I Seek to Understand the Evolution of Feathers

I am confused by what I understand about genetics and the proposed explanation for the evolution of Dinosaurs into birds. Or... perhaps I am not fully understanding the concept?

What I learned in a very basic rundown of genetics is that alleles are the genotypes that determine a species' phenotype. I understand this to mean that if an animal displays any favorable heritable trait, the observable trait is there by a pre-existing genotype within the genepool. Am I correct in my understanding? Please correct me if I am not.

Where I am having trouble is the introduction of a new genotype, which can alter or replace, the pre-existing "scale" genotype into something more like a feather. I understand mutation and/or natural selection is the key, and am having trouble with this... but perhaps my understanding is off?

I don't understand how a "reshuffling" of existing genes creates a new outcome. It would seem to me that if you mix up the color of scales, height, immunity to illness, etc. you would only end up with a different combination of those traits... which would not result in a new physical trait. Granted, speciation is certainly possibe. No argument there. It just doesn't sufficiently explain a brand new creature which now has a brand new, previously unseen, trait.

So... I have come here to gain a better understanding. If anyone can help me please do. I would very much appreciate it.

Maybe you should be looking at this fantastic creature. Its probably the best place to start when investigating the relationship between dinosaurs and birds

en.wikipedia.org...

Similar in size and shape to a European Magpie, Archaeopteryx could grow to about 0.5 metres (1.6 ft) in length. Despite its small size, broad wings, and inferred ability to fly or glide, Archaeopteryx has more in common with small theropod dinosaurs than it does with modern birds. In particular, it shares the following features with the deinonychosaurs (dromaeosaurs and troodontids): jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest homeothermy), and various skeletal features.

The features above make Archaeopteryx the first clear candidate for a transitional fossil between dinosaurs and birds.[1][2] Thus, Archaeopteryx plays an important role not only in the study of the origin of birds but in the study of dinosaurs.

Hopefully this helps a bit

i think he's asking how a new allele frequency can occur if the options available are finite and already present.

from what i understand it comes from either mutations or by the selective process. mutations are 99% inert as i understand it. they're a "mistake" amde in the dna replication process that produces new genes. (i think) i don't know if this is fact or fiction or if it's even possible but that's what they say.

now the selective process says something along the lines of. if a population (group of same species? or type) lives long enough then eventually certain phenotypes will become more prevalent. the common wisdom is that whichever ones survive will either

a. be more suited to their environment and keep producing the select genes while the rest die.

or

b. no one really knows why some creatures live and some die and it's just luck of the draw.

how does this answer your question? it doesn't really. it just means that that's what's being taught in basic biology classes. i don't think dna is greatly understood so science is kind of grasping at straws. if evolutino is true then i'd imagine the answer to your question is along the lines of the "form dictates function" theory"

no different than atoms having different properties by being arranged in different ways. dna is the same way. so one small change could possibly turn arms into wings. or millinos of small ones.

reply to post by Mozzy


Yes I am asking how a new allele frequency can occur if the options are finite and already present.

I wonder, though, how a small change in the DNA is going to bring about something for which there is no precedence. By that I mean that cells have their own mechanisms for error checking. Should something unexpected come up why would the seemingly erroneous information not be tossed aside?

Each cell within your body is coded to perform an individual function. Heart cells function as heart cells, brain cells function as brain cells, and skin cells function as skin cells. If something told the "scale" cell to function in a foreign way why would the checks and balances in place not simply say "no?"

So I have done some research and come to understand a little more about two things, one being natural selection and another being mutation.

Natural selection basically means that favorable heritable traits can become more prominant within a species (Keep in mind this is a very basic definition, and is not intended to be a precise definition).

Mutation is how new alleles appear within the genepool (Also very basic statement).

Given my understanding of the two concepts I have come to the conclusion that birds could not have evolved from Dinosaurs. This conclusion is drawn from the fact that mutation can rearrange alleles, and even transfer new alleles from one gene to another; However, the new gene being transfered, and thus appearing anew within the offspring, was a pre-existing trait within one of the parents. What I am really saying here is that two parents, who are sexually compatible and must then be from the same species, come together and create something slightly different. The offspring can potentially mutate into and entirely new species, however this does not mean the new species is an entirely new creation of nature. For example if a new species of bird came about naturally it would still be a kind of bird.

Natural selection is involved here... but it does not bring about anything new. It simply brings favorable traits to the greater population.

I am not saying Evolution is wrong. There is variation within the species, and over time a species can change. Evolution is therefore fact. Perhaps... we've come to a false conclusion as to just how far it can go.