Evolutionary stasis? – Change and abruptness

Recently I read something about species stasis and I thought that I would be nice to look into that in more detail.  First I want to define species stasis. In general  species stasis is defined as little or no morphological change in an evolutionary history, which spans several million years.

Naturally the punctuated equilibrium theory of Stephen Jay Gould comes to the mind of evolutionists. It is nowadays clear that many examples can be found that exhibit species stasis. The most well-documented examples are the Cheilostomes which show species stasis that spans 2-16 million years, without noticeable morphological change (Jackson and cheetham, 2001).

Normally it is assumed that when species display a stasis for a long period, that much of the morphological change is observed in a short time-span  in a brief time in which speciation occurs.  That’s also the core beneath the punctuated equilibrium theory of Gould (Eldredge and Gould 1972).

Experimental evolution experiments, in the famous experiment of Lenski show that over thousands of generation E. coli do not display major phenotypic evolution. The only source of variation in such experiments is variation from mutation (Cooper and Lenski, 2000).

Indeed, most of the diversification of a lineage occurs when the species invades a new environment coupled by a broad range of new possibilities for adaption. It is shown that species may diverge quickly, which is for example shown in Dropsophila experiments in which a wild population was transferred tot the laboratory and where it was observed that speciation occurs within one generation.

This post cannot go into the details of how such a species stasis is achieved in a population, but it is shown that an intricate and complex interaction of different evolutionary selection forces cause species stasis to happen.

The first and foremost reason that I write this post, is the implication of species stasis for creationism. Young-earth creationists often assume that the earth is around 6000-12000 years old. In such a time frame species stasis could not have spanned millions of years. In a creationist view, one would assume that species stasis is not stasis for millions, but rather for hundreds, or perhaps some thousands years.

Indirectly, the concept of species stasis also provides a justification for the theory that diversification after the Flood was very rapid and that within 400 years most of the species we observe were there. Brief periods of speciation could be correlated with environmental changes (Wood, 2003).

After the Flood, most of the earth was inhabitable, because whole ecosystems were vanished and had to be built up again. There was an enormous opportunity for ecological speciation (Woodmorappe, 1996).  So what we would expect is that major morphological changes and genetic diversification can be seen in the fossil record.

When searching in the literature I found that Kurt Wise had already proposed a theory about a creationist punctuated equilibrium theory in 1989 (Wise, 1989). His conslusion is that because of the observation that a world-wide devastation should cause species stasis, because the observation would not span millions of years, but one moment. In his article he proposed a ‘Punc Eq Creation Style’ (PECS) which is an extended theory which claims that species stais and abrupt appearance of new species is accounted for in a creation model.

I am not an paleontologist, but I have heard about the Cambrian explosion, which caused the abbrupt appearnce of major morphological forms and which is to this day not adequately explained by evolutionists.

This indeed fits perfect into a creationist model.

References:

Cheetham, A. H. 2.1.3 2001.  Evolutionary stasis versus change.  P. 137-142 in D. E. G. Briggs and P. R. Crowther (eds.), Palaeobiology II. Blackwell Science, Oxford, 583 p.

Wood, T.C., Perspectives on AGEing, a young-earth creation diversification model, Proceedings of the Fifth International Conference on Creationism, pp. 479–490, 2003

Cooper, V. S., and R. E. Lenski. 2000. The population genetics of ecological specialization in evolving E. coli populations. Nature 407:736-739

Eldredge, Niles and S. J. Gould (1972). “Punctuated equilibria: an alternative to phyletic gradualism” In T.J.M. Schopf, ed., Models in Paleobiology. San Francisco: Freeman Cooper. pp. 82-115. Reprinted in N. EldredgeTime frames. Princeton: Princeton Univ. Press, 1985, pp. 193-223

Woodmorappe, J., Noah’s Ark: A Feasibility Study, Institute for Creation Research, Santee, CA, Part IV, 1996.

Wise, K. P., 1989. ‘Punc eq creation style’, Origins (USA), 16:11–24.

Advertisements

One thought on “Evolutionary stasis? – Change and abruptness

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s