Tuesday, September 15, 2009
Suzanne Wagner, Bio 419, Darwin domestication
I don't necessarily agree with "Charles Darwin" when he stated that all of the animals that man has domesticated and their original ancestral origin will remain "vague", because with the wolves are the direct ancestor to the dogs. Plus, there are also wild horses in the southwestern part of the U.S.A. that for the most part are in their "aboriginal" state and therefore they are ancestors to some of our race horses. Even over time the phenotypes of animals or plants may change and most of the genotypes may have been lost from the original F1 generation, but not all genotypes because of mitochondrial DNA will still exist. Natural Selection will weed out some of the bad genotypes and the organisms will pass on the best traits for survival to their progeny. But, this too is only seen in their phenotypes and not in their genotypes. "Dawkin" notes that to be "stable is to be like an atom," and that mutations of genes through many generations of a species life may cause the organism to become more "fit." Ecology in human beings "hunter-and-gather" time period may have led to the domestication of the wolf because the people did not have any place to put their food and, therefore it became an easy meal for the wolves. So over time the human and wolf would become more acquainted with one another and less afraid too that perhaps started the domestication of the dog.
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I like your explanation of ecology having the effect on domestication utilizing different ideas than were shared in the class.
ReplyDeleteThank you Amanda Ashton,
ReplyDeleteBack in our aboriginal state of Homo sapiens we surely didn't know what a trash can was?
Suzanne
Yeah I guess I can see where your coming from with your response, but I still think that DNA alone does not explain evey thing. I think there is more to it, but thats just me
ReplyDeleteSamantha you are absolutely right that there is more than DNA alone but this technology can trace mitrochondrial DNA that only the mothers pass on and never leaves the cells.
ReplyDeleteSuzanne
Week # 2 Blog:
ReplyDeleteDawkins states that the first "replicators" were made possibly from molecules that may have been created coincidently, and the "replicator" also learned how to clone itself into many more "replicators"(Dawkins, Richard, 1976-1999, p. 15). Dawkins also notes that it isn't hard to believe that a simple molecule from the "Primevil Soup" theory could become the first start of "living" things, because molecules are consistent in their matter (Dawkins, Richard, 1976-1999, p. 15). Dawkin's states too, that after many clones of the first "replicator" that perhaps more complex molecules were further added(Dawkins, Richard, 1976-1999, p. 15). Dawkins also suggests that "Natural Selection" kept the best "replicators" and the others went extinct, and as a result, the best "survival machines"(Dawkins, Richard, 1976-1999, p. 19). The author, Richard Dawkins stated that the "replicators" became the blueprints for "life" and that DNA is responsible for the more complex-organisms-humans(Dawkins, Richard, 1976-1999, p. 21). There are so many different combinations that occur during either mitosis or meiosis with DNA; that it's like a lottery of what genotypes any "organism" may inherit. Plus how new species evolved and emerged with crossing-over and "Natural Selection" makes better species(My Own Words). In comparison, author, Peter Mayhew states that from the very first organized molecule that led to "life" went through many baby-steps over evolutionary time, and made several modifications, too(Mayhew, Peter, 2006, 2009, pp. 14, 15). Mayhew also notes that over time that the "living" cell became more complex and thus led to "multicellular" organisms"(Mayhew, Peter, 2006,2009, p. 15). I beleive that peter Mayhew's theory is more probable but not by very much compared to Richard Dawkins theory of the first "replicators." Autotrophic life I believe is the first recipients from the first mollecular cell because they are the "primary producers" on our planet. With the creation of autotrophic "life" (plants), the primitive "cell-of-life", thus became more complex over evolutionary time to create animals that eat the autotrophs. Both Autotrophs and heterotrophs mutually benefit from each other in everu aspect of their "life histories."
