Creationism in Crisis - Scientists Use Algae to Work Out How Plants Evolved in 600 Million Years

Microscope image of one of the closest algal relatives of land plants, a single-celled alga called Mesotaenium endlicherianum (20 micrometres corresponds to 0.02 millimetres)

Photo: Tatyana Darienko

Mesotaenium endlicherianum
Closest to the first algae to colonize the land

Press release: Algae provide clues about 600 million years of plant evolution

No doubt to the discomfort of creationists, a team of researchers led by Professor Jan de Vries of the University of Göttingen, Germany, have worked out how terrestrial plants have evolved in the 600 million years since the first marine algae colonize the land. This colonization is believed to have occurred just once, so all terrestrial plants are descended from that single colonizing species.

Note the question was not whether, but how this evolutionary process occurred. There was never a shadow of doubt that it was an evolutionary process in which there was no evidence of magic or supernatural interference with chemistry and physics.

Using the results of a series of experiments that have been running in the research lab in Gottingen for over 25 years, the team were able to identify key evolutionary changes that occurred as a prequel to land colonization and which are still to be found in terrestrial plants after 600 million years of evolutionary diversification.

Creationists must now draw on their repertoire of rehearsed dismissals of the science to cope with these finding and maintain the myth that land plants were created as is in one day about 8000 years ago, and have not evolved since:

• Redefine evolution ("They're still plants!").
• The dates are wrong ("Radiometric dating is flawed; it wasn’t hundreds of millions; it was just hundreds of years!").
• The scientists are lying ("It's a Satanic conspiracy to turn people away from Jesus!")

First, a lttle AI background:

For how long were there marine algae before they colonized the land? Marine algae have existed for at least 1.6 billion years, based on fossil evidence of red algae, which is the oldest known type of multicellular algae. Algae are thought to have been present in the oceans long before plants colonized the land.

Land colonization by plants, which likely involved early green algae (a group closely related to terrestrial plants), occurred about 470-500 million years ago during the Ordovician period. Therefore, marine algae existed for roughly 1 to 1.1 billion years before the first algae-like organisms adapted to life on land.

The early forms of algae played a crucial role in shaping Earth’s atmosphere and the evolution of life, particularly through their contribution to oxygen production in marine environments long before plants took root on land.

How long did it take marine algae evolve to the stage where terrestrial colonization was possible?

Marine algae evolved over a span of about 1 billion years before they developed the necessary adaptations to colonize land.

The first eukaryotic algae appeared around 1.6 billion years ago, and it wasn’t until around 470–500 million years ago during the Ordovician period that algae-like organisms evolved traits that allowed them to transition to land. This means that the evolutionary process from the first appearance of marine algae to land colonization took roughly 1 billion years.

This long period of evolution involved several key developments:

1. Photosynthesis and oxygen production: Algae were responsible for the oxygenation of Earth's atmosphere, a critical development for life on land.
2. Cellular complexity: Over time, algae evolved more complex multicellular forms, which later gave rise to land plants.
3. Adaptations to desiccation: To survive on land, ancestral algae needed mechanisms to deal with drying out, leading to the evolution of structures such as a waxy cuticle and mechanisms to manage water and gas exchange.

These adaptations occurred gradually, leading to the eventual colonization of land by early non-vascular plants like liverworts and mosses, which were derived from green algal ancestors.

Tell me all about terrestrial plant evolution from marine algae.

The evolution of terrestrial plants from marine algae is a remarkable chapter in Earth's history, involving multiple innovations that allowed plants to move from aquatic environments to land. This transition not only transformed terrestrial ecosystems but also shaped the global climate and atmosphere. Here's an overview of the key stages and events in the evolution of terrestrial plants from marine algae:

1. The Ancestry: Marine Algae
   The ancestors of land plants are believed to be green algae, specifically a group called charophytes, which are freshwater algae that share many characteristics with modern land plants.
   • Green Algae (Chlorophyta): First appeared around 1.6 billion years ago, these algae performed photosynthesis and contributed significantly to oxygen production, setting the stage for more complex life forms. Marine algae adapted to diverse environments but remained confined to water for most of their history.
   • Charophytes: These freshwater green algae are considered the closest living relatives of land plants. They had features that helped them survive in shallow waters, such as the ability to tolerate periodic drying.
   
