Holger Schielzeth

Holger Schielzeth
Friedrich Schiller University Jena | FSU · Population Ecology

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121
Publications
42,664
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18,980
Citations
Citations since 2017
52 Research Items
14458 Citations
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201720182019202020212022202305001,0001,5002,0002,5003,000
201720182019202020212022202305001,0001,5002,0002,5003,000
201720182019202020212022202305001,0001,5002,0002,5003,000

Publications

Publications (121)
Article
Full-text available
Insights into the processes underpinning convergent evolution advance our understanding of the contributions of ancestral, introgressed, and novel genetic variation to phenotypic evolution. Phylogenomic analyses characterizing genome-wide gene tree heterogeneity can provide first clues about the extent of ILS and of introgression and thereby into t...
Preprint
Full-text available
State variables, such as body condition, are important predictors of behavioural traits. Depending on the state of an individual, the costs and benefits associated with different behavioural decisions can vary. An individual's state could affect its average behavioural response and also the behavioural repeatability. Moreover, even for the same sta...
Preprint
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Assessing the biological relevance of variance components estimated using MCMC-based mixed-effects models is not straightforward. Variance estimates are constrained to be greater than zero and their posterior distributions are often asymmetric. Different measures of central tendency for these distributions can therefore be very different, and credi...
Preprint
Full-text available
Insights into the processes underpinning the evolution of phenotypic parallelism contribute to our understanding of the contributions of ancestral, introgressed, and novel genetic variation to phenotypic evolution. Phylogenomic analyses characterizing genome-wide gene tree heterogeneity can provide first clues about the extent of ILS and of introgr...
Article
Full-text available
We here develop a concept of an individualized niche in analogy to Hutchison’s population-level concept of the ecological niche. We consider the individualized (ecological) niche as the range of environmental conditions under which a particular individual has an expected lifetime reproductive success of ≥ 1. Our concept has primarily an ecological...
Article
Full-text available
Individuals differ in the way they judge ambiguous information: some individuals interpret ambiguous information in a more optimistic, and others in a more pessimistic way. Over the past two decades, such "optimistic" and "pessimistic" cognitive judgment biases (CJBs) have been utilized in animal welfare science as indicators of animals' emotional...
Article
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Organisms interact with their environments in various ways. We present a conceptual framework that distinguishes three mechanisms of organism–environment interaction. We call these NC3 mechanisms: niche construction, in which individuals make changes to the environment; niche choice, in which individuals select an environment; and niche conformance...
Article
Individuals differ in average phenotypes and in sensitivity to environmental variation. Such context‐sensitivity can be modelled as random‐slope variation. Random‐slope variation implies that the proportion of between‐individual variation varies across the range of a covariate (environment/context/time/age) and has thus been called ‘conditional’ re...
Article
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Orthopteran insects are characterized by high variability in body coloration, in particular featuring a widespread green-brown color polymorphism. The mechanisms that contribute to the maintenance of this apparently balanced polymorphism are not yet understood. To investigate whether morph-dependent microhabitat choice might contribute to the conti...
Preprint
Full-text available
Organisms interact with their environments in various ways. We present a conceptual framework that distinguishes three mechanisms of organism-environment interaction. We call these NC3 mechanisms: niche construction, in which individuals make changes to the environment; niche choice, in which individuals select an environment; and niche conformance...
Article
Full-text available
The study of consistent individual differences has become an important focus in research on animal behaviour. These behavioural differences are typically measured through standardized testing procedures. One frequently used paradigm is the novel object test, in which animals are exposed to unfamiliar objects and their reaction is quantified. We use...
Data
Code used in paper: Takola, E., Krause, E., Müller, C., & Schielzeth, H. (2021). Novelty at second glance: a critical appraisal of the novel object paradigm based on meta-analysis. Animal Behaviour, 180, 123-142. doi: 10.1016/j.anbehav.2021.07.018 | Data can be found in the file (Novelty_at_second_glance_Takolaetal2021_Data.csv).
Data
Data used in paper: Takola, E., Krause, E., Müller, C., & Schielzeth, H. (2021). Novelty at second glance: a critical appraisal of the novel object paradigm based on meta-analysis. Animal Behaviour, 180, 123-142. doi: 10.1016/j.anbehav.2021.07.018 | Explanation of variable names can be found in the code file (Novelty_at_second_glance_Takolaetal2021...
Article
Full-text available
The coefficient of determination R ² quantifies the amount of variance explained by regression coefficients in a linear model. It can be seen as the fixed-effects complement to the repeatability R (intra-class correlation) for the variance explained by random effects and thus as a tool for variance decomposition. The R ² of a model can be further p...
