Elise Biersma - Assistant Professor - Blog

Graduation Elise Ida Blum Samuelsen

Thu, 28 Jan 2021 00:00:00 GMT

Brighamia insignis growing at Limahuli Garden and Preserve, Kauaʻi. (Wiki commons)

Elise Ida Blum Samuelsen has finished her Bachelor of Science (BSc) in Biology at the Department of Biological and Environmental Sciences, Copenhagen University (KU), with lead supervisor Chris J. Barnes (GLOBE, KU).

Elise investigated the potential pathogens (bacteria and fungi and possible stem-boring insects as vectors) which are currently causing a disease threatening the critically endangered Hawaiian endemic plant Brighamia insignis. Using genetic markers she found some potential pathogens, so this is a valuable first step towards conservation efforts of this rare and special Hawaiian plant. She received the highest possible mark. Congratulations, Elise!

Thanks to collaborators Nina Rønsted and Seana Walsh and the National Tropical Botanical Garden in Hawaii.

Poem based on recent paper on how global wind systems have transported moss along Earth's latitudes!

Fri, 13 Nov 2020 15:33:31 GMT

It's not every day you find an email in your inbox with a poem based on your research!

I was honoured that my latest paper on the biogeography of Ceratodon purpureus and its spread across the globe inspired Sam Illingworth from thepoetryofscience.scienceblog.com to make this great poem :)

A Rolling Wind Gathers the Moss
November 13, 2020 by Sam Illingworth

Spread out like a living
blanket of dewy jade,
the fire moss basks
in its ubiquity.
Verdant carpets that
stretch out
across the forest,
over the pavement,
and up,
up,
on to the rooftops
of our fabricated
treetop homes.

Strips of mottled green
that lie in rootless
ordered bands,
carried across oceans
on unseen hands –
their delicate touch
brushing off
the hidden geographies
of this
turbulent dispersal.

Thank you, Sam Illingworth!

The poem will also feature in the next episode of his podcast, to be released on 16/11/2020.

For more information on the paper:
Biersma, E.M., Convey, P., Wyber, R., Robinson, S.A., Dowton, M., Van De Vijver, B., Linse, K., Griffiths H. & Jackson, J.A. (2020) Latitudinal biogeographic structuring in the globally distributed moss Ceratodon purpureus. Front. Plant Sci. 11:502359. https://doi.org/10.3389/fpls.2020.502359

Digitisation of the Greenlandic Sphagnum peat mosses

Mon, 02 Nov 2020 00:00:00 GMT

This year we were awarded a SYNTHESYS Virtual Access grant to digitise the labels of about 4450 Greenlandic Sphagnum moss collections (~26 species) at the herbaria at Copenhagen (C, c. 4200 specimens), Vienna (W, c. 150), Meise (BR, c. 50) and Leiden (L, c. 50). This effort would lead to a more than 3.5 times global increase in digitised Greenlandic Sphagnum specimens.

Why digitise Greenlandic Sphagnum collections?

Due to its large gradients in latitude, temperature and humidity, and fast-changing environments, Greenland is a key Arctic region to study ongoing changes in polar regions. Sphagnum peat mosses play a key role in polar tundra and wetland ecosystems in terms of biomass, carbon sequestration and nitrogen fixation. The peat-forming Sphagnum wetlands are of global importance as the largest carbon sinks on land. However, most studies investigating changes in the Arctic flora focus on Greenland’s vascular flora, despite the importance of bryophytes, and in particular the peat mosses, in the Arctic ecosystem.

Laws Prize

Fri, 16 Oct 2020 00:00:00 GMT

This autumn I was honoured to be awarded the Laws Prize for Early Career Scientists (within 10 years after the PhD) at the British Antarctic Survey.

Due to the Covid-19 situation the Laws Prize Winner's Lecture 2020 was held virtually on the 16th of October for BAS and several botanical societies in the UK about the biogeography of the Antarctic flora.

Erasmus project on the biogeography of Greenland’s national plant, the Dwarf Fireweed Chamerion latifolium

Tue, 01 Sep 2020 00:00:00 GMT

This autumn Erasmus student Minke Oostermeijer has begun a project to study the biogeography of Chamerion latifolium (Onagraceae). This plant inhabits many Artic and sub-Arctic regions including North America and central and northeastern Eurasia. Because if its widespread distribution in Greenland and ability to tolerate harsh environments, the evolutionary history of this species in Greenland is of particular interest.