   
2. The Transition to Land (~500–470 million years ago)
   The colonization of land occurred during the Ordovician period, around 470–500 million years ago, when Earth's climate was warm, and continents were mostly barren. Early green algae-like organisms made the jump to land, but they had to overcome a variety of challenges, including the absence of water, nutrient acquisition, and protection from UV radiation.
   
   Key adaptations that enabled this transition included:
   • Desiccation resistance: Early land plants evolved a waxy cuticle to prevent water loss.
   • Spores: These hardy reproductive structures could survive dry conditions, allowing plants to disperse and establish in different areas.
   • UV protection: They developed pigments to protect their cells from harmful ultraviolet radiation, which was more intense on land.
   • Symbiotic relationships: Early plants likely formed symbioses with fungi (mycorrhizae), helping them absorb nutrients from the soil, a key adaptation for life on land.
   
   
3. The Rise of Non-Vascular Plants (~470 million years ago)
   The earliest land plants were non-vascular plants, meaning they lacked specialized tissues to transport water and nutrients. Examples include liverworts, mosses, and hornworts. These plants lived in moist environments, as they still relied on water for reproduction (fertilization occurred when sperm swam through water to reach the egg).
   • Liverworts are among the oldest known land plants, and their ancestors probably looked similar to early Ordovician plants.
   • Mosses evolved from these early non-vascular plants and played a key role in soil formation, which helped create environments more suitable for other organisms.
   
   
4. The Evolution of Vascular Plants (~425 million years ago)
   Around 425 million years ago, during the Silurian period, plants evolved vascular tissues—xylem and phloem—which allowed them to transport water, minerals, and nutrients over long distances. This innovation enabled plants to grow taller and colonize drier environments.
   • Cooksonia, a genus of small, simple vascular plants, is one of the earliest known vascular plants.
   • Rhyniophytes, another early vascular plant group, evolved during this period, showing the first signs of specialized structures like stems and sporangia (spore-producing organs).
   
   
5. The Explosion of Plant Diversity (Devonian Period, 419–359 million years ago)
   The Devonian period is known as the "Age of Plants" because of the massive diversification of plant life. By this time, plants had evolved the following key innovations:
   • Roots: Evolved to anchor plants and absorb water and nutrients more effectively from the soil.
   • Leaves: Plants developed true leaves, improving their ability to capture sunlight and carry out photosynthesis.
   • Lignin: This complex organic polymer allowed plants to grow tall and stand upright by strengthening their cell walls.
   
   During the Devonian, the first trees appeared, such as Archaeopteris, a tree-like plant that had wood and leaves, representing a major step toward modern trees. Forests of vascular plants began to spread across the land.
6. The Rise of Seed Plants (~360 million years ago)
   As plants continued to evolve, a significant innovation was the development of seeds. Seeds allowed plants to reproduce without needing water, as seeds can survive in dry conditions for long periods before germinating.
   • Seed ferns were some of the earliest seed plants.
   • Gymnosperms (naked seed plants, like conifers) became dominant during the Carboniferous period (~360–300 million years ago) and created vast forests that laid down much of the coal deposits we use today.
   
   
7. The Evolution of Flowering Plants (Angiosperms, ~140 million years ago)
   The next major milestone in plant evolution was the appearance of angiosperms (flowering plants) around 140 million years ago during the Cretaceous period. Angiosperms developed flowers, which allowed for more efficient reproduction through the attraction of pollinators like insects, birds, and bats. They also produced fruit, which helped with seed dispersal.
   • Flowering plants rapidly diversified and became the dominant form of plant life on Earth. Their ability to adapt to a wide variety of environments contributed to their evolutionary success.
   
   
8. Plant Evolution and Global Impact
   As plants evolved, they transformed the Earth’s surface and atmosphere. Early land plants increased oxygen levels, leading to the oxygen-rich atmosphere we have today. Plants also helped shape soils, creating more hospitable environments for other life forms, including animals. The formation of forests had a dramatic cooling effect on the Earth's climate by reducing atmospheric carbon dioxide levels through photosynthesis and the burial of organic matter.