Preprint
Individuals differ. This seemingly trivial statement has nevertheless led to paradigm shifts, as three different fields of organismal biology have seen a marked change in key concepts over the past few decades. In animal behaviour, it has increasingly been realised that behavioural differences among individuals can be stable over time and across co...
Article
Full-text available
The green–brown polymorphism of grasshoppers and bush-crickets represents one of the most penetrant polymorphisms in any group of organisms. This poses the question of why the polymorphism is shared across species and how it is maintained. There is mixed evidence for whether and in which species it is environmentally or genetically determined in Or...
Preprint
Full-text available
We here develop a concept of an individualized niche in analogy to Hutchison’s population-level concept of the ecological niche. We consider the individualized (ecological) niche as the range of environmental conditions under which a particular individual has an expected lifetime reproductive success of ≥ 1. Our concept has primarily an ecological...
Preprint
Full-text available
The study of consistent individual differences in behaviour has become an important focus in research on animal behaviour. Behavioural phenotypes are typically measured through standardized testing paradigms and one frequently used paradigm is the novel object test. In novel object tests, animals are exposed to new (unknown) objects and their react...
Article
Full-text available
Animal behaviour can lead to varying levels of risk, and an individual’s physical condition can alter the potential costs and benefits of undertaking risky behaviours. How risk-taking behaviour depends on condition is subject to contrasting hypotheses. The asset protection principle proposes that individuals in better condition should be more risk...
Article
Animal ecologists often collect hierarchically‐structured data and analyze these with linear mixed‐effects models. Specific complications arise when the effect sizes of covariates vary on multiple levels (e.g., within vs among subjects). Mean‐centering of covariates within subjects offers a useful approach in such situations, but is not without pro...
Preprint
Full-text available
Animal behaviour can lead to varying levels of risk, and an individual’s physical condition can alter the potential costs and benefits of undertaking risky behaviours. How risk-taking behaviour depends on condition is subject to contrasting hypotheses. The asset protection principle proposes that individuals in better condition should be more risk...
Preprint
Full-text available
The coefficient of determination R ² quantifies the amount of variance explained by regression coefficients in a linear model. It can be seen as the fixed-effects complement to the repeatability R (intra-class correlation) for the variance explained by random effects and thus as a tool for variance decomposition. The R ² of a model can be further p...
Article
In species with internal fertilization, the female genital tract appears challenging to sperm, possibly resulting from selection on for example ovarian fluid to control sperm behaviour and, ultimately, fertilization. Few studies, however, have examined the effects of swimming media viscosities on sperm performance. We quantified effects of media vi...
Article
Full-text available
Eukaryotic organisms vary widely in genome size and much of this variation can be explained by differences in the abundance of repetitive elements. However, the phylogenetic distributions and turnover rates of repetitive elements are largely unknown, particularly for species with large genomes. We therefore used de novo repeat identification based...
Article
Full-text available
Linear mixed‐effects models are powerful tools for analyzing complex datasets with repeated or clustered observations, a common data structure in ecology and evolution. Mixed‐effects models involve complex fitting procedures and make several assumptions, in particular about the distribution of residual and random effects. Violations to these assump...
Article
Full-text available
The feasibility to sequence entire genomes of virtually any organism provides unprecedented insights into the evolutionary history of populations and species. Nevertheless, many population genomic inferences – including the quantification and dating of admixture, introgression and demographic events, and inference of selective sweeps – are still li...
Preprint
Full-text available
Individuals differ in average phenotypes, but also in sensitivity to environmental variation. Such variation is biologically relevant, because it reflects variation in reaction norms. Between-individual variation in average phenotypes is typically quantified as random-intercept variation in linear mixed-effects models or as intra-class correlations...
Preprint
Full-text available
The feasibility to sequence entire genomes of virtually any organism provides unprecedented insights into the evolutionary history of populations and species. Nevertheless, many population genomic inferences - including the quantification and dating of admixture, introgression and demographic events, and the inference of selective sweeps - are stil...
Article
Full-text available
Abstract Ectothermic animals depend on external heat sources for pursuing their daily activities. However, reaching sufficiently high temperature can be limiting at high altitudes, where nights are cold and seasons short. We focus on the role of a green‐brown color polymorphism in grasshoppers from alpine habitats. The green‐brown polymorphism is p...
Article
Capsule Surveys of the White-headed Duck Oxyura leucocephala at key breeding and staging sites in Kazakhstan suggest a positive trend for the migratory Eastern population and an underestimation of the global population. Aims To review and update the population estimate and distribution status of the White-headed Duck in Kazakhstan using the most r...
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Background The club-legged grasshopper Gomphocerus sibiricus is a Gomphocerinae grasshopper with a promising future as model species for studying the maintenance of colour-polymorphism, the genetics of sexual ornamentation and genome size evolution. However, limited molecular resources are available for this species. Here, we present a de novo tran...
