symbiosis – from organisms to earth

Symbiosis – from organisms to Earth

KAUST – Winter Enrichment Program31 January 2011

John CheesemanUniversity of Illinois, USA

http://www.life.illinois.edu/cheeseman/KAUST/symbiosis.ppt

Today - we will look at symbiosis at all levels, however briefly, with particular emphasis on some of the consequences of disrupting it at the planetary scale. 

Some implications for the future of humans on earth will also be discussed.

All organisms on earth occur in some sort of symbiotic relationship with other organisms.

•Symbiosis was probably critical for the colonization of land by multicellular organisms.

Symbiosis affects all parts of our lives…

•plant growth, productivity and survival•human pathogens and diseases•biogeochemical cycling•functioning of the planet itself

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Land colonization began ca 1.2 Ga with cyanobacterial mats• Fungi added (lichens) ca. 600 Ma

There are >13000 spp of lichen fungi… ~20% of all known fungi

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Plants arose ca. 500 Ma - no leaves or roots• Earliest fossils have fungal associations• Why? So what?

Aglaophyton - ca 420 Ma

Today, the most well-known mutualistic plant/fungal association is mycorrhizae…

• involves >80% of all plant species…

• critical to P, Zn and K nutrition

• especially in poor soils

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Rhizobium on soybean

Bacteroids in Rhizobium nodules

Frankia nodules on alderPlants also associate with bacteria•Bacterial N-fixation is agronomically and ecologically critical

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Following Nod or Myc factor signaling, a nuclear calcium/calmodulin dependent kinase is activated which phosphorylates transcription factors needed for nodule differentiation or AM development.

Nodulation and mycorrhizae formation share signalling pathways

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Single legume roots may be infected with both VA mycorrhizae and Rhizobium

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Spartina dominates East Coast, US salt marshes characterized by oligotrophic conditions

Rhizoplane bacteria

Symbiosis is not limited to nodules and mycorrhizae

… plants still provide C to the symbionts (as much as 40% of total photosynthate)

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Chemotaxis of Zoöspores

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Epichlöe – a fungal endosymbiont transmitted in seeds

•Protects its grass host from grazers – bad for grazing, great for turf grass•Confers stress tolerance

Other interesting symbioses – some examples

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• Photosynthetic sea slugs and sea anemones

• Corals• Bioluminscent squid and angler fish• Gut symbionts (ruminants, monkeys,

termites, people)• Leeches, tsetse flies, lice, bed bugs,

mites… can live on your blood because endosymbionts synthesize B vitamins and other nutritional supplements

Other interesting symbioses – some examples

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Endosymbionts of termites

Symbiotic archaeoprotist from the intestine of the termite Reticulitermes flavipes. … Trichonympha agilis… Pyrsonympha verteus … Dinenympha gracilis.

From Joseph Leidy (1881) - “The parasites of termites”

Symbionts eat the wood eaten by the termites, and their bacterial symbionts do the actual digestion.

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Dichanthelium lanuginosum (hot springs panic grass)

• Yellowstone and Lassen Volcanic National Parks, US

• Found on edges of hot springs, adjacent to thermal streams, and on fumaroles (steam vents)

• One of most thermotolerant vascular plants: rhizosphere temperatures range from 20˚C - 57˚C

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Seasonal records show soil temps > 45-55˚C for prolonged periods

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The problem:Grown in a greenhouse or other controlled condition, Dicanthelium is not tolerant above 40˚C

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Curvularia asciCurvularia protuberata on leaf and root of D. lanuginosum

The problem remains:Grown in controlled cultures, Curvularia is also not tolerant above 40˚C

Culturing leaves and roots reveals numerous fungal associations

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• Curvularia is not the only fungus that does this… Fusarium culmorum confers salt tolerance on dune grasses, watermelon and other plants… different strains dominate in different microhabitats.

