Evolutionary tree of life

Proteins serving the same function in different species may have different primary structures. The extent of the differences is a measure of their relatedness on the evolutionary tree of life. 

Fig. 32.2. Modern evolutionary tree of life. The view is based on Refs. [3] and [4]. For a more detailed view of fungi see Ref. [5].

The discovery of extreme environments and studies of extremophiles not only offered important insights into biology and evolution but also provided clues to extraterrestrial life since these microorganisms are widely accepted to represent the earliest forms of life. Moreover, taxonomic studies on extremophilic microorganisms enabled Archaea to find its place as the third domain in the evolutionary tree of life [54, 61],... 

With these fundamental aspects of water-micromolecule macromolecule interactions as a background, we now are prepared to analyze why evolutionary processes have led to the generation of the particular types of cellular solutions we find among the three major domains of the tree of life. This analysis will emphasize especially well the principle of unity in diversity that serves as a central theme of this volume. 

Figure 1.8. The Tree of Life. A possible evolutionary path from a common ancestral cell to the diverse species present in the modem world can be deduced from DNA sequence analysis.

F.S. Lawson, R.L. Charlebois, and J.A. Dillon. 1996. Phylogenetic analysis of carbamoylphosphate synthetase genes Complex evolutionary history includes an internal duplication within a gene which can root the tree of life Mol. Biol. Evol. 13 970-977. (PubMed)... 

Figure 1.3 The tree of life. A possible evolutionary path from a common ancestor approximately 3.5 billion years ago at the bottom of the tree to organisms found in the modern world at the top.

Although the rRNA tree of life is able to place organisms broadly into their correct relative positions, it does not have a reliable inbuilt clock (Graur. Martin, 2004), and so, until recently the timing of events on the tree of life has been poorly known. In a recent review Shen and Buick (2004) used fossil, rather than molecular evidence to place some initial time constraints on the evolutionary appearance of the Archaea, Bacteria and Eucarya (Fig. 6.6). 

It was the analysis of the 16S rRNAs that first revealed the unique evolutionary position of the archaebacteria, and defined the primary evolutionary divisions of life on this planet (4,6). Figure 1 shows an unrooted phylogenetic tree based upon complete 16S rRNA sequences of representatives of the three primary lines of evolutionary descent the archaebacteria, the eubacteria and the eukaryotes. Within these primary lines of descent other major lines of descent have been delineated. Within the eubacteria, for example, some ten major divisions are now recognized. It has been suggested that these be given a systematic rank equivalent to phylum (12). However, this chapter will not elaborate upon the emerging phylogenetic description of life on this planet. The reader is referred to a recent review for a dedicated treatment of this subject (4,12). 

Fig. 1.5 Evolutionary relationship of organisms based on rRNA sequence comparisons, with division of the tree of life into three fundamental domains Bacteria (or eubacteria),Archaea (or archaebacteria) and Eukarya (or eukaryotes) (afterWoese et al.

In conclusion, we can state that alkaloids are present in the eross-evolutionary tree of the organisms on our globe. Alkaloids therefore can be considered as chemical factors in the diversified life of the species. Moreover, these compounds diversify clearly the behavior of the species, which is extremely important from the evolutionary point of view. Alkaloids save the lives of many species. Moreover, they protect the life of many adult and young animal individuals and participate in the cross-competition of the species in the balance of life. Biological nature protects itself by molecular exchange, signaling, and reproduction. Alkaloids are in all these processes. 

The much Debated Tree of Life was set into three domains by Ernst Haeckel Monophyletischer Stammbaum der Organismen consisting of Protista, Plantae and AnimaUa. Extraordinary acquisition of genes through horizontal (lateral) routes invalidates the evolutionary pathways that were constmcted by tme vertical inheritance. Among Bacteria, Mycoplasmataceae vie with Aquifex aeolicus for the basic position regression of Mycoplasmataceae from Bacteroides is unacceptable... 

Tracing the early evolutionary diversification of the angiosperm flower, pp. 85-117 in Wanntrop, L., Ronse De Craene, (eds.). Flowers on the Tree of Life. Cambridge Cambridge University Press. 

Nature evolved a Umited number of photoreceptive molecules in the different evolutionary branches of the tree of life because of the closely similar needs of organisms to detect the external world. Two photoreceptor molecules are considered as underlying vision in microalgae rhodopsins and flavins. 

FIGURE 1-4 Phylogeny of the three domains of life. Phylogenetic relationships are often illustrated by a "family tree of this type. The fewer the branch points between any two organisms, the closer is their evolutionary relationship. 

As surely as intermediates between species are nonexistent, the intermediates between the primary ovum and the first stable fossilized creature are there for us to discover. They will be in the same horizon, only a few thousand years or less apart. Figure 12.3 gives the impression that all species had been washed into the present by a powerful wave so that the times of arrival are only minutely different. The time axis gives one a realistic impression of the awesome speed of appearance of species when compared to the total time of life on earth. The whole colorful world of anthropology that reverberates from fierce battles over what is a common ancestor, what limb should be attached where on which evolutionary tree, all of that fits into a little more than the width... 

As the tree shows, the true relatives of the archaea are not the bacteria but the eukaryotes. However, because the archaea branch-off closest to the root of the tree, the suggestion is that they are the most primitive of the three kingdoms of organisms whereas the eukaryotes are the least primitive (or the most derived). Placement of the archaea closest to the universal ancestor is supported by the fact that many archaea inhabit extreme environments involving high temperature, low pH, high salinity, and so on. Thus, archaea may well be evolutionary relics of the Earth s earliest forms of life. 

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