Using population genetic methods we will i) assess the origin of the populations of C. latifolium in Greenland, ii) estimate the age of the species in Greenland, and iii) assess past and ongoing genetic connectivity of C. latifolium within Greenland and outside Greenland.

The outcomes will increase the understanding of the origin, dispersal routes and mechanisms of C. latifolium in context of the glacial history of Greenland.

"Cosmopolitan" moss traveling the world on wind currents

Fri, 28 Aug 2020 09:21:09 GMT

Remarkable overlap of global wind patterns and biogeographic structure

Ceratodon purpureus is one of the most widespread plants in the world. It can be found almost everywhere - on roofs, pavements, on a remote valley in Antarctica... In a recent study we investigated how and when this species managed to spread to almost every corner of the Earth, and to assess the level of connectivity between its globally widespread populations.

Applying phylogenetic, population genetic, and molecular dating analyses to a global sampling data set, we found several distinct and geographically structured populations within the chloroplast DNA of Ceratodon purpureus. In particular the most widespread of these lineages, in the Northern Hemisphere, the Southern Hemisphere and in the tropics were remarkably structured in worldwide, latitudinal "bands" (see red, blue and green specimens on the world map in the left figure above).

The biogeographic patterns of these most widespread populations imply that connectivity is strongly influenced by global atmospheric circulation patterns (see right figure above), with dispersal and establishment beyond these latitudinal bands less common. Biogeographic patterns were less clear within the nuclear DNA, with gene duplication likely hindering the detection of these.

Ceratodon purpureus. Illustration by Christiaan Sepp (Kops et al., 1868; Wikimedia Commons)

Old Lineages in Distinct Biogeographic Regions

We applied molecular dating analyses to assess the age of the populations. These indicated that the current population structure within the chloroplast DNA of C. purpureus has developed over the past six million years, with lineages diverging during the late Miocene, Pliocene, and Quaternary.

This surprising finding implies that the global distribution of a weedy, cosmopolitan species such as C. purpureus is mainly the result of a worldwide spread achieved by dispersal and establishment over hundreds of thousands to million-year timescales rather than high-frequency long-distance dispersal events, as would be expected for a highly ruderal species.

Drivers of Dispersal and Establishment

As C. purpureus s.l. is a weedy species, characteristically found in a wide range of dry and disturbed habitats, an increase in environmental (e.g. glacial, fire-influenced and, more recently, anthropogenic) disturbances could have aided its spread across the globe.

The main distribution of C. purpureus, occupying the vast areas of the temperate regions (particularly clades V-VII), became established throughout the late Pliocene and Quaternary (see time-calibrated phylogeny on the right). This was a period of high disturbance globally, including global cooling and repeated glacial periods (see global surface temperature estimated from Hansen et al., 2013 in the same figure). It is likely that repeated glacial disturbance provided favorable conditions for the spread and population expansion of C. purpureus in high latitude areas of both hemispheres.

Time-calibrated phylogeny of Ceratodon purpureus, based on a concatenated cpDNA data (for more information see Fig. 5 in main study). Global surface temperature estimates (blue and solid line representing temperature variations and a 500 kyr smoothed resolution, respectively), reproduced from Hansen et al. 2013, are provided below.

Repeated glacial disturbance, such as occurred in the Antarctic pictured above, has likely been favourable for the spread of the ruderal moss species Ceratodon purpureus.

Additionally, the rise of modern flammable grass-, shrub- and woodlands (late Miocene onwards with peak origins in late Pliocene; Bond, 2015) could have promoted the spread of C. purpureus, as the species is also frequently found in fire-influenced habitats (it is even called “Fire Moss” as a common name in English). Furthermore, in the recent post-quaternary period, the origin and expansion of urban environments provided major sources of anthropogenically influenced disturbance potentially favorable to C. purpureus.

Multiple Antarctic Colonizations, Including an Ancient Lineage

We found at least three dispersal events to the Antarctic (see clades I, V and VI above). This reveals that Antarctica is not as isolated as is often assumed for spore-dispersed organisms (e.g. also seen in the Antarctic moss Chorisodontium aciphyllum; Biersma et al., 2018a).

