Biology subjects

Dochtermann, N.

Publications and source records attributed to Dochtermann, N..

8 recordsLinked to original sources

bioRxiv2025

Genetic and environmental sources of behavioral individuality: a test of the standard model

Behavioral variation is typically assumed to arise from the combination and interaction of genetic and environmental variation. However, recent work with genetically identical individuals has found that substantial behavioral individuality is expressed even when genetic and environmental variation are negligible. This surprising result requires direct testing of our standard model for the sources of behavioral individuality. Here, we tested the standard model by comparing among-individual variation in highly inbred crickets versus outbred crickets. Comparing inbred and outbred lines allows for direct testing of the standard model by contrasting the magnitude of among-individual variation in a uniform versus varied genetic background. We found substantial and significant differences in among-individual variances, with among-individual variances being roughly three times greater in outbred versus inbred crickets (posterior probability, p = 0.974). Repeatability was also significantly different between inbred and outbred crickets (0.15 versus 0.41, respectively; p = 0.984). This result supports our standard model and suggests that the surprising expression of behavioral variation in clonal and parthenogenic species may represent an important but unique pathway for the expression of behavioral individuality.

animal behavior and cognition↗

bioRxiv2025

A saga of agonistic interactions in house crickets (Acheta domesticus): A direct and indirect effects perspective

Agonistic behaviours are widely observed across multiple taxa and are critical in shaping hierarchies, influencing resource acquisition, survival, and reproductive success. Individuals often alter their behaviour in response to the traits of others, referred to as indirect effects. Individuals also differ in their mean behavioural responses, referred to as direct effects. The combination of indirect and direct effects produce the observed social interactions. Importantly, these effects are typically measured on isolated parts of the full sequence of behaviors and traits expressed during social interactions. Here, we used house crickets, Acheta domesticus, to investigate how direct and indirect effects shape behaviors and traits across an agonistic interaction. We found that the probability of initiating aggression, but not contact, was influenced by both direct and indirect effects independent of mass. Amplitude, peak frequency, and pulse duration of stridulations occurring during agonistic interactions were influenced by direct effects but were not strongly influenced by indirect effects. These results demonstrate that the strength of indirect and direct effects vary over the course of an agonistic interaction and differentially affect the specific components of these interactions. Understanding when and how these effects are important is necessary for understanding agonistic behaviour and its evolution.

animal behavior and cognition↗

bioRxiv2025

Social buffering as an indirect effect: mixed-effects modeling approaches

O_LIThe potential for an individuals social partners to buffer--or otherwise modify-- how individuals respond to their environment has been demonstrated to be important in many contexts. This buffering has the potential to affect responses to human modifications of environments. Unfortunately, statistical tools for identifying buffering effects have not been well developed. C_LIO_LIHere, we demonstrate how social buffering fits into the context of a phenotypic equation conceptual approach and then connects to mixed-effects modeling for estimating buffering and other modifying effects of social behavior. C_LIO_LIWe explore the power and accuracy for buffering in response to known environments, providing a guide for empirical investigation. We found that increasing the sampling of social interactions decreases bias and increases precision and power to a greater extent than increasing sampling of focal individuals. C_LIO_LIWe also introduce how buffering in response to unknown environmental variation can be statistically modeled and tested. If environments are unknown, social buffering can be statistically tested for using double hierarchical generalized linear models by including social partner identity as a random effect that influences residual variation. C_LIO_LIFinally, we discuss how these approaches fit into the broader literature on indirect effects and indirect genetic effects. Placing social buffering in the context of indirect effects reveals that the evolution of social buffering is affected by both variation in an individuals behavior and variation in how individuals affect each other. This has important implications for social and evolutionary organismal responses to changing environments. C_LI

animal behavior and cognition↗

bioRxiv2024

Global meta-analysis reveals urban-associated behavioral differences among wild populations

Urbanization is causing fundamental changes to natural environments, effecting rapid and substantial adaptive phenotypic change in wild populations. While a large body of work has investigated how urbanization may shape interspecific variation in behavioral traits, such as via urban environmental filtering, no study has yet quantitatively assessed global patterns of urban-associated intraspecific behavioral variation. Here, we conducted a phylogenetic meta-analysis to assess urban-associated behavioral differences in wild populations of birds, mammals, amphibians, reptiles, and insects. We focused on four commonly measured behaviors (boldness, aggression, activity, and exploration) and extracted paired urban-nonurban effect size estimates for phenotypic means and variances (k = 278), behavioral repeatability (k = 13), and behavioral correlations (k = 14) from 80 studies. We found clear evidence that urban populations exhibit heightened average boldness, aggression, exploration, and activity compared to nonurban conspecifics, a result that was robust among species, geographic region, and ecological niche. Further, our results suggested that "generalist" species have the strongest behavioral responses. Conversely, we did not find strong evidence linking urbanization to changes in phenotypic variation, behavioral repeatability, or behavioral correlations. Our results summarize data from a rapidly evolving field in urban ecology and demonstrate geographically and taxonomically widespread differences in behavior between urban and nonurban populations, suggesting parallel natural selection across urban species and populations.

