Phylogenetic tree - in 1866, Ernst Haeckel introduced the phylogenetic tree, or the tree of life. Until now, the theory about the existence of tree of life is still strong in most people thought. But in fact, is this the phylogenetic tree really exist? If
Name: Tran Ngoc Thuy Linh Foundation Certificate in Biomedical Sciences Foundation Certificate in Biomedical sciences
Fin number: G0930004Q Bioinformatics essay
Batch code: FUBDO 1015A Universal phylogenetic tree
Universal phylogenetic tree
In 1859, when Darwin published his most famous book: Origin of Life, it started the era of the theory of evolution. As we know, Darwinism proposes that all species of life have descended over time from common ancestors, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called NATURAL SELECTION. According to that theory, life developed from a single common ancestor and evolved gradually into a multitude of different species through the chain of small changes under the varying environment condition. That means the differences between species and the increasing complexity in the organism must occur in parallel over time. In short, life must be like a tree, with a common root and then split into many different branches. Thus, in 1866, Ernst Haeckel introduced the phylogenetic tree, or the tree of life. Until now, the theory about the existence of tree of life is still strong in most people thought. But in fact, is this the phylogenetic tree really exist? If not, is Darwin wrong?
The key point for the theory of the tree of life is homology. In 1848, Richard Owen introduce the term Homology to refer the structural similarities between two species that is not functionally necessary. According to Darwin, there are the structural similarities between species because they had all descended from their common ancestor. In the theory of evolution of Darwin, there are three conclusions:
- Natural Selection ultimately produces evolution
- The vast varieties of living creatures are a natural outgrowth of the vast ways to live within the environment, or niche that organisms can occupy.
- A species ability to adapt is the essence of evolution.
Overall, based on the Theory of Evolution, all species these days are evolved from only on species which is the root in the Tree of Life. Throughout over time, this ancestor evolved to many, many species with different time and environment conditions. Thus, the number of species would increase follow the geometric progression and between two branches of tree (in horizontal) should not have very close relative. However, life is not easy like we thought. The founding of the true about Cambrian periods was changing everything.
The history of life in the Earth started by the Precambrian Time (4500 – 543 million years ago) then come to the Phanerozoic Eon (543 million years ago to present). In the Cambrian periods (543 – 490 million years ago) in the Paleozoic Era in Phanerozoic Eon, there was an events called “Cambrian Explosion” (about 20 – 40 million years in the lower Cambrian Period) which marked an important point in the history of life because this was the time when first appearance of complex sediment-penetrating trace fossils (form of animal trails and markings are described from rocks as old as 600 Ma and these constitute the unequivocal Palaeontological evidence for earliest metazoan life) were founded. The term Cambrian Explosion describes the geologically sudden appearance of multi-cellular animals in the fossil record during the Cambrian period of geologic time. By the close of this event, as many as forty-one separate phyla first made their appearance on earth. All the branches of animals appear in a given state complete picture and all at once, in a very short period of time. The Cambrian period appeared in a geologically sudden manner also implies the absence of clear transitional intermediates connecting the complex. Indeed, in almost all cases, the body plans and structures present in Cambrian period animals have no clear morphological antecedents in earlier strata. Moreover, as we can see, in the period before the Cambrian have three branches in various protozoans. But in the Cambrian, about 60 to 100 branches in different animals appeared abruptly. In the period later, some sectors have become extinct, and only a handful has survived until our times. That means the number of species does not increase like Darwinians, conversely, after the Cambrian Explosion, many species are extinct.
