Comments on: How many species are there? My latest for the New York Times

By: Justthinkin

Justthinkin — Thu, 25 Aug 2011 12:46:40 +0000

Ken Ham and his Answers in Genesis group are well along with their real life sized Noah’s Ark theme park project in Kentucky, USA. They have announced that the ark will have between 2000 and 4000 individual species in it. Assuming no insects or fish, that puts the creationist upper limit on what constitutes a valid species. This should save scientists a lot of time in making classifications from now on. We can only hope that the dinosaurs are in a secure cage.

By: Acleron

Acleron — Thu, 25 Aug 2011 01:44:40 +0000

So they applied their method to well known groups like birds and mammals and found it fitted their relationship and then they conclude it works because these groups are well studied. But surely the ‘well studied’ part also includes modifications to the groupings called species, genera etc which doesn’t happen to the less well studied.

Some nice observations but hardly supportive of a predicted figure precise to 2 significant places.

By: Troy Britain

Troy Britain — Thu, 25 Aug 2011 01:40:24 +0000

Nick’s been drinking the Phylocode koolaid again.

By: How Many Species on Earth? « Life « Science Today: Beyond the Headlines

Wed, 24 Aug 2011 22:23:21 +0000

[...] Zimmer explains the method in his Discover blog, The [...]

By: Torbjörn Larsson, OM

Torbjörn Larsson, OM — Wed, 24 Aug 2011 19:36:07 +0000

As a comparison, in physics effective theories (or models) do have some predictive ability.

Not being a biologist, it seems to me here taxonomy compare to cladistics as newtonian gravity compare to general relativity as it “preserves a signal”. (And even general relativity is known to be effective, non-quantum. Similarly I assume cladistics gets modified by HGT, say.)

And at least in physics you don’t use the more complex methods if the simpler works. Though you may well want to know _why_ they work.

By: Joshua Zelinsky

Joshua Zelinsky — Wed, 24 Aug 2011 14:07:21 +0000

“may have foud”- foud should be “found”.

More substantively, I was thinking along lines similar to Nick’s. It is interesting that the lack of precise definitions doesn’t hamper this method too much. I’m also wondering if it might not handle the issue that some phylums and families are just tougher to find or detect distinct species. This might cause this method to undercount somewhat. I’m not sure. They’ve probably thought about this issue.

[CZ: Type fixed. Thanks. The authors said to me that their suspicion is that modern taxonomy is so closely tied to real phylogeny that it preserves a signal of how lineages diversify--on average.]

By: Günter Bechly

Günter Bechly — Wed, 24 Aug 2011 11:35:11 +0000

I completely agree with Nick Matzke that this kind of counting and estimating is rather worthless considering the fact that there is no non-arbitrary criterion at all for assigning ranks or to compare unrelated taxa of equal rank.
I do not agree with Gunnar that groups with Linnean rank are better supported as monophyeletic. Obsolete paraphyletic taxa like Protozoa, Invertebrata, Apterygota, Hemimetabola, Anamnia, Reptilia and Pisces all had well-established Linnean ranks. Furthermore, taxa like Mammalia or Aves are only well supported if they are restricted to the recent crown group and compared to their recent sister group, but they get more and more watered down in support when fossil stem group representatives are included.

By: Danny

Danny — Wed, 24 Aug 2011 11:00:22 +0000

There’s an fantastic new short film from WWF out about new species at the minute. Might be of interest.

http://www.youtube.com/watch?v=6hO5FFRykOA

By: Gunnar

Gunnar — Wed, 24 Aug 2011 06:22:31 +0000

Linnaeus’ genius was pretty much an accident, but its importance is hard to deny when one considers the facts. Even though he was himself a creationist, Linnaeus showed that relationships between biological organisms were hierarchical: Species within one genera are (ideally) more similar to each other than to members of other genera within the same family, genera within one family are more similar to each other than to members of other families etc. This pattern, which always was suspected, was formalised through Linnaean nomenclature and was thus made subject of constant testing.
The pattern of groups within groups corresponds very well to the modern paradigm of cladism, in which groups originate when their parent species branch in two or more.
Whereas Nick is right in that a group of one given Linnaean rank can not be directly compared to another group at that rank, often the groups that have Linnaean ranks are better supported than other groups in terms of monophyly, breadth of evidence etc. “Phylum Arthropoda”, “Phylum Mollusca”, “Class Insecta”, “Class Mammalia” etc. are supported as monophyletic both by genetic data and by the distribution of morphological characters in space and time, whereas most clades are supported by much smaller numbers of characters.
The Linnaean classification thus ensures both accuracy (the groups in the classification corresponds to actual groups generated by natural evolutionary processes) and stability (the groups in the classification do not change much over time).

By: Nick (Matzke)

Nick (Matzke) — Wed, 24 Aug 2011 04:20:29 +0000

“The scientists reasoned that we’re probably closer to having found most kingdoms, classes, and other high level groups.”

I’ll be impressed, as soon as someone can define “kingdom”, “class”, etc. for me. Any takers? And the figure seems to assume that “species is to genus as genus is to family, etc.”. What is the justification for this? We already know that “families” of plants are not comparable to “families” of insects or vertebrates, neither in age, nor diversity, nor disparity…so what exactly are we counting?

Down with Linneaus!

[CZ: Nick--the scientists don't think such a definition is necessary to use the hierarchy to get these estimates. As artificial as its origins may be, Linnean classification today captures something about the nature of diversification, as evidenced by the validation the scientists carried out on well-studied groups. At least, that's what they say.]

By: Jonathan Eisen

Jonathan Eisen — Wed, 24 Aug 2011 01:52:25 +0000

I wrote a blog post about the article with some additional comments about the microbial side of things: http://phylogenomics.blogspot.com/2011/08/bacteria-archaea-dont-get-no-respect.html