However, the analyses also revealed one old Antarctic clade (I), possibly isolated on the continent since the late Miocene or early Pliocene. Although more extensive sampling may be required to fully assess whether clade I is limited to Antarctica, its apparent ancient isolation suggests it may be a remnant lineage that has survived past glaciations in the maritime Antarctic in situ.

Molecular, phylogenetic and biogeographic studies also suggest in situ survival for many groups of terrestrial fauna in Antarctica throughout the Quaternary, Neogene and even Paleogene (see Convey et al., 2008, 2009, 2020, and references therein). Recently, increased evidence has also been found of million-year persistence of the Antarctic flora, e.g. several endemic species of Schistidium (Biersma et al., 2018b), and Bryum argenteum (Pisa et al., 2014). Here, our data indicate that at least one lineage (I) of C. purpureus may also have had a long-term Antarctic presence in situ.

Relevance for other organisms and evolutionary studies

Our general findings may also be relevant to understanding global environmental influences on the biogeography of other organisms with microscopic propagules (e.g., spores) dispersed by wind. The findings may also be of relevance to further evolutionary studies on bryophytes, as C. purpureus is commonly used as a model organism in genetic, physiological, and developmental studies, in particular for studying the evolution of developmental processes in bryophytes (e.g. McDaniel et al., 2007, and references therein; Szövényi et al., 2014). For this type of developmental research, good baseline knowledge on the evolutionary history and global biogeography of a species is fundamental, for instance, for underpinning interpretation of crossing experiments, trait mapping and marker discovery, and controlling for demographic or population effects. The matrilineal biogeographic structure identified here therefore provides a useful framework for future genetic and developmental studies on bryophytes.

For more information see:
Biersma, E.M., Convey, P., Wyber, R., Robinson, S.A., Dowton, M., Van De Vijver, B., Linse, K., Griffiths H. & Jackson, J.A. (2020) Latitudinal biogeographic structuring in the globally distributed moss Ceratodon purpureus. Front. Plant Sci. 11:502359. https://doi.org/10.3389/fpls.2020.502359

References:
Biersma, E. M., Jackson, J. A., Bracegirdle, T. J., Griffiths, H., Linse, K., Convey, P. (2018a). Low genetic variation between South American and Antarctic populations of the bank−forming moss Chorisodontium aciphyllum (Dicranaceae). Polar. Biol. 41, 599–610. doi: 10.1007/s00300-017-2221-1
Biersma, E. M., Jackson, J. A., Stech, M., Griffiths, H., Linse, K., Convey, P. (2018b). Molecular data suggest long-term in situ Antarctic persistence within Antarctica’s most speciose plant genus, Schistidium. Front. Ecol. Evol. 6:77. doi: 10.3389/fevo.2018.00077
Bond, W. J. (2015). Fires in the Cenozoic: a late flowering of flammable ecosystems. Front. Plant Sci. 5:749. doi: 10.3389/fpls.2014.00749
Convey, P., Gibson, J. A., Hillenbrand, C. D., Hodgson, D. A., Pugh, P. J., Smellie, J. L., et al. (2008). Antarctic terrestrial life - challenging the history of the frozen continent? Biol. Rev. Camb. Philos. Soc 83, 103–117. doi: 10.1111/j.1469-185X.2008.00034.x
Convey, P., Bindschadler, R., Di Prisco, G., Fahrbach, E., Gutt, J., Hodgson, D. A., et al. (2009). Antarctic climate change and the environment. Antarct. Sci. 21, 541–563. doi: 10.1017/S0954102009990642
Convey, P., Biersma, E. M., Casanova-Katny, A., Maturana, C. S. (2020). “Refuges of Antarctic diversity,” in Past Antarctica. Eds. Oliva, M., Ruiz-Fernández, J. (Cambridge, MA: Academic Press), 181–200. doi: 10.1016/B978-0-12-817925-3.00010-0
Hansen, J., Sato, M., Russell, G., Kharecha, P. (2013). Climate sensitivity, sea level and atmospheric CO2. Philos. Trans. R. Soc A. 371, 20120294. doi: 10.1098/rsta.2012.0294
Kops, J., Hartsen, F. A., van Eeden, F. W. (1868). Flora Batava, of Afbeeldingen en Beschrijving van Nederlandsche gewassen. XIII Deel 13(Amsterdam, the Netherlands: J. C. Sepp en Zoon).
McDaniel, S. F., Willis, J. H., Shaw, A. J. (2007). A linkage map reveals a complex basis for segregation distortion in an interpopulation cross in the moss Ceratodon purpureus. Genetics 176, 2489–2500. doi: 10.1534/genetics.107.075424
Pisa, S., Biersma, E. M., Convey, P., Patiño, J., Vanderpoorten, A., Werner, O., et al. (2014). The cosmopolitan moss Bryum argenteumin Antarctica: recent colonisation or in situ survival? Polar. Biol. 37, 1469–1477. doi: 10.1007/s00300-014-1537-3
Szövényi, P., Perroud, P. F., Symeonidi, A., Stevenson, S., Quatrano, R. S., Rensing, S. A., et al. (2014). De novo assembly and comparative analysis of the Ceratodon purpureus transcriptome. Mol. Ecol. Resour. 15, 203–215. doi: 10.1111/1755-0998.12284