An even more interesting problem:Cultured together, the pair is tolerant of 60˚C

And… it is not just the plant fungal interaction:The fungus is infected with a virus that is required for the heat tolerance

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Break

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An ecosystem is …

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An ecosystem is all the organisms living in a community as well as all the abiotic factors with which they interact.

Many ecologists regard the entire biosphere as a global ecosystem…

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Sustainability/stability of any ecosystem depends on biogeochemical cycles

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Ecosystems are ruled by energy flows and chemical cycling

What is heat?

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In a compost heap, respiratory heat released by detritivores and decomposers leads to high, but optimal internal temperatures.

Temperature rises because heat energy is transferred to water.

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Ecosystems are ruled by energy flows and chemical cycling

What is the role of detritivores?

What happens if detritus is removed?

What limits primary production?

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Physical and chemical factors limit primary production in ecosystems

Productivity is the product of productivity per unit area, and total area• Most highly productive ecosystems are small in total area

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Regional annual net primary productivity is spatially variable

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Sustainability/stability of any ecosystem depends on biogeochemical cycles

Generalized scheme

• Rate variations between systems largely reflect decomposition rates

• Affected by temperature and water

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Nutrient cycles are global

Nitrogen fertilizer applied to Illinois corn is consumed and excreted in European feedlots, or re-exported as meat products

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An more detailed example: the water cycle

Is this “local” or “global”?

How does this relate to symbiosis?

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Global climate changes affects huge areas and billions of people though the biogeochemical water cycle

Amazonian drought in 2005/6 fueled massive fires

Coincided with very active North Atlantic hurricane season

Effects of conversion of forests to savannah will affect even more people.

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Atmospheric and ocean circulations result in massive redistribution of energy and matter

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More on the water cycle

The water and sulfur cycles are linked:

• Oceanic cloud formation & rainfall requires nucleating effects of biogenic dimethylsulfide

• Pelagic birds may use DMS to find prey

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Atmospheric composition varies very little over very long periods Hyperreactive gases such as O2, O3 and CH4 exist at relatively stable levels

Earth is characterized by unexpected stabilities

Ocean salinity varies little even though ocean makeup is far from equilibrium:river salt inputs should raise SW well above 3.4% salinity as should ocean circulation through hot basaltic vents

CO2 cycle involves release from volcanoes, dissolution in ocean waters and precipitation in limestone both bioactively and inorganically… but changes are (were) slow over long periods.

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On Earth, temperature changes are generally gradual and (even today) means are relatively stable

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On Earth, temperature changes are generally gradual and (even today) means are relatively stable

January 2010 Global Temperature Update

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Most important environmental considerations at any scale are stability, and the magnitude and predictability of variation.

Oceans and atmosphere moderate variability• Year to year variations are small and long term changes are gradual

By contrast, on Mars…

• No oceans and a thin atmosphere• Low thermal inertia • Climate easily perturbed by external

influences, including solar variations• Mean temperature can change by

many degrees from year to year, depending on how active large scale dust storms are

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Martian climate is particularly sensitive to the strength and duration of hemispheric dust storms

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Within an ecosystem, the linkages are not always obvious

Three ecosystem components• Biosphere• Lithosphere• Atmosphere

… interact unpredictably

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Within an ecosystem, the linkages are not always obvious

Salpa aspera – the missing link for CO2 ?

One swarm covered 38,600 square miles (100,000 square kilometers) of the sea surface… perhaps trillions of thumb-sized salps…. Consumed up to 74 percent of surface microalgae per day… their sinking fecal pellets transported up to 4,000 tons of carbon a day to deep water.

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… a planetary physiological system that regulates the chemistry and climate … atmospheric homeostasis controlled by and for the biosphere… Earth is a single living organism … a symbiotic planet.

Gaia

"It is remarkable how exact the balance is between the carbon input from volcanoes and the output from rock weathering…; This suggests a natural thermostat which helps maintain climate stability."

