User talk:Sushant gupta/Mechanisms and processes of evolution

Under construction

The page is currently under MASSIVE CONSTRUCTION. kindly discuus before making any changes. Sushant gupta 14:33, 7 October 2007 (UTC)

Regarding this article

In order to create this summary style article, the content has been taken from the below listed links-

• Evolution
• Speciation

thanks, Sushant gupta 14:20, 8 October 2007 (UTC)

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Hi there

I'm a bit confused, what subjects does this article cover that are not covered in the main evolution article? I only ask since I might be able to help a bit with this if I had a better idea of what this article intends to cover. Tim Vickers 03:37, 15 October 2007 (UTC)

replied on user talk page. Sushant gupta 13:02, 15 October 2007 (UTC)

OK, no problem. Please bear in mind though that the classification of evolution into micro/macroevolution is controversial and not well supported by the literature. The main evolutionarticle touches on this but this is a good paper on the topic. Tim Vickers 14:57, 15 October 2007 (UTC)

thank you for the link. Sushant gupta 10:52, 16 October 2007 (UTC)

Adaptation

I don't really think adaptation has any effect on genetic variation. Isn't it an outcome of genetic change, rather than having any influence on allele frequencies? Tim Vickers 15:34, 19 October 2007 (UTC)

but adaptation leads to genetic diversity. and it increases the mechanism of genetic variation. ummhhh.... may i know why do you think that adaptation has no effect on genetic variation. the question is not whether it is an outcome of genetic change. the point is that what all things leds to genetic variation. well i thought that it do have a massive impact. if its is my misconception then can you please clarify it. Sushant gupta 09:59, 20 October 2007 (UTC)

To take an example, if a population is adapting under stabilizing selection then the amount of genetic diversity will be reduced as it adapts to its environment. Tim Vickers 16:13, 21 October 2007 (UTC)

but it do have an impact on genetic diversity. ok i will shift off the section. actually first you said you don't think that adaptation has any effect on genetic variation. thanks a lot for clarifying my doubt anyway. Sushant gupta 14:55, 22 October 2007 (UTC)

That's a good point. I think adaptation is a consequence, with the order of events running as Variation > Selection > Adaptation the adaptation is at the end of a chain of consequences. Tim Vickers 16:26, 22 October 2007 (UTC)

GA Review

Below listed issues have been discussed and addressed

This article isn't even close to GA status.

The introductory section needs a thorough rewrite. The opening sentence contains a capitalization error. The opening paragraph several times says gene when it clearly means allele. It misdefines sexual selection, genetic drift and mutation, which is an unforgivable mistake when the article is largely about those mechanisms and correctly defines them later in the article!

The article is biased towards the evolution of animals. The article does not give due consideration to the topics of artificial selection, polyploidy, and hybridization, perhaps because the authors are not versed in the works of G. Ledyard Stebbins and other leaders in the study of plant evolution. The article also fails to cover important aspects of bacterial adaptation, which are of critical interest in modern medicine.

The article contains a number of (common) errors and misunderstandings about evolution. Examples:

1. In the section on "Basic processes involved", a statement is made that a harmful mutation "dies out and goes nowhere". While this used to be a common belief in the early and mid-20th century, when eugenics programs were based on this idea, the belief is no longer held. Mutations can persist and be hidden in heterozygous individuals without dying out.
2. There is an erroneous statement that " the processes of mutation and natural selection have created every biological individual that exists in the world today, from the simplest viruses, microorganisms such as bacteria and archaea, to multicellular organisms such as plants and animals." This is problematic in two respects at least. (1) Viruses are not "biological individuals". (2) Artificial selection and hybridization have also created some biological individuals, such as breeds of dogs and the mule.

The article divides the processes into two groups labelled as the sections "Mechanisms that decrease genetic variation" and "Mechanisms that increase genetic variation". This is a faulty arrangment, especially so since genetic drift neither increases nor decreases genetic variation unless an allele becomes fixed. Genetic drift is a change in relative frequency between two or more alleles of the same gene, not the removal of an allele in most circumstances. Also, gene flow can incease or decrease genetic variation in a population, depending on whether there is immigration to the population or emigration from the population. This artificial and erroneous categorization of the mechanisms should be removed.

A number of sentences and paragraphs are missing context and seem to be misplaced in the article. Under the section "Sexual selection", for example, is this paragraph: "Natural selection can be broken down into many components, of which survival is only one. Sexual attractiveness is a very major component of selection." I have no idea what this paragraph is trying to say.

The section on "Macroevolution over microevolution" needs a complete rewrite. It does not explain what macroevolution is, nor does it present why paleontologists (and other evolutionary biologists) believe that microevolution is insufficient to explain patterns in th fossil record, and have therefore adopted the idea of macroevolution. The writing of the current incarnation of this section is impenitrable, and seems to be strongly POV in largely dismissing the idea without giving it proper consideration.

This is not a comprehensive list of problems I found in the article, however it should be extensive enough to demonstrate that this article does not yet qualify for GA. --EncycloPetey 19:58, 12 November 2007 (UTC)