News speciation Tree of life

Small size, large populations, make species formation difficult?

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File:Tree of life by Haeckel.jpg
Haeckel’s tree kind of looked like one.

A recent op-ed in The Scientist raised once again the question of when and where the very concept of “species” has validity.

File:Tree of life SVG.svg
current model interesting, not a tree/Ivica Letunic

In the previous post about Cretacean extinctions, I referred to extinct bee groups, not “bee species.” Intentionally.

The species concept is central to the checkboxes of orthodox biology, as in Darwin’s Origin of Species, the Holy Book which was written (as all true believers attest) before time began and before all worlds.

But is it nearly so central to the behaviour of the majority of actual life forms on this planet? Ecologist Axel G. Rossberg wonders:

The biological intuition about species formation is mostly based on observation of birds, mammals, and other larger creatures. However, it is the meiofauna (of body size around 0.05–1 mm) and smaller microorganisms that dominate biodiversity and ecosystem functioning on Earth. It is therefore important to ask if our current understanding of species formation is applicable to these organisms.

One way to approach this problem is through the study of simplified evolutionary models. Analysis of these models can give insights into real-world processes happening over many millions of years that cannot be directly observed. In this context, species formation can be interpreted as a particular instance of the general phenomenon of self-organized pattern formation. Just as a jet of water can break up into little drops, but will do so only under certain conditions, the ancestral tree of life on Earth may, near the tips of its branches, become structured into distinct species when the conditions are right. [Colour emphasis added.]

We predict that at around the millimeter scale of body size and smaller, populations become large enough to prohibit species formation. This is consistent with results of recent work in the field of environmental genomics, in which organisms are collected from environmental samples and parts of their genomes are read using high-throughput sequencing.

This op-ed may be a way of opening a sustained, long-overdue discussion of just what relevance “species” has in many situations. But this effort, like so many others, will probably just fall down the memory hole. Too many legacies and careers at stake now.

2 Replies to “Small size, large populations, make species formation difficult?

  1. 1
    goodusername says:

    The species concept is central to the checkboxes of orthodox biology, as in Darwin’s Origin of Species, the Holy Book which was written (as all true believers attest) before time began and before all worlds.

    Um, Darwin spends a great deal of time in Origin (and following works) arguing how vague the concept of “species” really is, and the difficulty in defining and identifying species, and in differentiating species from race and variety, etc. It’s a major theme of the book.

    This op-ed may be a way of opening a sustained, long-overdue discussion of just what relevance “species” has in many situations. But this effort, like so many others, will probably just fall down the memory hole. Too many legacies and careers at stake now.

    The problem of defining “species” has been one of the most discussed and controversial issues in biology for a couple of centuries.

  2. 2
    Robert Byers says:

    As a yEC I agree that species is not very fixed.
    since biblical creationism would teach diversity is the result of wealth and so was greatest in the beginning, and after the flood with a rich world to inhabit, then why not simply types of a creature just find their niche because there is so much to find.
    In other words speciation is not from competition but from leisaure classes. Soi the amazon is so rich because its so healthy and productive. a different type of bug for every tree and then it seems fixed. So finches on the Galapagos just shows leisure classes and not competition from over population and poverty.
    Evolution made the error of presuming poor original diversity and then later wealth when it was a option for the opposite.
    So species today only show the atrophy of biology from poverty. The ammazon simply lasted in its original glory longer so far.

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