Wastebasket taxa

[Kai]

Also known as the incertae sedis phenomenon. Incertae sedis is latin for "of unknown placement". When biologists don't know where a particular group or species of organisms should go taxonomically, they label it incertae sedis. Of course, the taxa cant just sit NOWHERE until we figure out where it goes. This leads to the wastebasket taxa, groups where organisms of unknown placement are all thrown together until the phylogeny is a huge mess (and the taxonomy is even WORSE) that needs to be sorted through and cleaned up.

The below blog posts courtesy of Catalogue of Organisms look at two different wastebasket taxa, the Amaurobioidea superfamily of spiders, and the huge order of fishes, Perciformes. I don't know if this would be of interest to anybody here, but I thought I would note it for its taxonomic and systematic relevance.

http://catalogue-of-organisms.blogspot.com/2008/08/amaurobioidea-rummaging-through.html (NSFF&S)

http://catalogue-of-organisms.blogspot.com/2008/12/bush-at-top-of-tree.html

[LMNO]

Heh.


SPIDERS!

[Cramulus]

I think it's interesting stuff. I used to study ethnomethodology, which is sort of like the study of scientific methods. Classification is really interesting to ethnomethodologists - those processes reveal a lot about how science works, and how scientific reality is manufactured. Interesting that there is a category for the stuff which doesn't fit in a category, ya know?

[Kai]

Oh, sorry. Should have marked that first link NSFF&S (not safe for fred and suu).

Another term that is discussed in these posts is plesiomorphy. A plesiomorphic character is one that is shared widely than just the group of interest. It is the scientific term for basal, ancestral or "primitive", and lacks the connotations those other terms have. Likewise, apomorphy is the term for a derived, "specialized" or "advanced" character special to the group of interest.

More information here: http://www.palaeos.com/Systematics/Cladistics/defApomorphy.html

[Kai]

I think it's interesting stuff. I used to study ethnomethodology, which is sort of like the study of scientific methods. Classification is really interesting to ethnomethodologists - those processes reveal a lot about how science works, and how scientific reality is manufactured. Interesting that there is a category for the stuff which doesn't fit in a category, ya know?

Not only is it a category of stuff that doesn't fit a category, its a category of stuff that doesn't fit a category UNTIL the right category can be found or a new category has to be made to accommodate. I just listened to a presentation about a genus of caddisflies last week. The presenter was able to group most of the species into subgeneral species groups, but 6 species could not be grouped in these and were called incertae sedis. This is more or less a fact of phylogenetic research; there are going to be a few i. s.'s pretty much no matter how good you are.

[Bebek Sincap Ratatosk]

When I started dating Sjaantze I was terribly surprised to find out that the taxonomic tree wasn't Fact, but rather a best guess.... It was post-JW, when I had fallen hard for Atheism and SCIENCE! I'm so glad she introduced me to the Goddess shortly afterward

[Kai]

The reason its not fact is:

A) Our knowlege of phylogenetic relationships is incomplete

and

B) the classical Linnaean taxonomic system fails in its ability to correctly show phylogenetic relationships between organisms, extinct and extant, and their common ancestors.

For example, with the information we have today, we know that birds (class aves) and some dinosaurs share a common ansestor, and that mammals (class mammalia) and some dinosarus share a common ancestor, and that these common ancestors are different from the joint common ancestor. If we want to be completely correct, all extant birds and mammals are actually in the clade Dinosauria! This is how the hierarchical system works in phylogenetic systematics, also known as Cladistics.

Both the Linnaean taxonomic system and Cladistics are useful for their own contexts. Linnaean taxonomy provides a good view of extant species and also the best method of species identification and diagnosis. Cladistics provides a deep view of the phylogeny of species but is very complicated and difficult to use for extant identification. Both are useful some of the time, depending on what you are interested in.

[Bebek Sincap Ratatosk]

The reason its not fact is:

A) Our knowlege of phylogenetic relationships is incomplete

and

B) the classical Linnaean taxonomic system fails in its ability to correctly show phylogenetic relationships between organisms, extinct and extant, and their common ancestors.

For example, with the information we have today, we know that birds (class aves) and some dinosaurs share a common ansestor, and that mammals (class mammalia) and some dinosarus share a common ancestor, and that these common ancestors are different from the joint common ancestor. If we want to be completely correct, all extant birds and mammals are actually in the clade Dinosauria! This is how the hierarchical system works in phylogenetic systematics, also known as Cladistics.

Both the Linnaean taxonomic system and Cladistics are useful for their own contexts. Linnaean taxonomy provides a good view of extant species and also the best method of species identification and diagnosis. Cladistics provides a deep view of the phylogeny of species but is very complicated and difficult to use for extant identification. Both are useful some of the time, depending on what you are interested in.

Oy, you sound just like her.



It was the first example she provided me which usefully showed my brain how the map is not the territory.

[Kai]

Contrasting the two systems.



Here is a modified Linnaean Tree of Life: http://www.fossilmuseum.net/TreeOfLife.htm

Here is a simplified Cladistic Tree of Life: http://www.tellapallet.com/tree_of_life.htm

and here is the first page of a much much more complex one: http://www.palaeos.com/Kingdoms/default.htm

Very very different ways of classifying. Most people with some knowlege of biology can find their way around the Linnaean classification system, but I still have trouble with the cladistic system.