Citizen science amongst tourists and penguins in the Antarctic

Wed, 01 Jul 2020 11:59:50 GMT

This month's issue in Aktuel Naturvidenskab features a four-page article (in danish) on last January's trip to the Antarctic Peninsula, where we did a citizen science project with tourists (read more in a previous blog post).
During this project, we measured soil-gas fluxes at guano-enriched areas along the Antarctic Peninsula at several different penguin colonies.

Download the article here:

an3-2020-pingviner.pdf
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Refuges of Antarctic diversity

Thu, 11 Jun 2020 09:54:32 GMT

Published this month we present a chapter on glacial refuges of Antarctic terrestrial biodiversity in the book "Past Antarctica: Paleoclimatology and Climate Change".

Biological research over the last decades has revealed that many of Antarctica's terrestrial biota are endemic to the continent, with nearly every group (invertebrates, microbes, plants) including species which show signals of Antarctic survival on multi-million-year timescales. Some species even show evidence that their Antarctic presence pre-dates the final breakup of Gondwana and the geographic isolation of Antarctica.

For terrestrial life to have existed continuously on the continent over these timescales, appropriate ice-free land must have existed through the multiple glacial cycles that took place throughout the Miocene, Pliocene and Pleistocene eras. In the new chapter, we discuss the evolutionary history of terrestrial life in Antarctica, evidence from glacial reconstructions, as well as the requirement for refugia across all biogeographical regions of Antarctica. We also discuss the likely form that such refugia may have taken, from nunataks, geothermal areas, glacier surfaces, subglacial habitats and cryptobiosis.

For more information see:
Convey, P., Biersma, E.M., Casanova-Katny, A., Maturana, C.S. (2020) Chapter 13: Refuges of Antarctic Biodiversity. In: "Past Antarctica" (ed. J.R. Fernandez). https://doi.org/10.1016/B978-0-12-817925-3.00010-0

https://www.researchgate.net/publication/341958687_Refuges_of_Antarctic_diversity

The evolution of globally occurring microorganisms is highly driven by dispersal and speciation in isolation

Wed, 13 May 2020 09:29:05 GMT

Many microorganism species can be found all across the globe. Their seemingly global distributions have long caused a debate whether microorganisms can disperse very easily and geographic barriers have any effect on them, or whether it has taken them a long time to get everywhere.
Trying to answer that question, a new large-scale genetic study in Nature Communications revealed how a single-celled alga has spread across the globe and in its journey radiated into an unprecedented species diversity since the Eocene/Oligocene global cooling period. In contrast to previous beliefs, it hereby shows that the evolution of microorganisms is highly driven by colonisation to suitable habitats and subsequent speciation in isolation. Although this has long been recognised as a driving force for speciation in larger organisms, it is now also shown to be an important force for speciation in microbial species.

