Artificial cells demonstrate that 'life finds a way'

"Listen, if there's one thing the history of evolution has taught us is that life will not be contained. Life breaks free. It expands to new territories, and it crashes through barriers painfully, maybe even dangerously, but . . . life finds a way," said Ian Malcolm, Jeff Goldblum's character in Jurassic Park, the 1993 science fiction film about a park with living dinosaurs.

You won't find any Velociraptors lurking around evolutionary biologist Jay T. Lennon's lab; however, Lennon, a professor in the College of Arts and Sciences Department of Biology at Indiana University Bloomington, and his colleagues have found that life does indeed find a way. Lennon's research team has been studying a synthetically constructed minimal cell that has been stripped of all but its essential genes. The team found that the streamlined cell can evolve just as fast as a normal cell -- demonstrating the capacity for organisms to adapt, even with an unnatural genome that would seemingly provide little flexibility.

"It appears there's something about life that's really robust," says Lennon. "We can simplify it down to just the bare essentials, but that doesn't stop evolution from going to work."

For their study, Lennon's team used the synthetic organism, Mycoplasma mycoides JCVI-syn3B -- a minimized version of the bacterium M. mycoides commonly found in the guts of goats and similar animals. Over millennia, the parasitic bacterium has naturally lost many of its genes as it evolved to depend on its host for nutrition. Researchers at the J. Craig Venter Institute in California took this one step further. In 2016, they eliminated 45 percent of the 901 genes from the natural M. mycoides genome -- reducing it to the smallest set of genes required for autonomous cellular life. At 493 genes, the minimal genome of M. mycoides JCVI-syn3B is the smallest of any known free-living organism. In comparison, many animal and plant genomes contain more than 20,000 genes.

In principle, the simplest organism would have no functional redundancies and possess only the minimum number of genes essential for life. Any mutation in such an organism could lethally disrupt one or more cellular functions, placing constraints on evolution. Organisms with streamlined genomes have fewer targets upon which positive selection can act, thus limiting opportunities for adaptation.

Although M. mycoides JCVI-syn3B could grow and divide in laboratory conditions, Lennon and colleagues wanted to know how a minimal cell would respond to the forces of evolution over time, particularly given the limited raw materials upon which natural selection could operate as well as the uncharacterized input of new mutations.

"Every single gene in its genome is essential," says Lennon in reference to M. mycoides JCVI-syn3B. "One could hypothesize that there is no wiggle room for mutations, which could constrain its potential to evolve."

The researchers established that M. mycoides JCVI-syn3B, in fact, has an exceptionally high mutation rate. They then grew it in the lab where it was allowed to evolve freely for 300 days, equivalent to 2000 bacterial generations or about 40,000 years of human evolution.

The next step was to set up experiments to determine how the minimal cells that had evolved for 300 days performed in comparison to the original, non-minimal M. mycoides as well as to a strain of minimal cells that hadn't evolved for 300 days. In the comparison tests, the researchers put equal amounts of the strains being assessed together in a test tube. The strain better suited to its environment became the more common strain.

They found that the non-minimal version of the bacterium easily outcompeted the unevolved minimal version. The minimal bacterium that had evolved for 300 days, however, did much better, effectively recovering all of the fitness that it had lost due to genome streamlining. The researchers identified the genes that changed the most during evolution. Some of these genes were involved in constructing the surface of the cell, while the functions of several others remain unknown.

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Short-distance migration critical for climate change adaptation

Short-distance migration, which accounts for the vast majority of migratory movements in the world, is crucial for climate change adaptation, according to new research from the University of East Anglia (UEA).

Contrary to common assumptions, most migratory movements are people moving short distances, largely due to economic, social and environmental factors, such as climate change.

A study of people living in the drylands of India and parts of Africa was carried out by UEA researchers in the School of International Development.

The paper, 'Everyday mobility and changing livelihood trajectories: implications for vulnerability and adaptation in dryland regions', is published today in a special issue on Everyday Adaptations in the journal Ecology and Society.

The research was led by Dr Mark Tebboth, Associate Professor in the Environment and International Development.

Dr Tebboth said: "Most attention is on international migration and how climate change will lead to huge numbers of people fleeing across borders, but actually the vast majority of people move short distances within their own country in order to take advantage of opportunities or in response to shocks and stresses in their lives.

"Supporting and enabling this migration will help people to continue to adapt the pressures in their lives."

The research looked at drivers and outcomes of people's mobility in the drylands of India, Ghana, Kenya and Namibia. Interviews were conducted during 2016 and 2017 with people living in those regions.

