Folks, it’s been fun. I feel like I had a pretty good run as a scientist. I met some amazing people, went to beautiful places, and learned things I never would have imagined (Hodgkinia, WTF?!). With all my frustrations and failures, I’ve never once regretted going back to school and becoming a biologist. But now I need to close the door on all of that and find a new way to make a living.
Recent headlines claim, “Scientists Have Witnessed a Single-Celled Algae Evolve Into a Multicellular Organism.” In reality, the experiment showed that nothing more than a crude clumping together of individual cells had occurred. A new multicellular organism was not created, nor was any real evolution observed.
That’s pretty damning, since the whole point of the paper in question was that we observed the evolution of multicellularity. So obviously, it’s time to find a new career. It will take a bit of time to wrap up loose ends, though, so as long as I’m here, let’s see what else Dr. Tomkins had to say.
One of the major hurdles in the grand story of molecules to man evolution is how life first transitioned from unicellular to multicellular organisms. Plants and animals are complex systems of interlocking cells that form tissues, structures and whole bodies. How could creatures like bacteria or algae make the grand evolutionary hurdle into complex multicellular creatures? There is no evidence of this ever occurring in the fossil record and we don’t see this sort of thing happening now.
What would that fossil evidence look like, exactly? We have outstanding fossils of very simple multicellular organisms dating back as far as 1.2 billion years ago:
But that doesn’t show the transition from unicellular to multicellular, at least not in a way I think would satisfy Dr. Tomkins. Bangiomorpha is already multicellular. We also have lots of unicellular fossils. But what would a fossil that was between unicellular and multicellular look like? What does Dr. Tomkins expect to find between one cell and multiple cells?
As far as “we don’t see this sort of thing happening now,” we do see this sort of thing happening now, at least in the lab:
Boraas and colleagues exposed cultures of the green alga Chlorella vulgaris to predation by the flagellate Ochromonas vallescia, resulting in the evolution of small, heritably stable algal colonies. Becks and colleagues showed that exposure to the predatory rotifer Brachionus calyciflorus selected for heritable changes in the rate of formation of multicellular palmelloids in the green alga Chlamydomonas reinhardtii. Ratcliff and colleagues have shown that selection for an increased rate of settling out of liquid suspension consistently results in the evolution of multicellular ‘snowflake’ colonies in the yeast Saccharomyces cerevisiae and also results in the evolution of simple multicellular structures in C. reinhardtii.
Dr. Tomkins continues:
Despite the futility of the evolutionary paradigm to explain real-world data, scientists who reject God will latch onto virtually any natural phenomena and then put some strange twist on it to support their paradigm.
I HATE it when people latch onto a natural phenomenon and put some strange twist on it to support their paradigm!
Such is the case with a new study involving a unicellular type of algae called Chlamydomonas reinhardtii. This type of creature is typically found as a free swimmer in either fresh or salt water with the help of two flagellum (whip-like tails). However, it’s also well known for its ability to form a gelatinous coat and then clump together with other algae cells to form small clusters of cells called palmelloids. This clumping behavior is an adaptive response that arises as a result of its interaction with its environment.
In 2006, scientists discovered that C. reinhardtii would form these clusters when cultured with rotifer—another microscopic creature that liked to eat them. The clustering together would help them avoid being eaten. Now, in this current study the same phenomena has been observed in a somewhat more elaborate experiment.
Dr. Tomkins sure knows a lot about palmelloid formation in Chlamydomonas (if not the plural of flagellum); I wonder where he learned that. Presumably not from the Discussion section of the new paper, where we spent three paragraphs discussing palmelloids and how they relate to the evolutionary change we observed.
In this new study, an inbred strain of C. reinhardtii was crossed with other genetically diverse types to create new populations with a large amount of genetic variability.
Let me stop you there. Chlamydomonas is haploid; the concept of inbreeding is meaningless. We didn’t cross an inbred strain with ‘other genetically diverse types’; rather, we crossed a bunch of genetically distinct strains with each other (I’m not sure which strain Dr. Tomkins thinks was ‘inbred’).
Then the researchers exposed isolates taken from these crosses to a single-celled predator called a paramecium. In two of the five isolates, the algae seemed to permanently express the tendency to cluster together. In the genetically diverse populations exposed to the predator, this never happened.
Well…yeah. That’s right.
Not only did the researchers make the extravagant claim that they had observed the evolution of multicellularity, but they also claimed that the “selection pressure” of a predator’s presence caused the alleged evolutionary process.
