Species and systematics
evolvingthoughts | November 19, 2006Some time back, I was doing driving duty for a conference of philosophers (that's the collective noun; another is a dispute of philosophers) on a skin diving trip, and one of my passengers was Jonathon Kaplan (actually, if I'd crashed and killed us all, a large swathe would have been cut through the philosophy of biology, not including me). Jon was talking about adaptive landscapes and the work of Sergey Gavrilets, who proposes that in a realistic view of adaptive landscapes with thousands of alleles there will be hyperplanes of high fitness connecting nearly all regions of genome space. This…
evolvingthoughts | November 1, 2006
The living world, it seems to me, causes no end of trouble for those who would classify it. Its levels, ranks, hierarchies and units all seem to be clear enough, until we encounter troublesome cases. Then they get very troublesome indeed. So I want to say, there are no ranks or set units in biology a priori, and very few and limited, a posterori.
Suppose we take one instance: the "units of selection debate" that was so widely discussed after the publication of a number of seminal works in the 1960s and 1970s. Genes were held to be what evolved, against group selectionists who thought…
evolvingthoughts | October 18, 2006
Well, Stranger Fruit beat me to it (after I told him about it!) but there's a new version of Darwin's works online that has many juicy goodnesses, such as the 2nd, 3rd, 4th and 5th editions of the Origin. Now we can check if these creationists are quoting properly. It has images as well as OCR'd text, and some of these editions were scanned from the Darwin family's own library. Also, there are field notebooks and lots of other stuff.
An OBE for John Van Wyhe, I say...
evolvingthoughts | October 13, 2006Those of you who live near San Francisco might be interested in this talk I'm giving at the Pizza Munch gathering at UC Berkeley in November.
For November we've made arrangements to meet jointly with the Bay Area Biosystematists in Berkeley on Thursday, November 9. John Wilkins (Queensland) will give a talk entitled "The Unseasonable Lateness of Being, Or, Essentialism Comes After Darwin, Not Before."
Abstract: The received view of the history of the species concept is that before Darwin, naturalists held to a view of essentialism, according to which species were constituted by necessary and…
evolvingthoughts | October 5, 2006Well, put a collar on me and call me a bloodhound. It seems that dogs aren't wolves after all. Darren Naish, of Tetrapod Zoology, discusses a whole range of recent literature and the arguments for and against in a truly excellent post.
The arguments against note the morphological and behavioural differences between domestic dogs and wolves, and the fact that dogs when feral seem not to backbreed into wild wolf populations, a sure sign (well, relatively sure) that the two are distinct species. However, there has been some crossbreeding, which is what one might expect if dogs and wolves are…
evolvingthoughts | October 1, 2006
Here is a working list of species concepts presently in play. I quote "Concepts" above because, for philosophical reasons, I think there is only one concept - "species", and all the rest are conceptions, or definitions, of that concept. I have christened this the Synapormorphic Concept of Species in (Wilkins 2003). More under the fold:
A Summary of 26 species concepts
There are numerous species "concepts" (i.e., conceptions of "species") at the research and practical level in the scientific literature. (Mayden 1997) has listed 22 distinct species concepts along with synonyms, which…
evolvingthoughts | September 27, 2006Tarantulas produce silk from their feet:"Researchers have found for the first time that tarantulas can produce silk from their feet as well as their spinnerets, a discovery with profound implications for why spiders began to spin silk in the first place."
I love these sorts of discoveries. Now we have an interesting project - what evolved first and why? Silk for climbing or silk for spinning and prey capture? Some previous work suggested that orb web spinning evolved twice, with one group spinning dry silk webs that use electrostatic forces to capture prey, while another group evolved glue-…
evolvingthoughts | September 24, 2006
Razib has a little post on cultural cladism, but I think he gets it quite wrong.
He repeats the usual trope canard that culture isn't like biology in terms of its evolution. I think it is exactly like it, and that the "analogy" between cultural traditions and species is quite exact. All that differs is the frequency of the various kinds of evolution.
For instance, take Razib's example. He says that because Judaism is very unlike Christianity in some respects, and much more strictly like Islam in its monotheism, it should be seen as a sister taxon to Islam and not Christianity, and the…
evolvingthoughts | September 21, 2006The Epoch Times is reporting the appearance of a snake with hindlegs in Shandong, China. Such reappearances of long-lost traits are called "atavisms", and in this case it appears this specimen has silenced genes that cause limb buds to stop growing and be resorbed. Quite a number of snakes form hind limb buds but lose them as they develop, while pythons retain spurs into adulthood and use them for mating.
What's interesting about this is not that atavisms exist from time to time, because we know now a lot more about the developmental triggering on genes and the conservation of genes across…
evolvingthoughts | September 7, 2006Every taxonomist has to check before they name a genus that the name hasn't been used before, or that their own taxon isn't a synonym of some previously named group. Eliminating synonyms is a complex task, involving a slew of literature from the 1758 edition of Linnaeus' Systema Naturae to the modern era. So a number of reference works were published which list where a taxon name was first published. One such was the ten volume Nomenclator Zoologicus which covered the zoological nomenclature from 1758 to 1994. It is now available in electronic format online, in a database format that can be…
evolvingthoughts | September 3, 2006The "Crocodile Hunter" guy has been reported killed in a freak skindiving accident off the coast of Queensland north of Cairns. Apparently he was pierced through the heart by a stingray.