Summary of Key Developments in Plant Evolution:

• 1.6 billion years ago: First marine algae (red and green algae) appear.
• ~500–470 million years ago: Transition from freshwater algae to land; development of desiccation-resistant structures and spores.
• ~470 million years ago: Emergence of non-vascular plants (liverworts, mosses).
• ~425 million years ago: Evolution of vascular plants with xylem and phloem (Cooksonia, Rhyniophytes).
• ~360 million years ago: Seed plants appear (seed ferns, gymnosperms).
• ~140 million years ago: Evolution of flowering plants (angiosperms).

The Legacy of Plant Evolution
From humble origins in the oceans, plants have become one of the most diverse and ecologically important groups of organisms on Earth. Their evolution has been a driving force in shaping the planet’s ecosystems, supporting animal life, and maintaining the balance of gases in the atmosphere.

The research, which is published open access in Nature Plants, is explained in a new release from Göttingen University:

Press release: Algae provide clues about 600 million years of plant evolution

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Research team led by Göttingen University investigates 10 billion RNA snippets to identify “hub genes”

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The Earth's surface is covered by plants. They make up the majority of biomass on land and exhibit a wide range of diversity, from mosses to trees. This astounding biodiversity came into existence due to a fateful evolutionary event that happened just once: plant terrestrialization. This describes the point where one group of algae, whose modern descendants can still be studied in the lab, evolved into plants and invaded land around the world. An international group of researchers, spearheaded by a team from the University of Göttingen, generated large scale gene expression data to investigate the molecular networks that operate in one of the closest algal relatives of land plants, a humble single-celled alga called Mesotaenium endlicherianum. Their results were published in Nature Plants.

Our study began by examining the limits of the alga's resilience – to both light and temperature. We subjected it to a wide temperature range from 8 °C to 29 °C. We were intrigued when we observed the interplay between a broad temperature and light tolerance based on our in-depth physiological analysis.

Janine Fürst-Jansen, co-lead author
Institute of Microbiology and Genetics
Department of Applied Bioinformatics
University of Goettingen, Goettingen, Germany

Samples of Mesotaenium endlicherianum that have been kept safe in the Algal Culture Collection at Göttingen University (SAG) for over 25 years. This image shows the unique experimental set-up there which allowed the researchers to expose Mesotaenium endlicherianum to a continuous range of different light intensities and temperatures.

Photo: Janine Fürst-Jansen

What is so unique about the study is that our network analysis can point to entire toolboxes of genetic mechanisms that were not known to operate in these algae. And when we look at these genetic toolboxes, we find that they are shared across more than 600 million years of plant and algal evolution!

Professor Jan de Vries, Senior author Institute of Microbiology and Genetics
Department of Applied Bioinformatics
University of Goettingen, Goettingen, Germany

Our analysis allows us to identify which genes collaborate in various plants and algae. It's like discovering which musical notes consistently harmonize in different songs. This insight helps us uncover long-term evolutionary patterns and reveals how certain essential genetic 'notes' have remained consistent across a wide range of plant species, much like timeless melodies that resonate across different music genres.

Armin Dadras, co-lead author
PhD student
Institute of Microbiology and Genetics
Department of Applied Bioinformatics
University of Goettingen, Goettingen, Germany

Using a strain of Mesotaenium endlicherianum that has been kept safe in the Algal Culture Collection at Göttingen University (SAG) for over 25 years and the unique experimental set-up there, the researchers exposed Mesotaenium endlicherianum to a continuous range of different light intensities and temperatures. How the algae respond was not only investigated on a morphological and physiological level, but also by reading the information of about 10 billion RNA snippets. The study used network analysis to investigate the shared behaviour of almost 20,000 genes simultaneously. In these shared patterns, “hub genes” that play a central role in coordinating gene expression in response to various environmental signals were identified. This approach not only offered valuable insights into how algal gene expression is regulated in response to different conditions but, combined with evolutionary analyses, how these mechanisms are common to both land plants and their algal relatives.

