iDAPT

iDAPT is a four year Leverhulme Trust funded project investigating how the earliest land plants were able to make the fundamental transition from freshwater to terrestrial habitats by examining how a group of closely-related freshwater microalgae are able to thrive in present day icy environments. We believe that ice surfaces represent an important intermediate niche between freshwater and terrestrial environments, and that they played an important role in driving the evolution of biological features required for the historic colonization of land by algae. Through genome sequencing, novel technology development and field expeditions, iDAPT will advance our understanding of how life excels within icy environments and its importance for fundamental transitions in the history of planet Earth. Read on to see the team behind the project, the project rationale, major research objectives, a summary of our major conclusions, the publications and presentations we have delivered, and a detailed reviews of each part of our project.

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The iDAPT Team

iDAPT is led by an interdisciplinary team that includes a polar microbiologist, a phytoplankton ecophysiologist, a paleobiologist, an evolutionary biologist and an industrial partner. Click below for links to our individual bios.

The main iDAPT work has all been done by our two fantastic postdocs:

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iDAPT Project Rationale

The colonization of land by the earliest land plants was one of the most important steps in the evolution of the Earth, resulting in the world as we know it today. That all land plants evolved from a single, freshwater lineage of microalgae is even more remarkable and raises the question; What was it about the biology of these algae that enabled the conquest of land? Moving from freshwater to terrestrial habitats required tolerance of new extremes in temperature, desiccation, visible and UV-radiation, and the algal ancestor of land plants likely evolved a number of adaptations for some purpose in water, that later proved advantageous on land. We still do not know how or why this environment drove adaptations that facilitated the move onto land.

Glacier algae thrive within surface ice across the cryosphere. (a) Ice camp established at 72^oN on the Greenland Ice Sheet to study glacier algal blooms during the summer melt season; (b) Supraglacial surface ice on the southwestern Greenland Ice Sheet heavily colonized by a glacier algal bloom; (c) a heavily pigmented glacier algae assemblage viewed down the microscope showing the major species including the filamentous Ancylonema nordenskiöldii and single-celled Mesotaenium berggrenii.

On the icy surfaces of glaciers and ice sheets, blooms of microalgae occur during summer melt seasons when liquid water and sunlight are available for growth. To survive within this unique icy environment, these so-called glacier algae must tolerate extremes in temperature, desiccation, visible and UV-radiation, key stressors important in the transition of algal life from water to land. Indeed, we believe that ice surfaces themselves represent an important intermediate between aquatic and terrestrial environments, being fundamentally made of water, but subject to terrestrial conditions. The other critical thing about glacier algae; they are amongst the closest living relatives to land plants.

Snowball Earth: iDAPT explores whether conditions prevailing during snowball Earth events were the catalyst for the evolution of biological features that allowed life to jump onto land.

iDAPT explores the idea that snowball Earth events, when the world was covered in snow and ice, were important drivers of adaptations in the algal ancestors of land plants that facilitated the colonization of dry land. By studying how closely related glacier algae are adapted to thrive within icy conditions today, we will identify what adaptations snowball Earth conditions promote in algae, whether these are also found in early land plants, and their role in the transition of life to land.

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iDAPT Research Plan

iDAPT is split into three broad areas of research that together allow us to study processes of terrestrialization from the perspective of the cryosphere.

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iDAPT Project Review and Outputs

iDAPT was a hugely successful project, answering all of its research questions, generating a ton of new papers, presentations and outreach materials, opening up the next set of questions for the research field, and setting up our two fantastic postdocs Dr Alex Bowles and Dr Jaz Millar in their future careers. Alex is now a fellow at Oxford University and Jaz has taken up a Lectureship position at Cardiff University.

