for determining either survival or mortality, perhaps owing to functional overlap in microbiota. C_LIO_LIWe highlight that measuring microbiome-fitness relationships at just one time point may be misleading, especially early in life. Instead, microbial-host fitness effects may be best investigated longitudinally to detect critical development windows for key microbiota and host traits associated with neonatal weight. Our findings should inform future hypothesis testing to pinpoint which features of the gut microbial community impact on host fitness, and when during development this occurs. Such confirmatory research will shed light on population level processes and could have the potential to support conservation. C_LI

ecology↗

bioRxiv2020

No evidence for cross-contextual consistency in spatial learning and behavioural flexibility in a passerine

Although the evolution of cognitive differences among species has long been of interest in ecology, whether natural selection acts on cognitive processes within populations has only begun to receive similar attention. One of the key challenges is to understand how consistently cognitive traits within any one domain are expressed over time and across different contexts, as this has direct implications for the way in which selection might act on this variation. Animal studies typically measure a cognitive domain using only one task in one context, and assume that this captures the likely expression of that domain in different contexts. This deficit is not surprising because, from an ecologists perspective, cognitive tasks are notoriously laborious to employ, and for design reasons most tasks can only be deployed in a specific context. Thus our knowledge of whether individual differences in cognitive abilities are consistent across contexts is limited. Using a wild population of great tits (Parus major) we characterised consistency of two cognitive abilities, each in two different contexts: 1) spatial learning at two different spatial scales, and 2) behavioural flexibility as both performance in a detour reaching task and reversal learning in a spatial task. We found no evidence of a correlation between the two spatial learning speeds, or between the two measures of behavioural flexibility. This suggests that cognitive performance is highly plastic and sensitive to differences across tasks, or that variants of these well-known tasks may tap into different combinations of both cognitive and non-cognitive mechanisms, or that they simply do not adequately measure each putative cognitive domain. Our results highlight the challenges of developing standardised cognitive assays to explain natural behaviour and to understand the selective consequences of that variation.

animal behavior and cognition↗

bioRxiv2019

Diet-induced changes to host gut microbiota are linked to foraging innovation in a wild bird.

The microbial community in the gut is influenced by environmental factors, especially diet, which can moderate host behaviour through the microbiome-gut-brain axis. However, the ecological relevance of microbiome-mediated behavioural plasticity in wild animals is unknown. We presented wild-caught great tits (Parus major) with a problem-solving task and showed that performance was weakly associated with variation in the gut microbiome. We then manipulated the gut microbiome by feeding birds one of two diets that differed in their relative levels of fat, protein and fibre content: an insect diet (low content), or a seed diet (high content). Microbial communities were less diverse among individuals given the insect compared to those on the seed diet. Individuals were less likely to problem-solve after being given the insect diet, and the same microbiota metrics that were altered as a consequence of diet were also those that correlated with variation in problem solving performance. Although the effect on problem-solving behaviour could have been caused by motivational or nutritional differences between our treatments, our results nevertheless raise the possibility that dietary induced changes in the gut microbiota could be an important mechanism underlying individual behavioural plasticity in wild populations.

ecology↗