More explanation is given in the abstract to the team's open access paper in Nature Planta:

Abstract

Plant terrestrialization brought forth the land plants (embryophytes). Embryophytes account for most of the biomass on land and evolved from streptophyte algae in a singular event. Recent advances have unravelled the first full genomes of the closest algal relatives of land plants; among the first such species was Mesotaenium endlicherianum. Here we used fine-combed RNA sequencing in tandem with a photophysiological assessment on Mesotaenium exposed to a continuous range of temperature and light cues. Our data establish a grid of 42 different conditions, resulting in 128 transcriptomes and ~1.5 Tbp (~9.9 billion reads) of data to study the combinatory effects of stress response using clustering along gradients. Mesotaenium shares with land plants major hubs in genetic networks underpinning stress response and acclimation. Our data suggest that lipid droplet formation and plastid and cell wall-derived signals have denominated molecular programmes since more than 600 million years of streptophyte evolution—before plants made their first steps on land.

Main
Plant terrestrialization changed the face of our planet. It gave rise to land plants (Embryophyta), the major constituents of Earth’s biomass¹ and founders of the current levels of atmospheric oxygen². Land plants belong to the Streptophyta, a monophyletic group that includes the paraphyletic freshwater and terrestrial streptophyte algae and the monophyletic land plants. Meticulous phylogenomic efforts have established the relationships of land plants to their algal relatives^3,4,5,6. These data brought a surprise: the filamentous and unicellular Zygnematophyceae—and not other morphologically more elaborate algae—are the closest algal relatives of land plants. Now, the first genomes of major orders of Zygnematophyceae (see ref. ⁷) are at hand: Mesotaenium endlicherianum⁸, Spirogloea muscicola⁸, Zygnema circumcarinatum⁹, Closterium peracerosum–strigosum–littorale¹⁰ and Penium margaritaceum¹¹. Using these, we are beginning to redefine the molecular chassis shared by land plants and their closest algal relatives. Included in this shared chassis will be those genes that facilitated plant terrestrialization. In this Article, we focus on one critical aspect: the molecular toolkit for the response to environmental challenges. For this, we used the unicellular freshwater/subaerial alga Mesotaenium endlicherianum.

Land plants use a multi-layered system for the adequate response to environmental cues. This involves sensing, signalling and response, mainly by the production of, for example, protective compounds. Some of the most versatile patterns in land plant genome evolution concern genes for environmental adaptation^12,13,14. That said, there is a shared core of key regulatory and response factors that are at the heart of plant physiology. These include phytohormones such as abscisic acid (ABA) found in non-vascular and vascular plants^15,16, protective compounds resting on specialized metabolic routes such as phenylpropanoid-derived compounds and proteins such as LATE EMBRYOGENESIS ABUNDANT (LEA)^17,18. Many of the genes integrated into these stress-relevant metabolic routes have homologues in streptophyte algae¹⁹. Taking angiosperms as reference, such stress-relevant pathways are often patchy. Whether these are also used under the relevant conditions is currently unknown. For example, while Zygnematophyceae have a homologue to the ABA-receptor PYL^8,20, this homologue works in a different, ABA-independent fashion²¹. Thus, it is important to put the genetic chassis that could act under environmental shifts to the test.

Here we used a fine grid of a bifactorial gradient for two key terrestrial stressors, variation in irradiance and temperature, to probe the genetic network that the closest algal relatives of land plants possess for the responsiveness to abiotic cues. Correlating environmental parameters, physiology and global differential gene expression patterns from 128 transcriptomes (9,892,511,114 reads, 1.5 Tbp of data) across 126 distinct samples covering a temperature range of >20 °C and light range of >500 µmol photons m⁻² s⁻¹, we pinpoint hubs in the circuits that have been shared along more than 600 million years of streptophyte evolution.

Dadras, A., Fürst-Jansen, J.M.R., Darienko, T. et al.
Environmental gradients reveal stress hubs pre-dating plant terrestrialization.
Nat. Plants (2023). https://doi.org/10.1038/s41477-023-01491-0

Copyright: © 2023 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

So, a series of evolutionary responses to stress enabled simple algae to colonize the land, some 600 million years ago, and all terrestrial plants have diverged from that singular event, complete with the evolutionary changes that enabled it to happen.

Creationists have masses of work to do to dismiss this evidence of common ancestry and an earth much older than their cult tells them Earth and life on it have existed. No wonder creationism is a notion in crisis as even religious people are rejecting it as a valid explanation of the observable facts and no serious scientists even considers it as a viable alternative to evolution.

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