Article
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Discrete color polymorphisms represent a fascinating aspect of intraspecific diversity. Color morph ratios often vary clinally, but in some cases, there are no marked clines and mixes of different morphs occur at appreciable frequencies in most populations. This poses the questions of how polymorphisms are maintained. We here study the spatial and...
Article
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Many animals show altitudinal clines in size, shape and body colour. Increases in body size and reduction in the length of body appendices in colder habitats are usually attributed to improved heat conservation at lower surface-to-volume ratios (known as Bergmann’s and Allen’s rule, respectively). However, the patterns are more variable and sometim...
Article
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Linear mixed effects models are frequently used for estimating quantitative genetic parameters, including the heritability, as well as the repeatability, of traits. Heritability acts as a filter that determines how efficiently phenotypic selection translates into evolutionary change, while repeatability informs us about the individual consistency o...
Article
Full-text available
The coefficient of determination R² quantifies the proportion of variance explained by a statistical model and is an important summary statistic of biological interest. However, estimating R² for generalized linear mixed models (GLMMs) remains challenging. We have previously introduced a version of R² that we called for Poisson and binomial GLMMs,...
Preprint
Full-text available
The coefficient of determination R ² quantifies the proportion of variance explained by a statistical model and is an important summary statistic of biological interest. However, estimating R ² for generalized linear mixed models (GLMMs) remains challenging. We have previously introduced a version of R ² that we called R ² GLMM for Poisson and bino...
Preprint
Full-text available
Linear mixed effects models are frequently used for estimating quantitative genetic parameters, including the heritability, of traits of interest. Heritability is an important metric, because it acts as a filter that determines how efficiently phenotypic selection translates into evolutionary change. As a quantity of biological interest, it is impo...
Article
Full-text available
Developmental plasticity is a key feature of many organisms and individuals can benefit from early programming to optimize their phenotypes for the expected environmental conditions. However, environmental conditions may sometimes change unexpectedly. Mismatches between early and adult life, for example, can have important repercussions for adult p...
Article
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Intra-class correlations (ICC) and repeatabilities (R) are fundamental statistics for quantifying the reproducibility of measurements and for understanding the structure of biological variation. Linear mixed effects models offer a versatile framework for estimating ICC and R. However, while point estimation and significance testing by likelihood ra...
Article
Sexual ornaments contribute substantially to phenotypic diversity and it is particularly relevant to understand their evolution. Ornaments can assume the function of signals-of-quality that the choosy sex uses to evaluate potential mating partners. Often there are no obvious direct benefits and investment into mate choice is primarily rewarded by b...
Article
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Identifying causal genetic variants underlying heritable phenotypic variation is a longstanding goal in evolutionary genetics. We previously identified several quantitative trait loci (QTL) for five morphological traits in a captive population of zebra finches (Taeniopygia guttata) by whole-genome linkage mapping. We here follow up on these studies...
Article
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Theory makes several predictions concerning differences in genetic variation between the X chromosome and the autosomes due to male X hemizygosity. The X chromosome should i) typically show relatively less standing genetic variation than the autosomes, ii) exhibit more variation in males compared to females because of dosage compensation, and iii)...
Article
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Methods for inference and interpretation of evolutionary quantitative genetic parameters, and for prediction of the response to selection, are best developed for traits with normal distributions. Many traits of evolutionary interest, including many life history and behavioural traits, have inherently non-normal distributions. The generalised linear...
Article
Full-text available
Phenotypic variation exists in and at all levels of biological organization: variation exists among species, within-populations among-individuals, and in the case of labile traits, within-individuals. Mixed-effects models represent ideal tools to quantify multi-level measurements of traits and are being increasingly used in evolutionary ecology. 2....
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Despite recent advances in high-throughput sequencing, difficulties are often encountered when developing microsatellites for species with large and complex genomes. This probably reflects the close association in many species of microsatellites with cryptic repetitive elements. We therefore developed a novel approach for isolating polymorphic micr...
Article
We had recently reported an association between song attractiveness and genome size in a population of bow-winged grasshoppers, Chorthippus biguttulus, with unattractive singers having larger genomes (Schielzeth et al. 2014). Camacho (2016) commented on our publication expressing doubts whether the data support our conclusions. We appreciate his cr...
Preprint
Full-text available
Methods for inference and interpretation of evolutionary quantitative genetic parameters, and for prediction of the response to selection, are best developed for traits with normal distributions. Many traits of evolutionary interest, including many life history and behavioural traits, have inherently non-normal distributions. The generalised linear...
Article
Full-text available
Colour polymorphisms are a fascinating facet of many natural populations of plants and animals, and the selective processes that maintain such variation are as relevant as the processes which promote their development. Orthoptera, the insect group that encompasses grasshoppers and bush crickets, includes a particularly large number of species that...