Microbial biogeography: putting the distribution of a global microbe on the map

Many microbial species, i.e. protists, bacteria, archaea and fungi, often have very similar appearances in various corners of the globe. It is therefore generally thought that they lack the biogeographic structure and the clear speciation patterns found in larger organisms. Instead, their supposedly high dispersal rates and large population sizes have long led to the assumption that many microorganisms have global geographic distributions.
To investigate this, Pinseel et al. (2020) studied the evolutionary history of a globally occurring terrestrial diatom species, Pinnularia borealis - a small type of single-celled algae living in terrestrial habitats such as soils and mosses. Sampling >1500 environmental samples across the globe containing >800 strains, the study looked into morphological and genetic analyses to study the species’ evolutionary history, and the timescale on which this small diatom managed to cover most of the planet’s far-flung corners of the globe.

Similar appearance, yet many species

The global dataset revealed an unexpected high level of genetic species-diversity: while the strains were very similar in morphological appearance, surprisingly, >120 genetically differentiated species could be found. This suggests that, What has previously been thought of as a globally occurring species, in fact is a so-called “species complex”, i.e. a group of closely related organisms that are similar in appearance, however composed of genetically distinguishable species.

Geographic isolation shaping diversity patterns

The study found that diversification was largely driven by dispersal of new geographic areas, and subsequent evolution in the resulting isolated populations. This might not be so surprising, as we have long known this mechanism to be an important driver for evolution in larger organisms (e.g. in the famous example of Darwin’s finches), yet it is contrasting to the long-held view of ‘global’ geographic distributions of many microscopic species.

Automated species delimitation methods showed a large diversity of species in what was thought to be just one species.

The analyses, however, also suggested that, despite P. borealis being a small, microscopic algae, has been quite good at dispersing. For example, the analyses revealed that all continents had been colonised multiple independent times. In particular, it was surprising that the sub-Antarctic and Antarctic, though highly isolated places, were colonised at least eight independent times, and in several cases through long-distance dispersal from the Northern Hemisphere.

Timing of species diversification and the transition to open terrestrial habitats

Luckily, diatoms have a very good fossil record, and species diversity can be quite accurately calculated over time. Using fossil evidence and genetic dating techniques the radiation of the diatom across the globe was found to have originated since the Eocene/Oligocene boundary (25.0–36.1 million years ago). This period was characterised by a profound change in climate, as the Earth shifted from a greenhouse to an icehouse state, and known as a time of large-scale extinction and floral and faunal turnover. The period, associated with colder and drier climates, also marks the onset of a global expansion of open terrestrial landscapes, in which P. borealis currently thrives.

Time-calibrated species tree of the P. borealis complex. Coloured bars next to the phylogeny indicate the biogeographic region(s) of each species: dark blue: Arctic zone; light blue: boreal zone; purple North America (excl. Arctic); grey: Madagascar; pink: South America; orange: Australasia; yellow: sub-Antarctic; dark red: Antarctic. In the middle-left: species accumulation curve showing the sample-based interpolation (rarefaction) and extrapolation of the P. borealis species delimited in this study. Below: raw (blue) and smoothed (black) oxygen-isotope data reflecting changes in global temperature and continental ice-sheet volume, overlaid with a "lineage-through-time plot" (semi-logarithmic scale) of the P. borealis complex.

How many times would one need to sample to get all extant diversity?

Indeed, despite that over 1500 samples were obtained, the large global sampling effort was still not nearly enough to capture al the diversity within P. borealis. Extrapolation analyses, investigating how the number of species increases with the number of added samples, suggested that that nearly ten thousand environmental samples would need to be gathered all across the globe to find the majority of lineages of just this species complex alone. This means that, at that point one will likely have found most of the global diversity that exists within P. borealis, which was estimated to equal about 415 species. This species diversity far exceeded previous estimates for a diatom lineage of this age (since the Eocene/Oligocene boundary). The high diversity within this species complex alone reflects the likely hidden diversity of other groups of the ‘rare biosphere’.

Implications for general understanding of drivers shaping microbial biogeography

All in all, the new study reveals how ‘rare biosphere’ taxa, which are key players in the global carbon and nutrient cycles, are composed of astonishingly high levels of diversity across the globe. It reveals, contrary to long-held views, how dispersal and subsequent evolution in isolation plays a large role in the evolution of small micro-organisms. The evolutionary history of this one, seemingly insignificant, microscopic algae, illuminates the hidden diversity within the world of small microscopic life, which we still know so little about.

