Biology subjects

Schou, M. F.

Publications and source records attributed to Schou, M. F..

7 recordsLinked to original sources

bioRxiv2026

Development shapes molecular responses to thermal extremes in a desert bird

Thermal extremes are among the most immediate environmental challenges faced by animals. Coping with these conditions across life is complex because growth changes body size, heat exchange and thermoregulatory demands. Consequently, adaptive responses in young, small individuals may be maladaptive, or require adjustment, later in life. However, in endotherms we know very little about how thermoregulatory responses to hot and cold temperatures change during development, or about the molecular mechanisms regulating responses. We examined the molecular responses to acute heat (40{degrees}C), cold (12{degrees}C) and benign (23{degrees}C) conditions in 1- and 8-week-old ostrich chicks (Struthio camelus), a rapidly growing species exposed to strong daily and seasonal temperature variation. We found that in 1-week-old chicks, 44% of temperature-related genes were involved in both heat and cold responses, indicating that responses to opposing temperatures involve overlapping molecular pathways. However, the response of 76% of these genes changed during development. For example, some genes that increased with heat exposure when young decreased with heat exposure later in development, and vice versa. Such opposing selection pressures may maintain genetic variation in thermoregulatory pathways. Consistent with this prediction, comparisons between ostrich subspecies adapted to different thermal environments revealed patterns of genomic variation compatible with balancing selection in differentially expressed genes. Our results show that hot and cold temperatures trigger overlapping molecular responses that change during development, which shape genetic variation in the thermoregulatory system.

evolutionary biology↗

bioRxiv2022

A thermal radiator underlies plasticity to extreme temperatures in the world's largest bird

Organisms inhabiting extreme thermal environments, such as desert birds, have evolved spectacular adaptations to thermoregulate during hot and cold conditions. However, our knowledge of selection for thermoregulation and the potential for evolutionary responses is limited, particularly for large organisms experiencing extreme temperature fluctuations. Here we use thermal imaging to quantify selection and genetic variation in thermoregulation in ostriches (Struthio camelus), the worlds largest bird species that is experiencing increasingly volatile temperatures. We found that females that are better at regulating their head temperatures ( thermoregulatory capacity) had higher egg-laying rates under hotter conditions. Thermoregulatory capacity was both heritable and showed signatures of local adaptation: females originating from more unpredictable climates were better at regulating their head temperatures in response to temperature fluctuations. Together these results reveal that past and present evolutionary processes have shaped genetic variation in thermoregulatory capacity, which appears to protect critical organs, such as the brain, from extreme temperatures during reproduction. Impact SummaryLarge animals inhabiting extreme thermal environments, such as deserts, are predicted to be particularly vulnerable to the increasing temperature fluctuations expected in the future. However, previous work on the evolutionary potential of thermoregulation has primarily focused on the effect of hot temperatures on the survival of small ectotherms. We know little about how large endothermic vertebrates, such as birds, will respond to changing temperatures. Here we study the ostrich (Struthio camelus), the worlds largest bird, that inhabits some of the hottest and driest regions on Earth. We show that the ability of females to reproduce during hot conditions is associated with the regulation of their head temperatures ( thermoregulatory capacity). Furthermore, variation in thermoregulation is heritable and related to past climatic conditions: females originating from parts of Africa with more extreme temperature fluctuations were better able to thermoregulate, indicating local adaptation to different climatic conditions. Together, these results suggest that thermoregulation in this large desert bird has evolved in response to past climatic conditions, remains genetically variable and is currently under selection through its effect on reproduction.

evolutionary biology↗

bioRxiv2022

Experimental evidence that animal societies vary in size due to sex differences in cooperation

Cooperative breeding societies allow the costs of reproduction to be shared. However, as groups become larger, such benefits often decrease and competition increases. This is predicted to select for an optimal group size, yet variation in groups is a ubiquitous feature of cooperative breeding animals. Here we experimentally established groups (ngroups=96) of cooperative breeding ostriches, Struthio camelus, with different numbers of males and females and manipulated the potential for cooperation over incubation. There was a clear optimal group size for males. Their reproductive success was maximized in groups with four or more females and no other males, irrespective of cooperation over incubation. Conversely, female reproductive success was strongly dependent on the benefits of cooperating over incubation, being maximized in groups with either many males or many females. In intermediate sized groups, both male and female reproductive success was reduced by sexual conflict over the timing of mating and incubation. Our experiments show that sex differences in the opposing forces of cooperation and competition can explain why variation in cooperative groups is widespread.

evolutionary biology↗

bioRxiv2021

Evolutionary trade-offs between heat and cold tolerance limit responses to fluctuating climates