Here’s a brief summary of iDAPTs conclusions

iDAPT was able to show how early land plants were related to one another and when they evolved, highlighting correspondence between this and the timing of Cryogenian snowball Earth events. This strongly suggested a key role of glaciations in land plant evolution. However, by integrating our glacier algal genome into this analysis, we demonstrated that glacier algal adaptations to ice evolved much later, so while glaciations were likely important in driving land plant evolution, this was probably not through direct adaptation to an icy lifestyle. Novel technology developed to study glacier algae across the cryosphere revealed many new aspects of their ecology, including how biofilm formation, transport within meltwater, and lower nutrient requirements are key adaptations that allow glacier algae to thrive within melting surface ice. We undertook some of the first direct measurements of their physiology under icy conditions and used these to understand their potential responses to future climate change, and their historic role throughout Earth’s history during previous mass glaciations. 

iDAPT Outputs

Heres a list of our major publications to-date – there are still many in the pipeline!

Lewis M, Broadwell ELM, Millar JL, Thomas ER, Sanchez-Baracaldo P, Williamson CJ (2025) Micromelt sampling of the glacier algal nutrient environment. FEMS Microbiology Ecology: fiaf098

Feng S, Williamson CJ, Cook JM, Onuma Y, Takeuchi N, Anesio AM, Benning LG, Tranter M (2025) A new dark ice albedo threshold and its applications. Environmental Research Letters 20 (8): 084066

Williamson CJ, Anesio AMB, Benning LG, Tranter M (2025) New method provides first evidence of fine-scale in situ heterogeneity in glacier algal photophysiology. European Journal of Phycology, 60(1): 35-42.

Bowles AMC, Williams TA, Donoghue PCJ, Campbell DA, Williamson CJ (2024) Metagenome-assembled genome of the glacier alga Ancylonema yields insights into the evolution of streptophyte life on ice and land. New Phytologist (Early View). https://doi.org/10.1111/nph.19860

Bowles AMC, Williamson CJ, Williams TA, Donoghue PCJ (2024). Cryogenian origins of multicellularity in Archaeplastida. Genome Biology and Evolution 16(2). https://doi.org/10.1093/gbe/evae026

Millar JL, Broadwell ELM, Lewis M, Tedstone AJ, Williamson CJ (2024). Alpine glacier algal bloom during a record melt year. Frontiers in Microbiology. 15:1356376.

Broadwell ELM, Pickford RE, Perkins RGR, Sgouridis F, Williamson CJ (2023) Adaptation versus plastic responses to temperature, light, and nitrate availability in cultured snow algal strains. FEMS Microbiology Ecology 99(9). https://doi.org/10.1093/femsec/fiad088

Bowles AMC, Williamson CJ, Williams TA, Lenton TL, Donoghue PCJ (2022) The origin and early evolution of plants. Trends in Plant Sciences.

Williamson CJ, Turpin-Jelfs T, Nicholes MJ, Yallop ML, Anesio AM, Tranter M (2021) Macro-nutrient stoichiometry of glacier algae from the southwestern margin of the Greenland Ice Sheet. Frontiers in Plant Science 12: 911

Heres a list of our major conference contributions to-date:

1. A Bowles, T Williams, P Donoghue, C Williamson (Jan. 2022, Oral Presentation) Can adaptations of ice-inhabiting Streptophyte algae illuminate the processes of plant terrestrialization? The British Phycological Society Annual Meeting, Online.  

2. JL Millar, D Campbell, Z Benedikty, C Williamson (Jan. 2022, Poster Presentation) Proposed novel instrumentation for the in-situ measurement of glacier algal physiology within ice. The British Phycological Society Annual Meeting, Online. 

3. JL Millar, D Campbell, Z Benedikty, C Williamson (Apr. 2022, Poster Presentation) Novel instrumentation for the in-situ measurement of glacier algal physiology within ice. UK Arctic Science Conference, Durham, UK. 

4. Williamson CJ, JL Millar, D Campbell, Z Benedikty (May 2022, Oral Presentation) Sensing the bio-cryosphere. Workshop on Signalling Transduction in Microbial Communities, Coimbra, Portugal. 

5. A Bowles, T Williams, P Donoghue, C Williamson (Jul. 2022, Poster Presentation) The phylogeny and timescale of early plant evolution. New Phytologist Next Generation Scientists 2022, Tartu, Estonia. 

6. JL Millar, D Campbell, Z Benedikty, C Williamson (Oct. 2022, Oral Presentation) Novel instrumentation for the in-situ measurement of glacier algal physiology within ice. Polar and Alpine Microbiology Conference, Potsdam, Germany. 

