Rosa Rubicondior: Refuting Creationism - Common Ancestry Of Mosses and Algae - 600 Million Years Before 'Creation Week'.

Refuting Creationism

Common Ancestry Of Mosses And Algae
600 Million Years Before 'Creation Week'.

The star-shaped algae Zygnema circumcarinatum shows similar stress reactions to the moss

Photo: Tatyana Darienko

The branching moss Physcomitrium patens, which the researchers used to study stress reactions and compare them to algae.

Photo: Tatyana Darienko.

600 million years of stress: plants retain shared gene hubs - Georg-August-Universität Göttingen

Like animals, plant life originated in the sea and only colonized land once they evolved the necessary adaptations. For animals, this meant developing mechanisms for breathing air and terrestrial locomotion. For plants, the primary challenge was desiccation, creating strong selection pressure for traits that mitigated water loss. This led to the evolution of a highly connected network of genes, known as a 'hub,' that regulates responses to environmental stress.

So fundamental is this genetic hub to plant survival that it has remained highly conserved throughout evolutionary history.

What information do you have on the evidence for the evolution of land plants and their divergence from marine algae?

The evolution of land plants from their algal ancestors is one of the most significant transitions in Earth's history. Multiple lines of evidence, including molecular phylogenetics, comparative genomics, palaeobotany, and developmental biology, support the hypothesis that land plants (embryophytes) evolved from a group of green algae, specifically within the Charophyte clade. Below is a summary of the key evidence:

Molecular and Phylogenetic Evidence

Shared Genetic Markers: Molecular phylogenetic studies show that land plants are most closely related to charophyte algae, such as Chara and Klebsormidium.
Chloroplast DNA Similarities: Land plants and charophytes share specific gene arrangements in their chloroplast DNA, supporting common ancestry.
Cellulose Synthase Genes: The enzyme responsible for cellulose biosynthesis (CesA) has similar genetic sequences in charophytes and land plants.
Regulatory Genes: Some transcription factors crucial for land plant development, such as KNOX and BELL genes, have homologs in charophyte algae.

Morphological and Structural Evidence

Cell Division Similarities: Charophyte algae and land plants share a phragmoplast-based cell division mechanism, distinct from other algal groups.
Sporopollenin Protection: Spores of early land plants and some charophytes are encased in sporopollenin, a tough biopolymer that protects against desiccation.
Plasmodesmata: Both groups have plasmodesmata, cell-to-cell communication channels that enable coordinated growth.
Branching Growth: Some charophyte algae, such as Coleochaete, show apical growth similar to land plants.

Fossil Evidence

Ordovician and Silurian Microfossils (470-440 Ma): Fossilized spores with sporopollenin coatings appear before macroscopic land plant fossils, indicating early adaptation to terrestrial environments.
Rhynie Chert (Early Devonian, ~407 Ma): Preserves some of the earliest land plants (Rhynia, Aglaophyton), showing vascular tissue development.
Cooksonia (Silurian-Devonian Transition, ~430-410 Ma): One of the earliest known vascular plants, showing transition from bryophyte-like ancestors to tracheophytes.

Biochemical and Physiological Adaptations

Desiccation Tolerance: Early land plants and some charophytes can survive drying out, an adaptation to terrestrial life.
Hormonal Pathways: Land plants and charophytes use similar hormones, such as auxin and abscisic acid, for growth and stress response.
Symbiosis with Fungi: Fossil evidence and molecular studies suggest that early land plants formed mutualistic associations with mycorrhizal fungi (Glomeromycota) to obtain nutrients.

Transitional Forms

Zygnematophyceae as a Key Group: Recent genomic studies suggest that the Zygnematophyceae, a subgroup of charophyte algae, are the closest relatives of land plants. These algae lack complex multicellularity but share stress tolerance genes with land plants.
From Simple Algae to Complex Embryophytes: Gradual increase in structural complexity, from filamentous and parenchymatous algae to early non-vascular land plants, suggests a stepwise transition to terrestrial life.

Conclusion

The divergence of land plants from marine algae is well-supported by multiple independent lines of evidence. The transition was driven by adaptations to terrestrial challenges such as desiccation, nutrient acquisition, and reproduction. The evolutionary path likely involved early colonization by freshwater charophyte algae, which evolved desiccation tolerance, protective spores, and symbiotic relationships that facilitated the transition to permanent land-based life.

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Now a team of researchers from Georg-August-Universität, Göttingen, Germany, led by Professor Jan de Vries, Göttingen University, who led the research, explains: has shown that this same 'hub' is present in both mosses and algae, even though they diverged 600 million years ago, the mosses having evolved out of simple algae.

