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Tytuł:
Hipotezy o powstaniu i wczesnej ewolucji życia
Hypotheses about the origin and early evolution of life
Autorzy:
Weiner, January
Wydawca:
Polskie Towarzystwo Przyrodników im. Kopernika
Powiązania:
https://bibliotekanauki.pl/articles/1196076.pdf  Link otwiera się w nowym oknie
Opis:
The current status of the research concerning the origin and early evolution of life on Earth is discussed. In contrast to popular opinion, Charles Darwin never speculated about the origin of life on Earth and regarded such attempts as hopeless. However, nowadays the topic is studied intensively and during recent decades several important results have been obtained. New geological data reveal that Earth became habitable as early as 4.4 billions years before present; indeed, the first biogeochemical and paleontological findings indicate for some advanced biological activity already 3.8-3.5 billions years before now. Phylogenomic analyses allowed to envisage the last common universal ancestor (LUCA) of all extant organisms as a population of microorganisms engaged in horizontal gene transfer, not later than some 2 billions years ago. Two major theoretical scenarios of life origin and early evolution are being currently developed and their predictions experimentally tested: (1) "cool primeval soup" or "heterotrophic" theory, rooted in Oparin-Haldane hypothesis and in early experiments by S.L. Miller, proposing that life has developed in slightly reducing atmosphere and ocean, originally utilizing the deposits of organic matter which was produced in some abiotic processes; (2) "hot pizza" or "autotrophic" theory postulates that life originated at hydrothermal vents, from the very beginning exploiting autotrophically mineral substrates and redox potential. Neither of the theories suffices to explain how large macromolecules capable of self-replication and metabolism developed, although the next step of early life evolution, the "RNA world" seems to be better supported experimentally, including a successful synthesis, in "prebiotic" conditions, an active pirymidyne nucleotide, a functioning artificial protocell, and an autocatalytic rybosyme system capable of exponential growth and evolution. Yet, it is still poorly understood how the alleged RNA world could possibly evolve into the "DNA-protein world".
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zmiany różnorodności biosfery: dawniej, dziś, jutro
Changing biodiversity: formerly, today, tomorrow
Autorzy:
Weiner, January
Tematy:
bioróżnorodność
Wielkie Wymierania
ewolucja
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:
https://bibliotekanauki.pl/articles/55995927.pdf  Link otwiera się w nowym oknie
Opis:
Life on Earth is a process carried out by billions of organisms belonging to a huge number of species. From the beginning of life to the present day, the number of species steadily increases, but the process is interrupted by deep crises (“Great Extinctions”) as the number of species rapidly declines. However, after a relatively short period of time – millions of years – the number of species returns to their previous heights and continues to rise until the next catastrophe. When the species Homo sapiens appeared on Earth, it found the greatest biotic diversity in the history of the Earth, but in a very short time – after its rapid population growth – the diversity began to decline again. Are we witnessing the beginning of another great extinction? If so, what would be the consequences for those species that survive? Is Homo sapiens also endangered? And life on Earth? Questions easy to ask, but difficult to answer.
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 67

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