Article
The view that the Y chromosome is of little importance for phenotypic evolution stems from early studies of Drosophila melanogaster. This species' Y chromosome contains only 13 protein coding genes, is almost entirely heterochromatic, and is not necessary for male viability. Population genetic theory further suggests that non-neutral variation can...
Article
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The two parental alleles at a specific locus are usually inherited with equal probability to the offspring. However, at least three processes can lead to an apparent departure from fair segregation: early viability selection, biased gene conversion and various kinds of segregation distortion. Here we conduct a genome-wide scan for transmission dist...
Article
Animals are faced with many choices and a very important one is the choice of a mating partner. Inter-individual differences in mating preferences have been studied for some time, but most studies focus on the location of the peak preference rather than on other aspects of preference functions. In this review, we discuss the role of variation in ch...
Article
1.Many aspects of animal behaviour differ consistently between individuals, giving rise to the growing field of animal personality research. While between-individual variation has long been of interest to biologists, the role of within-individual variation has received less attention. Indeed, many models assume that the extent of within-individual...
Article
Full-text available
Abstract Carotenoid-based coloration plays an important role in signaling, is often sexually dimorphic, and is potentially subject to directional and/or sex-specific selection. To understand the evolutionary dynamics of such color traits, it is essential to quantify patterns of inheritance, yet nonautosomal sources of genetic variation are easily o...
Article
Genome size is largely uncorrelated to organismal complexity and adaptive scenarios. Genetic drift as well as intragenomic conflict have been put forward to explain this observation. We here study the impact of genome size on sexual attractiveness in the bow-winged grasshopper Chorthippus biguttulus. Grasshoppers show particularly large variation i...
Article
A considerable challenge in evolutionary genetics is to understand the genetic mechanisms that facilitate or impede evolutionary adaptation in natural populations. For this, we must understand the genetic loci contributing to trait variation and the selective forces acting on them. The decreased costs and increased feasibility of obtaining genotypi...
Article
Full-text available
Abstract Males and females differ with respect to life span and rate of aging in most animal species. Such sexual dimorphism can be associated with a complex genetic architecture, where only part of the genetic variation is shared between the sexes. However, the extent to which this is true for life span and aging is not known, because studies of l...
Article
Human-altered environmental conditions affect many species at the global scale. An extreme form of anthropogenic alteration is the existence and rapid increase of urban areas. A key question, then, is how species cope with urbanization. It has been suggested that rural and urban conspecifics show differences in behaviour and personality. However, (...
Article
Byers and Dunn's (Reports, 9 November 2012, p.802) conclusion that predation constrains sexual selection is problematic for three reasons: their nonstandard calculation of Bateman slopes; their assertion that random processes do not influence reproductive success; and the statistically unjustifiable use of 6 variables to explain just 10 observation...
Article
Theory predicts that sex chromsome linkage should reduce intersexual genetic correlations thereby allowing the evolution of sexual dimorphism. Empirical evidence for sex linkage has come largely from crosses and few studies have examined how sexual dimorphism and sex linkage are related within outbred populations. Here, we use data on an array of d...
Article
Adaptive sex allocation has frequently been studied in sexually size dimorphic species, but far less is known about patterns of sex allocation in species without pronounced sexual size dimorphism. Parental optimal investment can be predicted under circumstances in which sons and daughters differ in costs and/or fitness returns. In common terns Ster...
Article
The use of both linear and generalized linear mixed-effects models (LMMs and GLMMs) has become popular not only in social and medical sciences, but also in biological sciences, especially in the field of ecology and evolution. Information criteria, such as Akaike Information Criterion (AIC), are usually presented as model comparison tools for mixed...
Article
Nested data structures are ubiquitous in the study of ecology and evolution, and such structures need to be modelled appropriately. Mixed-effects models offer a powerful framework to do so. Nested effects can usually be fitted using the syntax for crossed effects in mixed models, provided that the coding reflects implicit nesting. But the experimen...
Article
The use of both linear and generalized linear mixed‐effects models (LMMs and GLMMs) has become popular not only in social and medical sciences, but also in biological sciences, especially in the field of ecology and evolution. Information criteria, such as Akaike Information Criterion (AIC), are usually presented as model comparison tools for mixed...
Article
Full-text available
Animal collective patterns such as group size frequency distributions often show substantial intraspecific variation, suggesting low species-specific consistency. Here, we dissect intraspecific vs interspecific components of colony size variation to estimate the repeatability (R) of colony size frequency distribution (CSFD) statistics for seabird s...
Article
The intra- and interspecific diversity of avian beak morphologies is one of the most compelling examples for the power of natural selection acting on a morphological trait. The development and diversification of the beak have also become a textbook example for evolutionary developmental biology, and variation in expression levels of several genes i...
Article
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