For more information see:
Pinseel, E., Janssens, S.B., Verleyen, E., Vanormelingen, P., Kohler, T.J., Biersma, E.M., Sabbe, K., Van de Vijver, B. & Vyverman, W. (2020) Global radiation in a rare biosphere soil diatom. Nature Communications 11, 2382. https://doi.org/10.1038/s41467-020-16181-0

Multiple late-Pleistocene dispersal events of the Antarctic pearlwort Colobanthus quitensis (Caryophyllaceae) reveal a recent arrival of native Antarctic vascular flora

Mon, 20 Apr 2020 10:52:15 GMT

Antarctica's isolated and extreme terrestrial environments are inhabited by only two species of native vascular flora: the Antarctic pearlwort Colobanthus quitensis (Caryophyllaceae) and the Antarctic hair grass Deschampsia antarctica (Poaceae). While many other groups of terrestrial biota (e.g. mites, springtails, mosses) include species with a long-term (million-year) survival and high endemism in Antarctica, the age and origin of both vascular plants was until now not yet thoroughly studied.

A new paper in Journal of Biogeography on the Antarctic pearlwort C. quitensis (shown in Fig. 1), completing previous biogeographic assessments of the Antarctic hair grass, shows that the vascular flora of Antarctica is of likely late-Pleistocene origin. The vascular flora is hereby the first identified group of terrestrial organisms to be completely of recent arrival, with a likely origin after major glacial periods in Antartica.

Fig. 2. (a) Map with sampling locations of Colobanthus quitensis. Biogeographical regions are indicated with different colours. (b) Global distribution of C. quitensis

Multiple, recent colonisations of Colobanthus quitensis to Antarctica

Using population genetics and molecular dating analyses we investigated the genetic connectivity amongst its populations from South America, sub-Antarctic islands and Antarctic populations (see Fig. 2), to determine its origin and age in Antarctica. Surprisingly, the analyses revealed two different populations of C. quitensis in Antarctica: one including northern Maritime Antarctic, South Shetland Islands and South Georgia, and the other including the southern Antarctic Peninsula and South Georgia (see haplotype network in Fig. 3 and the map in Fig. 3d). The two Antarctic populations likely derived from two independent dispersal events to the Antarctic.

Molecular dating analyses to date when the dispersal events across the Drake Passage occurred were difficult due to a lack of genetic variation at the population level (which, by itself is informative of a likely recent connection). However, the analyses revealed that the species C. quitensis itself is a relatively young species (<1 Ma). The shared haplotypes and genotypes with specimens from South Georgia (Fig. 3), as well as the genetic similarity to specimens from South American regions (separated by only one mutational step, Fig. 3) suggest that C. quitensis reached the Antarctic on a relatively recent, late-Pleistocene timescale.

The overall findings of multiple colonisation events by a vascular plant species to Antarctica, and the recent timing of these events, are of also significance with respect to future colonisations of the Antarctic by vascular plants, particularly with predicted increases in ice-free land in the Antarctic Peninsula. The results also suggest the Antarctic is less isolated for this species than previously thought.

Fig. 3. Genotype and haplotype networks of Colobanthus quitensis based on nuclear (a) and chloroplast (b, e, f) markers, and nuclear and chloroplast regions combined (c). Map (d) showing sample locations of the two Maritime Antarctic haplotype groups identified in (c) (indicated in with dashed ellipses). Colours of different biogeographic regions are shown in the key.

Late-Pleistocene origin of vascular flora - a contrasting pattern to many other terrestrial biota

During the Last Glacial Maximum, as well as during previous glaciation periods, almost the entire continent of Antarctica is thought to have been covered by ice. The general assumption has therefore long been that basically no terrestrial life could have persisted in Antarctica throughout this time, and all life must be of recent (post-glacial) origin.
Recent biological research has challenged this view, revealing many examples of species with long-term pre-glacial persistence, suggesting that life must have persisted throughout previous glaciation periods in the Antarctic. Evidence can be found in almost every group of terrestrial organisms (e.g. nematode worms, diatoms, springtails, insects, mosses etc), with timespans of isolation in Antarctica ranging from hundreds of thousands to millions of years. Some groups even show ages of isolation since the break-up of ‘Gondwana’, where Antarctica broke off from the other Southern Hemisphere continents.