The evolutionary potential of species to cope with short-term temperature fluctuations during reproduction is critical to predicting responses to future climate change. Despite this, vertebrate research has focused on reproduction under high or low temperatures in relatively stable temperate climates. Here, we characterize the genetic basis of reproductive thermal tolerance to temperature fluctuations in the ostrich that lives in tropical and sub-tropical Africa. Both heat and cold tolerance are under selection and heritable, indicating that evolutionary responses to mean temperature change are possible. However, a negative, genetic correlation between heat and cold tolerance limits the potential for adaptation to fluctuating temperatures. Genetic constraints between heat and cold tolerance appears a crucial, yet underappreciated, factor influencing responses to climate change. One-sentence summaryReproductive success in fluctuating climates is constrained by a negative genetic correlation between heat and cold tolerance

evolutionary biology↗

bioRxiv2021

Drosophila Evolution over Space and Time (DEST) - A New Population Genomics Resource

Drosophila melanogaster is a leading model in population genetics and genomics, and a growing number of whole-genome datasets from natural populations of this species have been published over the last 20 years. A major challenge is the integration of these disparate datasets, often generated using different sequencing technologies and bioinformatic pipelines, which hampers our ability to address questions about the evolution and population structure of this species. Here we address these issues by developing a bioinformatics pipeline that maps pooled sequencing (Pool-Seq) reads from D. melanogaster to a hologenome consisting of fly and symbiont genomes and estimates allele frequencies using either a heuristic (PoolSNP) or a probabilistic variant caller (SNAPE-pooled). We use this pipeline to generate the largest data repository of genomic data available for D. melanogaster to date, encompassing 271 population samples from over 100 locations in >20 countries on four continents based on a combination of 121 unpublished and 150 previously published genomic datasets. Several of these locations have been sampled at different seasons across multiple years. This dataset, which we call Drosophila Evolution over Space and Time (DEST), is coupled with sampling and environmental meta-data. A web-based genome browser and web portal provide easy access to the SNP dataset. Our aim is to provide this scalable platform as a community resource which can be easily extended via future efforts for an even more extensive cosmopolitan dataset. Our resource will enable population geneticists to analyze spatio-temporal genetic patterns and evolutionary dynamics of D. melanogaster populations in unprecedented detail.

genomics↗

bioRxiv2020

The discovery, distribution and diversity of DNA viruses associated with Drosophila melanogaster in Europe

Drosophila melanogaster is an important model for antiviral immunity in arthropods, but very few DNA viruses have been described from the family Drosophilidae. This deficiency limits our opportunity to use natural host-pathogen combinations in experimental studies, and may bias our understanding of the Drosophila virome. Here we report fourteen DNA viruses detected in a metagenomic analysis of approximately 6500 pool-sequenced Drosophila, sampled from 47 European locations between 2014 and 2016. These include three new Nudiviruses, a new and divergent Entomopox virus, a virus related to Leptopilina boulardi filamentous virus, and a virus related to Musca domestica salivary gland hypertrophy virus. We also find an endogenous genomic copy of Galbut virus, a dsRNA Partitivirus, segregating at very low frequency. Remarkably, we find that Drosophila Vesanto virus, a small DNA virus previously described as a Bidnavirus, may be composed of up to 12 segments and represent a new lineage of segmented DNA viruses. Two of the DNA viruses, Drosophila Kallithea nudivirus and Drosophila Vesanto virus are relatively common, found in 2% or more of wild flies. The others are rare, with many likely to be represented by a single infected fly. We find that virus prevalence in Europe reflects the prevalence seen in publicly-available datasets, with Drosophila Kallithea nudivirus and Drosophila Vesanto virus the only ones commonly detectable in public data from wild-caught flies and large population cages, and the other viruses being rare or absent. These analyses suggest that DNA viruses are at lower prevalence than RNA viruses in D. melanogaster, and may be less likely to persist in laboratory cultures. Our findings go some way to redressing an earlier bias toward RNA virus studies in Drosophila, and lay the foundation needed to harness the power of Drosophila as a model system for the study of DNA viruses.

microbiology↗

bioRxiv2018

Genomic analysis of European Drosophila melanogaster populations on a dense spatial scale reveals longitudinal population structure and continent-wide selection

Genetic variation is the fuel of evolution, with standing genetic variation especially important for short-term evolution and local adaptation. To date, studies of spatio-temporal patterns of genetic variation in natural populations have been challenging, as comprehensive sampling is logistically difficult, and sequencing of entire populations costly. Here, we address these issues using a collaborative approach, sequencing 48 pooled population samples from 32 locations, and perform the first continent-wide genomic analysis of genetic variation in European Drosophila melanogaster. Our analyses uncover longitudinal population structure, provide evidence for continent-wide selective sweeps, identify candidate genes for local climate adaptation, and document clines in chromosomal inversion and transposable element frequencies. We also characterise variation among populations in the composition of the fly microbiome, and identify five new DNA viruses in our samples.

evolutionary biology↗