Question

A Tree of Life could be thought of as

A) a biological filing system for the facts of diversity, a catalogue constructed through classification and systematics;

B) An evolutionary model of descent with modification through natural selection, the process of species diversification;

C) the outcome of diversification, environmental change, chance and extinction. In a page, develop

A) the idea and limitations of classification ; in a second paragraph briefly describe how the process of

B) is represented by Cladistic phylogenies ; and in a third paragraph, the importance of extinction and chance in 'provisionally true’ phylogenies, when modelling the nature of animal evolution - for example .

Answer 1

1. Idea and limitations of classification: The idea behind classification of animals and plants is to divide them on the basis of different traits found in them. If we discuss about animal classifiaction in which animals are distinguished on the basis of their body organisation, symmetry, nature of coelom, body segmentation and the mode of reproduction. Limitation- the differentiation of some animals into different classes is not justified as they might be same in all their feature but belong to different classes as in dogs and wolves, Horses and donkeys.
2. Cladistic phylogeny is an approach where the organisms are being differentiated on the basis of their most common recent ancestor. In this approach cladograms are made that focus on the macro, molecular and genetic level of evolution and how that is favoured with natural selection. By this approach we can find out how we are related to unicellular organisms that ocurred before is and the first ones to live on this planet. It also help to find out how we are related to aquatic animals.
3. Importance of extinction is that it opens door for new species to evolve and settle down in an environment free from competition and having a large number of vacant niches. Importance of chance in evolution is that it is something random and unpredictable that lead a species evolution into the present stable form. Chance favours natural selection and evolution as per Darwin's theory but this chance factor is beyond description.