7. A Bowles, T Williams, P Donoghue, C Williamson (Oct. 2022, Oral Presentation) Cryogenian origins of multicellularity in algae. Polar and Alpine Microbiology Conference, Potsdam, Germany. 

8. JL Millar, E Bagshaw, A Jungblut, A Edwards, E Poniecka, D Campbell, Z Benedikty, C Williamson (Nov. 2022, Oral Presentation) Finding Snowball Earth. The EGO Virgo Diversity Group, UCLouvain, Belgium.  

9. Williamson C, Millar J, Campbell D, Benediktyova Z (Mar 2023, Invited Speaker) Sensing the bio-cryosphere: challenges and approaches to constraining life in ice Keck Institute of Space Science Workshop “Targeting Microhabitats for Life Detection”, Californian Institute of Technology, California, USA.  

10. A Bowles, T Williams, P Donoghue, C Williamson (Aug. 2023, Oral Presentation) Algal metagenomics provides insight into land plant terrestrialization European Phycological Congress 8, Brest, France.  

11. Williamson C, Bowles A, Millar J, Broadwell E, Lewis M, Donoghue P, Williamson T, Campbell D (Aug. 2023, Keynote Presentation) Biosphere – cryosphere interactions during periods of rapid environmental change European Phycological Congress 8, Brest, France.  

12. Millar JM, Broadwell E, Lewis M, Bowles A, Tedstone A, Williamson C (Jan 2024, Keynote Presentation) Glacier algal bloom during a record melt year British Phycological Society Winter Meeting, Reading, UK.  

13. Millar JM, Broadwell E, Lewis M, Bowles A, Tedstone A, Williamson C (Nov 2024, Oral Presentation) The spatial organisation of glacier algal biofilms The 5^th Snow Algal Meeting, Bodo, Norway. 

Heres a more detailed summary of the major iDAPT conclusions ordered per working package of the research grant:

Work Package 1 major conclusions and achievements: 

The genomics work undertaken for Work Package 1 was particularly successful and in our opinion pushed beyond our expectations for this part of iDAPT. Through our initial review of existing literature, genomes and fossil record resources we showed how no single unified view of the processes and timing of early plant evolution existed to-date, despite myriad fossil and geochemical evidence. Through this we highlighted how phylogenetically targeted genomic, morphological and Earth System data would be necessary to make significant advances in our understanding of early plant evolution, setting up our subsequent advances. By establishing a robust, time-calibrated, phylogenetic framework that covered the entirety of Archaeplastida, we were able to resolve deep archaeplastid relationships, identifying two clades of Viridiplantae and placing Bryopsidales as sister to the Chlorophyceae. Our molecular clock analysis inferred an origin of Archaeplastida in the late-Paleoproterozoic to early-Mesoproterozoic (1712 – 1387 Mya), with ancestral state reconstruction revealing how many of the independent origins of multicellularity across our phylogeny span the Cryogenian, supporting the Cryogenian multicellularity hypothesis. Our timing estimates for the origin of crown-Anydrophyta (796 to 671 Mya) supported the Cryogenian plant terrestrialization hypothesis, overall concluding an important role of Snowball Earth in land plant evolution. This work provided critical tools (extensive time-calibrated phylogeny) and novel insights to several disciplines concerned with the origin and timing of evolution across the entirety of Archaeplastida, processes of land plant terrestrialization, snowball Earth and its interactions with the Earth System.   

