Complicated Biological Evolution:

Discussion in 'Biology & Genetics' started by paddoboy, Apr 22, 2020.

  1. paddoboy Valued Senior Member

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    https://phys.org/news/2020-04-reveals-life-earliest-evolution-complicated.html

    New study reveals life's earliest evolution was more complicated than previously suspected:

    Biologists have long hoped to understand the nature of the earliest living organisms on Earth. If they could, they might then be able to say something about how, when, and where life arose on Earth, and perhaps by extension, whether life is common in the Universe.

    Previous studies have suggested this information can be obtained by comparing the genes present in modern organisms. New research indicates that only limited information can be derived using this approach.

    Biologists classify all living organisms into three major groups they call 'domains.' Two of these domains—the Bacteria and the Archaebacteria—consist of single-celled organisms, while the third—the Eukaryota—includes most of the larger, multicellular organisms we are all familiar with: fungi, plants and animals including ourselves. Of the three domains, the Eukaryota almost certainly evolved the most recently, but questions remain about which of the two single-celled domains arose first in the history of life.

    Over forty years ago, American biologists Carl Woese and George Fox suggested that these two domains both emerged from a more primitive organism or group of organisms scientists now call LUCA, or the Last Universal Common Ancestor. Scientists would love to be able to say something concrete about what LUCA was like, what types of environment it lived in, and how it made its living.
    more at link.....

    the paper:
    https://academic.oup.com/mbe/article/doi/10.1093/molbev/msaa089/5818498


    Abstract
    Comparative genomics and molecular phylogenetics are foundational for understanding biological evolution. Although many studies have been made with the aim of understanding the genomic contents of early life, uncertainty remains. A study by Weiss et al. (2016) identified a number of protein families in the last universal common ancestor of archaea and bacteria (LUCA) which were not found in previous works. Here we report new research that suggests the clustering approaches used in this previous study under-sampled protein families, resulting in incomplete phylogenetic trees which do not reflect protein family evolution. Phylogenetic analysis of protein families which include more sequence homologs rejects a simple LUCA hypothesis based on phylogenetic separation of the bacterial and archaeal domains for a majority of the previously identified LUCA proteins (∼82%). To supplement limitations of phylogenetic inference derived from incompletely populated orthologous groups, and to test the hypothesis of a period of rapid evolution preceding the separation of the domains, we compared phylogenetic distances both within, and between domains, for thousands of orthologous groups. We find a substantial diversity of interdomain vs. intradomain branch lengths, even among protein families which exhibit a single domain separating branch and are thought to be associated with the LUCA. Additionally, phylogenetic trees with long interdomain branches relative to intradomain branches are enriched in information categories of protein families in comparison to those associated with metabolic functions. These results provide a new view of protein family evolution, and temper claims about the phenotype and habitat of the LUCA.
     
    Write4U likes this.
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  3. Xelasnave.1947 Valued Senior Member

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    Great stuff.
    Only three days ago I was chatting with my daughter ( the rational one) and she was saying LUCA and I had to stop her and ask....
    She will enjoy reading this.
    Alex
     
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  5. Write4U Valued Senior Member

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  7. Zeno Registered Senior Member

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    Compare genomes and molecules of separately created species and use SpongeBob imagination.
     
  8. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Do you accept the mission?

    The mission, if you choose to accept, provide a improved explanation

    Throw away your equipment it will destroy itself in 10 seconds

    OK it won't, and I doubt you have a improved explanation

    Please Register or Log in to view the hidden image!

     
    exchemist likes this.
  9. Write4U Valued Senior Member

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    They do not come from separately created species, At the very basic level, all living things are made up from about 500 different chemicals most of them abundant in the earth's ecosphere. But also not all at the same place. Compatibility is dependent on proximity.
    https://en.wikipedia.org/wiki/Large_number_of_rare_events

    It is possible there may be different sites of origin at that level of bio-chemical evolution, but it is a proven fact that at the more complex levels, genomes and molecules usually are not compatible except at the most fundamental level. It is unlikely that the DNA from a deep ocean dweller like octopus is at all compatible with DNA from land dwellers. Their environments are alien to each other. Their inhabitants are the result of evolution in an alien living medium such as water and air or extreme pressures.

    An octopus has blue blood
    https://globalquiz.org/en/question/what-color-is-octopus-blood/

    It's obvious that the DNA of this species of slug is of little use to a say, a chicken's DNA
     
    Last edited: Apr 23, 2020
  10. billvon Valued Senior Member

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    There are no "separately created species." We can trace our origins all the way back to the first life.
     
  11. Write4U Valued Senior Member

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    I agree, but I believe Robert Hazen proposes that conditions with similar of bio-chemistry might have existed in several locations, i.e. a basic formula of some abundant biochemicals. About half of all known minerals can be found in just 5 locations. The earth's chemistry seems fairly well evenly distributed.

     

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