Drylands are the largest global biome, covering about 45 per cent of the Earth's land surface and accommodating more than a third of the globe's population.

Drylands are characterized by low and highly variable water availability and high temperatures. These regions are experiencing multiple pressures, including increasing rates of aridity and soil degradation; poorly planned and implemented development interventions; rapid population growth; historically high rates of poverty; poor communication infrastructure; and isolation from national centres of power -- stressing livelihoods reliant on natural resources.

In India, the study sites were in North Karnataka's Kolar district, where diversification to non-farm labour and daily commuting to Bangalore is common, and the Gulburga district, where agricultural livelihoods dominate and there has been historical outmigration to large cities.

In Kenya, the study sites were in Isiolo, the 'gateway to the north', where pastoralism, farming and tourism are common. Water is a scarce resource and this looks like it will become more severe in the future.

The study also included locations in the Upper West region of Ghana and the Omusati region of north-central Namibia.

Dr Tebboth said: "Far from being exceptional, this everyday mobility is ubiquitous and much removed from alarmist discourses of 'climate migration' that views movement as solely climate-driven.

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Large mammals can help climate change mitigation and adaptation

 When it comes to helping mitigate the effects of climate change by absorbing carbon, flora rather than fauna usually comes to mind. A new study published in Current Biology now explores the role of large wild animals in restoring ecosystems and battling climate change.

Professor Yadvinder Malhi, Environmental Change Institute at the University of Oxford, said:

'Conservation efforts usually focus on either trees and carbon or the broad conservation appeal of large mammals. This study looked at whether it was possible to align these agendas -- under what context could protecting and restoring large animal wildlife help us tackle and adapt to climate change.'

The researchers highlighted three key eco-touchpoints where large animals such as elephants, rhinoceroses, giraffes, whales, bison, and moose had the greatest potential to mitigate climate change: carbon stocks, albedo (the ability of surfaces to reflect solar radiation (energy from the sun) and fire regimes.

When they graze, large herbivores disperse seeds, clear vegetation and fertilise the soil, which helps build more complex and more resilient ecosystems. These activities can maintain and increase carbon stocks in the soil, roots and above-ground parts of plants, helping to reduce CO2 in the atmosphere.

When large animals graze and trample vegetation they can change the habitat from dense shrubs and trees to open mixes of grass and shrubs or trees, which can also reveal snow-covered ground in polar regions. These open habitats tend to be paler (with higher albedo) and reflect more solar radiation into the atmosphere, cooling the Earth's surface, rather than absorbing it and warming the Earth's surface.

In 2021, global wildfire CO2 emissions reached a record high. When wildfires burn, the carbon stored in trees and vegetation is released into the atmosphere as greenhouse gases. Elephants, rhinoceroses, zebras and other large grazing animals can lessen wildfire risk by browsing on woody vegetation that could otherwise fuel the fires, trampling paths and making other gaps in vegetation that act as firebreaks.

The research, commissioned by wildlife charity Tusk, also looked at how protecting and restoring large animal wildlife could support climate change efforts and found several animal-climate interaction points that could provide 'win-win' opportunities.

In temperate, tropical and subtropical grassland ecosystems, large animals can reduce forest and bush fires, increase albedo and help retain carbon in the vegetation and the soil. Protecting large animal wildlife and their role in these complex ecosystems supports local biodiversity and ecological resilience.

Dr Tonya Lander, Department of Plant Sciences at Oxford University said:

'Animals can also help with localised adaptation to climate change in these environments by diversifying vegetation and increasing habitat heterogeneity. Diversity of species and microhabitats can make the ecosystem as a whole more able to resist climate change, return to a stable state following a climate-related disturbance, or find a new stable state that functions within the changed and changing climate.'

When large herbivores are present in tundra ecosystems, they help to keep down woody plant encroachment which encourages local flowering plants and grasses -- and exposes more of the ground to the cold air. That exposure maintains the permafrost and prevents the carbon in the soil from getting released into the atmosphere. Programmes that rewild bison and other animals into the arctic tundra can play important roles in both conservation and climate change adaptation at a local scale.

In marine ecosystems, whales and other large animals fertilise phytoplankton. Phytoplankton is estimated to capture 37 billion tonnes of CO2 each year and may release particles into the air which can help seed clouds and reflect sunlight into the atmosphere.

Large terrestrial and marine carnivores also affect these processes through their influence on herbivore abundance and behaviour.

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