Biology subjects

Bruijning, M.

Publications and source records attributed to Bruijning, M..

5 recordsLinked to original sources

bioRxiv2026

Noisy information about the environment: A source of individual differences within and across generations

Despite sharing the same genes and the same environment, individuals often develop substantial phenotypic differences. While this pattern has been documented across diverse species and traits, the processes giving rise to this "stochastic" or non-shared environmental variation remain unclear. Recent mathematical models of development in which phenotypes are gradually constructed may offer some clues. These models show that imperfect environmental cues can generate striking variation in developmental trajectories and adult phenotypes. At the population level, such imperfect cues produce increasing stability of individual differences across ontogeny (e.g. animal personality) and patterned distributions of mature phenotypes (e.g. normal or skewed) that resemble those observed in real organisms. Our paper synthesizes existing models in which stochastic phenotypic variation arises solely as a by-product of mechanisms missing their phenotypic targets because of imperfect cues. We then link these models to related, but independent, mathematical theory exploring the environmental conditions under which stochastic phenotypic variation is favoured by natural selection. Our integration shows that stochastic sampling is often favoured over classic bet-hedging strategies involving non-plastic generalist or specialist strategies. Our findings provide new directions of research on stochastic sampling as a mechanism for adaptive stochastic variation within and across generations.

developmental biology↗

bioRxiv2025

Evidence for climate-mediated range expansion of hybrid wood ants

Climate change challenges many species. To persist, species can shift ranges, respond plastically, and adapt, which all require variation - often limited in natural populations. Hybridisation can quickly increase genetic variation, potentially facilitating climate adaptation, however it is unclear how hybrids respond to climatic changes. Here, we combine whole-genome, life-history, acute heat-shock, and climatic data of 69 wood ant populations across Finland to assess whether F. aquilonia x F. polyctena hybrids outperform their cold-adapted parent F. aquilonia in warming climates. Compared to F. aquilonia, hybrids are active and their offspring emerge earlier in spring, and they withstand acute temperatures relevant in nature better. Further, the hybrids border has shifted 200 km northwards, coinciding with the expansion of climatic conditions suitable for hybrids. Our results provide evidence that hybrids have an adaptive advantage over F. aquilonia due to their admixed ancestry, and recent climatic changes can lead to range expansion of hybrids.

evolutionary biology↗

bioRxiv2022

Relative abundance data can misrepresent heritability of the microbiome

Host genetics can shape microbiome composition, but to what extent it does, remains unclear. Like any other complex trait, this question can be addressed by estimating the heritability (h2) of the microbiome - the proportion of variance in the abundance of each taxon that is attributable to host genetic variation. However, unlike most complex traits, microbiome heritability is typically based on relative abundance data, where taxon-specific abundances are expressed as the proportion of the total microbial abundance in a sample. We derived an analytical approximation for the heritability that one obtains when using such relative abundances and we uncovered three problems: 1) The interdependency between taxa leads to imprecise heritability estimates. 2) Large sample size leads to high false discovery rates, overestimating the number of heritable taxa. 3) Microbial co-abundances lead to biased heritability estimates. We conclude that caution must be taken when interpreting heritability estimates and comparing values across studies.

evolutionary biology↗

bioRxiv2020

When the microbiome defines the host phenotype: selection on vertical transmission in varying environments

The microbiome can contribute to variation in fitness-related traits of their hosts, and thus to host evolution. Hosts are therefore expected to be under selection to control their microbiome, for instance through controlling microbe transmission from parents to offspring. Current models have mostly focused on microbes that either increase or decrease fitness. In that case, host-level selection is relatively straightforward, favouring either complete or no inheritance. In natural systems, however, vertical transmission fidelity varies widely, and microbiome composition is often shaped by a combination of vertical and horizontal transmission modes. We propose that such mixed transmission could optimize host fitness under fluctuating environments. Using a general model, we illustrate that decreasing vertical transmission fidelity increases the amount of microbiome variation, and thus potentially phenotypic variation, across hosts. Whether or not this is advantageous depends on environmental conditions, how much the microbiome changes during host development, and the contribution of other factors to trait variation. We discuss how environmentally-dependent microbial effects can favor intermediate transmission, review examples from natural systems, and suggest research avenues to empirically test our predictions. Overall, we show that imperfect transmission may be adaptive by allowing individuals to ensure phenotypic variability in their offspring in contexts where varying environments mean that this strategy increases long-term fitness.

evolutionary biology↗

bioRxiv2019

Can the microbiome influence host evolutionary trajectories?

The microbiome shapes many traits in hosts, but we still do not understand how it influences host evolution. To impact host evolution, the microbiome must be heritable and have phenotypic effects on the host. However, the complex inheritance and context-dependence of the microbiome challenges traditional models of organismal evolution. Here, we take a multifaceted approach to identify conditions in which the microbiome influences host evolutionary trajectories. We explore quantitative genetic models to highlight how microbial inheritance and phenotypic effects can modulate host evolutionary responses to selection. We synthesize the literature across diverse taxa to find common scenarios of microbiome driven host evolution. First, hosts may leverage locally adapted microbes, increasing survivorship in stressful environments. Second, microbial variation may increase host phenotypic variation, enabling exploration of novel fitness landscapes. We further illustrate these effects by performing a meta-analysis of artificial selection in Drosophila, finding that bacterial diversity also frequently responds to host selection. We conclude by outlining key avenues of research and experimental procedures to improve our understanding of the complex interplay between hosts and microbiomes. By synthesizing perspectives through multiple conceptual and analytical approaches, we show how microbiomes can influence the evolutionary trajectories of hosts.

evolutionary biology↗