Origin of Flowers: Evolutionists Don’t Even Know What They Don’t Know

A damaging preprint claims that data
on the origin of flowers is heavily biased

 

Add this to the “Darwin was wrong” department. Include all his followers, too.

Suppose a pollster tried to gauge the mood of the country by only interviewing students at Columbia University. Would the results be reliable? That’s a bit like the complaint lodged against evolutionary biologists by evolutionists about bias in the data used to infer the origin of flowering plants.

Meyer, Galloway and Eckert, writing in the biology preprint service bioRxiv on June 19, begin by dredging up Darwin’s well-known frustration trying to explain the explosive appearance and rapid diversification of flowering plants (angiosperms) in the fossil record:

An “abominable mystery”: angiosperm sexual systems have been a source of both interest and frustration for the botanical community since Darwin. The evolutionary stability, overall frequency, and distribution of self-fertilization and mixed-mating systems have been addressed in a variety of studies. However, there has been no recent study which directly addresses our knowledge of mating systems across families, the adequacy of existing data, or the potential for biases.

Notice that the frustration has been experienced not just by Charley, but by all his disciples in the 167 years since The Origin. Meyer et al. decided to investigate.

Here, we present an updated dataset of mating systems across flowering plants covering 6,781 species and 212 families. We find that the vast majority of our data on mating systems comes from a small number of disproportionally-sampled families, and that families with significant proportions of dioecious or monoecious species are much more likely to be undersampled. This suggests that systematic study bias may mean we know less about this vital facet of plant life than we think.

Systematic bias. Undersampling. Like the pollster at Columbia, this is not good. Plant evolutionists have tended to study the “interesting” cases

But perhaps better sampling would help Charley get over his stomach pains by solving the abominable and abdominal mystery. Do the authors think that is a possibility? Well, if so, not yet. The answer lies in the nebulous mists of futureware.

By assembling existing knowledge of selfing in an updated, harmonized, and publicly available dataset, we hope to promote further research in the rich field of plant reproductive systems. We especially hope to encourage studies which address the underlying distribution of selfing in angiosperms, and selfing-focused papers broadly to consider the adequacy of existing data. We also hope to promote additional investigation into as-of-yet understudied groups, such as understudied families with dioecious and monoecious species, or families which have been shown to be especially under-represented compared to their species diversity.

The authors note that inbreeding depression could lead to extinction (see bottom of this article for discussion).

Did Darwin Bring Understanding?

In their ending discussion, the authors admit with Tontological phraseology, “Our results suggest that we understand less about the underlying frequency of selfing across angiosperms than was previously thought.” Who previously thought that? “We” evolutionists.

Overcoming bias will require not only better sampling but a wider perspective. “As illustrated by our work, it will also be vital that we utilize a more holistic view of plant reproduction,” they say. From there, their preprint descends into Darwinese and climate change.

In an era of unprecedented anthropogenic disturbance, it thus seems plausible that an individual plant’s reproductive strategy could become a stronger predictor of its fitness than it has been in the past.

See “Fitness for Dummies,” 19 June 2014. Notice that there are no scientific laws of plausibility. Plausibility is in the eye of the beholder. Having admitted to bias and lack of understanding (“we understand less”) in their field of evolutionary botany, should their evidence-free plausibility measure (“seems plausible”) be given any more credence than the opinion of a biased pollster?

Status of Darwin’s Abominable Mystery

Now to the crux of the issue: did these authors solve Darwin’s abominable mystery? Or did they at least contribute with more data to the possibility of solving it? No. They only said that all previous studies were based on data that were systematically biased. In their last sentence, they admit that finding so much bias in the samples “illustrates the importance of understanding the prevalence of outcrossing, selfing and mixed-mating across angiosperms.” Earlier, they emphasized the risks of doing science with poor sampling:

Similarly, if our understanding of the true underlying distribution of selfing is biased, then we run the risk of making incorrect and overly simplifying assumptions when modeling mating system evolution with use of PCMs [phylogenetic comparative methods, an evolutionary approach to classifying plants]. Incorrect or biased assumptions, moreover, may more generally lead us to incorrect conclusions, even when estimating quantities as simple as the frequency of selfing and mixed mating across angiosperms.

Back to the drawing board.

We’ve given the Darwinians 165 years to figure out their mystery. How much longer do they deserve? Time’s up.