James Lovelock

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Gaia can be viewed not as an organism but as an emergent property of a complex system, reflecting interaction among organisms

Complex systems show non-linear behavior full of unknown unknowns.• Small changes have profound consequences• “Tipping points”

Lynn Margulis

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Homeostasis, homeorhesis and emergent properties

Population as an example of emergent properties in complex systems

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Break

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“An ecosystem is all the organisms living in a community as well as all the abiotic factors with which they interact.”

All aspects of the global ecosystem are dominated by a single organism - humans.

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There are no pristine environments. There is nowhere spared from human domination.

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6 trillion plastic bagsper year

try as I mightI cannot conceivecannot fathom inmy wildest imagination

16,438,356,164 per day684,931,506 per hour11,415,525 per minute190,258 per second, for each beat of my heart as I rest in bed at dawn9513 in the blink of an eye or a single frame in a moving picture

882 for each living, breathing human soul on the planet163 for every acre of land2.3 for each corn plant in the US15 for every tree

43,011 per square mile of ocean

101,694,915 for each species of mammal20,689,655 for each species of plant1.5 billion for each species of cockroach200 million for each sea turtle waiting to eat a jellyfish

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A known known - Environmental change is brought about by “forcing agents”

Forcing agents include:• CO2 (up 40% since 1750)• Aerosols• CH4 (up 150%)• NOx and other

greenhouse gases• Orbital variations• Solar output

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A known known - Environmental change is brought about by “forcing agents”

Forcing effects are manifest as changes in the solar constant• Small changes are important• Since 1750, the effective solar constant has increased ca. 1.5 W/m2 (ca. 0.1%)

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A known known - Environmental change is brought about by “forcing agents”

75% of change due to fossil fuel burning25% due to land use changes (especially deforestation)Annual imbalance is only 2-4 GT/yrEmission are still rapidly rising

In 1990s – 1.3%/yr.Since 2000 – 3.3%/yr

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Environmental change is brought about by “forcing agents”

Graph shows “anthropogenic global warming”50

Environmental change is brought about by “forcing agents”

Thermal inertia keeps Earth’s systems stable… but once change starts, it is hard to stop

2030-20502050-2070

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Environmental change is brought about by “forcing agents”

2030-20502050-2070

• 2˚ is now a given; 3˚ is potential catastrophe• Staying within 3˚ means reducing CO2 emissions 80% by 2030

• Bush’s “plan” was to stop increasing emission rates by 2025• EU “plan” is to decrease emissions 20% by 2030• China doesn’t have a plan• Copenhagen didn’t help at all

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Temperature changes are not and will not be uniformly distributed

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Temperature changes are not and will not be uniformly distributed

• Melting of permafrost, decomposition and degassing of peat• Arctic sea ice disappearance, de-glaciation of Greenland/Antarctica• Expansion of current deserts• Disruption of glacial based water supplies• Conversion of tropical rainforests to savannahs (short term) or deserts• Disruptive positive feedback effects

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Transition – from Global warming to challenges facing human societies

• Oil supplies and security• Water security• Temperature effects• Collapse of natural systems• Remediation of established declines and system failures

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Challenges facing human societies

• Oil supplies and security• What is the true price of a gallon of gas?• What is “peak oil”? When is it?• Oil and crop production/fertilizer (US vs world)• Oil and irrigation• Post-harvest energy use is 2/3 of total

In 1970 - 1 bushel of wheat would buy 1 barrel of oilIn 2005 - 13 bushels …In 2007 - approx. 18 bushels

Food vs. fuel - the biofuels controversy

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Challenges facing human societies

• Oil supplies and security• Water security

• Two thirds of global water use is for irrigation• In US, water is being diverted to leisure• In US, subsidized water for surplus crops• In Saudi Arabia - deep wells and desalinization …• In mid-east, water is a matter of national policy

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Challenges facing human societies

• Oil supplies and security• Water security

• Two thirds of global water use is for irrigation• Aquifer drawdown

• Water tables, irrigation and salinity

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Challenges facing human societies

• Oil supplies and security• Water security

• Water tables and irrigation• Diversion from rivers

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Challenges facing human societies

