Research in the Rowe Group is primarily focused on understanding how ecology and evolution shape the reproductive biology and behaviour of individuals, and the consequences of variation in sexual traits for fitness. We are particularly interested in the evolution and functional significance of ejaculates, and assessing how biotic and abiotic factors shape variation in ejaculate traits within- and among-males, populations, and species. More broadly, we are interested in understanding how ecology and sexual selection shape adaptations that enable animals to survive and reproduce in different environments.
In our work, we use a multidisciplinary toolbox spanning field-based population studies, laboratory analysis of sperm performance and quality, immunological assays, phylogenetic comparative analyses, microbial sequencing, and proteomic and functional genomic analyses. We maintain a captive colony of breeding house sparrows in the NIOO aviary facilities and have established the NIOO Sperm Lab as a resource for studying sperm quality.
The Rowe Group values a supportive research environment, curiosity, transparency and open science, collaboration, and having fun doing science. We are always happy to discuss research ideas and projects with interested students and to explore fellowship/funding opportunities with post-docs. If you are interested in joining the group, please get in touch.
Science is revealing a myriad of ways in which the microbes present in your gut can impact your health. But what about microbes in the reproductive system: can these ‘reproductive microbiomes’ impact fertility? And, if so, which microbes have the greatest effect and what factors determine whether these microbes are present? In humans, the vaginal microbiome can influence fertility, but what relevance do reproductive microbiomes have for the fertility of wild animals?
We are using molecular and culture-based approaches to address these questions and gain an understanding of the microbial communities present in the reproductive systems of males and females. Using house sparrows as a model system, and complementary work with wild and captive populations, we aim to:
- Quantify variation in the male ejaculate microbiome, female cloacal microbiome, and the microbial communities of fertilised eggs.
- Determine the extrinsic and intrinsic factors that shape avian reproductive microbiomes.
- Unravel the potential role of reproductive microbiomes in determining fertility and reproductive success in birds.
- Investigate possible repercussions of reproductive microbiomes for host evolution, with particular focus on evolutionary processes related to sexual selection and sexual conflict.
Sperm biology and evolution
The function of sperm is universal – to find and fertilise ova. Yet sperm cells are the most morphologically variable cell type known, exhibiting remarkable levels of variation among species, among populations of the same species, among males within a population, as well as among and within ejaculates from a single male. Critically, our understanding of the evolutionary causes and adaptive significance of this variation remains surprisingly limited.
A recurrent theme in our previous and ongoing research is to understand why sperm cells are so diverse and to investigate the adaptive and functional significance of sperm phenotypic variation. We are also especially interested in understanding how various abiotic and biotic factors influence variation in sperm performance and, ultimately, fertilisation success. Sperm, however, do not travel alone (at least not in birds). Instead, sperm are accompanied by the non-sperm component of an ejaculate – the seminal fluid. We are therefore also interested in understanding the composition and functional evolution of avian seminal fluid.
Evolutionary causes and consequences of human-commensalism in Eurasian Passer sparrows
Humans have drastically altered the planet and are continuing to do so. We commonly think of human activity as having a negative effect on nature; however, some species have rapidly adapted to novel niches opened up by human activity. The house sparrow is prime example of a human commensal species that thrives in human created niches. It has adapted to urban and agricultural habitats almost everywhere humans are present. Intriguingly, a number of other Passer sparrows are also human commensals having likely experienced similar selective pressures. In this project we will investigate the causes and consequences of human-commensalism in Eurasian Passer sparrows. Our goals are to:
- Determine the evolutionary consequences of human-commensalism and how it might drive divergence in morphology, diet, behaviour, immunity, and microbiomes of sparrows.
- Determine whether human-commensalism has a single evolutionary origin in the house sparrow.
- Investigate potential differences in urban versus rural populations of house sparrows at the genomic and phenotypic level, including testing for differences in morphology, behaviour, diet, immune function, and gut microbiome composition and function.
This work – which is supported by several fantastic collaborators – will contribute to our understanding and management of biodiversity by providing knowledge on the adaptive potential of species entering human altered habitats and the processes involved in adaptation to anthropogenic environments. The work is led by PhD student Ruth Rawthrop under the supervision of Melissah Rowe
Impact of temperature extremes on male fertility and reproductive success
Human-induced climate change is having a dramatic effect on the global thermal environment. In addition to increases in average local temperatures, climate change is predicted to drive increases in climatic extremes, including heatwaves. The range of temperatures that organisms can physiologically tolerate plays a critical role in their distributions across space and time, thus heatwaves can pose a significant threat to the persistence of natural populations. Thermal tolerance studies, however, focus on how extreme heat events impact survival, ignoring potentially critical sublethal impacts of extreme temperature. Most notably, temperature effects on fertility traits, such as the number and viability of eggs and sperm, can lead to infertility and reproductive failure. Ultimately, thermal limits to reproduction rather than lethal temperature limits can dictate global species distributions. Thus, extreme heat events may have important wider impacts on biodiversity.
Our previous work found that heatwaves negatively impacts sperm quality in zebra finches. Currently, our work is focused on studies of the false widow spider. This work is led by PhD student Yuting Dong under the supervision of Melissah Rowe and Jeff Harvey.