|
Register | Sign In |
|
QuickSearch
Thread ▼ Details |
Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
|
Thread Info
|
|
|
Author | Topic: Interweaving Evolution & Hybrid Vigor | |||||||||||||||||||||||||||||||||||||||
RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
I was rereading the Peter & Rosemary Grant, Darwin's Finches and Evolution thread and in particular noted this passage from the initial quote (Message 1):
quote: And I also recall the discussion on New Species of Homo Discovered: Homo nalediHomo[/i] Discovered: Homo nalediHomo[/i] Discovered: Homo naledi of a "braided" history ... from the article:
quote: Because Homo naledi is a mosaic of features some modern derived features and some preserved ancestral features, and that applies to other species, such that there is some mixing and matching going on, this suggests some hybridization in the past. We also know from DNA analysis that there was some hybridization with Homo neanderthalus (alt Homo sapiens neanderthalus ) Wikipedia defines Heterosis as:
quote: An example of outbreeding depression would be horses, donkeys and mules, where reproductive isolation is not complete but usually results in sterility. So outbreeding can result in hybrids that are more fit, equally fit or less fit, at which point natural selection would favor the more fit (heterotic) varieties becoming dominant in the population/s, leading to a new species group. Crossbreeding is done a lot in animal husbandry and agriculture to develop improved stock, so it should not come as a surprise that it can occur naturally when daughter populations regain contact after undergoing different evolutionary experiences, but before they have evolved reproductive isolation. The amount of independent evolution could vary a lot, as it is the development of reproductive isolation that would stop such interbreeding. Certainly when we see that hybrids can be made between lions and tiger or between lamas and camels after long periods of separation. We also see this between European invaders and Native peoples of the Americas. So the tree became a bush becomes an interlinked\braided bush. A Where C is not the same as A, but is a braided mosaic of B and D. Note that A, B, C and D still form a clade descended from A. This does not mean that evolution does not happen, just that the process is not a cut-and-dried cookie-cutter proposition. This also means that the definition of "species" is a little muddier than before ... and it was muddied before. Enjoy Edited by RAZD, : subtby our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
|
|||||||||||||||||||||||||||||||||||||||
RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined:
|
Another application of this to the debate is when we look at animal husbandry, agriculture and breeding programs.
So outbreeding can result in hybrids that are more fit, equally fit or less fit, at which point natural selection would favor the more fit (heterotic) varieties becoming dominant in the population/s, leading to a new species group. Now we can see in dog breeding that some dogs are bred to create an extremely inbred population in order to maintain the "breed" and that these types of breeds often exhibit inbreeding depression. These are the "show" dogs, but they are not the only breeds. Another class of dog breeds are "working" dogs, where the appearance of the dog is not as important as the function. The sheep herding dogs come to mind. To my view they seem to exhibit Heterosis and not exhibit any of the inbreeding symptoms. We can also look at cow and pig breeding, where the purpose is not some aesthetically "pretty" animal but one that fills a function (more milk, more meat). From the Wikipedia definition of Heterosis again:
quote: When the aspects of rapid growth, size and robust health are considered it is easy to see why this is pursued in husbandry. Again, we can see how (properly applied) artificial husbandry practices offer a window into how natural evolution (mutation and selection) can operate. Enjoyby our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
|
|||||||||||||||||||||||||||||||||||||||
RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Punctuated equilibrium - Wikipedia
quote: The standard view iirc, is that a small subpopulation evolves in isolation, and then returns to the habitat of the parent population and displaces it with their better adapted phenotypes. With the emerging thoughts on "braided" beginnings to new species and hybrid interactions during the early stages of new species formation, it seems more logical to me that the returning subpopulation interbreeds with the parent population and the hybrid offspring inherit traits from both populations, which are then selected for fitness, leaving a new population with hybrid vigor and a mosaic of traits. This has the benefit of mixing the best of both populations within a larger breeding population. Enjoyby our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
|
|||||||||||||||||||||||||||||||||||||||
RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Discussion, on how evolution works in regards to speciation. It's not always straight line process of speciation, but a little tangled, a little messy.
Also, I think punctuated equilibria when a population experiences a period of rapid evolution, as opposed to relative stasis. The population could subsequently return to displace the original parent population, but I think that's just competition, not punctuated equilibrium. The basic idea behind punctuated equilibria, as I understand it, is that a smaller relatively isolated population undergoes rapid evolution, possibly to adapt it to a slightly different ecology. Then it returns to the parent ecology which has been in stasis (continually readapting to a static ecology) and has an advantage for survival or breeding, and then it takes over and displaces the parent population. The question I am raising on this is whether full speciation of this daughter population is necessary, or would not a new varietal phenotype that can interbreed and form hybrids that join the best features in a mosaic of phenotypic traits be a valid or better explanation. We have evidence of such mosaic evolution, the braided stream pattern noted on the Homo naledi thread for instance, and the Darwin Finch hybrid "big Bird" as another. Enjoyby our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
|
|||||||||||||||||||||||||||||||||||||||
RAZD Member (Idle past 1436 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Possibly. Or it might migrate somewhere else. Or nowhere else. Or it might return to the parent ecology and co-exist with the parent. Or it might return to the parent ecology and find that there is no longer any parent population to compete against because it's gone extinct. True. Part of the reason I want to open this to debate with others, particularly those that know more about this than I do.
I thought what was novel about the punctuated equilibria idea was that the episodic nature of the fossil record wasn't necessarily just an artifact of an incomplete fossil record, that it could also be real. Indeed, but for my argument ("the part I want to focus on" ... ), especially in those areas where successive fossil layers show noticeably different forms. Now, I would like to credit Faith for leading me to think in this direction while formulating responses to her argument and her questions on this phenomenon in the fossil record. And I have another example that I am working on, which I will save till after promotion and some confirmation from others that I am not just blowing smoke. Enjoyby our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
|
|
|
Do Nothing Button
Copyright 2001-2023 by EvC Forum, All Rights Reserved
Version 4.2
Innovative software from Qwixotic © 2024