• Oil supplies and security• Water security

• Water tables and irrigation• Diversion from rivers• Disappearing lakes

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Challenges facing human societies

• Oil supplies and security• Water security

• Water tables and irrigation• Diversion from rivers• Disappearing lakes• Farm vs. city (China)• Cross border scarcities• Global food security

Example problems• Panamá canal• Hoover Dam and Lake Mead• China and the Olympic games• Israel and Palestine

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Challenges facing human societies

• Oil supplies and security• Water security• Temperature effects

• Crop yield declines• Rainfall pattern changes and losses• Rising seas• Destructive storms• Environmental refugees

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Challenges facing human societies

• Oil supplies and security• Water security• Temperature effects• Collapse of natural systems

• Shrinking forests, soil loss, rangeland destruction, desertification

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Challenges facing human societies

• Oil supplies and security• Water security• Temperature effects• Collapse of natural systems

• Shrinking forests, soil loss, rangeland destruction, desertification• Collapsing fisheries• Extinctions

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Challenges facing human societies

• Oil supplies and security• Water security• Temperature effects• Collapse of natural system• People

Refugee children – expelled to Nepal from Bhutan68

On population69

Saving civilization

Can the human species be saved? How?

"I've never seen a problem that wouldn't be easier to solve with fewer people, or harder, and ultimately impossible, with more." David Attenborough

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On population71

Current population

What is the current population? What does that mean?

6.8 billion

9% of the all time total human population

500 Mtonnes - ~ same as Antarctic krill

95-99% of total vertebrate biomass(Humans, livestock and pets)

45/km2 (120/mi2)

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Population and growth

Growth rate is declining? What does that mean?

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Population and growth

Growth rate is declining? What does that mean?

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Population and growth

Growth rate is declining? What does that mean?

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96% of current growth is in less developed countries (including China)

+43% +280%

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Saving civilization

“Saving civilization is not a spectator sport.”Lester Brown

• Heart of climate stabilization is cutting CO2 emissions by 80% by 2020

• A race between tipping points in natural and political systems

Can the human species be saved? How?

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Carrying capacity

What is Earth’s carrying capacity (for humans)?

At what standard of living?At what levels of consumption?

What are we using now?

Based on global averages with huge spatial variability• Agriculture, land occupation, grazing, forestry• Humans use 20 Pg Carbon = 32% of the total TNPP

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pollution

How will population growth be constrained?

War and Genocide?

• World population in 1900 was ca. 1.5 billion• The combined deaths due to all wars, epidemics and genocides since

1900 was no more than 200,000,000• The population in 2000 was 6 billion• War is not the answer

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pollution

How will population growth be constrained?

Continually worsening pollution? Former Soviet Union

• 11% of children have birth defects• 55% have health problems other than normal childhood diseases• 10% of food supply and 50% of drinking water is chemically contaminated• Life expectancy is declining

China - Olympics called attention to grave and worsening pollution• Trans-Pacific export of air pollution• Water and soil pollution • Heavy metals from high-tech trash

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Water supplies

How will population growth be constrained?

Water supplies/shortages?

• Japan - 1993 - imported water by ship load• Australia - current water use restrictions nation-wide• China - too little rainfall, insecure supplies• India - retreating water tables, encroaching saline water, drought

In US, 21% of all irrigation is by over-pumping ground waterSame in China and India

… even before indoor plumbing, flush toilets, kitchen water… 300 of largest cities have severe water scarcity

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Water use for food

How will population growth be constrained?

Water supplies and food supplies

http://news.bbc.co.uk/2/hi/in_depth/7284196.stm

Why do we care what the Chinese eat?

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Masses

“Whenever you multiply anything by 1.2 billion, it’s a lot.” - Lester Brown

+1 beer per year = 370,000 tons of grain

= Australia’s total grain export in a good year

+4 eggs per week = 260 billion eggs

+30 kg beef = 300 km3 H2O

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Food

How will population growth be constrained?

