Tuesday, September 6, 2011

Did Silene maritima evolve waving in order to seduce bees?

Silene maritima  
More information and photos in Rob's plants page

Are flowers really waving in order to attract pollinators?

According to an interesting study by J.Warren and P.James they apparently do! It is as if they are winking in wind at passing bees and butterflies for their attention! 

Do flowers wave to attract pollinators? A case study with Silene maritima
(Journal of Evolutionary Biology 2008 Vol 21.4:1024-1029)

The problem is that evolutionary biologists commonly use the verb evolve as if the species were the subject of the action: "plants evolved waving in order to..."

Well, how does a nice Silene maritima suddenly decide that it will from now on start to wave in wind to attract those pollinators? What particular part of the plant takes the decision for such a line of action?

Of course, the biologist does not mean what the active mode implies - that the plant itself decides to change in some way beneficial to its survival in nature.

Instead, the Darwinist idea of natural selection is that the plant has variants in its living environment. Some mutations have tough but short stem for the attractive flower, others have taller and thinner stems that wave in the wind. Because insects notice the movement these plants are more successful and have more seeds than those with shorter stems that do not move so much. At some point the genetically inherited stem may grow so tall that the plant suffers from other difficulties and so the ideal height is eventually achieved by the force of natural selection.
(BBC article)

The plant itself is not an active player as if intending to reach some beneficial goal. In evolutionary biology the organism is only a passive player. It provides the genetic raw material through random mutation and is thus raw material in the process. Evolution follows from the combination of many environmental factors, for example the local wind patterns or humidity in the place where it is growing. For the evolution of flowers the behavior of insects is of crucial importance and there are many other things modifying its "behavior."

So we can look at this explanation as a beautiful theory that

- more or less explains the ideal length that evolved for the waving movement
- as a look at the divine lathe that was sued to shape Silene maritima

The two views do not necessarily contradict each other and the latter does not add anything to the details of the working of the evolutionary lathe! It just expresses the faith that it is not the result of chance changes but that God of Israel is behind its design and proper working in a process of evolution of life forms living in complex symbiosis.

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