600 million years of stress: plants retain shared gene hubs
Research team led by Göttingen University studies evolution of plant networks for environmental stress response
Without plants on land, humans could not live on Earth. From mosses to ferns to grasses to trees, plants are our food, fodder and timber. All this diversity emerged from an algal ancestor that conquered land long ago. The success of land plants is surprising because it is a challenging habitat. On land, rapid shifts in environmental conditions lead to stress, and plants have developed an elaborate molecular machinery for sensing and responding. Now, a research team led by the University of Göttingen has compared algae and plants that span 600 million years of independent evolution and pinpointed a shared stress response network using advanced bioinformatic methods. The results were published in Nature Communications.

The closest algal relatives of land plants are the filamentous and unicellular conjugating algae, the zygnematophytes. This group of organisms has received major attention because when researchers compared data about land plants with data about these algae, they could trace back to the very first plants on land. One of the big questions is how the earliest land plants overcame the terrestrial stressors. To find out, the team generated hundreds of samples from a moss model system and two zygnematophyte algae challenged by environmental stressors found on land. Using high throughput sequencing of the active genes and profiling of the compounds produced by the moss and algae under stress, they obtained a comprehensive picture of how the organisms react to the challenges over a time-course of several hours. By combining evolutionary analysis with statistical modelling and machine learning methods, a shared network of gene regulation was predicted.

One of the big surprises was that we found several highly connected genes – known as ‘hubs’ – in the network shared by these very different organisms that actually split from each other in evolutionary terms around 600 million years ago. These hubs appear to bundle information and shape the overall network response.

Professor Jan de Vries, lead author.
University of Göttingen
Institute of Microbiology and Genetics
Department of Applied Bioinformatics, Göttingen, Germany.

Now we have a comprehensive dataset of stress responses, combining genetic and biochemical information that can be further explored for its physiological impact across plant diversity.

Dr Tim Rieseberg, co-first author.
University of Göttingen
Institute of Microbiology and Genetics
Department of Applied Bioinformatics, Göttingen, Germany.

Original publication:
Rieseberg T. et al,
Time-resolved oxidative signal convergence across the algae–embryophyte divide.
Nature Communications 2025. DOI: 10.1038/s41467-025-56939-y

Abstract
The earliest land plants faced a significant challenge in adapting to environmental stressors. Stress on land is unique in its dynamics, entailing swift and drastic changes in light and temperature. While we know that land plants share with their closest streptophyte algal relatives key components of the genetic makeup for dynamic stress responses, their concerted action is little understood. Here, we combine time-course stress profiling using photophysiology, transcriptomics on 2.7 Tbp of data, and metabolite profiling analyses on 270 distinct samples, to study stress kinetics across three 600-million-year-divergent streptophytes. Through co-expression analysis and Granger causal inference we predict a gene regulatory network that retraces a web of ancient signal convergences at ethylene signaling components, osmosensors, and chains of major kinases. These kinase hubs already integrated diverse environmental inputs since before the dawn of plants on land.

Introduction
Earth’s surface teems with photosynthesizing life. Biodiverse cyanobacteria and algae form green biofilms on rocks and tree barks, and lichens thrive on the bleakest mountaintops. All of this is however dwarfed by the lineage that conquered land globally: the land plants (embryophytes)¹. Together with streptophyte algae, land plants belong to the streptophytes². Phylogenomic analyses established that the Zygnematophyceae are the closest streptophyte algal relatives of land plants^2,3,4 and comparative genomics have ushered in major progress in establishing a shared catalog of genes for key traits between streptophyte algae and land plants^5,6,7,8,9,10. Yet, we are only beginning to understand how these genes might have been used in a functional advantage at the time of the conquest of land¹¹. Several synergistic properties that hinge on a complex genetic chassis have shaped the plants that conquered land¹², including multicellular development^13,14, propagation¹⁵, symbiosis^16,17, and stress response¹⁸. In case of the latter, the earliest land plants had to overcome a diverse range of stressors to which modern land plants dynamically respond by adjusting their growth and physiology¹⁹. One of the hallmarks of abiotic stress on land in contrast to water is its more dynamic nature: life on land involves rapid and drastic shifts in temperature, light or water availability¹⁸. We focus on two terrestrial stressors: strongly fluctuating temperatures (cold and heat stress) and light conditions (high light stress and recovery).

Terrestrial stressors impact plant and algal physiology especially through the generation of reactive oxygen species (ROS) in the plastid; the plastid acts as a signaling hub upon environmental challenge^20,21,22. Carotenoids are integral in the oxidative stress mitigation networks of Chloroplastida and found in nearly any photosynthetic organism^23,24. By quenching oxidative stress of different nature, oxidative breakdown products of the polyene backbone called apocarotenoids are a consequence^25,26. Apocarotenoids act as signals in attuning plant and plastid physiology to stress^{27,28,29,30,31}. The diversity of apocarotenoids is vast, including land plant hormones like abscisic acid (ABA)32,33 and strigolactones³⁴ but also small volatiles like β-ionone (β-IO) and β-cyclocitral (β-CC) with a growing number of recognized functions^{27,28,29,30,31,35}. The involvement of β-CC in high light stress response was confirmed by several studies in Arabidopsis thaliana^27,29 and some data also suggests a role in retrograde signaling^36,37. A physicochemical consequence of the elevation of atmospheric oxygen levels due to plant terrestrialization and radiation³⁸ might have been higher rates of apocarotenogenesis—even independent of the evolution of carotenoid-cleaving enzymes. The utilization of signals derived from carotenoids in the first land plants is hence plausible and adaptive.