Antarctica only continent with a recent (thousand year-scale) vascular flora

In the new study on the cushion plant Colobanthus quitensis we find that the Antarctic populations of the species likely derived from two independent, late-Pleistocene dispersal events. Adding to previous inferences on the other Antarctic vascular plant species (a grass called Deschampsia antarctica), we suggest that both vascular plant species are likely to have arrived on a recent (late-Pleistocene) timescale. Contrary to the other groups of terrestrial biota, the vascular flora stands out as the first identified terrestrial group that appears to be entirely of recent origin.

Fig. 4. The two native Antarctic vascular plants, Colobanthus quitensis and Deschampsia antarctica, growing on Lagotellerie Island, Antarctica

For more information see:
Biersma, E.M., Torres-Díaz, C., Molina-Montenegro, M.A., Newsham, K.K., Vidal, M.A., Collado G.A., Acuña-Rodríguez, I.S., Ballesteros, G., Figueroa, C.C., Goodall-Copestake, W.P., Leppe, M.A., Cuba-Díaz, M., Valladares, M.A., Pertierra, L.R. & Convey, P. (2020) Multiple post-glacial colonisation events of the Antarctic pearlwort Colobanthus quitensis (Caryophyllaceae) reveal the recent arrival of native Antarctic vascular flora. Journal of Biogeography

Fieldwork on soil-gas fluxes at different penguin colonies along the Antarctic Peninsula

Tue, 21 Jan 2020 13:20:50 GMT

Penguin colonies are extremely nutrient rich compared to the surroundings. Recent studies have shown that the high nitrogen availability in these areas result in very high nitrous oxide (N2O) emissions, high carbon dioxide (CO2) emissions, as well as a reduction in the methane (CH4) consumption capacity. In combination, penguin colonies represent natural hotspots for a net greenhouse gas emission.

Based on a previous paper on the effects of soil greenhouse gas fluxes on guano-influenced soil by King Penguins at St. Andrews Bay, South Georgia (see previous blog post), this January we aimed to repeat the same types of measurements on different penguin colonies along the Antarctic Peninsula, and measure their influence on soil formation, soil nutrient cycles and greenhouse gas emissions.

Bo Elberling taking gas samples at the Adelie penguin colony at Paulet Island

Different from previous fieldwork, this year Bo Elberling, his daughter and I joined a tourist ship (Albatros Expeditions). We took samples and measurements at each penguin colony, while giving guests hands-on experience on how scientific studies are conducted and how data are collected in the field (citizen science). It was a great success, and we got measurements done at all three common penguin colonies at the Antarctic Peninsula (Gentoo, Adelie and Chinstrap penguins). We also gave several presentations onboard the ship on topics related to climate change, marine and terrestrial biology, conservation and biogeography with a specific focus on the polar regions, which led to engaging discussions and interactions with the guests.

Bo Elberling and his daughter taking gas samples at the Gentoo penguin colony at Port Lockroy

The combined influence of glacial retreat and penguin guano on soil greenhouse gas fluxes in South Georgia

Fri, 15 Nov 2019 00:00:00 GMT

The transfer of nutrients from sea to land at marine bird colonies such as penguins has a major influence on regional soil processes. In many polar areas retreating glaciers open up new coastal ground for marine animals to colonise, yet, little is known about on the combined effect of glacial retreat and penguin-induced fertilisation on soil processes, succession and gas fluxes with the atmosphere.

A new paper revealed the combined effects of glacial retreat and fertilisation by King Penguins on soil greenhouse gas fluxes on the soil succession at St. Andrews Bay, South Georgia; the largest King Penguin colony in the world (~150,000 breeding pairs). The production and consumption of three greenhouse gasses (CO2, CH4 and N2O) were assessed based on laboratory incubations of soil cores, as well as incubation experiments with added nutrients and water.

