Tagged: Variation Under Nature

Variation abound!

After four sessions of variation, I think we kinda got the hang of what Darwin is trying to say in Chapter 2. The crux hasn’t differed much from what we had gathered from our first discussion of the chapter. The difference is a tinge of light peeking through the haze of all that confusion. There’s one thing that struck me while I was reading the second chapter for the third or fourth time. Darwin was writing this manuscript at a time when the creationist point of view was dominant. It’s hard for us (ecologists/biologists) to think of something like that right now in this era when we’ve been schooled to think that evolution is the only explanation to life, the universe and everything (ok, I’m exaggerating). But let’s just step back into time and place ourselves in Darwin’s shoes…figuratively speaking. I have no clue what his shoe size was. That’s when you’ll realise why he’s being so cautious in his approach to asking the ultimate questions, “Why should there be so much variability in nature?” and “Why should some genera have more variability than others?” if there was a God/Almighty Creator who just decided to create and populate the Earth. Darwin must have realised it’s not because God just felt like it. There was too much of a pattern that emerged from analysing all his tables (by the way, I have no clue what tables he was talking about) for variation to be attributed to something as random as God creating species. Where there is pattern, there is process. And Darwin very cautiously introduces and speculates on the processes which he thinks are at work that gives rise to those observed patterns.

In this chapter he introduces (very slowly) his ideas on the slow “manufactory of species” that is “still in action”. And the action is through “natural selection accumulating… differences of structure in certain definite directions.” He doesn’t define what natural selection is yet, although he does mention that such action is not only because of the physical environment in which an individual organism resides, but because of other factors such as competition with other individuals. Of course, there’s an entire chapter dedicated to natural selection. I’m sure he goes into great detail there. But before that he’ll be dealing with another of his musings…about the Struggle for Existence. That’s chapter 3, and, thankfully, a very straight-forward one. Looking forward to discussing that one this Wednesday, February 20th, 5:30pm.

PS: There were some points that we were still not clear about while discussing this chapter. I’ll list those out here so that we can continue the discussion online:

1. Viraj had asked if natural selection is something that would act on a population or an individual. Navendu and I thought that it would act on individual traits, but Viraj and Vijay thought it would most likely act on a population. Now, considering that a population is a group of individuals, what do you think?

2. A trivial point, but Navendu and I were very confused on a distinction that Darwin had made with the distribution of a species, because he had used “wide-ranging” and “diffused” to mean two very different things. Well, at least he explicitly said so. So to help us out with that you’ll have to read the chapter. Good luck with that.

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Variation

“TIME OUT!!!”

No, this isn’t a basketball game we were attending, but rather a desperate attempt by a clueless group discussion leader to bring a house to order. Little short of a parliamentary session, if you’d like an Indian analogy.

There was much variation in opinion within the group Friday last when we were discussing the second chapter of “The Origin of Species”, the larger group slowly diversifying into sub-groups and sub-sub-groups, with much confused looks on faces. Let me try and explain some of this confusion..

The second chapter “Variation under Nature” is where Darwin uses the classification of life (the Linnaean classification system) as

Darwin’s Shells Image from http://www.guardian.co.uk

a means to describe his theory of the origin of species, in a very brief way. The presence of “varieties” within a group of organisms was the baseline for the origin of “a new and distinct species” by “Divergence of Character”, was Darwin’s argument. Now here was where the confusion began… what did he mean by a “variety”?

In chapter one Darwin uses the terms “species” and “variety” without defining the terms (yes, I know, we researchers are hung up on definitions) leaving a lot of room for assumption. In the second chapter, he goes into great detail on the distinction between species and variety, and tries his best in defining what he means by a variety. I say tries his best because we were still confused even after all that discussion around the subject,  leading to confusion number one. The confusion wasn’t limited to us though.. Darwin also surmises that taxonomists (of his day) are a confused bunch over the topic, not being able to decide how much of a difference is necessary to distinguish variety from a species. However, he does mention his own definition of a variety as a form the characteristics of which “…. can be inherited for at least some few generations.“. This is an important point that he brings forth in the discussion, that of inheritance, which is, of course, a repeated theme in the book, but gets first mention here. It also got us thinking about whether he was alluding to epigenetics, and if he meant that forms otherwise just exhibited phenotypic plasticity. That got us arguing for at least a half-hour. We were just in the first para, by the way.

chapter2 2nd

Variety

On to confusion number two, and a jump to the concluding para of the chapter (as you can see, we were an organised bunch). Darwin talks about genera, how large genera have the most variation, and “larger genera thus tend to become larger”. But then he also says that “larger genera also tend to break up into smaller genera”. Now, pray tell, if this does happen, how do the large genera remain large?!

The gist of the chapter seemed to clear, but his justifications need more reading into, perhaps. We’ll be continuing with the confusions, sorry, discussion, this Wednesday, the 6th of February at 5.30 pm in the Tea Room. Do join us to add to the confusion. 🙂

Chapter 3 will be discussed most probably, on Wednesday next week on February 20th.