Here, we studied the integration of apocarotenoid signals and oxidative stress networks in three genome-sequenced non-vascular streptophytes: the algae Zygnema circumcarinatum^107,11, and the land plant Physcomitrium patens³⁹. Of data on pigment profiles and photophysiology correlations were calculated with time-resolved global gene expression profiles from 270 biological samples in total. Using gene co-expression and gene regulatory network inference, we retrace a web of ancient kinase hubs where environmental and apocarotenoid signals converged already in the last common ancestor of embryophytes and algae.

Rieseberg, T.P., Dadras, A., Darienko, T. et al.
Time-resolved oxidative signal convergence across the algae–embryophyte divide. Nat Commun 16, 1780 (2025). https://doi.org/10.1038/s41467-025-56939-y

Copyright: © 2025 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

This discovery provides compelling evidence for the theory of evolution, demonstrating that complex genetic networks can be preserved across vast evolutionary timescales due to their fundamental roles in organismal survival. The conservation of these gene hubs suggests a shared ancestral mechanism for stress responses, supporting the concept of common descent. In contrast, creationist perspectives, which often reject such evolutionary continuity, are challenged by this finding, as it highlights the deep genetic connections linking diverse life forms through evolutionary history.

Of course, we can refute the inevitable creationist excuse for these conserved common mechanisms across related clades, that this is evidence of common design rather than common descent, because, although highly conserved, they nevertheless show evidence of divergence. A common design by an omniscient creator would show no such modification because its design would be optimal and fitted for purpose. It would therefore not need to be modified over time in response to changing environmental pressures.

As an aside, I asked ChatGPT4.5 to response to creationists claim that this is evidence of common design, not common ancestry. Creationists might like to ignore the response:

A likely creationist response will be to argue that this shows common design, not common ancestry. How can this be refuted?

Creationists often argue that genetic similarities between organisms are evidence of "common design" rather than common ancestry. However, this argument fails under scientific scrutiny for several reasons:

Predictive Power: Evolution vs. Common Design

The theory of evolution makes testable predictions about genetic inheritance, including the presence of nested hierarchies, conserved genetic sequences, and transitional forms.
The concept of common design, on the other hand, lacks predictive power. If an intelligent designer created life, there would be no reason to expect conserved genetic "hubs" specifically among land plants and their closest algal relatives while being absent in other unrelated groups.
Evolutionary theory predicts that gene regulatory networks essential for adaptation (such as the stress response genes in algae and mosses) should be conserved in closely related lineages. This is exactly what was observed in the study.

Imperfections and Evolutionary Constraints

The stress-response gene hubs found in mosses and algae are not designed from scratch but are modified versions of pre-existing genetic networks.
If life forms were designed independently, there would be no need for such modifications or inherited constraints. Instead, we would expect optimal, tailor-made designs for each organism.
Evolution explains why organisms retain suboptimal, repurposed features due to descent with modification. A designer could have created perfect stress-response mechanisms without reliance on ancient, inherited gene networks.

Phylogenetic Evidence and Nested Hierarchies

The gene hubs found in this study are not universally distributed across all plants but are specifically conserved in land plants and their closest relatives, the charophyte algae.
Evolution predicts such nested hierarchies-where more closely related species share more similarities—because genetic traits are inherited and modified over time.
If an intelligent designer had reused the same gene networks across all plants or even across all organisms, the pattern of descent would not match evolutionary relationships.

Molecular Fossil Record and Gradual Transitions

Fossil evidence already shows the gradual transition from aquatic algae to land plants.
The discovery that the same genetic networks exist in charophytes and land plants provides a molecular fossil record, further supporting this transition.
The theory of common descent is the only explanation that unifies fossil, genetic, and developmental evidence into a coherent framework.

Lack of a Mechanism for Common Design

Creationists argue that a designer reused genetic blueprints, but they fail to explain how this design process occurred.
Evolution provides a clear, evidence-based mechanism (natural selection, genetic drift, and gene duplication) for the presence of conserved genetic networks.
Without a defined mechanism or testable predictions, "common design" is not a scientific explanation but rather a theological assertion.

Conclusion
The discovery of conserved gene hubs in algae and land plants strongly supports common ancestry, as it fits within the framework of evolutionary theory. The argument for common design is refuted by its lack of predictive power, the presence of evolutionary constraints, the hierarchical distribution of genetic similarities, and the absence of an explanatory mechanism. Evolution provides the only scientifically supported explanation for these observations.

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