Something Changed Evolution 170 Million Years Ago

Written by Alan Williams, University of Plymouth

On the Fast Track: Do the Evolution! | Isha Sadhguru

The ocean as we understand it today was shaped by a global evolutionary regime shift around 170 million years ago, according to new research.

Until that point, the success of organisms living within the marine environment had been strongly controlled by non-biological factors, including ocean chemistry and climate.

 

Calcified plankton dating from 95 million years ago. Images captured in the Plymouth Electron Microscopy Centre

However, from the middle of the Jurassic period onwards (some 170 million years ago), biological factors such as predator-prey relationships became increasingly important.

Writing in Nature Geoscience, scientists say this change coincided with the proliferation of calcium carbonate-secreting plankton and their subsequent deposition on the ocean floor.

They believe the rise of this plankton stabilized the chemical composition of the ocean and provided the conditions for one of the most prominent diversifications of marine life in Earth’s history.

The research was led by academics from the University of Plymouth’s School of Geography, Earth and Environmental Sciences and School of Computing, Electronics and Mathematics, in cooperation with scientists from the University of Bergen in Norway, and the University of Erlangen-Nuremberg in Germany.

PhD candidate Kilian Eichenseer, the study’s lead author, explained the impact of calcifying plankton: “Today, huge areas of the ocean floor are covered with the equivalent of chalk, made up of microscopic organisms that rose to dominance in the middle of the Jurassic period. The chalky mass helps to balance out the acidity of the ocean and, with that balance in place, organisms are less at the mercy of short-term perturbations of ocean chemistry than they might have been previously. It is easier to secrete a shell, regardless of its mineralogy, if the ocean chemistry is stable.”

The aim of the research was to test the hypothesis that the evolutionary importance of the non-biological environment had declined through geological time.

Since its emergence more than 540 million years ago, multicellular life evolved under the influence of both the non-biological and the biological environment, but how the balance between these factors changed remained largely unknown.

Calcified seashells provide an ideal test to answer this question, as aragonite and calcite – the minerals making up seashells – also form non-biologically in the ocean.

In their study, the authors used the vast global fossil record of marine organisms that secreted calcium carbonate, which encompasses more than 400,000 samples dating from 10,000 years BC up to around 500 million years ago.

Using reconstructions of the temperature and the ocean water composition of the past, the authors estimated the proportion of aragonite and calcite that formed inorganically in the ocean in 85 geological stages across 500 million years.

Images captured in the Plymouth Electron Microscopy CentreThrough a series of specially developed statistical analyses, this inorganic pattern of aragonite-calcite seas was then compared with seashell mineral composition over the same time.

The results show that up until the middle of the Jurassic period, around 170 million years ago, the ecological success of shell-secreting marine organisms was tightly coupled to their shell composition: organisms that secreted the mineral that was environmentally favoured had an evolutionary advantage.

However, the Earth-Life system was revolutionised forever by the rise of calcifying plankton, which expanded the production of calcium carbonate from continental shelves to the open ocean.

This ensured that the evolutionary impact of episodes of severe climate changes, and resulting ocean acidification, was less severe than comparable events earlier in Earth history.

Dr Uwe Balthasar, Lecturer in Palaeontology, first published research exploring the dominance of aragonite and calcite in the marine environment in 2015. He said: “During the Earth’s history there have been several major events that shaped the evolution of life on our planet, such as the five big mass extinctions or the radiation of complex animals during the ‘Cambrian Explosion’. Our research identifies a previously overlooked event of this magnitude around 170 million years ago when the emergence of calcium carbonate-secreting plankton lifted constraints on the evolution of other marine organisms that we did not know existed. As a result, life in the ocean has diversified to levels far beyond what existed before.”
The full study – Eichenseer et al: Jurassic shift from abiotic to biotic control on marine ecological success – will be published in Nature Geoscience https://www.nature.com/articles/s41561-019-0392-9

Contacts and sources:
Alan Williams, University of PlymouthCitation: Jurassic shift from abiotic to biotic control on marine ecological success.
Kilian Eichenseer, Uwe Balthasar, Christopher W. Smart, Julian Stander, Kristian A. Haaga, Wolfgang Kiessling. Nature Geoscience, 2019; DOI: 10.1038/s41561-019-0392-9