How much “understanding” did these evolutionary biologists deliver? Do you like it? Is it satisfying? Consider a different source of understanding.

You, through Your commandments, make me wiser than my enemies;
For they are ever with me.
I have more understanding than all my teachers,
For Your testimonies are my meditation.
I understand more than the ancients,
Because I keep Your precepts.
Psalm 119:98-100

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Addendum: Selfing and Mutational Meltdown

Because inbreeding could be an “evolutionary dead end,” it would have been advantageous, therefore, for plants to “evolve” more cases of outcrossing instead of self-pollinization, or “selfing”. The authors found systematic biases in the data: “our collective knowledge about the underlying distribution of selfing, if based on meta-analyses using these studies, will likely be biased.”

If selfing is an evolutionary dead end, why does it appear so often?

Considerable theoretical work has evaluated the evolutionary costs and benefits of selfing (Darwin 1876; Fisher 1941; Nagylacki 1976; Lloyd 1977, 1979, 1980; Cheptou 2019). Most straightforwardly, self-fertilization holds a transmission advantage of gene copies over two-parent reproduction (Fisher 1941). Based on this alone, without an evolutionary cost to selfing, it would become commonplace. The obvious evolutionary cost to selfing is the increased expression of recessive deleterious phenotypes leading to inbreeding depression. Thus, to explain the variation we observe in plant reproductive systems, we must explain both the continued existence of selfing plants in the face of inbreeding depression and the persistence of outcrossing in spite of the two-fold transmission advantage of selfing. The fitness cost incurred by inbreeding depression (Charlesworth and Charlesworth 1987) may explain why selfing does not outcompete outcrossing based on transmission advantage alone (Lloyd 1979). Under circumstances where the cost of inbreeding depression does not outweigh the transmission advantage of selfing, however, selfing can still persist (Lloyd 1979). Another commonly cited advantage of selfing is reproductive assurance in the absence of a mate, or pollen limitation (Darwin 1876; Kalisz 2004; reviewed by Busch and Delph 2012). Selfing has thus also been proposed as a mechanism to aid colonization of new habitats, with self-compatible organisms more likely to be successful colonizers than self-incompatible species (Baker 1955). This is also sometimes referred to as “Baker’s Law.”

Other parts of the discussion waffle between “it could be this” or “it could be that.” But even now, the authors admit that “we remain extremely uncertain about what percentage of angiosperm species are capable of selfing.”

Regardless of the direction of this interaction, the inevitable result is that our understanding of the evolution, ecological characteristics, and frequency of selfing arises disproportionately from a limited number of families that may not be representative of angiosperms overall.

Here’s another outcome of persistent selfing in plants: mutational meltdown. Why hasn’t it happened?

From this body of literature, two prominent – but not mutually exclusive – hypotheses emerged about the expected frequency of selfing across angiosperms. Stebbins (1957) proposed that selfing is an evolutionary “dead end,” with selfing species more prone to extinction. He suggested that the limitations placed on genetic diversity by selfing would constrain adaptation to new environments. This hypothesis suggests, even if the deleterious alleles associated with inbreeding depression could be purged, that over time the loss of genetic diversity would doom selfing species to extinction. However, if transitions to selfing were sufficiently frequent, at any given point in evolutionary time, we could still potentially observe extant selfing species (Stebbins 1957).

Schemske and Lande (1985) proposed that the distribution of selfing should be bimodal, with most species either primarily selfing or primarily outcrossing. Outcrossing would represent a stable strategy by avoiding inbreeding depression and promoting diversity through biparental sexual reproduction. Similarly, highly selfing species would be able to avoid inbreeding depression by purging deleterious alleles and would thus persist due to their transmission advantage and reproductive assurance. Species with mixed mating, however, should be less common, as purging of deleterious alleles would be more difficult under intermediate levels of selfing, yet the risks of inbreeding depression and loss of genetic diversity remain.

Neither hypothesis rises above the level of anecdote. The authors point to a subsequent “wealth of empirical papers addressing selfing in various plant systems” since Stebbins, Schemske and Lande. “However, this larger dataset has the potential to continue promoting the existing biases” identified by these authors and others.

Here’s a solution: “evolutionary time” is a myth. Selfing plants have not been around long enough to suffer extensive inbreeding depression and extinction. They were created thousands of years ago, not hundreds of millions of years ago. Once again, belief in Deep Time is a problem, not a solution.