The evolutionary stability stragety is used in evolution to make sure that deleterious genes wil either better the organism or cause the organism population to die-out. In either case, sexual organisms versus asexual organisms are better equipped with having to haploid sex cells that fuse in order to stablize the future progeny and hopefully try to delete or find a use for the mutation in other generations to come. Whereas, asexual reproduction is cloning oneself over and over again and the mutations can cause devastating affects on the whole species and can cause extinction. "Fisher" beleives that the 50/50 ratio of female to male offspring's are a stable evolutionary trait in order for the survival of the species to try to balance the sexes can stop many more mutations that may affect one sex or the other. Plus, "Fisher" notes that female chromosomes carry more deletrious mutations than male chromosome of Y and therefore, can be passed on to more offspring's fvia the mother than the father. Equality is a neccessary ESS strategy in evolution for any species that are not asexual and to have recombination of gene flow to keep species' evolving against harmful mutations. Mitochondria DNA exists in all cells of an organism via its ancesteral mother and is neccessary for protein synthesis in organisms and also for the cytoplasmic cell to carry out instructions for replication of DNA in both the sex cells and autosomal cells, too. Mitochrodian DNA is like a blueprint for cells and without it the organisms would not evolve properly in gamete fusion.
ReplyDeleteSo I am guessing that you believe every single one favors the 50:50 sex ratio?
ReplyDeleteJacqui,
ReplyDeleteNo I don't beleive that evolution favors the 50:50 ratio at all but rather that "Natural Selection" in diploid organisms that may acquire a harmful mutation is less dangerous for the species compared to an "asexual" organism that clones itself over and over again and the ESS in ecological terms tries to maintain an equal balance between the sexes, so that there isn't an overpopulation of more males to females or visa versa. Mayhew points this out as well that the 50:50 ratio is fairly constant over evolutionary time in most species; but he also states that some herbaceous plants will favor more female organ parts on a monoecious plant over male parts because their ratio is higher on some plants to female parts.
Asexual reproduction does seem to be more dangerous then sexual reproduction however don't you think by having asexual organisms in the enviornment it helps stabilize the ESS?
ReplyDeleteK. Carter,
ReplyDeleteOh absolutely asexual organisms are definitely needed because they help alleviate some viruses and other mutations that may well spread into the sexual populations. In addition, some microbe species are beneficial for the communities as a whole; and without them it may lead to disatorous outcomes for all living organisms.
Week 6, Blog: Natural Selection and Sexual Selection:
ReplyDeleteDarwin states that Natural Selection is to make future generations "more fit" than the previous generations "in character and color may have better reproductive outcomes for the organism" (Darwin, The Origin of the Species, p. 92). This can either contribute to "Sexual Selection" by either female or male preferences (Natural Selection) in order for the trait that either sex prefers to mate with, and thus pass on the "good genes" hypothesis as a ESS. But, there will still be some species that do not possess the ideal character of female or male choice in "Sexual Selection" and may not recieve the same amount of copulations compared to its more attractive counterparts. There is always a cost that incurs to the "sexier" male or female species, which is easier detection from a predator, and rivalry form other members of its species. So, perhaps the less attractive organism in the long run survives to reproduce, and not be as prone to predation like the more attractive organisms. Plus, females may be choosier in their preference for mating with a male due to parental investment, territory, and parasitic load. Dawkin's states that "Trivers" hypothesis is that in Sexual Selection in females may also occur before any copulations are given by the female to the male in bird species, until he has shown what type of nest that he can build (Dawkins, p. 150). Sperm competition can also be either an ESS strategy as in spiders or birds that the male can either stay plugged to the female during copulation to keep other males away or wash away the previous male's sperm to ensure that he is the paternal father.
Very good entry. How come you keep post your entrys at comments though? The explaination of both sexual and natural selection was very clear.
ReplyDeleteK Carter,
ReplyDeleteBecause I don't know what I am doing and Guadelupe is going to help me change it; and I have tried to get help from my computer geek husband, but he has been to bogged down with his studies to help me rearrange this site. Sorry, Suzanne
I do agree with you that the more unattractive organism do live longer. Such as plants with brighter colors attract more predation and so do other animals. But also, concerning sexual selection an organism wants their mate to have the best genes as possible.
ReplyDelete