Food?• Grain supplies?• Fisheries?

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Grain

How will population growth be constrained?

Food?• Grain supplies?

Per capita grain production increased from 1950-1990• Irrigation• Fertilizer• Genetics

Worldwide, 10-50% of world food supply is wasted.

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Recent prices

How will population growth be constrained?

Food?• Grain supplies?

http://news.bbc.co.uk/2/hi/in_depth/7284196.stm85

Recent prices

How will population growth be constrained?

Food?• Grain supplies?

http://news.bbc.co.uk/2/hi/in_depth/7284196.stm86

China

How will population growth be constrained?

Food?• Grain supplies?

“If we continue to squander our land and water resources [to industrialize], we will need to import 400 million tons of grain… and even all the grain produced in the US will not be enough…”

Prof. Zhu-Guang Zhao

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Land use changes

How will population growth be constrained?

Food?• Land use and degradation?

ca. 10 Mha/yr are lost from production due to • Erosion• Salinization• Waterlogging• Urbanization

ca. 16 Mha/yr are added by deforestation

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Fisheries

How will population growth be constrained?

Food?• Grain supplies?• Fisheries?

Fisheries output increased 4.6 times from 1950-1989… flattened, then declined

Per capita availability is declining rapidly

(FAO) all 17 oceanic fisheries now being fished at or beyond capacity… 9 are in state of decline, or collapsing

No longer the protein choice for the poor… too expensive

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Fisheries

How will population growth be constrained?

Disease?Obesity (current rankings)# 1 United States: 30.6% # 2 Mexico: 24.2% # 3 United Kingdom: 23% # 4 Slovakia: 22.4% # 5 Greece: 21.9% # 6 Australia: 21.7% # 7 New Zealand: 20.9% # 8 Hungary: 18.8% # 9 Luxembourg: 18.4% # 10 Czech Republic: 14.8% # 11 Canada: 14.3% # 12 Spain: 13.1% # 13 Ireland: 13% # 14 Germany: 12.9% # 15 Portugal: 12.8% # 15 Finland: 12.8% # 17 Iceland: 12.4% # 18 Turkey: 12% # 19 Belgium: 11.7% # 20 Netherlands: 10%

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Fisheries

How will population growth be constrained?

Disease?• Pandemics of known diseases?• Pandemics of new and emerging diseases?

• “Only” 20 million died in the 1918 flu epidemic, or about 1.3% of world population

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Fisheries

How will population growth be constrained?

Personal choice?

•Japan, Russia, France, Germany, US (except for immigration) are losing people•Even that is a problem – strains on social security systems

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Failed states

What if we don’t do something? Deciding for collapse.

UNEP lists 60 failed states

• Can no longer perform basic functions of education, security, or governance

• Vulnerable to or beset by violence and internal conflict• Severely uneven development• Loss of governmental legitimacy

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Refugees

• More than 100 million between-country refugees• Within China, more than 100 million migrants• Wanderers reflect and precipitate crisis and terrorism• More than 70 of the last 80 major conflicts have been within countries

Climate refugees - Astrodome

What if we don’t do something? Deciding for collapse.

UNEP lists 60 failed states

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Four futures - summary

Winning the battle – Plan B 4.0

Stabilize CO2 – cut emissions by 80% by 2020Stabilize population at ≤ 8 billionEradicate poverty ($77 B/yr)Restore natural systems ($110 B/yr)

All that is needed for the triumph of evil is for good folks to do nothing.

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Four futures - summary

Winning the battle

Stabilize CO2 – cut emissions by 80% by 2020Stabilize population at ≤ 8 billionEradicate poverty ($77 B/yr)Restore natural systems ($110 B/yr)

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Four futures - summary

Winning the battle

Stabilize CO2 – cut emissions by 80% by 2020Stabilize population at ≤ 8 billionEradicate poverty ($77 B/yr)Restore natural systems ($110 B/yr)

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"You can't have a light without a dark to stick it in." Arlo Guthrie

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