I visited his Australia Zoo a few years back and was pleasantly surprised how well it presented the animals. I also saw him do the croc feeding routine, with his daughter.
My condolences to his wife Terri and children Bindi and Bob. This is a tragic loss of a real enthusiast, who by reports was as dedicated off-camera as on.
evolvingthoughts | August 31, 2006Go check out Darren Naish's excellent series on the south east Asian wild pig, the babirusas, at Tetrapod Zoology, to see an excellent example of scientific blogging.
evolvingthoughts | August 24, 2006Another group (in this case, pair) of scientists have come up with a species concept. In this case, it's published in the Journal of Mammalogy [304kb PDF], and it turns on species being protected gene pools.
It's not new. It's not even a repeat of prior concepts. It's a collation of several species concepts, given a single name - the "Genetic Species Concept". And the authors know this: unlike many such papers they give citations as far back as the teens and 20s.
The concept they give relies on the recent explosion of techniques for sequencing DNA, however, and that is new. New technology,…
evolvingthoughts | August 24, 2006evolgen reports on debates in Nature about whether the term "prokaryote" is meaningful. Norman Pace argued that the term is a negative one ("privative" in Aristotle's sense), defined by what they do not have (which is to say, a nuclear membrane surrounding the genetic material). Now Bill Martin and Eugene Koonin have weighed in with a letter in which they say
Prokaryotes are cells with co-transcriptional translation on their main chromosomes; they translate nascent messenger RNAs into protein. The presence of this character distinguishes them from cells that possess a nucleus and do not…
evolvingthoughts | August 18, 2006Lawmakers ponder the meaning of fish ...
Here is a case in which taxonomic categories are defined by political and legal considerations. In order to regulate the use of marine species for commercial reasons, to enforce export controls over crocodile (archosaurian) products, shellfish (molluscs), and prawns (arthropods). So the Bill (currently not online, due it seems to a Microsloth IIS error, *sigh*) treats these all as "fish". Reuters notes wryly that this is somewhat in contradiction to the definition in the Australian English dictionary, but that is less of concern than the fact that we…
evolvingthoughts | August 16, 2006Razib at Gene Expression has called for a followup to the "evolution in ten words or less" post he previously had and which I responded to (linked in his post above) with a call for "ten assertions about evolution". So I just saw this, and of course I rise to the challenge...
1. All progress in evolution is local. Any longer term trends are either responses to long term environmental changes or stochastic.
2. Natural selection is not evolution (as Fisher said in his Genetical Theory in 1930. Evolution also covers taxonomic diversity, random processes, sexual selection, and so forth.
3.…
evolvingthoughts | August 15, 2006Occasionally one comes across odd stories in the late medieval literature on natural history, and one is inclined to dismiss them as fablous stories born of credulous superstition. But they illustrate a much more important phenomenon - the shift from seeing nature as a source of moral lessons to seeing nature as something worth studying for its own sake. One such is the tale of the Barnacle Goose.
The Barnacle Goose, Branta leucopsis, is a small (less than 2kg) black and white goose of the order Anseriformes. It lives during the winter months in the Atlantic coasts of Scotland and Ireland,…
evolvingthoughts | August 2, 2006Here is a worthwhile short essay on biodiversity and the role of social norms in science. I particularly liked these paragraphs:
To begin with, it is apparent that "biodiversity" is not a factual observation, but a cultural construction. One way to construct it is by considering only biodiversity that arises from evolutionary processes, in which case loss of "traditional" species equates to loss of biodiversity. Alternatively, one can consider only designed biodiversity, in which case gains in constructed forms of life, such as GMOs or engineered bacteria constitute gains in biodiversity. Or…
evolvingthoughts | August 1, 2006COSMOS magazine is reporting that the local bank, the Bank of Queensland, has bought a Linnean name for themselves. Yes, that's right: they paid for a spider to be named after them officially.
Now, I don't know what you think of the relation between spiders and banks (some spiders aren't venomous, after all), but this strikes me as a good way to fund research into biodiversity. What next? Naming wetlands after Hollywood movie stars? Bogs after federal politicians?
I can think of a few people whose reputations could only be enhanced by having a slug named after them. But seriously, folks, the…
evolvingthoughts | June 20, 2006
Well after reading many papers by various bacteriologists, mycologists, and other non-vertebrates specialists, I have come to the conclusion that there is no single set of conceptions or criteria (that much abused word!) for something being a species in non-sexual organisms, which I am here calling "microbial". Of course, as I noted, microbes can be "sexual" in various ways. They can share genes via cross-species viral infection (transfection or transduction), via gene fragment uptake (transformation), via sharing in a protosexual way (conjugation), and so on, with it being occasional and…