Yes, that’s how experimental controls work. When you set up two experimental conditions with only one difference between them, you can generally conclude that the different outcomes you observe are because of the difference in experimental treatments. Multicellularity evolved in (some of) the populations with Paramecium and in none without; thus we conclude that the evolution of multicellularity was because of the presence of Paramecium.
But a newly evolved multicellular creature was never observed—just globs of algae documented previously as in other studies.
Multicellular globs of algae.
The fact that some isolates expressed the trait permanently likely meant that a loss of information had occurred.
I would love to know how Dr. Tomkins knows that a loss of information occurred.
Perhaps a mutation of a gene occurred in the adaptive response pathway enabling them to cycle back and forth between clumping and free-living.
Perhaps it did! If so, and if such a mutation became fixed in the population, that would be evolution. This is worth exploring a bit, because I’ve heard similar criticisms even from real scientists, who should know better. Wild-type Chlamydomonas can form multicellular clusters in response to certain environmental stimuli, including the presence of some predators. This is a form of phenotypic plasticity, the ability of an individual to express different traits in response to different environments. It is not evolution. But when a plastic phenotype becomes genetically fixed, so that only one trait is ever expressed regardless of the environment, that is evolution.
Evolution is heritable change in populations over time. The idea that heritable change only counts as evolution if it involves an increase in information, or an increase in complexity, or the production of a new ‘kind’, or if it spans ‘molecules to man’ is a misconception. If a population that is capable of phenotypic plasticity experiences heritable change that leaves it incapable of phenotypic plasticity, yes, that is evolution. Furthermore, what we observed wasn’t just a loss of phenotypic plasticity. The wild-type algae form palmelloids in the presence of certain predators. The evolved algae express this phenotype whether the predators are present or not. The phenotype that was previously induced by predators is now expressed regardless of the environment.
In the genetically diverse populations, this never happened. Typically, mutations like this do not allow such creatures to survive in the wild because they are handicapped and can’t flexibly adapt.
All of the replicate populations were founded using the same starting stock, so I’m not sure what Dr. Tomkins means by ‘the genetically diverse populations.’ He’s probably right that our evolved algae would not do well in the wild; a former undergrad in my lab wrote a whole paper about this.
In a previous study, the researchers had wisely noted that the ability of the algae to dynamically adapt their size and clumping traits to their environment was evidence that they could “track environmental changes and respond appropriately.” This new study is yet just another example of evidence for what ICR scientist Dr. Randy Guliuzza has documented called “continuous environmental tracking”—a hallmark of built-in engineered adaptability.
I never knew it was an ICR scientist who discovered phenotypic plasticity!
Research like this ought to be giving glory to the Creator that engineered the pre-programmed adaptability of these creatures, not the illogic of evolutionary myth.
With thanks to Dr. Tomkins for the advice, I’ll take that under advisement.
Boraas, M. E., Seale, D. B. & Boxhorn, J. E. 1998. Phagotrophy by a flagellate selects for colonial prey: a possible origin of multicellularity. Evol. Ecol. 12, 153–164.
Boyd M, Rosenzweig F, Herron MD. 2018. Analysis of motility in multicellular Chlamydomonas reinhardtii evolved under predation. PLoS One 13, e0192184. doi:10.1371/journal.pone.0192184
Becks, L., Ellner, S. P., Jones, L. E. & Hairston, N. G. 2010. Reduction of adaptive genetic diversity radically alters eco-evolutionary community dynamics. Ecol. Lett. 13, 989–997.
Campbell MA, Meister RC, McCutcheon JP, Carey KM, Simon C, Van Leuven JT. 2015 Genome expansion via lineage splitting and genome reduction in the cicada endosymbiont Hodgkinia . Proc. Natl. Acad. Sci. 112, 10192–10199. doi:10.1073/pnas.1421386112
Herron MD, Borin JM, Boswell JC, Walker J, Chen I-CK, Knox CA, Boyd M, Rosenzweig F, Ratcliff WC. 2019. De novo origins of multicellularity in response to predation. Sci. Rep. 9, 2328. doi:10.1038/s41598-019-39558-8
Ratcliff, W. C., Denison, R. F., Borrello, M. & Travisano, M. 2012. Experimental evolution of multicellularity. Proc. Natl. Acad. Sci. USA 109, 1595–1600.
Ratcliff, W. C. et al. Experimental evolution of an alternating uni- and multicellular life cycle in Chlamydomonas reinhardtii. 2013. Nat. Commun. 4, 2742.