animal behavior and cognition↗

bioRxiv2020

Sexual signaling and the persistence of alternative reproductive tactics: a test of game theoretic predictions

In many species, males produce signals to attract females. However, in some species and populations, only some males produce these signals with other males competing for and intercepting reproductive opportunities. In these systems, at least three tactics are expected: always signal, signal only when others are not (assessors), and never signal. The expected representation of these tactics within a population is frequently unknown in part because the costs of signaling (C) and the fitness value of a single reproductive bout (V) are difficult to quantify. Using a game-theoretic model, we predicted that the always signal strategy should only be present in a population if the fitness value of calling is greater than twice the cost (2C < V). We found that always signal males are apparently absent in decorated crickets (Gryllodes sigillatus), at least in our sampling of a laboratory housed population. Moreover, males were not strict assessors and instead signaled infrequently (30% of the time) when signaling by others was constant. Males also exhibited substantial among-individual variation in the propensity to call when other males were not signaling ({tau} = 0.3). Our results indicate a high relative cost of signaling (2C > V). The presence of among-individual variation in propensity to call is also suggestive of underlying genetic variation and a mixed evolutionary stable strategy. More generally, the apparent high cost of signaling and presence of variation in calling propensity suggests that reduced-cost strategies should spread quickly in populations.

animal behavior and cognition↗

bioRxiv2020

Integration of intra- and inter-sexual selection signaling

Sexual selection can drive the evolution of dramatic morphological and behavioral signals. This selection acts on both specific components of signals and overall signals that combine multiple sources of information. By studying the structure and variability of signals and their components we can improve our understanding of how sexual selection operates. Signal integration can be understood through the lens of classical signaling hypotheses or more recently defined systems approaches. Using crickets (Acheta domesticus), we evaluated competing hypotheses about signal integration and how observed patterns of signal integration fit into both systems approaches and classic signaling hypotheses. We measured three call types of 127 male crickets multiple times for a total of 930 observations. We found evidence for an underlying integrated signaling syndrome from which both intra- and intersexual signals stemmed. This syndrome was also affected by mass, suggesting honest signaling in the species. The presence of an integrated syndrome demonstrates that intra- and intersexual signals are incorporated in a redundant signal strategy in Acheta domesticus. This support for honest and redundant signaling is also consistent with a systems framework description of signals as degenerate and functionally modular--demonstrating one way in which classic hypotheses can be integrated with modern systems approaches.

animal behavior and cognition↗

bioRxiv2020

The effects of exposure to predators on personality and plasticity

Past experiences are known to affect average behavior but effects on "animal personality", and plasticity are less well studied. To determine whether experience with predators influences these aspects, we compared the behavior of Gryllodes sigillatus before and after exposure to live predators. We found that emergence from shelter and distance moved during open-field trials (activity) changed after exposure, with individuals becoming less likely to emerge from shelters but more active when deprived of shelter. We also found that plasticity in activity increased after exposure to predators and some indications that differences among individuals (i.e. "personality") in emergence from shelter and the amount of an arena investigated increased after exposure. Our results demonstrate that experience with predators affects not only the average behavior of individuals but also how individuals differ from each other--and their own prior behavior--even when all individuals have the same experiences.

animal behavior and cognition↗

bioRxiv2019

Animal personality shapes evolutionary trajectories via conserved genetic architecture

Behaviors are often correlated within broader syndromes, creating the potential for evolution in one behavior to drive evolutionary changes in other behaviors. Despite demonstrations that behavioral syndromes are common across taxa, whether this potential for evolutionary effects is realized has not yet been demonstrated. Here we show that populations of field crickets (Gryllus integer) exhibit a genetically conserved behavioral syndrome structure despite differences in average behaviors. We found that the distribution of genetic variation and genetic covariance among behavioral traits was consistent with genes and cellular mechanisms underpinning behavioral syndromes rather than correlated selection. Moreover, divergence among populations average behaviors was constrained by the genetically conserved behavioral syndrome. Our results demonstrate that a conserved genetic architecture linking behaviors has shaped the evolutionary trajectories of populations in disparate environments--illustrating an important way by which behavioral syndromes result in shared evolutionary fates.

genetics↗