3 Favorites for the Week

Here are my three favorite hpb-oriented posts from around the blogosphere in no particular order:

John Wilkins has an interesting commentary on a new speciation paper in PNAS (by Funk, Nosil, and Etges) in, "Speciation of Invaders by Natural selection," at Evolving Thoughts. Wilkins wonders whether the PNAS paper establishes much more than the obvious point that "ecology plays a role in shaping the structure and function  of new species." He says:

"I think it does. The import lies not in the fact that species are isolated reproductively from their relatives, but that they are cohered with their own by selection. In short, what causes a species is that it is a genetically compatible group with a shared reproductive "reach". And this contributes to the fitness of variants, largely for the very obvious reason that if you can't interbreed with your neighbours, you have a zero fitness. What causes isolation is either geography (allopatry) or divergent selection in sympatry. So being a different species is due to RI; being the same species is due to selection for a range of properties, including reproductive reach and ecological adaptation.

I distinguish between extrinsic and intrinsic selection for this conspecific cohesion. Some aspects of being a species are caused by extrinsic environmental selection - of course we should expect that, for those that cannot flourish cannot breed. But also, in sexual organisms, one has to be compatible with potential mates, and so selection for intrinsic properties that facilitate this must also play a role.

If we think of speciation as "what makes a species" then we get ecological and other selective processes. If we think of speciation as "what makes it not the same species", then the explanatory focus shifts, and here the answer is, in cases when divergent selection is not going on, populations simply drift away from the reproductive reach of the ancestral population."

Carl Zimmer makes a fairly obvious point about the nature of biological inquiry in "The Dawn of Brains and Bones," at The Loom. I say "obvious." But in the current public "debate" over the claims of evolutionary biology, the point needs to be made again and again. Among other things, he says:

"Scientists learn new things about the world. They revise their theories. They do not pull away a curtain, to reveal Truth with a capital T, and walk away. And just because they do not deal in Truth with a capital T does not mean that they deal in pure nonsense. Their knowledge improves, although it never reaches perfection.

The origin of vertebrates is a case in point."

The case is, indeed, a lovely illustration of Zimmer's methodological point.

Finally, there's a nice post on the origins of naturalistic explanations of the world in "Naturalistic Biological Evolution," at Gene Expression. After pointing out that such modes of explanation originated with the Pre-Socratics, Razib says:

I have expressed the opinion that the human mind is biased against Darwinian evolution, but, the idea space that our species explores can be rather large. Even if you have an expectation, human variation (variance or error) often dictates that there are always those who swim against the current and generate some inevitable turbidity in the sea of human experience. In The Alternative Tradition:  A Study of Unbelief in the Ancient World we see that movements like the Epicureans in ancient Greece, the Carvaka in India or the non-supernatural strain in Confucianism exemplified by sage Xunzi exhibit the naturalistic strain in intellectual history. This strain comes to the fore in complex literate civilizations where dissenters can attain critical mass and organize a counter-culture against normative supernaturalism (for instance, the Pyrrohnian Skeptics dominated the intellectual life of Athens until the rise of Neoplatonism during the Roman period). Of course we don't need to look just to the naturalistic paradigm to see glimmers of a conception of evolution, the legends and mythologies of most peoples are riddled with transformation of animal to man and vice versa, so extracting the magical elements should naturally occur to some."

Reading the whole of each post is worth the time and effort.

Comments

[Tetsuji]

Hi Rob,
Long time no see.
Nice to see you are doing fine.
This blog looks very informative.
Good work.

[Robert Skipper]

Long time no see.

Indeed! I hope you're doing well!

Good work.

Thanks!