Source: http://www.ineffableisland.com/2019/07/something-changed-evolution-of-life-in.html

Comments (1)

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    tom0mason

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    From the video at starting at about 2:40 I heard something like —
    “Today we’re dealing with biodiversity crisis, we’re dealing with climate change, ocean acidification,
    It feels like everything, em, is out of control a little bit — and a lot of it has to do with us humans tinkering with [the] planet”

    The usual intellectually LAZY reasoning!
    To which I ask …
    1. What biodiversity crisis? Show me the list of ALL the animals and plants on the planet.
    2. Climate change? — natural climate change is all that is apparent. Our ability to deal with it is variable.
    3. Ocean acidification? — surely the first part of the video explains that because of the complex nature of the oceans and seas acidifying the oceans to the point it is a problem CAN NOT HAPPEN!
    4. Everything is a bit out of control? More intellectually LAZY thinking! Humans have never been in control of any of the factors mentioned.
    Just because most westerners lives have become comfortable, with easy communication channels available, and have few risk, modern western thinking is that ALL risks can be reduced — no they can not!
    Humans DO NOT control the weather or climate.
    Humans DO NOT control how much CO2 there is in the atmosphere!
    Humans DO NOT control the level of CO2 in the oceans and seas.
    All of these factors are controlled by nature through many, many complexly interlinked processes.
    Here’s just one called Cyanobacteria …

    Cyanobacteria are important though, for now they are very, very abundant, they are also some of the most efficient photosynthetic bacteria at converting CO2 to other useful chemicals. Among the marine plankton, the global biomass of Prochlorococcus reaches 120 × 10^12 grams of carbon (g C), and that of Synechoccus some 43 × 10^12 g C. This makes Prochlorococcus and Synechococcus, in that order, the most abundant cyanobacteria on Earth.
    Tropical marine blooms of Trichodesmium account for an additional 10 × 10^12 g C worldwide. In terrestrial environments, the mass of cyanobacteria in arid land soil crusts is estimated to reach 54 × 10^12 g C and that of arid land endolithic communities an additional 14 × 10^12 g C. The global biomass of planktic cyanobacteria in lakes is estimated to be around 3 × 10^12 g C. This does not include some potentially significant biomass reservoirs such as polar and subarctic areas, topsoils in subhumid climates, and shallow marine and freshwater benthos. Indications are that the total global cyanobacterial biomass is in the order of 3 × 10^14 g C, surpassing a thousand million metric tons (10^15 g) of wet biomass.
    (see https://www.researchgate.net/publication/233522504_Estimates_of_global_cyanobacterial_biomass_and_its_distribution )
    In fact from this study https://link.springer.com/article/10.1007/s10584-013-0702-y called ‘Projected climate change impact on Baltic Sea cyanobacteria’ Inga Hense et al show how hugely important they are.
    And from research paper https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010821 )
    “… photosynthesizing Cyanobacteria have been shown to be a significant species in the global carbon cycle, accounting for 20–30% of Earth’s photosynthetic productivity and convert solar energy into biomass-stored chemical energy at the rate of ~450 TW”

    From all my searches of many other studies, some cyanobacteria are extremophiles with some surviving and flourishing at very hot temperatures, or in strong salines, or others in alkaline, or others in acidic environments. However cyanobacteria are not very good when temperatures drop, and cyanobacteria that tolerate extreme cold ( from the documents I have found), show they are not particularly fast at growing or good fixers of CO2.

    All in all I take is to mean that as we come out of the LIA (say the last 200 years), Cyanobacteria should increase in both range and numbers, fixing CO2 and storing solar energy as they go.
    They add greatly to the the totality of life on the planet.

    I wonder how well the UN-IPCC see them in the CO2 cycle of this planet. And of course it runs against their avowed belief that any spike up in CO2 is human caused. The UN and their cAGW adherents could never think that this brief spike in atmospheric CO2 level could be nature’s doing (as we move away from the LIA).

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