Nav: Home

Genome sequence of polar alga explains evolutionary adaptation to extreme variable climate

January 16, 2017

An international team of researchers has identified the genetic mutations which allowed microalgae (phytoplankton) from the Southern Ocean to adapt to extreme and highly variable climates -- a step towards understanding how polar organisms are impacted by climate change.

The team led by Prof Thomas Mock from the University of East Anglia (UEA) School of Environmental Sciences investigated the evolutionary genomics of the polar diatom Fragilariopsis cylindrus, which has evolved to thrive in the Southern Ocean but also occurs in the Arctic Ocean. Genome sequencing was carried out at the U.S. Department of Energy Joint Genome Institute (Walnut Creek, US) and the Earlham Institute (EI) (Norwich, UK).

How phytoplankton have evolved to cope with polar marine conditions of strong seasonality, sub-zero temperatures and extended periods of darkness was largely unknown. The genome sequence from Fragilariopsis cylindrus represents the first complete genome of a polar eukaryote -- a 'higher' organism with complex cells.

Fragilariopsis cylindrus is a key species especially in the Southern Ocean and thrives in sea ice, underpinning one of the most unique food webs on Earth feeding krill, penguins, seals and whales.

Most phytoplankton in the Southern Ocean face inclusion into sea ice every winter and are released again in summer when most of the sea ice melts. Species such as Fragilariopsis cylindrus have evolved adaptations to cope with these drastic environmental changes.

The researchers found that they do this by varying their alleles, which has not been shown in any marine organism before. Alleles are variant forms of a gene, which are located at the same position, or genetic locus, on a chromosome. Fragilariopsis cylindrus is a diploid organism because it has two alleles at each genetic locus.

Prof Mock said: "Our study identified that almost a quarter of the genome contained allelic variants. These alleles were differentially expressed across important environmental conditions, and we found evidence that those conditions were causing the allelic differentiation. As the effective population size of this polar diatom is huge, there is an allele for every occasion, which seems to make this organism extremely adaptable to changing environmental conditions."

The study, published today in the journal Nature, is a significant step in understanding how polar organisms have evolved to cope with their extremely variable environmental conditions and therefore their potential to adapt to environmental changes induced by human activity. Limited research is carried out into polar organisms because of the many challenges presented by working in polar regions and by working with these organisms in the laboratory and this work has taken more than nine years from the initial idea.

Scientists at EI used cutting edge genomics technology and bioinformatics expertise to carry out additional studies on the original genome assembly provided by the Joint Genome Institute (US). With funding from an Institute Development Grant1, Dr Mark McMullan, Dr Pirita Paajanen in the group of Dr Matt Clark (Technology Development) used the latest PacBio long-read sequencing and assembly software to generate a new genome assembly and assign the allelic variations to separate chromosomes.

Dr Paajanen said: "This is the first time at EI that a genome of this type was assembled into chromosomes. It is only very recently that the technology has been developed to cope with such a highly heterozygous organism and the data show that this diatom does actually have a large amount of variation within their genes. This result adds weight to the theory that this is an important to help the organism deal with the extreme environments in the ocean around the Antarctic continent. Using our assembly, we showed that the original genome assessment was correct, and were able to prove it, due to EI's strengths in advanced sequencing technology and high-performance computing."

Dr Clark, added: "This was a very interesting biological question that the latest technologies make much easier to address. Using long DNA sequencing and assembly methods to assemble both the allelic copies of a gene helped demonstrate the unusual genome biology necessary for this species to succeed in the Southern Ocean surrounding the Antarctic continent."

The work is also relevant to the biotechnology industry, which has an interest in extremophiles -- organisms which thrive in extreme conditions and are a potentially valuable source of industrially important enzymes.
-end-
Funding for this work came from the U.S. Department of Energy's Office of Science, Biological and Environmental Research Program, the Natural Environment Research Council (NERC), the Biotechnology and Biological Sciences Research Council (BBSRC), the Royal Society and the Earth & Life Systems Alliance (ELSA).

'Evolutionary genomics of the cold-adapted diatom Fragilariopsis cylindrus' is published in the journal Nature on 16 January 2017.

University of East Anglia

Related Climate Change Articles:

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.
Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.
Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.
Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.
A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.
Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).
Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.
Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.
Could climate change cause infertility?
A number of plant and animal species could find it increasingly difficult to reproduce if climate change worsens and global temperatures become more extreme -- a stark warning highlighted by new scientific research.
Predicting climate change
Thomas Crowther, ETH Zurich identifies long-disappeared forests available for restoration across the world.
More Climate Change News and Climate Change Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Climate Mindset
In the past few months, human beings have come together to fight a global threat. This hour, TED speakers explore how our response can be the catalyst to fight another global crisis: climate change. Guests include political strategist Tom Rivett-Carnac, diplomat Christiana Figueres, climate justice activist Xiye Bastida, and writer, illustrator, and artist Oliver Jeffers.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at Radiolab.org/donate.