Sequencing, assembly and interrogation of our Ancylonema glacier algal genome within our established framework served to answer a major iDAPT research question on the role of ice for land plant terrestrialization, providing highly significant contributions to the fields of polar microbiology, land plant evolution, and snowball Earth science. Specifically, this work provided the first ever genome-scale dataset for a supraglacial Streptophyte algae, a resource of great interest to both the polar microbiology and land plant terrestrialization research communities. It gave novel insight into how glacier algae are adapted to icy conditions through lineage-specific diversification of existing genetic pathways, showing for the first time a key genomic mechanism underlying glacier alga’s ability to thrive in surface ice conditions (unique expansion of the DHQD/SD purpurogallin synthesis pathway). Time-scale analysis demonstrated that glacier algae split from their closest ancestors approximately 455-520 million years ago during the early Phanerozoic, whereas Anydrophyta, the algal ancestor of all land plants, emerged during the Cryogenian period. This led us to reject the hypothesis that adaptation to ice in extant glacier algae resulted from exaptations derived from ancestral Streptophytes. Instead, we demonstrated the large-scale genome reduction that occurred in Zygnematophyceae and the role of genome streamlining in the emergence of unicellular and filamentous algae from a multicellular ancestor. In contrast, we showed that the origin of Anydrophyta was accompanied by a peak in gene novelty allowing to establish in terrestrial environments. Our dating of Anydrophyta evolution to the Cryogenian lends support to the hypothesis that glaciations were a driver of land plant diversification, but we showed here that this was not through direct adaptation to an icy lifestyle. 

Work Package 2 major conclusions and achievements: 

The major achievement of Work Package 2 is the production of new technologies optimised for the study of microbial life in supraglacial environments. Prior to iDAPT, we were unable to directly measure the physiology of glacier algae within their natural habitat, instead relying on sampling, melting and subsequently studying their physiology – a process that removes the algae from their icy home and significantly changes the physiology measured. By optimising fluorescence techniques and twinning these with direct microscopy, new sensor capabilities, and new downstream data analysis pipelines, iDAPT was able to tackle this challenge and undertake (in Work Package 3) highly novel in-situ monitoring of glacier algae, yielding numerous new insights into how life can thrive in this extreme environment. Outputs in the form of publications detailing our new methodologies and data analysis pipelines have made significant contributions to the wider polar microbiology community.  

Work Package 3 major conclusions and achievements: 

iDAPT field expeditions across the cryosphere served to significantly expand our understanding of how microalgal life can thrive in icy conditions and what this means for its future under climate change and back throughout Earth’s geological history. In the first instance, successful completion of several highly specialised field campaigns across remote polar and alpine environments was a key achievement of Work Package 3, reflected in the large number of published contributions and publications currently in preparation.

Overall, Work Package 3 served to highlight several new aspects of glacier algal ecology within surface ice and uncover several unknowns. We have shown how at the micro-scale, glacier algal biofilm formation and lateral cell transport are important factors regulating bloom development during summer melt seasons. Though the cryosphere is currently experiencing unprecedented melt, glacier algal growth does not scale linearly with meltwater availability on steep valley glaciers. Instead, we identified a threshold whereby meltwater shifts from being a promotor of glacier algal growth to a regulator of overall carrying capacity via lateral export of cells from the system.

Our frequent observation of abundant glacier algal growth within highly oligotrophic surface ice led us to define and further explore the ‘oligotrophic-bloom-paradox’, with subsequent micro-melt characterisation highlighting how glacier algae experience a more heterogenous nutrient environment in their thin melt-water film habitat that can be significantly impacted by local aeolian deposition. Measurement of glacier algal cellular stoichiometry across myriad settings twinned with nutrient-spiking incubations further evidenced how glacier algae ultimately require lower cellular quotients of scare macronutrients (N and P), a likely key adaptation to life in low nutrient surface ice. As more of the cryosphere is unlocked into the future by climate change this suggests that an expansion in blooms should be anticipated.

Looking backwards, it highlights that we would expect to find glacier algal blooms proliferating on melting glacier ice across the cryosphere during previous mass glaciations – information key to reconstructing the cryo-biosphere throughout Earth’s geological history. Development and implementation of new ways to monitor glacier algal in-situ physiology further demonstrated, however, that fine-scale differences in abiotic stressors across glacier surfaces do translate into notable physiological responses, showing that we are only just beginning to understand how glacier algae regulate their physiology relative to the myriad stressors apparent on glaciers. Finally, fine-scale abundance observations and modelling provided the first ever insight into the spatial heterogeneity apparent across glacier algal blooms at the landscape scale. The ongoing comparison of this dataset with meteorological, topographical and geochemical datasets generated in parallel is likely to yield significant new insight into the major controls on glacier algal growth within surface ice and bloom proliferation and impacts.