We found that soils located at a greater distance from the retreating glacier front showed a successive development, with expanding vegetation cover and increasing soil nutrient content, coinciding with increased CO2 production and CH4 consumption rates. Towards sites with an increase in penguin activity and guano deposition, the CO2 production increased by 4–16-fold while the CH4 consumption decreased by about half. N2O production rates were not affected by exposure time since glacial retreat, but increased markedly (approximately 120-fold) at the site with the highest penguin activity. Along the transect, labile C and moisture were considered the key limiting factors for CO2 production, while moisture likely explain the limitation of CH4 consumption.

CO2, CH4 and N2O production/consumption rates based on incubated intact soil cores (n = 10). The transect (A-E) runs from the glacier front (A) to the penguin colony (E), with increasingly older soil and more penguin-affected soil at E. Different lower-case letters indicate significance between sites at p=0.05 using non-parametric Kruskal-Wallis multiple comparison tests. For more detail see paper.

Overall, we can conclude that recently deglaciated coastal areas with expanding penguin colonies are high greenhouse gas emission hotspots, with a particularly strong influence on N2O emissions. A future expansion of penguins into newly available ice-free polar coastal areas may therefore markedly increase the local greenhouse gas budget.

For more information see:
Wang P., D'Imperio L., Biersma E.M., Ranniku R., Xu W., Tian Q., Ambus P., Elberling B. (2019). Combined effects of glacial retreat and penguin activity on soil greenhouse gas fluxes on South Georgia, sub-Antarctica. Science of the Total Environment, 135255.

Back from Greenland and start of new fellowship in Copenhagen!

Tue, 03 Sep 2019 12:22:21 GMT

This last part of August was spent on fieldwork in the region of Kangerlussuaq (Søndre Strømfjord) in western Greenland to sample plants for my future postdoctoral project on finding out more on the evolutionary history of the Greenlandic flora.

The aim of this project is to study the routes and timings of floral colonisation into and within Greenland to place Arctic floral biogeography more firmly into the contexts of the northern landmasses and the glaciation history of Greenland itself. In addition, I hope to gain a better understanding of speciation processes of plants in polar regions (e.g. effects of past climate, bottlenecks, asexual reproduction, polyploidy and hybridisation). For this project I will use a combination of fresh and herbarium material, combined with population genetic and molecular dating methods.

The project will be based at the Natural History Museum of Denmark and the University of Copenhagen, and is funded by the Carlsberg Foundation.

The project will start part-time and in the meanwhile I will continue to work at the British Antarctic Survey as well.

New map of Greenland and the Arctic!

Thu, 13 Jun 2019 19:24:18 GMT

BAS cartographers have produced a new map of Greenland and the Arctic in the North Atlantic region. The map (1:4,000,000) is the most detailed paper map available of the entire region, with up-to-date detail of current ice margins and Greenlandic names.

On the back, it features a science information sheet where scientists at various UK universities and institutes, (e.g. BAS, the UK Met Office and WWF) have provided concise summaries highlighting current issues at play in the Arctic, ranging from human development to climate change, as well as a description of the fascinating wildlife present in these regions.

Find out more on the BAS website and the BBC - the latter with a nice interview of Laura Gerrish, the cartographer behind the map!

Thanks to the NERC Arctic Office and BAS for the opportunity to be involved in the science part of the map!

Fieldwork on invasive species in the sub-Antarctic, in Navarino Island, southern Chile

Fri, 21 Dec 2018 12:06:24 GMT

Small plastic plates to study the effects of shelter (e.g. by a large species of invasive vascular plant) on the native flora.

This December I joined Stef Bokhorst for a fieldwork trip in Navarino Island in the Cape Horn region in southern Chile, to study the effect of invasive species in the Antarctic and sub-Antarctic.

We set up several sets of long-term experiments on the mountain top near Puerto Williams, as this experimental side showed a lot of similarities with the type of fellfield habitat you can find in many parts of the Maritime Antarctic.

The experiments were designed to study the effect of new species on the growth of the native Antarctic flora, as well as disentangling possible elements which may be of importance to future establisment of invasive species, e.g. the effects of water-retention in the native species on the establishment of new species, or what species may enhance or inhibit each others presence.

It was a busy but productive trip, and great to be back in the beautiful Beagle Channel area! Many thanks to Stef for inviting me to be part of this fieldwork, and thanks to Tamara Contador, Roy Mackenzie and others from the Puerto Williams Biological Field Station for help with the work!