Bio
I was born in the UK, and moved to SW France when I was a baby so I learned French at school and English at home. During my childhood I quickly became fascinated by nature, and spent most of my free time playing outdoors, in the woods and by the local river with my brothers and friends. All through school I was mostly interested in science, in particular biology.
My undergrad was in organismal biology, and after a stint working in a factory which rekindled my interest in academia, I started a Masters in Ecology in Bordeaux. During my first year, I went to England for a 2 month internship with Guillaume Besnard, working on the genetics of the olive complex across the Meditteranean Bassin. We also determined haplotypes of invasive olives in Australia, to reconstruct the history of the invasion. Then during my second year, I started working on conifers drought resistance, in Sylvain Delzon's lab in Bordeaux. There I deepened my knowledge of plant water relations and various methods to measure the water status of a plant. I worked mainly on measurements of embolism resistance with Herve Cochard's Cavitron method. Conifers, a group of 615 species of gymnosperms (in 7 different families), are a diverse group found all over the globe in a wide range of habitats. Many are adapted to xeric or cold environments. In my first internship, we described the wide variation of embolism resistance across conifer species, with members of Pinaceae typically more vulnerable, and some Cupressaceae and Podocarpaceae more resistant to drought. In my second internship, we found that P50 displays strong phylogenetic signal in Pinaceae, along with other results suggesting some level of evolutionary conservatism in this family.
These results helped us to formulate questions that led to my PhD. We were interested in how drought resistance (through embolism resistance) evolved across all conifers. To answer this question, we expanded our database of conifer embolism resistance to species belonging all families and around 90% of the ~75 genera. The Cupressaceae family was of great interest to me, notably the Australian & New Caledonian genus Callitris, which had previously been identified as drought-adapted. Through a collaboration with some colleagues Down-under (i.e. Sebastian Pfautsch in Sydney and Callitris expert Tim Brodribb at UTas), I obtained a grant to travel to Australia. After sampling among wild populations of the remaining 15 species, we discovered some record resistant species, namely Callitris canescens and Callitris tuberculata (P50 of -16.8 and -18.8 MPa, respectively).
At a broader evolutionary scale, we found an evolutionary association between narrower inter-tracheid pits and increased embolism resistance. In a separate thesis chapter, we identified shifts in the rate of evolution of this trait early within the Callitris and Cupressus-Juniperus clades, which also coincide with an uptick in clade diversification rate (still unpublished...).
To better understand trait evolution, it is often crucial to know the genetic basis for a trait and the mechanisms that lead to shifts within phenotypic space. To explore these questions further, and to get a better grasp on comparative methods and evolutionary convergence, I moved to Colorado (USA), and started a post-doc with Stacey Smith at CU Boulder. Here I'm working on the evolution of the anthocyanin pathway in Iochrominae, a group of South American Solanaceae. In the first part of my project, we found that in this tribe, the ancestral state blue delphinidin anthocyanins has been lost several times, with multiple lineages having lost pigmentation totally. This character change was the result of severe down-expression of the 3 latest core genes, F3'5'h, Dfr, and Ans. Further investigations are under way, using transcriptomics to understand how these genes are downregulated.
We also found that within polymorphic species, other things were happening. Unpigmented flowers are sometimes produced while these late pathway genes are normally expressed. This provides support for the hypothesis that non-regulatory mutations with higher pleiotropic effects can exist within populations but over longer time periods tend to be filtered out by selection. This species-level mutational "funnel" results in a bias at broader evolutionary scales, creating a pattern with convergence in molecular and/or genetic mechanisms in cases of phenotypic convergent evolution.
Herb hydraulics, positive root pressure and drought resistance
In 2019, I moved to Leiden (NL) for a post-doc with Frederic Lens in the at Naturalis Biodiversity Center, to work on drought-resistance and root pressure in herbaceous plants, in particular in family Brassicaceae. This project combines classical plant hydraulics adapted to non-woody species (minimum water potential measurements, cavitation resistance, hydraulic conductance) with xylem anatomy (optical and scanning electron microscopy), micro-computed tomography in-vivo visualization and modeling to aim for a holistic vision of herb hydraulic functioning during drought.
Some plants are known to develop positive root pressure, and this process has been hypothesized to aid in recovering from drought by refilling xylem conduits, thereby allowing growth to resume. We hope to elucidate this potential role of positive root pressure in providing plants with a way to avoid death during drought.
We hope to obtain these data across multiple species within a range of environmental conditions to gain insight into how these traits are coordinated at evolutionary timescales. Finally, we hope to use this dataset to look for support of the hypothesis linking the evolution of increased stem woodiness in herbs to an increase in drought tolerance.
Drought and cold stress
In 2021, I moved back to France to rejoin Sylvain's lab on a project aiming to characterize forest trees climatic tolerance traits to both drought and cold stress. This ANR project is led by Georges Kunstler in Grenoble, and features other cool folks like Anne Baranger, Laura Touzot, Thomas Cordonier and Frank Jabot. I'm lucky to be working with Guillaume Charrier on all the cold tolerance stuff, and building on preliminary work led by Constance Bertrand as part of her BSc research project putting together a cool cold hardiness database from the litterature.
Because tree species tend to be limited by drought on the rear-edge of their distribution, and cold stress on the leading edge of the range, we think that trade-offs between being stress tolerant and competitive (overall fitness traits) will combine to determine species ranges and trait combinations. We could use this to predict species distributions (eg under different climate *wink wink*), by linking them with growth & competiton data from northern hemisphere forest inventories, which is the ultimate end goal of the project. My part of the project is building trait databases for as many tree species as possible to look for broad relationships between stress tolerance traits and with growth traits.